Tyrosine Hydroxylase Immunoreactivity Research Articles

Effects of Acute Haloperidol Treatment on Dopaminergic Markers, GAD67, and A2A Receptors in Rats with High and Low VCMs.

Vacuous chewing movements (VCM) have been utilized as an experimental model of orofacial dyskinesia (OD) in rodents to study the underlying molecular mechanisms related to tardive dyskinesia (TD). This study aimed to investigate if the acute treatment with haloperidol can alter components of the dopaminergic synapse or its modulators such as glutamic acid decarboxylase (GAD67) and adenosine 2A (A2A) receptor. Furthermore, to evaluate if changes in molecular markers are associated with the number of VCMs induced by haloperidol in rats it is proposing a method to classify the animals into High and Low VCM groups. Here, we treated rats with haloperidol decanoate (single injection, intramuscularly, 28mg/Kg of unconjugated haloperidol) and evaluated the number of VCMs after 4 weeks. Haloperidol-treated rats were divided into three groups (Low, High, and Spontaneous VCM) according to the evaluation of the VCM profile proposed here. After, dopamine (DA) levels, monoamine oxidase (MAO) activity, and the immunoreactivity of tyrosine hydroxylase (TH), dopamine transporter (DAT), D2 receptor, GAD67, and A2A were determined in brain structures. No significant differences were found in DA levels, MAO activity, and immunoreactivity of the TH, DAT, D2 receptor, GAD67, and A2A receptor in brain structures. VCM intensity was correlated with TH immunoreactivity in Sn in the High VCM group while it was inversely correlated with the immunoreactivity of the A2A receptor in the striatum of the Spontaneous VCM group. Other significant correlations were found considering the VCM profile suggesting that High VCM after acute haloperidol treatment seems to be associated with the lack of ability to reorganize the neurotransmission in the nigrostriatal pathway. Further studies could clarify the main targets involved in the motor side effects of antipsychotics. The present study demonstrated an easy way to separate the animals into High and Low VCMs.

Early α-synuclein/synapsin III co-accumulation, nigrostriatal dopaminergic synaptopathy and denervation in the MPTPp mouse model of Parkinson's Disease

Parkinson's disease (PD) is characterized by the loss of nigrostriatal dopaminergic neurons and the presence of Lewy bodies (LB), intraneuronal inclusions mainly composed of α-synuclein (α-Syn) fibrils. Compelling evidence supports that, in PD brains, synapses are the sites where neurodegeneration initiates several years before the manifestation of motor symptoms. Furthermore, the amount of α-Syn deposited at synaptic terminals is several orders greater than that constituting LB. This hints that pathological synaptic α-Syn aggregates may be the main trigger for the retrograde synapse-to-cell body degeneration pattern characterizing early prodromal phases of PD. Identifying reliable biomarkers of synaptopathy is therefore crucial for early diagnosis. Here, we studied the alterations of key dopaminergic and non-dopaminergic striatal synaptic markers during the initial phases of axonal and cell body degeneration in mice subjected to 3 or 10 administrations of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine + probenecid (MPTPp), a model for early prodromal PD. We found that MPTPp administration resulted in progressive deposition of α-Syn, advancing from synaptic terminals to axons and dopaminergic neuron cell bodies. This was accompanied by marked co-accumulation of Synapsin III (Syn III), a synaptic protein previously identified as a component of α-Syn fibrils in post-mortem PD brains and as a main stabilizer of α-Syn aggregates, as well as very early and severe reduction of vesicular monoamine transporter 2 (VMAT2), dopamine transporter (DAT) and tyrosine hydroxylase (TH) immunoreactivity in nigrostriatal neurons. Results also showed that striatal α-Syn accumulation and VMAT2 decrease, unlike other markers, did not recover following washout from 10 MPTPp administrations, supporting that these changes were precocious and severe. Finally, we found that early changes in striatal α-Syn, Syn III, VMAT2 and DAT observed following 3 MPTPp administrations, correlated with nigrostriatal neuron loss after 10 MPTPp administrations. These findings indicate that α-Syn/Syn III co-deposition characterizes very early stages of striatal dopaminergic dysfunction in the MPTPp model and highlight that VMAT2 and Syn III could be two reliable molecular imaging biomarkers to predict dopamine neuron denervation and estimate α-Syn-related synaptopathy in prodromal and early symptomatic phases of PD.

Oral Trehalose Intake Modulates the Microbiota–Gut–Brain Axis and Is Neuroprotective in a Synucleinopathy Mouse Model

Parkinson’s disease (PD) is a neurodegenerative disease affecting dopaminergic neurons in the nigrostriatal and gastrointestinal tracts, causing both motor and non-motor symptoms. This study examined the neuroprotective effects of trehalose. This sugar is confined in the gut due to the absence of transporters, so we hypothesized that trehalose might exert neuroprotective effects on PD through its action on the gut microbiota. We used a transgenic mouse model of PD (PrP-A53T G2-3) overexpressing human α-synuclein and developing GI dysfunctions. Mice were given water with trehalose, maltose, or sucrose (2% w/v) for 6.5 m. Trehalose administration prevented a reduction in tyrosine hydroxylase immunoreactivity in the substantia nigra (−25%), striatum (−38%), and gut (−18%) in PrP-A53T mice. It also modulated the gut microbiota, reducing the loss of diversity seen in PrP-A53T mice and promoting bacteria negatively correlated with PD in patients. Additionally, trehalose treatment increased the intestinal secretion of glucagon-like peptide 1 (GLP-1) by 29%. Maltose and sucrose, which break down into glucose, did not show neuroprotective effects, suggesting glucose is not involved in trehalose-mediated neuroprotection. Since trehalose is unlikely to cross the intestinal barrier at the given dose, the results suggest its effects are mediated indirectly through the gut microbiota and GLP-1.

Anatomic and functional evidence for renal autonomic innervation in normotensive and hypertensive rats.

Renal denervation (RDN) has been used for treating resistant hypertension. A few recent studies have shown vagal innervation of kidneys causing confusion. This study aimed to provide anatomical and functional evidence for renal autonomic innervation. Experiments were performed in male Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Pseudorabies virus (PRV) in the paraventricular nucleus and rostral ventrolateral medulla was prevented by bilateral RDN, but not subdiaphragmatic vagotomy. PRV did not appear in the dorsal motor nucleus of the vagus and nucleus tractus solitarii 72 h after renal injection of PRV. Adrenergic fibers were approximately seven times more than cholinergic fibers in the main renal artery (MRA) and its first (1RA) and second grade (2RA) branches. Adrenergic fibers in 1RA were more than those in MRA and 2RA. Tyrosine hydroxylase immunoreactivity in these arteries was higher in SHR than in WKY. Norepinephrine (NE) increased and α-receptor antagonist reduced vascular ring tension of renal arteries. The effect of NE was greater in 1RA and 2RA than in MRA, which was prevented by α-receptor antagonist. Acetylcholine (ACh) or blockage of β-receptors, M receptors, or N receptors had no significant effects on vascular ring tension and the effect of NE. Renal blood flow was reduced by electrical stimulation of renal nerves but not affected by stimulation of the subdiaphragmatic vagus. These results provide anatomical and functional evidence that kidneys are innervated and renal blood flow is regulated by renal sympathetic nerves rather than the vagus. Renal vasoconstriction is regulated by NE and adrenergic fibers rather than ACh or cholinergic fibers in WKY and SHR.NEW & NOTEWORTHY Kidneys are innervated by renal nerves rather than the vagus. Adrenergic fibers in renal arteries are about seven times more than cholinergic fibers. Renal vasoconstriction is regulated by norepinephrine and adrenergic fibers rather than acetylcholine or cholinergic fibers. Renal blood flow is regulated by renal sympathetic nerves and is not affected by the vagus. These findings provide anatomical and functional evidence for renal autonomic innervation in normotensive and hypertensive rats.

Unveiling Lobophytum sp. the neuroprotective potential of Parkinson's disease through multifaceted mechanisms, supported by metabolomic analysis and network pharmacology

A main feature of neurodegenerative diseases is the loss of neurons. One of the most prevalent neurodegenerative illnesses is Parkinson disease (PD). Although several medications are already approved to treat neurodegenerative disorders, most of them only address associated symptoms. The main aim of the current study was to examine the neuroprotective efficacy and underlying mechanism of Lobophytum sp. crude extract in a rotenone-induced rat model of neurodegeneration mimicking PD in humans. The influence of the treatment on antioxidant, inflammatory, and apoptotic markers was assessed in addition to the investigation of TH (tyrosine hydroxylase) immunochemistry, histopathological changes, and α-synuclein. Metabolomic profiling of Lobophytum sp. crude extract was done by using High-Resolution Liquid Chromatography coupled with Mass Spectrometry (HR-LC–ESI–MS), which revealed the presence of 20 compounds (1–20) belonging to several classes of secondary metabolites including diterpenoids, sesquiterpenoids, steroids, and steroid glycosides. From our experimental results, we report that Lobophytum sp. extract conferred neuroprotection against rotenone-induced PD by inhibiting ROS formation, apoptosis, and inflammatory mediators including IL-6, IL-1β, and TNF-α, NF-кB, and subsequent neurodegeneration as evidenced by decreased α-synuclein deposition and enhanced tyrosine hydroxylase immunoreactivity. Moreover, a computational network pharmacology study was performed for the dereplicated compounds from Lobophytum sp. using PubChem, SwissTarget Prediction, STRING, DisGeNET, and ShinyGO databases. Among the studied genes, CYP19A1 was the top gene related to Parkinson’s disease. Dendrinolide compounds annotated a high number of parkinsonism genes. The vascular endothelial growth factor (VEGF) pathway was the top signaling pathway related to the studied genes. Therefore, we speculate that Lobophytum sp. extract, owing to its pleiotropic mechanisms, could be further developed as a possible therapeutic drug for treating Parkinson's disease.

Effect of sex on chronic stress induced alterations in hindbrain catecholaminergic system and autonomic dysfunction resulting in gastrointestinal dysmotility

It has been reported that the clinical symptoms of functional dyspepsia (FD) exacerbate upon stress while the gender-related factors have been incompletely understood. This study aims to investigate the role of sex in chronic heterotypic stress (CHS)-induced autonomic and gastric motor dysfunction. For CHS, the rats were exposed to the combination of different stressors for 7 consecutive days. Subsequently, electrocardiography was recorded in anesthetized rats to evaluate heart rate variability (HRV) for the determination of autonomic outflow and sympathovagal balance. Solid gastric emptying (GE) was measured in control and CHS-loaded male and female rats. The immunoreactivities of catecholaminergic cell marker tyrosine hydroxylase (TH), choline acetyltransferase (ChAT), corticotropin releasing factor (CRF), and estrogen receptor (ER-α/β) were evaluated in medullary and pontine brainstem sections by immunohistochemistry. Compared with the controls, CHS significantly delayed GE in males but not in females. There was no significant sex-related difference in parasympathetic indicator HF under either control or CHS conditions. Sympathetic indicator LF was significantly higher in control females compared to the males. The higher sympathetic output in females was found to be attenuated upon CHS; in contrast, the elevated sympathetic output was detected in CHS-loaded males. No sex- or stress-related effect was observed on ChAT immunoreactivity in the dorsal motor nucleus of N.vagus (DMV). In males, greater number of TH-ir cells was observed in the caudal locus coeruleus (LC), while they were more densely detected in the rostral LC of females. Regardless of sex, CHS elevated immunoreactivity of TH throughout the LC. Under basal conditions, greater number of TH-ir cells was detected in the rostral ventrolateral medulla (RVLM) of females. In contrast, CHS remarkably increased the number of TH-ir cells in the RVLM of males which was found to be decreased in females. There was no sex-related alteration in TH immunoreactivity in the nucleus tractus solitarius (NTS) of control rats, while CHS affected both sexes in a similar manner. Compared with females, CRF immunoreactivity was prominently observed in control males, while both of which were stimulated by CHS. ER-α/β was found to be co-expressed with TH in the NTS and LC which exhibit no alteration related to either sex or stress status. These results indicate a sexual dimorphism in the catecholaminergic and the CRF system in brainstem which might be involved in the CHS-induced autonomic and visceral dysfunction occurred in males.

The distribution and evolutionary dynamics of dopaminergic neurons in molluscs.

Dopamine is one of the most versatile neurotransmitters in invertebrates. It's distribution and plethora of functions is likely coupled to feeding ecology, especially in Euthyneura (the largest clade of molluscs), which presents the broadest spectrum of environmental adaptations. Still, the analyses of dopamine-mediated signaling were dominated by studies of grazers. Here, we characterize the distribution of dopaminergic neurons in representatives of two distinct ecological groups: the sea angel - obligate predatory pelagic mollusc Clione limacina (Pteropoda, Gymnosomata) and its prey - the sea devil Limacina helicina (Pteropoda, Thecosomata) as well as the plankton eater Melibe leonina (Nudipleura, Nudibranchia). By using tyrosine hydroxylase-immunoreactivity (TH-ir) as a reporter, we showed that the dopaminergic system is moderately conservative among euthyneurans. Across all studied species, small numbers of dopaminergic neurons in the central ganglia contrast to significant diversification of TH-ir neurons in the peripheral nervous system, primarily representing sensory-like cells, which predominantly concentrated in the chemotactic areas and projecting afferent axons to the central nervous system. Combined with α-tubulin immunoreactivity, this study illuminates the unprecedented complexity of peripheral neural systems in gastropod molluscs, with lineage-specific diversification of sensory and modulatory functions.

Effect of Selenium nanoparticles on Paraquat-induced-neuroinflammation and oligodendocyte modulation: Implication of the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway

BackgroundParaquat (PQ), is an extensively used herbicide and is a well-established powerful neurotoxin. However, the mechanism underlying its neurotoxicity still needs further investigation. Aim of workThe study investigated the pathogenesis of PQ-induced neuroinflammation of the substantia nigra pars compacta (SNPC) and cerebellum and evaluated the potential effect of selenium nanoparticles (SeN) against such neurotoxicity. MethodsThirty-six mice were randomly divided into three groups; Control group, PQ group: mice received PQ 10 mg/kg (i.p), and PQ + SeN group; mice received PQ in addition to oral SeN 0.1 mg/kg. All regimens were administered for 14 days. The mice's brains were processed for biochemical, molecular, histological, and immune-histochemical assessment. ResultsSeN increased the SNPC and cerebellum antioxidants (reduced glutathione, glutathione peroxidase, and superoxide dismutase 1) while decreasing malondialdehyde concentration. Also, SeN increased the anti-inflammatory interleukin (IL)-10 and decreased the pro-inflammatory IL-1β and −6 along with improving the angiogenic nitric oxide and reducing caspase-1. Further, western blots of phosphorylated Janus kinase (JAK2)/signal transducer and activator of transcription3 (STAT3) proteins showed a significant decline. Those improving effects of SeN on SNPC, and cerebellum were supported by the significantly preserved dopaminergic and Purkinje neurons, the enhanced myelin fibers on Luxol fast blue staining, and the marked increase in Olig-2, Platelet-derived growth factor-alpha, and tyrosine hydroxylase immunoreactivity. ConclusionSeN could mitigate PQ-induced neurotoxicity via its antioxidant, anti-inflammatory, and antiapoptotic properties.

Effect of methylglyoxal on Parkinson’s disease pathophysiology in the rotenone model

Objective: Type 2 diabetes mellitus patients have been reported to have a higher incidence of Parkinson’s disease. This study aimed to explore the effect of advanced glycation end products precursor methylglyoxal (MGO) on the pathophysiology of Parkinson’s disease in a rotenone model. Materials and Methods: Adult female Wistar rats (n=42) were divided into four groups. Rotenone toxicity was assessed by daily weight measurements and mortality rates. Effect of MGO on blood glucose was evaluated. Locomotor activity, rearing, and rotarod tests were performed to evaluate motor functions, and for neurodegeneration, tyrosine hydroxylase immunoreactivity in the striatum and substantia nigra regions was assessed. Results: The mortality rate was 9% in the rotenone-applied rats. The mean weight, locomotor activity, rearing activity, and longest time spent on a rotarod were lower in the MGO+Rotenone group than in the Control group. Tyrosine hydroxylase immunoreactivity in the striatum rostral to the anterior commissure in the MGO+Rotenone group was lower than that in the Control and MGO groups. The number of tyrosine hydroxylase positive cells in the substantia nigra pars compacta was comparable among the groups. Conclusion: When nigrostriatal degeneration was triggered, MGO was found to worsen motor dysfunction and increase damage to dopaminergic neuron projections.

Revealing functional-molecular parasympathetic dysfunction in PVC-induced cardiomyopathy via dual stressor PVC and exercise

Abstract Background Exercise intolerance is a common presentation of premature ventricular contractions-induced cardiomyopathy (PVC-CM). In a canine PVC-CM model, previous studies have shown cardiac autonomic nervous system remodeling, resulting in persistent sympathetic excess. Nevertheless, the molecular mechanisms and functional implications of this neural remodeling, as well as parasympathetic alterations, remain unclear. Purpose We aim to evaluate the functional-molecular mechanisms of parasympathetic remodeling and its potential contribution to exercise intolerance in an animal model of PVC-CM. Methods We studied 15 canines (8 experimental vs 7 sham controls) chronically instrumented with pacemakers and telemetry devices to deliver 12-weeks of bigeminal PVCs (200ms coupling) to induce PVC-CM and to record sympathetic (SNA), vagal nerve activity (VNA) and heart rate (HR) over this period. Exercise challenge was conducted in sinus rhythm (SR) and in the presence of bigeminal PVCs ("dual stressor") at baseline and after development of PVC-CM. Sympatho-vagal neural and HR responses were assessed during and after exercise at baseline and after PVC-CM development, with and without PVCs, thus comparing baseline SR, baseline with PVCs, CM SR and CM with PVCs. Western Blot was performed on intrinsic and extrinsic cardiac neural tissues to evaluate molecular mechanisms of neural remodeling. Results Compared to baseline, SNA was significantly higher in PVC-CM in all phases of exercise (rest, exercise, recovery, p=0.03). In contrast, VNA was significantly lower in PVC-CM than baseline during exercise recovery (P=0.014). After exercise, HR recovery (HRR) was impaired (p=0.001), VNA lower (p=0.014) and SNA (p=0.03) higher in PVC-CM compared with baseline. Tyrosine hydroxylase (TH) immunoreactivity in the left ventricle (LV, p=0.001) and stellate ganglia (SG, p=0.03) and trans-cardiac plasma NE levels (p=0.03) were higher in PVC-CM compared with sham. Choline Acetyltransferase (CHAT) was not significantly different in either vagus (p=0.33) or LV (p=0.8) between PVC-CM vs sham. Cardiac (LV) Nerve Growth Factor (NGF), Growth Associated Protein (GAP-43) and beta 1-adrenoreceptor levels were lower (p=0.042, p=0.003, p=0.002 respectively) whereas beta 2-adreno- and muscarinic M2-cholinergic receptors were higher (p=0.02, p<0.01 respectively) in PVC-CM compared with sham. Conclusion Neural remodeling in PVC-CM results in an imbalanced sympathetic excess and sympathetic-parasympathetic dysfunction characterized by a loss of sympathetic functional reserve during exercise and impaired parasympathetic activity and HRR after exercise. Adaptive downregulation of NGF might explain this imbalance and dysfunction. These data open the intriguing possibility of neural-targeted therapies to reverse remodeling and restore autonomic function disrupted by chronic PVCs.GraphsMolecular

Nasal application of kisspeptin-54 mitigates motor deficits by reducing nigrostriatal dopamine loss in hemiparkinsonian rats

Parkinson’s Disease is a progressive neurodegenerative disorder characterized by motor symptoms resulting from the loss of nigrostriatal dopaminergic neurons. Kisspeptins (KPs) are a family of neuropeptides that are encoded by the Kiss-1 gene, which exert their physiological effects through interaction with the GPR54 receptor. In the current investigation, we investigated the prospective protective effects of central KP-54 treatments on nigrostriatal dopaminergic neurons and consequent motor performance correlates in 6-hydroxydopamine (6-OHDA)-lesioned rats. Male adult Sprague Dawley rats underwent stereotaxic injection of 6-OHDA into the right medial forebrain bundle to induce hemiparkinsonism. Following surgery, rats received chronic central treatments of nasal or intracerebroventricular KP-54 (logarithmically increasing doses) for seven consecutive days. Motor performance was evaluated seven days post-surgery utilizing the open field test and catalepsy test. The levels of dopamine in the striatum were determined with mass spectrometry. Immunohistochemical analysis was conducted to assess the immunoreactivities of tyrosine hydroxylase (TH) and the GPR54 in the substantia nigra. The dose-response curve revealed a median effective dose value of ≈3 nmol/kg for both central injections. Due to its non-invasive and effective nature, nasal administration was utilized in the second phase of our study. Chronic administration of KP-54 (3nmol/kg, nasally) significantly protected 6-OHDA-induced motor deficits. Nasal KP-54 attenuated the loss of nigrostriatal dopaminergic neurons induced by 6-OHDA. Additionally, significant correlations were observed between motor performance and nigrostriatal dopamine levels. Immunohistochemical analysis demonstrated the localization of the GPR54 within TH-positive nigral cells. These findings suggest the potential efficacy of central KP-54 on motor impairments in hemiparkinsonism.

Remodeling of Ventricular Catecholaminergic Axons Following Chronic Intermittent Hypoxia in Mice

Chronic intermittent hypoxia (CIH) is a widely employed model for sleep apnea. The imbalance of autonomic control may contribute to CIH-induced cardiovascular diseases. Previously, we demonstrated that CIH increases sympathetic innervation of the atria. In this study, we determined whether CIH remodels peripheral cardiac tyrosine hydroxylase (TH, a marker for sympathetic efferent axons) innervation in the whole ventricles. The two challenges here were: 1) labeling the entire TH-IR axon innervation in the full thickness (~500 μm) of whole flat-mount ventricles. 2) Quantifying the topographical distribution of TH-IR axons through the thick ventricular walls at the single axon/varicosity scale. In this study, C57BL/6J mice (male, 2 months old, n=7/group) were exposed to room air (RA, 21% O2) or CIH (alternating between 21% and 5.7% O2 every 6 minutes for 10 hours/day) for 8-10 weeks. We prepared flat-mounts of the whole ventricles and septum and processed them with immunohistochemical labeling for TH. Using the Zeiss M2 Imager, confocal microscope, Zeiss Arivis Vision 4D, and Neurolucida system, we traced and digitized the TH-IR axons. We found that: 1) In RA and CIH mice, several large TH-immunoreactive (TH-IR) bundles from the base area entered the ventricles and septum. These large bundles branched into numerous smaller bundles as they traveled downward toward the apex and finally developed into fine varicose axons and terminals in the epicardial and myocardial layers. 2) Using Vision 4D, we were able to accurately detect, trace, and digitize all TH-IR axons in the ventricle walls with high accuracy. 3) CIH increased overall TH-IR axon density and network complexity of the whole ventricles and septum. 3) Abnormal CIH TH-IR axon terminal structures were frequently seen. 4) We geometrically and precisely registered the tracing data into a scaffold map for presentation and comparison in 3D. Altogether, CIH increased sympathetic innervation of the heart which may contribute to the augmented sympathetic drive. Our success in mapping data in the 3D heart scaffold will establish a heart-brain connectome/atlas. Supported by NIH 1 U01 NS113867-01 NIH R15 1R15HL137143-01A1, 2R01HL137832-05 and Carl Zeiss. 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.

Parvalbumin interneuron deficiency in the prefrontal and motor cortices of spontaneously hypertensive rats: an attention-deficit hyperactivity disorder animal model insight.

Attention deficit hyperactivity disorder (ADHD) is characterized by impairments in developmental-behavioral inhibition, resulting in impulsivity and hyperactivity. Recent research has underscored cortical inhibition deficiencies in ADHD via the gamma-aminobutyric acid (GABA)ergic system, which is crucial for maintaining excitatory-inhibitory balance in the brain. This study explored postnatal changes in parvalbumin (PV) immunoreactivity, indicating GABAergic interneuron types, in the prefrontal (PFC) and motor (MC) cortices of spontaneously hypertensive rats (SHRs), an ADHD animal model. Examining PV- positive (PV+) cells associated with dopamine D2 receptors (D2) and the impact of dopamine on GABA synthesis, we also investigated changes in the immunoreactivity of D2 and tyrosine hydroxylase (TH). Brain sections from 4- to 10-week-old SHRs and Wistar Kyoto rats (WKYs) were immunohistochemically analyzed, comparing PV+, D2+ cells, and TH+ fiber densities across age-matched SHRs and WKYs in specific PFC/MC regions. The results revealed significantly reduced PV+ cell density in SHRs: prelimbic (~20% less), anterior cingulate (~15% less), primary (~15% less), and secondary motor (~17% less) cortices. PV+ deficits coincided with the upregulation of D2 in prepubertal SHRs and the downregulation of TH predominantly in pubertal/postpubertal SHRs. Reduced PV+ cells in various PFC regions could contribute to inattention/behavioral alterations in ADHD, while MC deficits could manifest as motor hyperactivity. D2 upregulation and TH deficits may impact GABA synthesis, exacerbating behavioral deficits in ADHD. These findings not only shed new light on ADHD pathophysiology but also pave the way for future research endeavors.

Sleep deprivation induces late deleterious effects in a pharmacological model of Parkinsonism.

Parkinson's disease is a degenerative, chronic and progressive disease, characterized by motor dysfunctions. Patients also exhibit non-motor symptoms, such as affective and sleep disorders. Sleep disorders can potentiate clinical and neuropathological features and lead to worse prognosis. The goal of this study was to evaluate the effects of sleep deprivation (SD) in mice submitted to a progressive pharmacological model of Parkinsonism (chronic administration with a low dose of reserpine). Male Swiss mice received 20 injections of reserpine (0.1mg/kg) or vehicle, on alternate days. SD was applied before or during reserpine treatment and was performed by gentle handling for 6h per day for 10 consecutive days. Animals were submitted to motor and non-motor behavioral assessments and neurochemical evaluations. Locomotion was increased by SD and decreased by reserpine treatment. SD during treatment delayed the onset of catalepsy, but SD prior to treatment potentiated reserpine-induced catalepsy. Thus, although SD induced an apparent beneficial effect on motor parameters, a delayed deleterious effect on alterations induced by reserpine was found. In the object recognition test, both SD and reserpine treatment produced cognitive deficits. In addition, the association between SD and reserpine induced anhedonic-like behavior. Finally, an increase in oxidative stress was found in hippocampus of mice subjected to SD, and tyrosine hydroxylase immunoreactivity was reduced in substantia nigra of reserpine-treated animals. Results point to a possible late effect of SD, aggravating the deficits in mice submitted to the reserpine progressive model of PD.

Role of GBA variants in Lewy body disease neuropathology.

Rare and common GBA variants are risk factors for both Parkinson's disease (PD) and dementia with Lewy bodies (DLB). However, the degree to which GBA variants are associated with neuropathological features in Lewy body disease (LBD) is unknown. Herein, we assessed 943 LBD cases and examined associations of 15 different neuropathological outcomes with common and rare GBA variants. Neuropathological outcomes included LBD subtype, presence of a high likelihood of clinical DLB (per consensus guidelines), LB counts in five cortical regions, tyrosine hydroxylase immunoreactivity in the dorsolateral and ventromedial putamen, ventrolateral substantia nigra neuronal loss, Braak neurofibrillary tangle (NFT) stage, Thal amyloid phase, phospho-ubiquitin (pS65-Ub) level, TDP-43 pathology, and vascular disease. Sequencing of GBA exons revealed a total of 42 different variants (4 common [MAF > 0.5%], 38 rare [MAF < 0.5%]) in our series, and 165 cases (17.5%) had a copy of the minor allele for ≥ 1 variant. In analysis of common variants, p.L483P was associated with a lower Braak NFT stage (OR = 0.10, P < 0.001). In gene-burden analysis, presence of the minor allele for any GBA variant was associated with increased odds of a high likelihood of DLB (OR = 2.00, P < 0.001), a lower Braak NFT stage (OR = 0.48, P < 0.001), a lower Thal amyloid phase (OR = 0.55, P < 0.001), and a lower pS65-Ub level (β: -0.37, P < 0.001). Subgroup analysis revealed that GBA variants were most common in LBD cases with a combination of transitional/diffuse LBD and Braak NFT stage 0-II or Thal amyloid phase 0-1, and correspondingly that the aforementioned associations of GBA gene-burden with a decreased Braak NFT stage and Thal amyloid phase were observed only in transitional or diffuse LBD cases. Our results indicate that in LBD, GBA variants occur most frequently in cases with greater LB pathology and low AD pathology, further informing disease-risk associations of GBA in PD, PD dementia, and DLB.

Ultrastructural analysis of nigrostriatal dopaminergic terminals in a knockin mouse model of DYT1 dystonia.

DYT1 dystonia is associated with decreased striatal dopamine release. In this study, we examined the possibility that ultrastructural changes of nigrostriatal dopamine terminals could contribute to this neurochemical imbalance using a serial block face/scanning electron microscope (SBF/SEM) and three-dimensional reconstruction to analyse striatal tyrosine hydroxylase-immunoreactive (TH-IR) terminals and their synapses in a DYT1(ΔE) knockin (DYT1-KI) mouse model of DYT1 dystonia. Furthermore, to study possible changes in vesicle packaging capacity of dopamine, we used transmission electron microscopy to assess the synaptic vesicle size in striatal dopamine terminals. Quantitative comparative analysis of 80 fully reconstructed TH-IR terminals in the WT and DYT1-KI mice indicate (1) no significant difference in the volume of TH-IR terminals; (2) no major change in the proportion of axo-spinous versus axo-dendritic synapses; (3) no significant change in the post-synaptic density (PSD) area of axo-dendritic synapses, while the PSDs of axo-spinous synapses were significantly smaller in DYT1-KI mice; (4) no significant change in the contact area between TH-IR terminals and dendritic shafts or spines, while the ratio of PSD area/contact area decreased significantly for both axo-dendritic and axo-spinous synapses in DYT1-KI mice; (5) no significant difference in the mitochondria volume; and (6) no significant difference in the synaptic vesicle area between the two groups. Altogether, these findings suggest that abnormal morphometric changes of nigrostriatal dopamine terminals and their post-synaptic targets are unlikely to be a major source of reduced striatal dopamine release in DYT1 dystonia.

Prehatching development of the adrenal gland in Japanese quail (Coturnix japonica): Histological, immunohistochemical, and electron microscopic studies.

The adrenal glands play a key role in maintaining the physiological balance of birds and helping them to survive environmental changes. The objective of the present work was to give a detailed investigation of the histological, ultrastructural, and immunohistochemical findings of the adrenal gland in Japanese quail during the prehatching phase. The current study was performed on 45 healthy Japanese quail embryos at different prehatching periods. Our results showed the primordium of the quail's adrenocortical tissue appeared at 3 days of incubation as a thickening of the splanchnic mesoderm. The prospective chromaffin cells appeared at 5 days as clusters of cells migrated from the neural crest cells along the dorsal aorta toward the interrenal tissue. TH immunoreactivity was observed in the neural crest cells during their migration toward the adrenal primordium. Furthermore, these TH immunopositive cells were intermingled with the developing interrenal cell cords that developed from the coelomic epithelium. NSE immunostaining was detected within the cytoplasm of interrenal cells, chromaffin cells, and ganglion cells. Sox10 is expressed in chromaffin and ganglion cells with different staining intensities. On the 13th day of prehatching, both interrenal and chromaffin cells were β-catenin immunonegative, but on the 17th day, both cells were immunopositively. Our findings show that during prenatal life, the adrenal gland undergoes significant morphological changes. Together, the present data suggest that studying the prenatal development of the adrenal gland in birds is important for advancing our understanding of this critical organ and its functions. RESEARCH HIGHLIGHTS: The present study aimed to give a detailed study of the histological, ultrastructural, and immunohistochemical investigations of the adrenal gland in Japanese quail during the prehatching period. The interrenal primordium was observed on the third embryonic day, on the fifth ED the primordium of the chromaffin tissue appeared as row of migrating neural crest cell. At the ultrastructural level, the interrenal cells take steroid-secreting cells characters, they have varying amounts of lipid droplets and abundant mitochondria at 15th ED contained moderate number of lysosomes and mitochondria.

Oral Administration of Lactobacillus Inhibits the Permeability of Blood-Brain and Gut Barriers in a Parkinsonism Model.

It has recently been shown that the administration of probiotics can modulate the microbiota-gut-brain axis and may have favorable effects in models of Parkinson's disease. In this study, we used a hemiparkinsonism model induced by the neurotoxin 6-OHDA to evaluate the efficacy of the administration of a four-week administration of a mixture containing the microorganisms Lactobacillus fermentum LH01, Lactobacillus reuteri LH03, and Lactobacillus plantarum LH05. The hemiparkinsonism model induced an increase in rotations in the apomorphine test, along with a decrease in the latency time to fall in the rotarod test on days 14 and 21 after surgery, respectively. The administration of probiotics was sufficient to improve this condition. The model also showed a decrease in tyrosine hydroxylase immunoreactivity in the striatum and the number of labeled cells in the substantia nigra, both of which were counteracted by the administration of probiotics. The permeability of the blood-brain barrier was increased in the model, but this effect was reversed by the probiotics for both brain regions. The gut barrier was permeated with the model, and this effect was reversed and dropped to lower levels than the control group after the administration of probiotics. Finally, lipid peroxidation showed a pattern of differences similar to that of permeabilities. The inhibition of the permeability of the blood-brain and gut barriers mediated by the administration of probiotics will likely provide protection by downregulating oxidative stress, thus affecting the rotarod test performance.

The mesocortical dopaminergic system cannot explain hyperactivity in an animal model of attention deficit hyperactivity disorder (ADHD)- Spontaneously hypertensive rats (SHR)

BackgroundAttention deficit hyperactivity disorder (ADHD) is one of the most prevalent neuropsychiatric disorders with morphological brain abnormalities. There is a growing body of evidence that abnormalities in the dopaminergic system may account for ADHD pathogenesis. However, it is not clear whether the dopaminergic system is hyper or hypoactive. To determine whether the DA neurons and/or axons deficiency might be the cause of the postulated dopaminergic hypofunction in spontaneously hypertensive rats (SHR, animal model of ADHD), this study examined the dopaminergic neurons and fibers in the brain tissues of SHRs and Wistar Kyoto rats (WKY, control animals). Here, we performed immunohistochemical tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) staining on brain sections collected on juveniles from SHR and WKY. Moreover, behavioral testing to examine the hyperactivity in the open field area was also elucidated.ResultsThe mesocortical dopaminergic system appears to be normal in juvenile SHR, as suggested by (i) no alteration in the area density of TH-immunoreactive (TH-ir) dopaminergic neurons in the ventral tegmental area (VTA), (ii) no alterations in the volume density of TH-ir fibers in layer I of the prelimbic (PrL) subregion of medial PFC (mPFC), (iii) no alteration in the percentage of TH-ir dopaminergic fibers in layer I of the PrL subregion of mPFC as revealed by TH and/or DBH immunoreactivity. Furthermore, the SHR showed increased locomotor activity than WKY in the open field test.ConclusionsThe demonstration of no alteration in mesocortical dopaminergic neurons and fiber in SHR raises some concern about the position of SHR as an animal model of the inattentive subtype of ADHD. However, these results strengthen this strain as an animal model of hyperactive/impulsive subtype ADHD for future studies that may elucidate the underlying mechanism mediating hyperactivity and test various treatment strategies.

Effects of liquid diet intake on nerve growth in salivary glands of growing rats.

The growth of parotid glands is inhibited by liquid diet intake during growing period, while that of submandibular glands is not affected. This study examined how liquid diet intake affects nerve growth in the parotid and submandibular glands of growing rats, because nerves are closely involved in the maintenance of salivary gland structure. Male Wistar rats were weaned at 21 days of age. Then, rats were fed a pellet diet and a liquid diet in the control group and experimental group, respectively. At 0, 2, 4, or 8 weeks, they were euthanised by isoflurane overdose, and parotid and submandibular glands were removed. The frozen sections were made and immuno-stained with anti-protein gene product 9.5 (PGP 9.5) antibody (general nerve marker), anti-tyrosine hydroxylase (TH) antibody (sympathetic nerve marker), or anti-neuronal nitric oxide synthase (nNOS) antibody (parasympathetic nerve marker). In control parotid glands, scattered punctate or short linear patterns of PGP 9.5-positive sites were observed at week 0. After 2 weeks, PGP 9.5-positive sites, some of which were arranged in long linear patterns, increased in number. There were some TH-positive sites at week 0. After 2 weeks, there were increasing numbers of TH-positive sites, often in long linear patterns. At week 0, there were very few nNOS-positive sites, and nNOS immunoreactivity increased over time. After week 4, they demonstrated linear patterns. In the experimental parotid glands, there were fewer PGP 9.5- and nNOS-positive sites than in control parotid glands at each time point, although TH immunoreactivity was similar between two groups at each time point. In control submandibular glands, few punctate exhibited PGP 9.5-positive site were observed at week 0. At week 4, PGP 9.5 immunoreaction increased and showed linear patterns. TH-positive sites demonstrated punctate or short linear patterns at week 0, and thereafter TH immunoreactivity increased and were arranged in long linear patterns. There were few nNOS-positive sites at week 0, and they gradually increased after week 4. The immunoreactivities of all antibodies in the experimental submandibular glands were similar to those in the control at each time point. Parasympathetic nerve growth in rat parotid glands was inhibited by liquid diet intake during the growth period, while liquid diet intake did not affect parasympathetic nerve growth nor sympathetic nerve growth in rat submandibular glands.