Modulation Of Cholinergic System Research Articles

Evaluation of nootropic and neuroprotective properties of Siddha drug Poorana Chandrothaya Chenthuram (PCC) in scopolamine-induced amnesia in mice

BackgroundPoorana Chandrothaya Chenthuram (PCC) is a gold-based Siddha drug, for treating diverse diseases. Rooted in centuries-old traditional use, Siddha texts categorize PCC as a kayakarpa entity that emphasizes holistic well-being. AimThis study assesses the nootropic potential of Poorana Chandrothaya Chenthuram (PCC) in scopolamine-induced amnesic mice, and elucidate the underlying mechanisms, specifically focusing on the modulation of cholinergic system and anti-oxidant effects. MethodsPreliminary finger printing with FTIR was done. Scopolamine-induced memory impaired mice were administered PCC (15 or 30 mg/kg) for 28 days. Memory assessments were done using elevated plus-maze and passive avoidance tasks. RT-PCR gauged mRNA expression levels of AChE, MChR, BAX, and BCL2 in brain samples were also done. ResultsFTIR confirmed the presence of functional groups in PCC. In the EPM test, pre-treatment with PCC (15 and 30 mg/kg) significantly reduced the time taken (p < 0.05 and 0.01, respectively), comparable to the reference control, piracetam. The PAT revealed a significant increase (p < 0.01) in the time taken to step down from the escape platform which demonstrates that significant efficacy in reversing scopolamine-induced amnesia in mice. Gene expression studies reported a significant up-regulation (p < 0.01) in AChE, MChR, and BAX mRNA expressions, along with a down-regulation in BCL2 expression compared to normal mice. ConclusionThis study demonstrates the anti-amnesic activity of the Siddha drug PCC, elucidating its mechanism involving a reduction in AChE levels and an augmentation of antioxidant levels in which implicates modulation of cholinergic and apoptotic pathways. In-depth exploration of PCC's neuroprotective properties may unveil novel avenues for combating memory and cognitive decline.

Dammarane Sapogenins Improving Simulated Weightlessness-Induced Depressive-Like Behaviors and Cognitive Dysfunction in Rats.

Background: Our studies demonstrated that the space environment has an impact on the brain function of astronauts. Numerous ground-based microgravity and social isolation showed that the space environment can induce brain function damages in humans and animals. Dammarane sapogenins (DS), an active fraction from oriental ginseng, possesses neuropsychic protective effects and has been shown to improve depression and memory. This study aimed to explore the effects and mechanisms of DS in attenuating depressive-like behaviors and cognitive deficiency induced by simulated weightlessness and isolation [hindlimb suspension and isolation (HLSI)] in rats.Methods: Male rats were orally administered with two different doses of DS (37.5, 75 mg/kg) for 14 days, and huperzine-A (1 mg/kg) served as positive control. Rats were subjected to HLSI for 14 days except the control group during drug administration. The depressive-like behaviors were then evaluated by the open-field test, the novel object recognition test, and the forced swimming test. The spatial memory and working memory were evaluated by the Morris water maze (MWM) test, and the related mechanism was further explored by analyzing the activity of choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and superoxide dismutase (SOD) in the hippocampus of rats.Results: The results showed that DS treatment significantly reversed the HLSI-induced depressive-like behaviors in the open-field test, the novel object recognition test, and the forced swimming test and improved the HLSI-induced cognitive impairment in the MWM test. Furthermore, after DS treatment, the ChAT and SOD activities of HLSI rats were increased while AChE activity was significantly suppressed.Conclusions: These findings clearly demonstrated that DS might exert a significant neuropsychic protective effect induced by spaceflight environment, driven in part by the modulation of cholinergic system and anti-oxidation in the hippocampus.

M(4) muscarinic receptors and locomotor activity regulation.

M(4) muscarinic receptors (M(4) MR) represent a subfamily of G-protein coupled receptors serving a substantial role in spontaneous locomotor activity regulation, cognition and modulation of cholinergic system. With increasing body of literature discussing the role of M(4) MR some controversies arose. Thus, we try here to summarize the current evidence regarding the M(4) MR, with the special focus on their role in Locomotor activity control. We review the molecular function of M(4) MR in specific brain areas implicated in locomotor regulation, and shortly in other CNS processes that could be connected to locomotor activity. We also focus on brain areas implicated in locomotor activity biorhythm changes like suprachiasmatic nucleus, subparaventricular zone posterior hypothalamic area, striatum and thalamus. Gender-related aspects and differences in locomotor activity in males and females are discussed further.

Allosteric modulation of cholinergic system: Potential approach to treating cognitive deficits of schizophrenia

Allosteric modulation of cholinergic system: Potential approach to treating cognitive deficits of schizophrenia

Vesicular acetylcholine transporter knock-down mice show sexual dimorphism on memory

The key neural substrates involved in memory and cognitive tasks have been reported to receive important modulation from ovarian hormones. In fact, neurochemical systems associated with cognitive functions, such as the cholinergic system, are, at least in part, under modulation of estrogens. Here we show that vesicular acetylcholine transporter (VAChT) mutant mice, which express lower levels of the VAChT (VAChT KD) and reduced acetylcholine release, present sexual dimorphism on memory. We evaluate short- and long-term object recognition memories (STM and LTM) in both sexes. We have showed previously, and confirm here, that VAChT KDHET male mice present deficits in both STM and LTM object recognition memories in comparison with WT. In contrast, VAChT KDHET female mice present deficit in LTM, but not in STM. To test if the female hormones levels could be a determinant factor on sexual dimorphism observed, we submitted female mice to ovariectomy (OVX) or sham-surgery. After 1 week (1 w), we evaluate STM. Female hormone deprivation promotes STM impairment in VAChT KDHET, but not in WT female mice. Our results strongly suggest that the sexual dimorphism observed in VAChT KDHET mice on STM is due to modulation of cholinergic system by ovarian hormones.

Long-term treatment of l-3-n-butylphthalide attenuated neurodegenerative changes in aged rats

It is shown that l-3-n-butylphthalide (l-NBP), the isomer of dl-NBP (racemic 3-n-butylphthalide, a new anti-cerebral ischemic agent) significantly attenuated cerebral hypoperfusion-induced learning dysfunction and brain damage in rats. In the present study, l-NBP (10 and 30 mg/kg) long-term (3-month) treatment of aged rat (21-month-old) significantly improved the learning and memory capability measured by the Morris water maze test. Hematoxylin-eosin-stained slices showed that both l-NBP at 30 mg/kg, and memantine as control at 20 mg/kg, attenuated the neurodegenerative changes in aged rats. L: -NBP treatment significantly increased the choline acetyltransferase activity and dose-dependently decreased the acetylcholinesterases activity in the hippocampus of aged rats. The immunohistological study demonstrated that expressions of beta-secretase and hyperphosphorylated tau protein were significantly increased in the hippocampus CA1 subfield and parietal cortex in aged rats. However, they were decreased significantly by treatment of l-NBP and memantine for 3 months. Our results indicated that long-term treatment with l-NBP might prevent age-related neurodegenerative changes by modulation of cholinergic system, reduction of phosphorylated tau and maintain structure and morphology of neurons. Therefore, l-NBP might be a potential drug for treatment of senile dementia.

Estrogen Therapy and brain muscarinic receptor density in healthy females: A SPET study

Estrogen Therapy (ET) may protect against age-related cognitive decline and neuropsychiatric disorders (e.g. Alzheimer's disease). The biological basis for this putative neuroprotective effect is not fully understood, but may include modulation of cholinergic systems. Cholinergic dysfunction has been implicated in age-related memory impairment and Alzheimer's disease. However, to date no one has investigated the effect of long-term ET on brain cholinergic muscarinic receptor aging, and related this to cognitive function. We used Single Photon Emission Tomography (SPET) and ( R, R)[ 123I]-I-QNB, a novel ligand with high affinity for m 1/m 4 muscarinic receptors, to examine the effect of long-term ET and age on brain m 1/m 4 receptors in healthy females. We included 10 younger premenopausal subjects and 22 postmenopausal women; 11 long-term ET users (all treated following surgical menopause) and 11 ET never-users (surgical menopause, n = 2). Also, verbal memory and executive function was assessed in all postmenopausal subjects. Compared to young women, postmenopausal women (ET users and never-users combined) had significantly lower muscarinic receptor density in all brain regions examined. ET users also had higher muscarinic receptor density than ET never-users in all the brain regions, and this reached statistical significance in left striatum and hippocampus, lateral frontal cortex and thalamus. Moreover, in ET users, ( R, R)[ 123I]-I-QNB binding in left hippocampus and temporal cortex was significantly positively correlated with plasma estradiol levels. We also found evidence for improved executive function in ET users as compared to ET never-users. However, there was no significant relationship between receptor binding and cognitive function within any of the groups. In healthy postmenopausal women use of long-term ET is associated with reduced age-related differences in muscarinic receptor binding, and this may be related to serum estradiol levels.

Ultrastructural evidence for mu-opioid modulation of cholinergic pathways in rat dentate gyrus

Within the rat hippocampal formation, cholinergic afferents and μ-opioid receptors (MORs) are involved in many crucial learning processes, including those associated with drug reward. Pharmacological data, and the overlapping distributions of cholinergic and μ-opioid systems, particularly in the dentate gyrus, suggest that MOR activation is a potential mechanism for endogenous opioid modulation of cholinergic activity. To date, anatomical evidence supporting this has not been reported. To delineate the relationship between cholinergic afferents and MOR-containing processes in the dentate gyrus, hippocampal sections were dually immunolabeled for vesicular acetylcholine transporter (VAChT) and MOR-1 and examined by electron microscopy. VAChT immunoreactivity was in unmyelinated axons and axon terminals, and was most often associated with small synaptic vesicles. MOR immunoreactivity was found in axons, axon terminals and, to a lesser extent, perikarya, which resembled GABAergic basket cells. Semi-quantitative ultrastructural analysis revealed that from 5% to 13% (depending on laminar location) of VAChT-immunoreactive (ir) presynaptic profiles contained MOR immunoreactivity. Additionally, 7% of VAChT-ir presynaptic profiles directly apposed MOR-ir axons and terminals, and there were almost no appositions to MOR-ir dendrites. These data suggest that opioids may directly and indirectly modulate acetylcholine release and/or reuptake. In the hilus and molecular layer, 4% of VAChT-ir terminals contacted dendritic shafts that were also contacted by MOR-ir terminals. This suggests that cholinergic afferents and MOR-containing afferents can converge on granule cell dendrites (which are restricted to the molecular layer) and on interneuron dendrites in the hilus. The results of this study provide ultrastructural evidence for direct and indirect modulation of cholinergic systems by μ-opioids in the hippocampal formation.

Histamine H3 receptor-mediated impairment of contextual fear conditioning and in-vivo inhibition of cholinergic transmission in the rat basolateral amygdala.

We investigated the effects of agents acting at histamine receptors on both, spontaneous release of ACh from the basolateral amygdala (BLA) of freely moving rats, and fear conditioning. Extensive evidence suggests that the effects of histamine on cognition might be explained by the modulation of cholinergic systems. Using the microdialysis technique in freely moving rats, we demonstrated that perfusion of the BLA with histaminergic compounds modulates the spontaneous release of ACh. The addition of 100 mm KCl to the perfusion medium strongly stimulated ACh release, whereas, 0.5 microm tetrodotoxin (TTX) inhibited spontaneous ACh release by more than 50%. Histaminergic H3 antagonists (ciproxifan, clobenpropit and thioperamide), directly administered to the BLA, decreased ACh spontaneous release, an effect fully antagonized by the simultaneous perfusion of the BLA with cimetidine, an H2 antagonist. Local administration of cimetidine alone increased ACh spontaneous release slightly, but significantly. Conversely, the administration of H1 antagonists failed to alter ACh spontaneous release. Rats receiving intra-BLA, bilateral injections of the H3 antagonists at doses similar to those inhibiting ACh spontaneous release, immediately after contextual fear conditioning, showed memory consolidation impairment of contextual fear conditioning. Post-training, bilateral injections of 50 microg scopolamine also had an adverse effect on memory retention. These observations provide the first evidence that histamine receptors are involved in the modulation of cholinergic tone in the amygdala and in the consolidation of fear conditioning.

D-1 Agonist, SKF 38393, but not a D-2 agonist, produces a cholinergically mediated analeptic effect in rabbits

SKF 38393 (2–15 mg/kg, IV), but not quinpirole, shortened the duration of loss of righting reflex produced in pentobarbital-narcotized rabbits. This effect was blocked by atropine (2–5 mg/kg, IV), but not by atropine methylbromide, suggesting that a central cholinergic mechanism was involved. The analeptic effect was also blocked by SCH 23390 (0.1 mg/kg, IV) or raclopride (5 mg/kg, IV). These results indicate that SKF 38393 activates central cholinergic neurons, which in turn initiate the analeptic effect. However, the fact that raclopride also blocked the SKF 38393 analeptic effect, but quinpirole did not exert any analeptic effect, suggests that a D-1/D-2 modulation of cholinergic systems may be involved in the SKF 38393-induced analeptic effect. These results also support our earlier findings and view that cocaine-induced analeptic activity is mediated by a dopaminergic cholinergic mechanism.

Serotonergic Modulation of Cholinergic Systems Involved in Learning and Memory in Rats

Rats received either N-methyl-&lt;i&gt;D&lt;/i&gt;-aspartic-acid-induced bilateral lesions (50 nmol/l µl/side) of a major forebrain cholinergic nucleus (nucleus basalis of Meynert, nbM) or sham operations. After an approximate 1-month recovery period, all subjects were trained and tested on a one-trial passive avoidance task. Thirty minutes prior to training, half of the subjects in each surgical condition were injected with the serotonergic releasing/depleting agent &lt;i&gt;p&lt;/i&gt;-chloroamphetamine (2.5 mg/kg), while the other half of subjects received saline injections. Immediately after training, half of the &lt;i&gt;p&lt;/i&gt;-chloroamphetamine-injected and saline-injected subjects in each surgical condition were injected with the cholinesterase inhibitor physostigmine (0.06 mg/kg), while the other half were injected with saline. All animals were tested for retention 72 h following training. Disruption of test performance was seen in (1) saline-injected nbM-lesioned animals; (2) sham animals treated with physostigmine alone, and (3) sham and nbM-lesioned animals treated with either &lt;i&gt;p-&lt;/i&gt;chloroamphetamine alone, or with &lt;i&gt;p&lt;/i&gt;-chloroamphetamine plus physostigmine. Only nbM-lesioned subjects injected with physostigmine alone exhibited enhanced test performance. Lesions of the nbM produced stern depletions in cortical cholinergic enzyme markers (choline acetyltransferase, CAT, and acetylcholinesterase, AChE). Interestingly, &lt;i&gt;p&lt;/i&gt;-chloroamphetamine exaggerated both the CAT and AChE depletions in nbM-lesioned animals. These data were interpreted as providing further evidence in support of the view that the cholinergic and serotonergic systems interact at a cognitive and at a neurochemical level. Implications for the therapeutics of Alzheimer''s disease are discussed.

The effects of intrahypothalamic hemicholinium-3 on muricide, irritability and feeding

Male Long-Evans rats that consistently killed mice when food deprived were injected unilaterally in the lateral hypothalamus with 20 μg and 30 μg of the acetylcholine synthesis inhibitor hemicholinium-3 (HC-3) and saline in a counterbalanced order. Rats were evaluated 1,2,3,24,48 and 72 hours post-injection for effects on muricide, irritability and feeding. HC-3 suppressed muricide and feeding and produced a trend toward reduced irritability during the first three hours post-injection. These data indicate that modulation of cholinergic systems in the lateral hypothalamus influences several behaviors and not any one behavior specifically.