Reduction Of Acetylcholine Research Articles

Voluntary wheel running exercise rescues behaviorally-evoked acetylcholine efflux in the medial prefrontal cortex and epigenetic changes in ChAT genes following adolescent intermittent ethanol exposure.

Adolescent intermittent ethanol (AIE) exposure, which models heavy binge ethanol intake in adolescence, leads to a variety of deficits that persist into adulthood-including suppression of the cholinergic neuron phenotype within the basal forebrain. This is accompanied by a reduction in acetylcholine (ACh) tone in the medial prefrontal cortex (mPFC). Voluntary wheel running exercise (VEx) has been shown to rescue AIE-induced suppression of the cholinergic phenotype. Therefore, the goal of the current study is to determine if VEx will also rescue ACh efflux in the mPFC during spontaneous alternation, attention set shifting performance, and epigenetic silencing of the cholinergic phenotype following AIE. Male and female rats were subjected to 16 intragastric gavages of 20% ethanol or tap water on a two-day on/two-day off schedule from postnatal day (PD) 25-54, before being assigned to either VEx or stationary control groups. In Experiment 1, rats were tested on a four-arm spontaneous alternation maze with concurrent in vivo microdialysis for ACh in the mPFC. An operant attention set-shifting task was used to measure changes in cognitive and behavioral flexibility. In Experiment 2, a ChIP analysis of choline acetyltransferase (ChAT) genes was performed on basal forebrain tissue. It was found that VEx increased ACh efflux in the mPFC in both AIE and control male and female rats, as well as rescued the AIE-induced epigenetic methylation changes selectively at the Chat promoter CpG island across sexes. Overall, these data support the restorative effects of exercise on damage to the cholinergic projections to the mPFC and demonstrate the plasticity of cholinergic system for recovery after alcohol induced brain damage.

High Intensity Interval Exercise Causes Acute Microvascular Dysfunction in Elderly Individuals with Low Cardiorespiratory Fitness - A Pilot Study

Background: Frailty is strongly associated with low physical and cardiorespiratory fitness, and unfortunately is observed in 20-50% of the ~50 million adults that experience surgical stress in the U.S. each year. The peripheral microvasculature may serve as a potential target to increase resilience to stress and improve postoperative outcomes. A better understanding of how the microvasculature responds to stress in elderly individuals with low fitness is thus needed. Objective: To define the relationship between cardiorespiratory fitness and microvascular resiliency to stress in elderly individuals. Hypothesis: Elderly individuals with low cardiorespiratory fitness will show acute reductions in acetylcholine (Ach)-mediated dilation of the skin microvasculature following the physiological stressful stimulus of high intensity interval exercise (HIIE). Methods: This was a prospective, observational study that enrolled elderly individuals aged 65-85 years from the community. Each participant was asked to complete two study visits. During visit 1, participants completed the Frailty Index and performed a graded cardiopulmonary exercise test (CPET) on a cycle ergometer with a metabolic cart to measure peak total body oxygen consumption (VO2 Peak). During visit 2, laser Doppler flowmetry with dermal microdialysis was performed on the ventral forearm to measure peak cutaneous microvascular vasodilation to Ach (10 mM). After baseline assessment, the participants performed a HIIE protocol where they repetitively switched between exercising at 70% of the peak workload achieved during the CPET for 60 seconds, followed by a 60 second active recovery at 10 watts. These intervals were repeated 12 times, for a total exercise duration of 24 min. Thirty minutes following exercise, Ach-mediated dilation of the cutaneous microvasculature was reassessed. Maximum dilator capacity of each site was assessed by infusing sodium nitroprusside (28 mM) and heating the skin to 43 °C. Results: Six individuals (1 male, 5 females; mean age 68 ±4 years) completed all study procedures. Based on age- and sex-predicted normative values for VO2 Max, three of the individuals had high physical fitness while three had low fitness (mean VO2 Peak = 27.5±1.1 vs. 13.6±3.4 ml/kg/min, respectively). Prior to HIIE there was no difference in peak dilation to Ach between the individuals with high vs. low fitness (% max dilation = 72±13 vs. 83±13, respectively). During HIIE, the individuals reached a Borg rating of perceived exertion of 15±4 (out of 20) and their peak heart rate was 74±15% of their age-predicted maximum. Ach-mediated dilation of the dermal microvasculature was reduced following HIIE in elderly individuals with low cardiorespiratory fitness (pre vs. post % maximum dilation = 82±13 vs. 49±27, respectively; mean change = -34±40 %) but unchanged in those with high fitness (pre vs. post % maximum dilation = 72±13 vs. 78±10, respectively; mean change = 5±3 %). Using Pearson correlation tests there was a strong correlation between the change in peak Ach-mediated dilation pre vs. post HIIE and both VO2 Peak (r=0.82, p=0.04) and Frailty Index score (r=-0.98, p<0.001). Conclusion: Microvascular resilience to acute stress is decreased in elderly individuals with low cardiorespiratory fitness compared to those with high fitness. None. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

An adenoviral vector encoded with the GPx-1 gene attenuates memory impairments induced by β-amyloid (1-42) in GPx-1 KO mice via activation of M1 mAChR-mediated signalling

In the present study, we examined whether glutathione peroxidase-1 (GPx-1), a major H2O2 scavenger in the brain, affects memory deficits induced by Aβ (1-42) in mice. Treatment with 400 pmol/5 μl Aβ (1-42) (i.c.v.) resulted in a reduction of GPx-1 expression in wild-type (WT) mice. An Aβ (1-42)-induced reduction in acetylcholine (ACh) level was observed in the hippocampus. Treatment with Aβ (1-42) consistently resulted in reduced expression and activity of choline acetyltransferase (ChAT) and in an increase in expression and activity of acetylcholinesterase (AChE). Upon examining each of the muscarinic acetylcholine receptors (mAChRs) and nicotinic AChRs, we noted that Aβ (1-42) treatment selectively reduced the levels of M1 mAChR. In addition, Aβ (1-42) induced a significant reduction in phospho-cAMP response element-binding protein (p-CREB) and brain-derived neurotrophic factor (BDNF) expression. The cholinergic impairments induced by Aβ (1-42) were more pronounced in GPx-1 knockout mice than in WT mice. Importantly, an adenoviral vector encoded with the GPx-1 gene (Ad-GPx-1) significantly rescued Aβ (1-42)-induced cholinergic impairments in GPx-1 knockout mice. In addition, M1 mAChR antagonist dicyclomine significantly counteracted Ad-GPx-1-mediated increases in p-CREB and BDNF expression, as well as memory-enhancing effects in GPx-1 knockout mice, thus indicating that M1 mAChR might be a critical mediator for the rescue effects of Ad-GPx-1. Combined, our results suggest that GPx-1 gene protected against Aβ (1-42)-induced memory impairments via activation of M1 mAChR-dependent CREB/BDNF signalling.

Interactions of Antibodies to the Gram-Negative Gastric Bacterium Helicobacter pylori with the Synaptic Calcium Sensor Synaptotagmin 5, Correlate to Impaired Vesicle Recycling in SiMa Human Neuroblastoma Cells

Due to molecular mimicry, maternal antibacterial antibodies are suspected to promote neurodevelopmental changes in the offspring that finally can cause disorders like autism and schizophrenia. Using a human first trimester prenatal brain multiprotein array (MPA), we demonstrate here that antibodies to the digestive tract bacteria Helicobacter pylori (α-HPy) and Campylobacter jejuni (α-CJe) interact with different synaptic proteins, including the calcium sensor synaptotagmin 5 (Syt5). Interactions of both antisera with Syt5 were confirmed by Western blot with a HEK293-cells overexpression lysate of this protein. Immunofluorescence and Western blotting revealed SiMa cells to express Syt5, which also co-migrated with a band/spot labeled by either α-HPy or α-CJe. Functionally, a 12-h pretreatment of SiMa cells with 10 μg/ml of either α-HPy or α-CJe resulted in a significant reduction of acetylcholine(ACh)-dependent calcium signals as compared to controls. Also ACh-dependent vesicle recycling was significantly reduced in cells pretreated with either α-HPy or α-CJe. Similar effects were observed upon pretreatment of SiMa cells with Syt5-specific antibodies. In conclusion, the present study supports the view that prenatal maternal antibacterial immune responses towards HPy and by this to Syt5 are able to cause functional changes, which in the end might contribute also to neurodevelopmental disorders.

Electrophysiological Alterations of Pyramidal Cells and Interneurons of the CA1 Region of the Hippocampus in a Novel Mouse Model of Dravet Syndrome.

Dravet syndrome is a developmental epileptic encephalopathy caused by pathogenic variation in SCN1A To characterize the pathogenic substitution (p.H939R) of a local individual with Dravet syndrome, fibroblast cells from the individual were reprogrammed to pluripotent stem cells and differentiated into neurons. Sodium currents of these neurons were compared with healthy control induced neurons. A novel Scn1aH939R/+ mouse model was generated with the p.H939R substitution. Immunohistochemistry and electrophysiological experiments were performed on hippocampal slices of Scn1aH939R/+ mice. We found that the sodium currents recorded in the proband-induced neurons were significantly smaller and slower compared to wild type (WT). The resting membrane potential and spike amplitude were significantly depolarized in the proband-induced neurons. Similar differences in resting membrane potential and spike amplitude were observed in the interneurons of the hippocampus of Scn1aH939R/+ mice. The Scn1aH939R/+ mice showed the characteristic features of a Dravet-like phenotype: increased mortality and both spontaneous and heat-induced seizures. Immunohistochemistry showed a reduction in amount of parvalbumin and vesicular acetylcholine transporter in the hippocampus of Scn1aH939R/+ compared to WT mice. Overall, these results underline hyper-excitability of the hippocampal CA1 circuit of this novel mouse model of Dravet syndrome which, under certain conditions, such as temperature, can trigger seizure activity. This hyper-excitability is due to the altered electrophysiological properties of pyramidal neurons and interneurons which are caused by the dysfunction of the sodium channel bearing the p.H939R substitution. This novel Dravet syndrome model also highlights the reduction in acetylcholine and the contribution of pyramidal cells, in addition to interneurons, to network hyper-excitability.

Ginseng berry aqueous extract prevents scopolamine-induced memory impairment in mice.

Ginseng berry exhibits a diverse range of pharmacological activities. The present study aimed to examine the neuroprotective effects of ginseng berry aqueous extract (GBE) against oxidative stress and to assess the impact of GBE on memory impairment in mice. In HT-22 cells, GBE pretreatment significantly inhibited glutamate- and hydrogen peroxide-mediated cytotoxicity in a concentration-dependent manner, while treatment with up to 100 µg/ml GBE alone did not change cell viability. In a murine model of scopolamine (SCP)-induced memory impairment, results from the passive avoidance test and the Morris water maze test indicated that GBE administration for 4 weeks prolonged step-through latency time and shortened escape latency time, suggesting that GBE can attenuate deficits in long-term memory induced by SCP. Additionally, GBE prevented SCP-induced reductions in acetylcholine by decreasing acetylcholinesterase activity and upregulating choline acetyltransferase mRNA levels in the hippocampus. GBE mitigated SCP-mediated mRNA decreases in brain-derived neurotrophic factor levels and its associated signaling molecules. Furthermore, GBE administration significantly suppressed malondialdehyde production and increased glutathione levels, catalase activity and superoxide dismutase activity in SCP-induced memory impaired mice. Therefore, the results of the current study indicated that ginseng berry may be a potential candidate for treating or preventing memory deficits that are associated with neurodegenerative disorders.

Aversive Training Induces Both Presynaptic and Postsynaptic Suppression in Drosophila.

The α'β' subtype of Drosophila mushroom body neurons (MBn) is required for memory acquisition, consolidation and early memory retrieval after aversive olfactory conditioning. However, in vivo functional imaging studies have failed to detect an early forming memory trace in these neurons as reflected by an enhanced G-CaMP signal in response to presentation of the learned odor. Moreover, whether cellular memory traces form early after conditioning in the mushroom body output neurons (MBOn) downstream of the α'β' MBn remains unknown. Here, we show that aversive olfactory conditioning suppresses the calcium responses to the learned odor in both α'3 and α'2 axon segments of α'β' MBn and in the dendrites of α'3 MBOn immediately after conditioning using female flies. Notably, the cellular memory traces in both α'3 MBn and α'3 MBOn are short-lived and persist for <30 min. The suppressed response in α'3 MBn is accompanied by a reduction of acetylcholine (ACh) release, suggesting that the memory trace in postsynaptic α'3 MBOn may simply reflect the suppression in presynaptic α'3 MBn. Furthermore, we show that the α'3 MBn memory trace does not occur from the inhibition of GABAergic neurons via GABAA receptor activation. Because activation of the α'3 MBOn drives approach behavior of adult flies, our results demonstrate that aversive conditioning promotes avoidance behavior through suppression of the α'3 MBn-MBOn circuit.SIGNIFICANCE STATEMENTDrosophila learn to avoid an odor if that odor is repeatedly paired with electric shock. Mushroom body neurons (MBns) are known to be major cell types that mediate this form of aversive conditioning. Here we show that aversive conditioning causes a reduced response to the conditioned odor in an axon branch of one subtype of the MBn for no more than 30 min after conditioning, and in the dendrites of postsynaptic, MB output neurons (MBOns). Because experimenter-induced activation of the MBOn induces approach behavior by the fly, our data support a model that aversive learning promotes avoidance by suppressing the MBn-MBOn synapses that normally promote attraction.

Improving effects of Echium amoenum aqueous extract on rat model of Alzheimer'sdisease.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder greatly accompanied by oxidative stress and acetylcholine reduction in synaptic cleft that leads to dementia. Previously approved there is correlation between nucleus basalis of Meynert (NBM) degeneration and loss of memory, learning ability and thought. The aim of this study was to investigate improving effects of Echium amoenum aqueous extract on memory deficient, pathophysiological and oxidative damages imposed by NBM lesion in rats as documented AD model. Results showed NBM destruction causes hash oxidative stress that possibly leads to neurodegeneration in hippocampus tissue. Orally administration of plant extract significantly reduced oxidative stress by reactive molecules scavenging that resulted to decrease lipid peroxidation also. Plant extract treatment inhibited acetylcholine esterase enzyme (more than 5 folds) in hippocampus tissue related to NBM lesioned rats. Histological studies approved NBM lesion causes harsh neurodegeneration in hippocampus tissue possibly by acetylcholine reduction that was compensated by plant extract protective effects. Interestingly improving effects of plant in molecular level causes improved spatial learning ability in Morris water maze test. By considering pathophysiological and molecular similarities between AD and NBM lesion model, E. amoenum could be used as a therapeutic adjuvant in patients suffering from Alzheimer or similar cognitive disorders.

Cholinergic and adenosinergic systems exert a pro-inflammatory profile in peripheric and splenic lymphocytes of Rhamdia quelen experimentally infected by Aeromonas caviae

It has been recognized that the cholinergic and adenosinergic systems, through the enzymes acetylcholinesterase (AChE) and adenosine deaminase (ADA), exert an important role in the immune and inflammatory responses during bacterial fish diseases. The immune response against Aeromonas caviae remains poorly understood, and the involvement of these systems, through the anti-inflammatory molecules acetylcholine (ACh) and adenosine (Ado), has not been studied. Thus, the aim of this study was to evaluate the involvement of cholinergic and adenosinergic systems on the inflammatory and immune responses in peripheric and splenic lymphocytes of fish experimentally infected with A. caviae. AChE and ADA activities in peripheric and splenic lymphocytes increased in infected animals on day 4 post-infection compared to uninfected animals, while the ACh and Ado levels decreased. Moreover, spleen histopathology revealed an increase in the number of melano-macrophage centers, as well as lipid inclusions and cellular debris in the ellipsoids. This evidence indicates that infection by A. caviae alters the cholinergic and adenosinergic systems, suggesting the involvement of AChE and ADA activities in the impairment of the immune system, since infection leads to a reduction in ACh and Ado levels, respectively. In summary, the upregulation of AChE and ADA activities in peripheric and splenic lymphocytes exerts a pro-inflammatory profile, contributing to systemic and tissue inflammatory damage, and consequently to disease pathogenesis.

Nrf2 Activation Attenuates Hemolysis but Promotes Pulmonary Vascular Dysfunction in Sickle Mice

Nuclear factor erythroid 2-related factor 2 (Nrf2) is the major transcription factor that coordinates the body’s antioxidant and cytoprotective defense against a variety of toxins. Several Nrf2 activators can reactivate gamma globin gene expression and augment fetal hemoglobin production. More recently, genetic and pharmacologic evidence have shown that Nrf2 activation can specifically mitigate the severity of hemolytic anemia, and systemic and local inflammation in transgenic sickle cell disease (SCD) mice. Based on these encouraging results Nrf2 activation has emerged as an attractive therapeutic strategy in SCD. However, the BEACON trial of the Nrf2 activator CDDO-Methyl Ester (CDDO-Me) showed that this therapeutic approach can cause adverse cardiovascular events in patients with chronic kidney disease with comorbid diabetes. Hitherto, the efficacy-toxicity profile generated by individual Nrf2 activating drugs has not been investigated in SCD. There are hundreds of synthetic and naturally occurring Nrf2 activating compounds, and each class of Nrf2 activating compound has a unique pharmacokinetic, pharmacodynamic, toxicokinetic and toxicodynamic profile. We have recently demonstrated that intravascular hemolysis deteriorates with aging in transgenic sickle (SS) mice in a process that can be mitigated by the Nrf2 activator 3H-1,2-dithiole-3-thione (D3T) (Ghosh et al., JCI Insight, 2016). In this study, an in vitro screen of five Nrf2 activating compounds revealed CDDO-Me to be the most potent inducer of cytoprotective enzymes in human pulmonary microvascular endothelial cells. Thus, we performed a long-term prophylactic CDDO-Me treatment of SS mice and examined the effect of the drug on intravascular hemolysis and vascular dysfunction. A cohort of newly weaned SS mice aged ~4 weeks were randomly assigned to receive CDDO-Me (20µmoles/kg/TIW, n=6) or Vehicle (DMSO/TIW, n=10) by oral gavage for 4 months. After the treatment, the total hemoglobin increased by 10% in the CDDO-Me group while it decreased by 5% in the vehicle-treated group (p<0.05). Plasma concentration of VCAM-1 increased in both groups compared to their respective baseline (vehicle p<0.001; CDDO-Me p<0.05). The lack of impact on VCAM-1 by CDDO-Me was contrary to our results with D3T (Ghosh et al., JCI Insight, 2016). To examine this further, we performed vascular reactivity studies on isolated pulmonary arteries. Second order pulmonary arteries were isolated, cut into 2mm rings, and mounted using 40 μm wire. Rings were set at a resting tension equivalent to 100 mmHg transmural pressure. Cumulative dose response curves of endothelin-1 (100 pM-10 nM) and acetylcholine (10nM-100 μM) were used to study vasoconstriction and vasodilation, respectively. Pulmonary arteries isolated from the CDDO-Me treated SS mice showed a 15% reduction in acetylcholine stimulated vasodilation compared to the arteries isolated from the vehicle treated littermates (vehicle n=5, CDDO-Me n=5; p<0.001). In vitro studies of rat smooth muscle cells revealed significant up-regulation of endothelin receptor subtype A (ETA) mRNA by CDDO-Me (p < 0.01, n=6). We obtained similar results of increased ETA expression in rat smooth muscle cells treated with another Nrf2 activator, Dimethyl Fumarate (DMF) (p < 0.01, n=6). Upregulation of endothelin or the ETA is frequently found in pulmonary hypertension. The hypertensive phenotype that we report here in SS mice treated with CDDO-Me is consistent with the adverse cardiovascular events found in the BEACON trial. Together our results show that while CDDO-Me can stabilize and potentially improve hemolytic anemia in SCD, this drug and potentially other Nrf2 activators may promote the development of pulmonary hypertension, which is a major adult complication of SCD. DisclosuresNo relevant conflicts of interest to declare.

In vivo neurochemical evidence that delta1-, delta2- and mu2-opioid receptors, but not mu1-opioid receptors, inhibit acetylcholine efflux in the nucleus accumbens of freely moving rats

Cholinergic neurons in the nucleus accumbens express delta- and mu-opioid receptors that are thought to inhibit neural activity. Delta- and mu-opioid receptors are divided into delta1- and delta2-opioid receptors and mu1- and mu2-opioid receptors, respectively. We analysed the roles of delta- and mu-opioid receptor subtypes in regulating accumbal acetylcholine efflux of freely moving rats using in vivo microdialysis. Other than naloxonazine, given intraperitoneally, delta- and mu-opioid receptor ligands were administered intracerebrally through the dialysis probe. Doses of these compounds indicate total amount (mol) over an infusion time of 30–60min. To monitor basal acetylcholine, a low concentration of physostigmine (50nM) was added to the perfusate. The delta1-opioid receptor agonist DPDPE (3 and 300pmol) and delta2-opioid receptor agonist deltorphin II (3 and 30pmol) decreased accumbal acetylcholine in a dose-related manner. DPDPE (300pmol)- and deltorphin II (3pmol)-induced reductions in acetylcholine were each inhibited by the delta1-opioid receptor antagonist BNTX (0.3pmol) and delta2-opioid receptor antagonist naltriben (15pmol), respectively. The mu-opioid receptor agonists endomorphin-1 and endomorphin-2 (6 and 30nmol) decreased acetylcholine in a dose-related manner. Endomorphin-1- and endomorphin-2 (30nmol)-induced reductions in acetylcholine were prevented by the mu-opioid receptor antagonist CTOP (3nmol). The mu1-opioid receptor antagonist naloxonazine (15mg/kg ip), which inhibits endomorphin-1 (15nmol)-induced accumbal dopamine efflux, did not alter endomorphin-1- or endomorphin-2 (30nmol)-induced reductions in acetylcholine efflux. This study provides in vivo evidence for delta1-, delta2- and mu2-opioid receptors, but not mu1-opioid receptors, that inhibit accumbal cholinergic neural activity.

Simple New Method of Detecting Lies By Identifying Invisible Unique Physiological Reflex Response Appearing Often Less Than 10-15 Seconds on the Specific Parts of Face of Lying Person; Quick Screening of Potential Murderers &amp; Problematic Persons

Frequently, we cannot find any significant visible changes when somebody lies, but we found there are significant invisible changes appearing in specific areas of the face when somebody lies and their location often depends on whether the lie is serious with or without physical violence involvement. These abnormalities were detected non-invasively at areas: 1) lobules and c) a small round area of each upper lateral side of forehead; 2) the skin between the base of the 2 orifices of the nose and the upper end of upper lip and 3) Alae of both sides of nose. These invisible significant changes usually last less than 15 seconds after telling a lie. In these areas, Bi-Digital O-Ring Test (BDORT), which received a U.S. Patent in 1993, became significantly weak with an abnormal value of (-)7 and TXB2, measured non-invasively, was increased from 0.125-0.5ng to 12.5-15ng (within the first 5 seconds) and then went back down to less than 1ng (after 15 seconds). These unique changes can be documented semi-permanently by taking photographs of the face of people who tell a lie, within as short as 10 seconds after saying a lying statement. These abnormal responses appear in one or more of the above-mentioned 3 areas 1), 2) & 3). At least one abnormal pupil with BDORT of (-)8-(-)12 & marked reduction in Acetylcholine and abnormal increase in any of 3 Alzheimer's disease associated factors Apolipoprotein (Apo) E4, β-Amyloid (1-42), Tau protein, viral and bacterial infections were detected in both pupils and forehead of murderers and people who often have problems with others. Analysis of well-known typical examples of recent mass murderers was presented as examples. Using these findings, potential murderers and people who are very likely to develop problems with others can be screened within 5-10 minutes by examining their facial photographs and signatures before school admission or employment.

Stochastic cortical neurodynamics underlying the memory and cognitive changes in aging

The relatively random spiking times of individual neurons provide a source of noise in the brain. We show how this noise interacting with altered depth in the basins of attraction of networks involved in short-term memory, attention, and episodic memory provide an approach to understanding some of the cognitive changes in normal aging. The effects of the neurobiological changes in aging that are considered include reduced synaptic modification and maintenance during learning produced in part through reduced acetylcholine in normal aging, reduced dopamine which reduces NMDA-receptor mediated effects, reduced noradrenaline which increases cAMP and thus shunts excitatory synaptic inputs, and the effects of a reduction in acetylcholine in increasing spike frequency adaptation. Using integrate-and-fire simulations of an attractor network implementing memory recall and short-term memory, it is shown that all these changes associated with aging reduce the firing rates of the excitatory neurons, which in turn reduce the depth of the basins of attraction, resulting in a much decreased probability in maintaining in short-term memory what has been recalled from the attractor network. This stochastic dynamics approach opens up new ways to understand and potentially treat the effects of normal aging on memory and cognitive functions.

Rivastigmine for vascular cognitive impairment

Vascular dementia represents the second most common type of dementia after Alzheimer's disease. In older patients, in particular, the combination of vascular dementia and Alzheimer's disease is common, and is referred to as mixed dementia. The classification of vascular dementia broadly follows three clinico-pathological processes: multi-infarct dementia, single strategic infarct dementia and subcortical dementia. Not all victims fulfil strict criteria for dementia and may be significantly cognitively impaired without memory loss, when the term vascular cognitive impairment (VCI) is more useful. Currently, no established standard treatment for VCI exists. Reductions in acetylcholine and acetyltransferase activity are common to both Alzheimer's disease and VCI, raising the possibility that cholinesterase inhibitors - such as rivastigmine - which are beneficial in Alzheimer's disease, may also be beneficial for VCI. To assess the efficacy of rivastigmine compared with placebo in the treatment of people with vascular cognitive impairment (VCI), vascular dementia or mixed dementia. We searched ALOIS (the Cochrane Dementia and Cognitive Improvement Group's Specialized Register) on 12 February 2013 using the terms: rivastigmine, exelon, "SDZ ENA 713". ALOIS contains records of clinical trials identified from monthly searches of a number of major healthcare databases (The Cochrane Library, MEDLINE, EMBASE, CINAHL, PsycINFO, LILACS), numerous trial registries and grey literature sources. All unconfounded randomized double-blind trials comparing rivastigmine with placebo in the treatment of people with VCI, vascular dementia or mixed dementia were eligible for inclusion. Two reviewers extracted and assessed data independently, and agreement was reached after discussion. They noted results concerning adverse effects. Three trials, with a total of 800 participants, were identified for inclusion. The participants in one trial did not have dementia, while the other two studies included participants with dementia of different severities. The dose of rivastigmine was different in each study. No pooling of study results was attempted because of these differences between the studies.One trial included 40 participants with subcortical vascular dementia (age range 40 to 90 years) with a mean mini-mental state examination (MMSE) score of 13.0 and 13.4 in the rivastigmine and placebo arms, respectively. Treatment over 26 weeks was limited to 3 mg rivastigmine twice daily, or placebo. No significant difference was found on any outcome measure relevant to cognition, neuropsychiatric symptoms, function or global rating, or in the number of withdrawals before the end of treatment.Another trial included 710 participants with vascular dementia, including subcortical and cortical forms (age range 50 to 85 years). Over 24 weeks, a mean dose of rivastigmine of 9.4 mg/day was achieved versus placebo. Baseline MMSE was identical for both groups, at 19.1. Statistically significant advantage in cognitive response (but not with global impression of change or non-cognitive measures) was seen with rivastigmine treatment at 24 weeks (MMSE change from baseline MD 0.6, 95% CI 0.11 to 1.09, P value 0.02; Vascular Dementia Assessment Scale (VaDAS) change from baseline MD -1.3, 95% CI-2.62 to 0.02, P value 0.05 ). Significantly higher rates of vomiting, nausea, diarrhoea and anorexia and withdrawals from treatment were noted in the participants randomized to rivastigmine compared with placebo (withdrawals rivastigmine 90/365, placebo 48/345, OR 2.02, 95% CI 1.38 to 2.98) (withdrawals due to an adverse event rivastigmine 49/365, placebo 19/345, OR 2.66, 95% CI 1.53 to 4.62, P value 0.0005).The third study included 50 participants (age range 48 to 84 years) with mean MMSE scores of 23.7 and 23.9 in the rivastigmine and placebo arms, respectively. Over a 24-week period, participants labelled as having cognitive impairment but no dementia (CIND) following ischaemic stroke were given up to 4.5 mg rivastigmine twice daily, or placebo. Primary and secondary outcome measures showed no statistically significant difference when considering neurocognitive abilities, function, neuropsychiatric symptoms and global performance. One participant in the rivastigmine group and two in the placebo group discontinued their medication because of an adverse effect. There is some evidence of benefit of rivastigmine in VCI from trial data from three studies. However, this conclusion is based on one large study. Rivastigmine is capable of inducing side effects that lead to withdrawal in a significant proportion of patients.

Increased interactions between PKA and NF-κB signaling in the hippocampus following loss of cholinergic input

Neuropsychiatric disorders such as depression are frequently associated with Alzheimer's disease (AD) and the degeneration of cholinergic basal forebrain neurons and reductions in acetylcholine that occur in AD have been identified as potential mediators of these secondary neuropsychiatric symptomologies. Indeed, removal of cholinergic innervation to the hippocampus via selective immunolesions of septohippocampal cholinergic neurons induces dysfunction of the hypothalamic-pituitary-adrenocortical (HPA) axis and decreases glucocorticoid receptor expression (GR). A subsequent study showed that loss of cholinergic input decreases the activity of the catalytic subunit of protein kinase A (PKAc) and lessens the interaction of protein kinase A (PKA) with GR. Because cross-coupling between nuclear factor-κB (NF-κB) p65 and GR depends on PKA signaling, the present study was conducted to evaluate the status of NF-κB as well as interactions of PKA with NF-κB in the hippocampus following cholinergic denervation. Expression of cytosolic NF-κB p65 was diminished and IκB was degraded in the hippocampus of cholinergic immunolesioned rats compared to the controls. Immunolesions also increased NF-κB p65 Ser276 phosphorylation, as well as interactions between PKAc and NF-κB p65. These results indicate that loss of cholinergic input to the hippocampus results in decreased PKA activity and increased NF-κB activity. Such altered signaling may contribute to psychiatric symptoms, including depression, in patients with AD.

Age-related responses of the rat cerebral cortex: influence of vitamin E and exercise on the cholinergic system

In this study, we have assessed the impact of vitamin E and exercise on acquisition and retention of spatial memory for a given task in aging rats, using a T-maze. Acetylcholine esterase (AChE) and cholineacetyl transferase (ChAT) activities and acetylcholine (ACh) were measured in the cerebral cortex (CC) of male Wistar rats of 4- (adult), 12- (middle-aged) and 18-months (old) of age. Animals were categorized into sedentary [(SEC (N)], sedentary supplemented [SEC (+E)], swim trained [SWT (N)] and swim trained supplemented [SWT (+E)]. In the old, ChAT activity increased in the SEC (+E). AChE activity was highest in the adults, irrespective of training or supplementation. By contrast, ACh concentration remained unaltered with age, exercise and supplementation. Middle-aged and old rats were benefited in terms of a better acquisition and retention in the case of those that were trained and supplemented with Vitamin E. Adults showed better retention in all the groups after 7 and 15 days, while in the middle-aged, training was beneficial after 15 days. We observed decreased AChE activity when old rats were trained with the supplement. Our results also suggest that this regimen may be analogous to the AChE inhibitors that are widely advocated to derive positive benefits in up-regulating the possible reduction in ACh and in turn age-associated memory deficits.

Ectopic expression of caveolin-1 restores physiological contractile response of aged colonic smooth muscle

Reduced colonic motility has been observed in aged rats with a parallel reduction in acetylcholine (ACh)-induced myosin light chain (MLC(20)) phosphorylation. MLC(20) phosphorylation during smooth muscle contraction is maintained by a coordinated signal transduction cascade requiring both PKC-alpha and RhoA. Caveolae are membrane microdomains that permit rapid and efficient coordination of different signal transduction cascades leading to sustained smooth muscle contraction of the colon. Here, we show that normal physiological contraction can be reinstated in aged colonic smooth muscle cells (CSMCs) upon transfection with wild-type caveolin-1 through the activation of both the RhoA/Rho kinase and PKC pathways. Our data demonstrate that impaired contraction in aging is an outcome of altered membrane translocation of PKC-alpha and RhoA with a concomitant reduction in the association of these molecules with the caveolae-specific protein caveolin-1, resulting in a parallel decrease in the myosin phosphatase-targeting subunit (MYPT) and CPI-17 phosphorylation. Decreased MYPT and CPI-17 phosphorylation activates MLC phosphatase activity, resulting in MLC(20) dephosphorylation, which may be responsible for decreased colonic motility in aged rats. Importantly, transfection of CSMCs from aged rats with wild-type yellow fluorescent protein-caveolin-1 cDNA restored translocation of RhoA and PKC-alpha and phosphorylation of MYPT, CPI-17, and MLC(20), thereby restoring the contractile response to levels comparable with young adult rats. Thus, we propose that caveolin-1 gene transfer may represent a promising therapeutic treatment to correct the age-related decline in colonic smooth muscle motility.

Galantamine for vascular cognitive impairment.

Vascular dementia is the second most common form of dementia. Cholinesterase inhibitors modestly improve a broad range of symptoms in some patients with Alzheimer's disease through enhancement of cholinergic neurotransmission. These drugs may also be beneficial in vascular dementia as reductions in acetylcholine and acetyltransferase activity have been reported. To assess the efficacy of galantamine in the treatment of people with vascular cognitive impairment or vascular dementia or "mixed" dementia. Trials were identified from a search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group on 19 April 2005 using the terms: galantamine. galanthamine, reminyl. All major health care databases and many ongoing trial databases within the scope of the group are searched regularly to keep this Register up to date. All unconfounded randomised double-blind trials comparing galantamine with placebo were eligible for inclusion. Two RCTs fulfilling the inclusion criteria were included in this review. Two reviewers independently extracted the data from these two inclusion studies. Two trials employing randomized, double-blind, parallel-group methodology were included. GAL-INT-6 reported sub-group data for a pure population of vascular dementia patients showing no significant differences in Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog/11) and Clinician's Interview-based Impression of Change (CIBIC-plus) when galantamine was compared against placebo. When data combining patients with vascular dementia diagnosed according to recognised criteria with a population of patients with Alzheimer's disease and coincidental radiographic findings of cerebrovascular disease was analysed, statistically significant improvements in cognition (ADAS-cog), global functioning (CIBIC-plus), activities of daily living (DAD) and behaviour (NPI) were noted. In the galantamine treated group, significantly higher numbers of patients dropped out and withdrew due to an adverse event. Limited data was available at the time of publication for a second larger trial (GAL-INT-26) involving patients with vascular dementia diagnosed using standard criteria. Statistically significant benefits favouring galantamine over placebo in assessments of cognition (ADAS-cog/11; p < 0.001) and executive function (Executive Interview, EXIT-25, p = 0.041) were recorded. No differences in outcome in measures of behaviour (Neuropsychiatric Inventory, NPI), daily living (Alzheimer's Disease Cooperative Study-Activities of Daily Living inventory, ADCS-ADL) and global functioning (CIBIC-plus) in this trial were seen. Limited data were available when considering the impact of galantamine on vascular dementia or vascular cognitive impairment. The data available at the time of review suggest some advantage over placebo in the areas of cognition and executive functioning in one trial but this was not seen in a second trial which included smaller numbers of relevant patients. In both considered trials galantamine produced higher rates of gastrointestinal side-effects. More studies are needed before firm conclusions can be drawn.

Insulin and insulin-like growth factor expression and function deteriorate with progression of Alzheimer's disease: Link to brain reductions in acetylcholine

Reduced glucose utilization and energy metabolism occur early in the course of Alzheimer's disease (AD) and correlate with impaired cognition. Glucose utilization and energy metabolism are regulated by insulin and insulin-like growth factor I (IGF-I), and correspondingly, studies have shown that cognitive impairment may be improved by glucose or insulin administration. Recently, we demonstrated significantly reduced levels of insulin and IGF-I polypeptide genes and their corresponding receptors in advanced AD relative to aged control brains. The abnormalities in gene expression were accompanied by impaired survival signaling downstream through PI3 kinase-Akt. The present work characterizes the abnormalities in insulin and IGF gene expression and receptor binding in brains with different Braak stage severities of AD. Realtime quantitative RT-PCR analysis of frontal lobe tissue demonstrated that increasing AD Braak Stage was associated with progressively reduced levels of mRNA corresponding to insulin, IGF-I, and IGF-II polypeptides and their receptors, tau, which is regulated by insulin and IGF-I, and the Hu D neuronal RNA binding protein. In contrast, progressively increased levels of amyloid beta protein precursor (AbetaPP), glial fibrillary acidic protein, and the IBA1/AIF1 microglial mRNA transcripts were detected with increasing AD Braak Stage. Impairments in growth factor and growth factor receptor expression and function were associated with increasing AD Braak stage dependent reductions in insulin, IGF-I, and IGF-II receptor binding, ATP levels, and choline acetyltransferase (ChAT) expression. Further studies demonstrated that: 1) ChAT expression increases with insulin or IGF-I stimulation; 2) ChAT is expressed in insulin and IGF-I receptor-positive cortical neurons; and 3) ChAT co-localization in insulin or IGF-I receptor-positive neurons is reduced in AD. Together, these data provide further evidence that AD represents a neuro-endocrine disorder that resembles a unique form of diabetes mellitus (? Type 3) and progresses with severity of neurodegeneration.

Effect of ginkgolides on beta-amyloid-suppressed acetylocholine release from rat hippocampal slices.

As Ginkgo has been shown to improve age-related memory de fi cits and beta-amyloid-related peptides have been suggested to play a signi fi cant role in memory degeneration in Alzheimer's disease, the present study was carried out to examine the effect of two major ginkgolides, A and B, on beta-amyloid peptide-modulated acetylcholine (ACh) release from hippocampal brain slices. Addition of beta-amyloid fragment(25-35) (0.01-1 micro M) in the superfusion medium suppressed the K(+)-evoked [(3)H]-ACh release from the rat hippocampal slices in a concentration-related manner; a 40% reduction in ACh out fl ow was observed with the highest amyloid concentration used (1 micro M). Inclusion of ginkgolide B (GKB, 0.01-10 micro M) caused a concentration-related reversion of the inhibitory effect elicited by the effective concentration of beta-amyloid (1 micro M). The reversal of the beta-amyloid-inhibited ACh release by GKB (1 micro M) was not blocked by tetrodotoxin (1 micro M) indicating a direct interaction of GKB on the cholinergic nerve terminals. In contrast, addition of the same concentration range of ginkgolide A (GKA, 0.01-10 micro M) had no effect on beta-amyloid-inhibited ACh release. These results suggest that GKB may elicit its anti-amnesic effect by minimizing the inhibitory effect of beta-amyloid peptides on cholinergic transmission.