Tyrosine Hydroxylase Immunoreactivity Research Articles

Astaxanthin attenuates neurotoxicity in a mouse model of Parkinson’s disease

Background: Astaxanthin (AXT) is a natural carotenoid with diverse biological activities. Although it is best known as a potent antioxidant, recent work suggests additional mechanisms of action that have the potential to oppose the ongoing pathophysiology of Parkinson’s disease (PD). For example, AXT has a putative role in modulating microglial activity and preserving mitochondrial function, thereby implicating this compound as a neuroprotective agent. Both oxidative stress and inflammation are involved in the progression of many neurodegenerative diseases. Therefore, we examined the efficacy for AXT to reduced neurotoxicity in a toxic model of PD in mice. Methods: In this study, we used a 4-week dietary supplementation of algae derived AXT to reduce 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced dopaminergic cell death.Results: AXT treated mice were protected against the loss of tyrosine hydroxylase (TH) staining in the substantia nigra (SN) after MPTP exposure compared to the control diet. This effect of preserved TH immunoreactivity was also observed in the striatum. Furthermore, AXT administration was able to interrupt the neuroinflammatory process known to contribute to neurodegeneration in this model.Conclusions: We demonstrate that AXT neuroprotection was associated with attenuated microglial activation as indicated by reduced immunohistochemical detection of IBA-1 in the SN and striatum of AXT treated mice. Altogether, these studies suggest that AXT has neuroprotective property in the central nervous system against MPTP neurodegeneration.Keywords: Astaxanthin, Neuroprotection, Neurodegeneration, Neuroinflammation, Parkinson’s disease

Neuroprotective Effects of Intranasal IGF-1 against Neonatal Lipopolysaccharide-Induced Neurobehavioral Deficits and Neuronal Inflammation in the Substantia Nigra and Locus Coeruleus of Juvenile Rats

Neonatal lipopolysaccharide (LPS) exposure-induced brain inflammation resulted in motor dysfunction and brain dopaminergic neuronal injury, and increased the risks of neurodegenerative disorders in adult rats. Our previous studies showed that intranasal administration of insulin-like growth factor-1 (IGF-1) protects against LPS-induced white matter injury in the developing rat brain. To further examine whether IGF-1 protects against LPS-induced brain neuronal injury and neurobehavioral dysfunction, recombinant human IGF-1 (rhIGF-1) at a dose of 50 µg/pup was administered intranasally 1 h following intracerebral injection of LPS (1 mg/kg) in postnatal day 5 (P5) Sprague-Dawley rat pups. Neurobehavioral tests were carried out from P7 to P21, and brain neuronal injury was examined at P21. Our results showed that LPS exposure resulted in disturbances of motor behaviors in juvenile rats. Moreover, LPS exposure caused injury to central catecholaminergic neurons, as indicated by a reduction of tyrosine hydroxylase (TH) immunoreactivity in the substantia nigra (SN), ventral tegmental area (VTA) and olfactory bulb (OB), and brain noradrenergic neurons, as indicated by a reduction of TH immunoreactivity in the locus coeruleus (LC) of the P21 rat brain. The LPS-induced reduction of TH+ cells was observed at a greater degree in the SN and LC of the P21 rat brain. Intranasal rhIGF-1 treatment attenuated LPS-induced central catecholaminergic neuronal injury and motor behavioral disturbances, including locomotion, beam walking test and gait analysis. Intranasal rhIGF-1 administration also attenuated LPS-induced elevation of IL-1β levels and numbers of activated microglia, and cyclooxygenase-2+ cells, which were double labeled with TH+ cells in the SN, VTA, OB and LC of the P21 rat brain. These results suggest that IGF-1 may provide protection against neonatal LPS exposure-induced central catecholaminergic neuronal injury and motor behavioral disturbances, and that the protective effects are associated with the inhibition of microglia activation and the reduction of neuronal oxidative stress by the suppression of the neuronal cyclooxygenase-2 expression.

Immunolesion of melanopsin neurons causes gonadal regression in Pekin drakes (Anas platyrhynchos domesticus)

Several light sensitive receptors have been described in the avian brain that are thought to regulate the reproductive axis independently from the eyes and pineal gland. Recently, our lab has described the presence of three of these photoneuroendocrine systems in the Pekin duck: opsin, opsin 5, & melanopsin. We set out to test the hypothesis that melanopsin receptive neurons are necessary to maintain seasonal reproductive status along with growth and development in the Pekin drake. To accomplish these goals we first investigated 50-week-old Pekin drakes that were housed in the aviary at Hope College under long day length (18h lights on) conditions in floor pens. To specifically lesion melanopsin-receptive neurons, 3μl of an anti-melanopsin-saporin conjugate (MSAP, 100ng/ul) was injected into the lateral ventricle (n=10). Control drakes were injected with 3μl of equimolar unconjugated anti-melanopsin and saporin (SAP, n=10). Reproductive behaviors were analyzed weekly in a test pen with adult hens and MSAP drakes showed a significant (p<0.01) reduction in reproductive behaviors after week 2. After 5weeks, drakes were euthanized and body weights were measured, and brains, pituitaries, and testes collected and stored for analyses. Mature MSAP-treated drakes had significantly (p<0.001) reduced relative teste weights compared to SAP controls. qRT-PCR analyses of hypothalamus showed a significant reduction (p<0.001) in GnRH and melanopsin mRNA levels, but not opsin 5, vertebrate ancient opsin, or opsin 2 (rhodopsin). Immunocytochemical analyses showed a significant reduction (p<0.01) in tyrosine hydroxylase-immunoreactivity in the PMM. These data suggest that although blue light alone is not able to maintain testicular function, the blue-light sensitive melanopsin activity is critical to maintain gonadal function.

Low doses of 17α-ethinyl estradiol alter the maternal brain and induce stereotypies in CD-1 mice exposed during pregnancy and lactation

Maternal care is critical for the survival, development and long-term success of offspring. Despite our current understanding of the role of endogenous estrogen in both maternal behavior and the maternal brain, the potential effects of exogenous estrogens on these endpoints remain poorly understood. Here, pregnant CD-1 mice were exposed to low doses of 17α-ethinyl estradiol (EE2), commonly used as a positive control in studies of other xenoestrogens, from day 9 of pregnancy until weaning. Using traditional maternal behavior assays, we document no significant changes in maternal behavior throughout the lactational period. However, EE2 induced increases in repetitive tail retrieval, which may indicate a stereotypy or obsessive compulsive (OCD)-like behavior. We also observed a significant reduction in tyrosine hydroxylase (TH) immunoreactivity in the ventral tegmental area (VTA), a region important for maternal motivation. These results suggest that pregnant adult females are not immune to the effects of this compound.

Neurovascular Specifications intheAlzheimer-Like Brain of Mice Affected by Focal Cerebral Ischemia: Implications for Future Therapies.

Alzheimer's disease (AD), the most frequent type of dementia, is a prototypical neurodegenerative disease, but shares with stroke certain common risk factors. Consequently, how vascular pathology may modulate AD pathogenesis has gained scientific attention. Therefore, aside from typical features of AD (e.g., amyloid-β, tau hyperphosphorylation, and cholinergic dysfunction), changes within the 'neurovascular unit' (NVU) are of particular interest. This study focused on cholinergic, choline acetyltransferase (ChAT)-immunopositive, and tyrosine hydroxylase (TH)-containing neurons in association with the vasculature to explore the neurovascular complex of the AD brain affected by stroke. Wild-type and triple-transgenic (3xTg) mice of different ages underwent unilateral permanent focal cerebral ischemia. Histochemical analyses comprised diverse neuronal and vascular NVU components, and markers of AD. Immunofluorescence labeling confirmed the existence of Aβ deposits and phospho-tau together with glial reactions and morphologically altered endothelia, visualized by Solanum tuberosum lectin. Twenty-four hours after ischemia induction, immunoreactivities for ChAT and TH declined in the ischemia-affected striatum and, at least in part, in the ischemic border zone and ipsilateral neocortex. Correlation analyses indicated simultaneous degeneration of neuronal and vascular components. A trend for more severe affection of ChAT was observed in younger as compared with older mice. The present findings suggest complex interactions within the NVU of the AD-like brain affected by ischemia, comprising alterations of the cholinergic system in conjunction with vascular pathology. Hence, it may be worthwhile to explore the impact of a cellular stabilization approach on vascular and glial elements in AD in terms of a potential disease-alleviating strategy.

A Tyrosine-Hydroxylase Characterization of Dopaminergic Neurons in the Honey Bee Brain.

Dopamine (DA) plays a fundamental role in insect behavior as it acts both as a general modulator of behavior and as a value system in associative learning where it mediates the reinforcing properties of unconditioned stimuli (US). Here we aimed at characterizing the dopaminergic neurons in the central nervous system of the honey bee, an insect that serves as an established model for the study of learning and memory. We used tyrosine hydroxylase (TH) immunoreactivity (ir) to ensure that the neurons detected synthesize DA endogenously. We found three main dopaminergic clusters, C1–C3, which had been previously described; the C1 cluster is located in a small region adjacent to the esophagus (ES) and the antennal lobe (AL); the C2 cluster is situated above the C1 cluster, between the AL and the vertical lobe (VL) of the mushroom body (MB); the C3 cluster is located below the calyces (CA) of the MB. In addition, we found a novel dopaminergic cluster, C4, located above the dorsomedial border of the lobula, which innervates the visual neuropils of the bee brain. Additional smaller processes and clusters were found and are described. The profuse dopaminergic innervation of the entire bee brain and the specific connectivity of DA neurons, with visual, olfactory and gustatory circuits, provide a foundation for a deeper understanding of how these sensory modules are modulated by DA, and the DA-dependent value-based associations that occur during associative learning.

Widespread reduction of dopamine cell bodies and terminals in adult rats exposed to a low dose regimen of MDMA during adolescence

Although MDMA (3,4-methylendioxymethamphetamine, ecstasy) neurotoxicity in serotonin neurons is largely recognized in a wide variety of species including man, neurotoxicity in dopamine (DA) neurons is thought to be species-specific. MDMA is mainly consumed by adolescents, often in conjunction with caffeine (Energy Drinks) and this association has been reported to exacerbate MDMA toxic effects. In order to model these aspects of MDMA use, vis-à-vis their impact on DA neurons, we investigated the effects of adolescent exposure to low doses of MDMA (5 mg/kg for 10 days), alone or in combination with caffeine (10 mg/kg) on neuronal and functional DA indices and on recognition memory in adult rats. MDMA reduced density of tyrosine hydroxylase (TH) positive neurons in the ventral tegmental area and in the substantia nigra pars compacta, and immunoreactivity of TH and DA transporter in the nucleus accumbens (NAc) shell and core, and caudate-putamen. This same treatment caused a reduction of basal dialysate DA in the NAc core. MDMA-pretreated rats also showed behavioral sensitization to a MDMA challenge at adulthood and potentiation of MDMA-induced increase of dialysate DA in the NAc core, but not in the NAc shell. In addition, MDMA-treated rats displayed a deficit in recognition memory. Caffeine co-administration did not affect the above outcomes. Our results show that adolescent exposure of rats to low doses of MDMA induces long-lasting and widespread reduction of DA neurons indicative of a neurotoxic effect on DA neurons and suggestive of a degeneration of the same neurons.

A role for interleukin 17A in IBD‐related neuroplasticity

Changes to the structure and function of the innervation of the gut contribute to symptom generation in inflammatory bowel diseases (IBD). However, delineation of the mechanisms of these effects has proven difficult. Previous work on sympathetic neurons identified interleukin (IL)-17A as a novel neurotrophic cytokine. Since IL-17A is involved in IBD pathogenesis, we tested the hypothesis that IL-17A contributes to neuroanatomical remodeling during IBD. Immunohistochemistry for tyrosine hydroxylase was used to identify sympathetic axons in mice with dextran sulphate sodium (DSS)-induced colitis and controls. Axon outgrowth from sympathetic neurons in response to incubation in cytokines or endoscopic patient biopsy supernatants was quantified. DSS-induced colitis led to an increase in tyrosine hydroxylase immunoreactivity in the inflamed colon but not the spleen. Colonic supernatants from mice with colitis and biopsy supernatants from Crohn's disease patients increased axon outgrowth from mouse sympathetic neurons compared to supernatants from uninflamed controls. An antibody that neutralized IL-17A blocked the ability of DSS-induced colitis and Crohn's disease supernatants to induce axon extension. These findings identify IL-17A as a potential mediator of neuroanatomical remodeling of the gut innervation during IBD.

Neuroprotective effects of ceftriaxone treatment on cognitive and neuronal deficits in a rat model of accelerated senescence

Rats of OXYS strain are characterized by genetically defined accelerated senescence. Ceftriaxone (CEF) exerts neuroprotective effects by decreasing the excitotoxicity and activation of antioxidant system. Here, we studied the effects of CEF (50 or 100mg/kg/day, i.p., 36 days) on cognitive and neuronal deficits in 5-month-old OXYS rats. Chronic CEF administration in a dose of 100mg/kg partially inhibited impairments of movement and restored the deficit in the novel object recognition in OXYS rats. Neuromorphologically, control OXYS rats exhibited a lowered neuronal density in the hippocampal CA1 area and there was a tendency to decrease in the substantia nigra pars compacta compared to Wistar controls. Both doses of CEF increased the density of pyramidal neurons in the CA1 area in OXYS rats. Control OXYS rats demonstrated a tendency to lower tyrosine hydroxylase (TH) immunoreactivity in the striatum compared with Wistar rats, while CEF treatment at a dose of 50mg/kg significantly augmented this parameter. In control OXYS rats, the levels of neurogenesis in the subgranular zone of the dentate gyrus of the hippocampus were significantly higher than in Wistar rats indicating compensatory processes that probably prevented the further induction of neurogenesis by CEF. Restoration of the recognition function and neuronal density in the CA1 area in OXYS rats after CEF treatment might be related to activation of the mechanisms that provide survival of newborn and mature neurons. The data suggested CEF as a promising pharmacological tool for the prevention of cognitive decline at accelerated aging.

Partial rescue of neuropathology in the murine model of PKU following administration of recombinant phenylalanine ammonia lyase (pegvaliase).

Pegylated recombinant phenylalanine ammonia lyase (pegvaliase) is an enzyme substitution therapy being evaluated for the treatment of phenylketonuria (PKU). PKU is characterized by elevated plasma phenylalanine, which is thought to lead to a deficiency in monoamine neurotransmitters and ultimately, neurocognitive dysfunction. A natural history evaluation in a mouse model of PKU demonstrated a profound decrease in tyrosine hydroxylase (TH) immunoreactivity in several brain regions, beginning at 4weeks of age. Following treatment with pegvaliase, the number of TH positive neurons was increased in several brain regions compared to placebo treated ENU2 mice.

Age-related changes in immunoreactivity for dopamine β-hydroxylase in carotid body glomus cells in spontaneously hypertensive rats.

The purpose of this study was to investigate immunoreactivity for dopamine β-hydroxylase (DBH) and tyrosine hydroxylase (TH) in carotid body (CB) glomus cells in spontaneously hypertensive rats (SHR/Izm) at 4 (prehypertensive stage), 8 (early stage of developmental hypertension), 12 (later stage of developmental hypertension), and 16weeks of age (established hypertensive stage). Age-matched Wistar Kyoto rats (WKY/Izm) were used as controls. Staining properties for TH were similar between both strains at each age. Regarding DBH immunostaining, although some glomus cells showed intense DBH immunoreactivity at 4weeks of age, these cells were rarely observed at 8, 12, and 16weeks of age in WKY/Izm. In SHR/Izm, intense DBH immunoreactivity was observed in some glomus cells at 4weeks of age, these cells were also observed at 8 and 12weeks of age, and their number increased at 16weeks of age. An image analysis showed that the percentage of DBH-immunopositive glomus cells in WKY/Izm was approximately 30% at 4weeks of age and significantly decreased to approximately 10% at 8, 12, and 16weeks of age (p<0.05). This percentage in SHR/Izm was approximately 40% at each age. The gray scale intensity for DBH immunoreactivity in DBH-immunopositive glomus cells was similar in both strains at 4weeks of age, but became significantly lower in WKY/Izm and higher in SHR/Izm with increase in age (p<0.05). These results suggest that noradrenaline in glomus cells plays an important role in the regulation of neurotransmission between CB and afferent nerves during developmental hypertension.

The role of system Xc− in methamphetamine-induced dopaminergic neurotoxicity in mice

The cystine/glutamate antiporter (system Xc−, Sxc) transports cystine into cell in exchange for glutamate. Since xCT is a specific subunit of Sxc, we employed xCT knockout mice and investigated whether this antiporter affected methamphetamine (MA)-induced dopaminergic neurotoxicity. MA treatment significantly increased striatal oxidative burdens in wild type mice. xCT inhibitor [i.e., S-4-carboxy-phenylglycine (CPG), sulfasalazine] or an xCT knockout significantly protected against these oxidative burdens. MA-induced increases in Iba-1 expression and Iba-1-labeled microglial immunoreactivity (Iba-1-IR) were significantly attenuated by CPG or sulfasalazine administration or xCT knockout. CPG or sulfasalazine significantly attenuated MA-induced TUNEL-positive cell populations in the striatum of Taconic ICR mice. The decrease in excitatory amino acid transporter-2 (or glutamate transporter-1) expression and increase in glutamate release were attenuated by CPG, sulfasalazine or xCT knockout. In addition, CPG, sulfasalazine or xCT knockout significantly protected against dopaminergic loss (i.e., decreases in tyrosine hydroxylase expression and immunoreactivity, and an increase in dopamine turnover rate) induced by MA. However, CPG, sulfasalazine or xCT knockout did not significantly affect the impaired glutathione system [i.e., decrease in reduced glutathione (GSH) and increase in oxidized glutathione (GSSG)] induced by MA. Our results suggest that Sxc mediates MA-induced neurotoxicity via facilitating oxidative stress, microgliosis, proapoptosis, and glutamate-related toxicity.

Locus coeruleus at asymptomatic early and middle Braak stages of neurofibrillary tangle pathology.

The present study analyses molecular characteristics of the locus coeruleus (LC) and projections to the amygdala and hippocampus at asymptomatic early and middle Braak stages of neurofibrillary tangle (NFT) pathology. Immunohistochemistry, whole-transcriptome arrays and RT-qPCR in LC and western blotting in hippocampus and amygdala in a cohort of asymptomatic individuals at stages I-IV of NFT pathology were used. NFTs in the LC increased in parallel with colocalized expression of tau kinases, increased neuroketal adducts and decreased superoxide dismutase 1 in neurons with hyperphosphorylated tau and decreased voltage-dependent anion channel in neurons containing truncated tau were found. These were accompanied by increased microglia and AIF1, CD68, PTGS2, IL1β, IL6 and TNF-α gene expression. Whole-transcriptome arrays revealed upregulation of genes coding for proteins associated with heat shock protein binding and genes associated with ATP metabolism and downregulation of genes coding for DNA-binding proteins and members of the small nucleolar RNAs family, at stage IV when compared with stage I. Tyrosine hydroxylase (TH) immunoreactivity was preserved in neurons of the LC, but decreased TH and increased α2A adrenergic receptor protein levels were found in the hippocampus and the amygdala. Complex alteration of several metabolic pathways occurs in the LC accompanying NFT formation at early and middle asymptomatic stages of NFT pathology. Dopaminergic/noradrenergic denervation and increased expression of α2A adrenergic receptor in the hippocampus and amygdala occur at first stage of NFT pathology, suggesting compensatory activation in the face of decreased adrenergic input occurring before clinical evidence of cognitive impairment and depression.

Evaluation of specific neural marker GAP-43 and TH combined with Masson-trichrome staining for forensic autopsy cases with old myocardial infarction.

It has been a puzzling forensic task to determine the cause of death as a result of old myocardial infarction (OMI) in the absence of recognizable acute myocardial infarction. Recent studies indicated that the heterogeneous cardiac nerve sprouting and sympathetic hyperinnervation at border zones of the infarcted site played important roles in sudden cardiac death (SCD). So, the present study explored the value of growth associated protein-43 (GAP-43) and tyrosine hydroxylase (TH) as objective and specific neural biomarkers combined with Masson-trichrome staining for forensic autopsy cases. Myocardium of left ventricle of 58 medicolegal autopsy cases, 12 OMI cases, 12 acute/OMI cases, and 34 control cases, were immunostained with anti-GAP-43 and anti-TH antibodies. Immunoreactivity of GAP-43 and TH identified nerve fibers and vascular wall in OMI cases and acute/OMI cases. Specifically, TH-positive nerve fibers were abundant at border zones of the infarcted site. There were a few GAP-43 and TH expressions in the control cases. With Masson-trichrome staining, collagen fibers were blue and cardiac muscle fibers were pink in marked contrast with the surrounding tissue, which improved the location of nerve fibers. Thus, these findings suggest that immunohistochemical detection of GAP-43 and TH combined with Masson-trichrome staining can provide the evidence for the medicolegal expertise of SCD due to OMI, and further demonstrate a close relationship between sympathetic hyperinnervation and SCD.

Protective role of apigenin on rotenone induced rat model of Parkinson's disease: Suppression of neuroinflammation and oxidative stress mediated apoptosis

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra which is associated with oxidative stress, neuroinflammation and apoptosis. Apigenin (AGN), a non-mutagenic flavone found in fruits and vegetables, exhibits a variety of biological effects including anti-apoptotic, anti-inflammatory, and free radical scavenging activities. The current study was aimed to investigate the neuroprotective effects and molecular mechanisms of AGN in a rat model of PD induced by rotenone (ROT). Unilateral stereotaxic intranigral infusion of ROT caused the loss of tyrosine hydroxylase (TH) immunoreactivity in striatum and substantia nigra. AGN treatment (10 and 20 mg/kg, i.p.) showed a significant improvement in behavioral, biochemical and mitochondrial enzyme activities as compared to ROT exposed rats. The mRNA expression of inflammatory markers and neurotrophic factors was quantified by reverse transcriptase polymerase chain reaction (RT-PCR). Administration of AGN significantly attenuated the upregulation of NF-κB gene expression in ROT induced group and prevented the neuroinflammation in substantia nigra pars compacta (SNpc). Further, AGN inhibited the release of pro-inflammatory cytokines TNF- α, IL-6 and pro-inflammatory enzyme iNOS-1 induced by ROT. Additionally, AGN prevents the reduction of neurotrophic factors BDNF and GDNF mRNA expression in ROT lesioned rats. Immunoblot results illustrated that AGN treatment downregulated α-synuclein aggregation and upregulated the TH protein expression as well as dopamine D2 receptor (D2R) expression in ROT lesioned rats. Thus, the present findings collectively suggest that AGN exerts its neuroprotection in ROT model of PD and may act as an effective agent for treatment of PD.

A Non‐invasive Novel Method to Assess Necrotizing Enterocolitis in Rodents

Necrotizing enterocolitis (NEC) is the leading cause of mortality due to gastrointestinal (GI) disease in premature neonates. The precise pathogenesis of NEC is unknown, but early stages are thought to be characterized by damage to the intestinal mucosa and changes to the microbiota; while full intestinal necrosis, perforation, and multi‐system failure occur during the later stages. The early diagnosis of NEC would drastically reduce morbidity and mortality, but there are currently no predictive tests available to clinicians.Heart rate variability (HRV) is a non‐invasive way to measure changes in vagal tone, and our laboratory has shown that the high frequency power spectra, an indicator of vagal tone, is a useful factor to predict NEC in neonates before the onset of clinical symptoms (Doheny et al. Neurogastroenterol. Motil., 2014). Technical issues prevent the same power analysis in rodents; however, time‐domain analysis of HRV analyzes inter‐beat‐interval differences (IBID) to discriminate vagal tone. Our unpublished data indicate a correlation between IBID and GI motility, thus validating the usefulness of cardiac vagal tone measures as a non‐invasive indicator of GI motility (Meister and Travagli, unpublished).In the present work we hypothesize that: i) in rodents IBID is a valid marker of NEC; and, ii) the alterations of the neurochemical phenotype of myenteric and vagal preganglionic neurons are proportional to the severity of NEC.Increasing severity stages of NEC are induced in newborn Sprague‐Dawley rats including i) mild NEC (&lt;Stage 2) through twice daily exposure to cold stress and hypoxia, ii) mild NEC and vagotomy (Stage 2–3), and iii) NEC (Stage 4) through maternal separation and formula feeding in addition to cold stress and hypoxia. Rats underwent HRV measures using bilateral electrodes before and after stress exposure on postnatal days (PD) 1 and 5, before being sacrificed on PD9. Gastrointestinal and brain tissues were fixed and analyzed with H&amp;E (to identify NEC stages) and fluorescence immunohistochemistry (to assess the neurochemical phenotype).Control rats displayed typical developmental increases in IBID, while NEC treatments attenuated this effect. Control and all NEC rat groups showed similar numbers of neurons in the myenteric plexus (MP; PGP 9.5 staining) and similar proportion of choline acetyltransferase immunoreactivity (ChAT) in both the MP and DVC. NEC rats showed increases in nitric oxide synthase immunoreactivity (NOS) in both the MP and DVC. Finally, both mild NEC and NEC rats showed decreases in tyrosine hydroxylase immunoreactivity (TH) in the MP, but increases in the DVC. Data are summarized in the Table below.Our data indicate that: i) NEC rodents had an attenuated IBID, consistent with human HRV data; and, ii) myenteric and vagal preganglionic neurons undergo alterations in the NEC model proportional to the severity of the treatments.We suggest that HRV measures are a promising predictive measure of decreased vagal tone and therefore NEC in rodents. This novel NEC model provides a non‐invasive tool to test the efficacy of preventative experimental measures.Support or Funding InformationNIH DK99350 IBIDPD1 IBIDPD5 PGP 9.5 (neurons/field) ChAT NOS TH (MP: % of total; DVC: neurons/slice) MP MP DVC MP DVC MP DVC ControlN=2–7 1.039 ± 0.106 2.361 ± 0.505* 52 ± 2 67 ± 4 157 ± 16 22 ± 4 5 ± 1 26 ± 11 2 ± 1 Mild NECN=2–7 1.004 ± 0.146 1.300 ± 0.011 48 ± 3 60 ± 1 168 ± 20 31 ± 1 ‐‐‐ 18 ± 5* 40 ± 18* Mild NEC + vagotomyN=2–7 1.161 ± 0.218 1.465 ± 0.171 ‐‐‐ ‐‐‐ ‐‐‐ ‐‐‐ ‐‐‐ ‐‐‐ ‐‐‐ NECN=2–7 ‐‐‐ ‐‐‐ 58 ± 10 56 ± 2 194 ± 19 44 ± 3* 11 ± 4* 10 ± 1* 24 ± 6* p&lt;0.05

Brilliant Blue G, but not Fenofibrate, Treatment Reverts Hemiparkinsonian Behavior and Restores Dopamine Levels in an Animal Model of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder, characterized by the loss of dopaminergic neurons in the substantia nigra and their projections to the striatum. Several processes have been described as potential inducers of the dopaminergic neuron death, such as inflammation, oxidative stress, and mitochondrial dysfunction. However, the death of dopaminergic neurons seems to be multifactorial, and its cause remains unclear. ATP-activating purinergic receptors influence various physiological functions in the CNS, including neurotransmission. Purinergic signaling is also involved in pathological scenarios, where ATP is extensively released and promotes sustained purinergic P2X7 receptor (P2X7R) activation and consequent induction of cell death. This effect occurs, among other factors, by oxidative stress and during the inflammatory response. On the other hand, peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) is involved in energy metabolism and mitochondrial biogenesis. Expression and activity upregulation of this protein has been related with reduction of oxidative stress and neuroprotection. Therefore, P2X7R and PGC-1α are potential targets in the treatment of PD. Here hemiparkinsonism was induced by unilateral stereotactic injection of 6-OHDA in a rat model. After 7 days, the establishment of PD was confirmed and followed by treatment with the P2X7R antagonist Brilliant Blue G (BBG) or PGC-1α agonist fenofibrate. BBG, but not fenofibrate, reverted hemiparkinsonian behavior accompanied by an increase in tyrosine hydroxylase immunoreactivity in the substantia nigra. Our results suggest that the P2X7R may be a therapeutic target in Parkinson's disease.

Comparative analysis of monoaminergic cerebrospinal fluid-contacting cells in Osteichthyes (bony vertebrates).

Cerebrospinal fluid‐contacting (CSF‐c) cells containing monoamines such as dopamine (DA) and serotonin (5‐HT) occur in the periventricular zones of the hypothalamic region of most vertebrates except for placental mammals. Here we compare the organization of the CSF‐c cells in chicken, Xenopus, and zebrafish, by analyzing the expression of synthetic enzymes of DA and 5‐HT, respectively, tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH), and draw an evolutionary scenario for this cell population. Due to the lack of TH immunoreactivity in this region, the hypothalamic CSF‐c cells have been thought to take up DA from the ventricle instead of synthesizing it. We demonstrate that a second TH gene (TH2) is expressed in the CSF‐c cells of all the three species, suggesting that these cells do indeed synthetize DA. Furthermore, we found that many CSF‐c cells coexpress TH2 and TPH1 and contain both DA and 5‐HT, a dual neurotransmitter phenotype hitherto undescribed in the brain of any vertebrate. The similarities of CSF‐c cells in chicken, Xenopus, and zebrafish suggest that these characteristics are inherited from the common ancestor of the Osteichthyes. A significant difference between tetrapods and teleosts is that teleosts possess an additional CSF‐c cell population around the posterior recess (PR) that has emerged in specific groups of Actinopterygii. Our comparative analysis reveals that the hypothalamus in mammals and teleosts has evolved in a divergent manner: placental mammals have lost the monoaminergic CSF‐c cells, while teleosts have increased their relative number.

Defining the contribution of neuroinflammation to Parkinson\u2019s disease in humanized immune system mice

BackgroundReactive microglia have been associated with the histological changes that occur in Parkinson’s disease brains and mouse models of the disease. Multiple studies from autopsy brains have verified the presence of microgliosis in several brain regions including substantia nigra, striatum, hippocampus and various cortical areas. MPTP injections in rodents have also shown striato-nigral microgliosis correlating with the loss of dopaminergic neurons. However, consistent data with respect to cytokine and immune cell changes during Parkinson’s disease have not been fully defined.ResultsIn order to improve understanding of the role of neuroinflammation in Parkinson’s disease, we employed the MPTP injection model using humanized CD34+ mice along with age-matched C57BL/6 mice. NSG mice engrafted with hu-CD34+ hematopoietic stem cells were injected with MPTP to quantify cytokine changes, neuron loss, gliosis, and behavioral dysfunction. The mice were also treated with or without the calcineurin/NFAT inhibitor, FK506, to determine whether modulating the immune response could attenuate disease. MPTP injections produced impairment of motor performance, increased microgliosis, elevated brain cytokine levels, and reduced tyrosine hydroxylase immunoreactivity in the substantia nigra and striatum of both humanized CD34+ mice and C57BL/6 mice with a strikingly different profile of human versus mouse cytokine elevations observed in each. Interestingly, FK506 injections significantly attenuated the MPTP-induced effects in the humanized CD34+ mice compared the C57BL/6 mice. In addition, analyses of human plasma from Parkinson’s disease donors compared to age-matched, healthy controls demonstrated an increase in a number of pro-inflammatory cytokines in female patients similar to that observed in MPTP-injected female CD34+ mice.ConclusionsThis study demonstrates for the first time, induction of Parkinson’s disease-like symptoms in female humanized CD34+ mice using MPTP. The profile of cytokine changes in the serum and brains of the humanized CD34+ mice following MPTP injection differed significantly from that occurring in the more commonly used C57BL/6 strain of mice. Moreover, several cytokine elevations observed in the MPTP injected humanized CD34+ mice were similarly increased in plasma of PD patients suggesting that these mice offer the more relevant model for the inflammatory aspects of human disease. Consistent with this, the effects of MPTP on loss of tyrosine hydroxylase immunoreactivity, loss of motor strength, and increase in proinflammatory cytokines were attenuated using an immunosuppressant drug, FK506, in the humanized CD34+ but not the C57BL/6 mice. Collectively, these findings suggest that MPTP injected, humanized CD34+ mice represent a more accurate model for assessing inflammatory changes in PD.

Hypercholesterolemia causes psychomotor abnormalities in mice and alterations in cortico-striatal biogenic amine neurotransmitters: Relevance to Parkinson's disease

The symptoms of Parkinson's disease (PD) include motor behavioral abnormalities, which appear as a result of the extensive loss of the striatal biogenic amine, dopamine. Various endogenous molecules, including cholesterol, have been put forward as putative contributors in the pathogenesis of PD. Earlier reports have provided a strong link between the elevated level of plasma cholesterol (hypercholesterolemia) and onset of PD. However, the role of hypercholesterolemia on brain functions in terms of neurotransmitter metabolism and associated behavioral manifestations remain elusive. We tested in Swiss albino mice whether hypercholesterolemia induced by high-cholesterol diet would affect dopamine and serotonin metabolism in discrete brain regions that would precipitate in psychomotor behavioral manifestations. High-cholesterol diet for 12 weeks caused a significant increase in blood total cholesterol level, which validated the model as hypercholesterolemic. Tests for akinesia, catalepsy, swimming ability and gait pattern (increased stride length) have revealed that hypercholesterolemic mice develop motor behavioral abnormalities, which are similar to the behavioral phenotypes of PD. Moreover, hypercholesterolemia caused depressive-like behavior in mice, as indicated by the increased immobility time in the forced swim test. We found a significant depletion of dopamine in striatum and serotonin in cortex of hypercholesterolemic mice. The significant decrease in tyrosine hydroxylase immunoreactivity in striatum supports the observed depleted level dopamine in striatum, which is relevant to the pathophysiology of PD. In conclusion, hypercholesterolemia-induced depleted levels of cortical and striatal biogenic amines reported hereby are similar to the PD pathology, which might be associated with the observed psychomotor behavioral abnormalities.