Decreased Tyrosine Hydroxylase Research Articles

An exploratory study on the ability of manganese to supplement rotenone neurotoxicity in rats

Parkinson’s disease (PD) is a complex disorder, primarily of idiopathic origin, with environmental stressors like rotenone and manganese linked to its development. This study explores their potential interaction and resulting neurotoxicity, aiming to understand how environmental factors contribute to PD. In an eight-day experiment, male Wistar rats weighing 280–300 g were subjected to rotenone, manganese, or a combination of both. Various parameters were assessed, including body weight, behavior, serum markers, tissue damage, protein levels (tyrosine hydroxylase, Dopamine- and cAMP-regulated neuronal phosphoprotein –DARPP-32-, and α-synuclein), and mitochondrial function. Manganese heightened rotenone’s impact on reducing food intake without causing kidney or liver dysfunction. However, the combined exposure intensified neurotoxicity, which was evident in augmented broken nuclei and decreased tyrosine hydroxylase and DARPP-32 levels in the striatum. While overall mitochondrial function was preserved, co-administration reduced complex IV activity in the midbrain and liver. In conclusion, our findings revealed a parallel toxic effect induced by rotenone and manganese. Notably, while these substances do not target the same dopaminergic regions, a notable escalation in toxicity is evident in the striatum, the brain region where their toxic effects converge. This study highlights the need for further exploration regarding the interaction of environmental factors and their possible impact on the etiology of PD.

Bifenthrin Caused Parkinson's-Like Symptoms Via Mitochondrial Autophagy and Ferroptosis Pathway Stereoselectively in Parkin-/- Mice and C57BL/6 Mice.

It has been proposed that pyrethroid exposure contributes to the increasing prevalence of neurodegenerative diseases. However, the potential mechanisms remain unclear. The current study aimed to investigate the effects of the widely used pyrethroid bifenthrin on Parkinson's disease (PD) risk. Bifenthrin (1S-cis-bifenthrin, 1R-cis-bifenthrin, raceme) was administered to male Parkin-/- mice and C57BL/6 mice by oral gavage at a dose of 10mg/kg bw/day for 28days. Bifenthrin exposure significantly increased the time of pole climbing and decreased the period of rotarod running, indicating that bifenthrin decreased motor coordination in Parkin-/- mice, which was more evident by 1S-cis-bifenthrin. Furthermore, administration of bifenthrin induced obvious decreases in tyrosine hydroxylase (TH)+ cell count and the protein expression of TH. Increased protein of mitochondrial autophagy LC3B and p62 was observed after exposure to bifenthrin. Increased iron deposition and protein expression of iron transport transferrin (Tf) and transferrin receptor 2 (TfR2) was detected. 1S-cis-bifenthrin bound with Tf, TfR2, and GPX4 with lower binding energies than 1R-cis-bifenthrin, resulting in stronger interactions with these proteins. These results show structure-dependent PD-like effects of bifenthrin on motor activity and coordination associated with the disturbed mitochondrial autophagy and ferroptosis-related pathway. These data demonstrate that pyrethroid exposure increases the potential of Parkinson's-like symptoms via the ferroptosis pathway in Parkin-/- mice that is more pronounced than in C57BL/6 mice, providing a prospective enantioselective toxic effect of environmental neurotoxins on PD risk.

Role of Inflammation in the Development of COVID-19 to Parkinson's Disease.

The coronavirus disease 2019 (COVID-19) can lead to neurological symptoms such as headaches, confusion, seizures, hearing loss, and loss of smell. The link between COVID-19 and Parkinson's disease (PD) is being investigated, but more research is needed for a definitive connection. Datasets GSE22491 and GSE164805 were selected to screen differentially expressed gene (DEG), and immune infiltration and gene set enrichment analysis (GSEA) of the DEG were performed. WGCNA analyzed the DEG and selected the intersection genes. Potential biological functions and signaling pathways were determined, and diagnostic genes were further screened using gene expression and receiver operating characteristic (ROC) curves. Screening and molecular docking of ibuprofen as a therapeutic target. The effectiveness of ibuprofen was verified by constructing a PD model in vitro, and constructing "COVID19-PD" signaling pathway, and exploring the role of angiotensin-converting enzyme 2 (ACE2) in PD. A total of 13 DEG were screened from the GSE36980 and GSE5281 datasets. Kyoto encyclopedia of genes and genomes (KEGG) analysis showed that the DEG were mainly associated with the hypoxia-inducible factor (HIF-1), epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance, etc. After analysis, it is found that ibuprofen alleviates PD symptoms by inhibiting the expression of nuclear factor kappa-B (NF-κB), interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α). Based on signal pathway construction, the importance of ACE2 in COVID-19-induced PD has been identified. ACE2 is found to have widespread distribution in the brain. In the 1-methyl-4-phenyl-1,2,3,6-te-trahydropyridine (MPTP)-induced ACE2-null PD mice model, more severe motor and non-motor symptoms, increased NF-κB p65 and α-synuclein (α-syn) expression with significant aggregation, decreased tyrosine hydroxylase (TH), severe neuronal loss, and neurodegenerative disorders. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection increases the risk of PD through an inflammatory environment and downregulation of ACE2, providing evidence for the molecular mechanism and targeted therapy associated with COVID-19 and PD.

The roles of extrinsic neurons in modulating neuroimmune crosstalk during acute enteric infection with Citrobacter rodentium

Background: The intestinal tract is one of the most densely innervated organs in our body, containing extrinsic sensory and sympathetic neurons. With their cell bodies located outside of the gut, these neurons directly detect enteric pathogens and release immunomodulatory neurotransmitters or neuropeptides to communicate with immune cells in the gut. Specifically, sympathetic neurons secrete neurotransmitter norepinephrine, which activate β2 adrenergic receptors (β2ΑR) on immune cells to regulate immune functions. Recent studies from our lab, as well as others, have begun to highlight the neural regulation of immune responses during enteric infections. However, the precise pathways responsible for orchestrating these effects remain elusive. Hypothesis: We sought to determine whether extrinsic sensory and sympathetic neurons are implicated in host protective responses against enteric pathogen Citrobacter rodentium (C. rodentium). Methods: Mice were inoculated by oral gavage with C. rodentium (108 colony-forming units) or sterile luria broth. Bacterial colonization was quantified by homogenization of distal colon tissues and plating serial dilutions onto MacConkey agar. Relevant tissues were collected for qPCR, flow cytometry or histology. Genetically engineered Arc Targeted Recombination in Active Population (TRAP) mice were used to identify neurons that were activated during infection. These ArcTRAP mice received single intraperitoneal (i.p.) injection of 4-hydroxytamoxifen post-infection to “trap” active neurons, marking them tdTomato+. 6-hydroxydopamine (6OHDA) was used to chemically ablate sympathetic innervations to the colon via 3 consecutive daily i.p. injections. Results: At day 4 post-infection, there were significantly more active tdTomato+ neurons in the rostral ventrolateral medulla (RVLM) of the infected mice compared to the non-infected controls. This increase was more pronounced as the infection peaked at day 10, indicating that more neurons were being activated in the RVLM in response to C. rodentium in the gut. 6OHDA treatment significantly increased bacterial burden in distal colon at day 10 post-infection. This was associated with decreased tyrosine hydroxylase expression compared to the vehicle controls. Subsequently, qPCR revealed that there was increased pro-inflammatory cytokines expression in the colon of sympathectomized infected mice compared to the infected controls. Similarly, β2AR knockout significantly increased bacterial burden in distal colon at day 3 and 10 post-infection. Increased pro-inflammatory cytokines expression suggests an immunomodulatory role for β2AR during C. rodentium infection. Conclusions: These studies provided novel insights into the neuroimmune crosstalk that is crucial for acute enteric infections with C. rodentium. Specifically, these experiments may reveal how extrinsic neurons shape local immune responses in the gut. NIH NIAID R01AI150647; Graduate Student Support Program (UC Davis: School of Veterinary Medicine). 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.

Renal denervation improves cardiac function independently of afterload and restores myocardial norepinephrine levels in a rodent heart failure model.

Renal nerves play a critical role in cardiorenal interactions. Renal denervation (RDN) improved survival in some experimental heart failure (HF) models. It is not known whether these favorable effects are indirect, explainable by a decrease in vascular afterload, or diminished neurohumoral response in the kidneys, or whether RDN procedure per se has direct myocardial effects in the failing heart. To elucidate mechanisms how RDN affects failing heart, we studied load-independent indexes of ventricular function, gene markers of myocardial remodeling, and cardiac sympathetic signaling in HF, induced by chronic volume overload (aorto-caval fistula, ACF) of Ren2 transgenic rats. Volume overload by ACF led to left ventricular (LV) hypertrophy and dysfunction, myocardial remodeling (upregulated Nppa, MYH 7/6 genes), increased renal and circulating norepinephrine (NE), reduced myocardial NE content, increased monoaminoxidase A (MAO-A), ROS production and decreased tyrosine hydroxylase (+) nerve staining. RDN in HF animals decreased congestion in the lungs and the liver, improved load-independent cardiac function (Ees, PRSW, Ees/Ea ratio), without affecting arterial elastance or LV pressure, reduced adverse myocardial remodeling (Myh 7/6, collagen I/III ratio), decreased myocardial MAO-A and inhibited renal neprilysin activity. RDN increased myocardial expression of acetylcholinesterase (Ache) and muscarinic receptors (Chrm2), decreased circulating and renal NE, but increased myocardial NE content, restoring so autonomic control of the heart. These changes likely explain improvements in survival after RDN in this model. The results suggest that RDN has remote, load-independent and favorable intrinsic myocardial effects in the failing heart. RDN therefore could be a useful therapeutic strategy in HF.

Mice Expressing A53T/A30P Mutant Alpha-Synuclein in Dopamine Neurons Do Not Display Behavioral Deficits.

Alpha-synuclein has been implicated in neurodegenerative diseases such as Parkinson's disease and dementia with Lewy bodies, with A53T and A30P mutations shown to be disease causing. It has been reported that hemizygous transgenic mice with tyrosine hydroxylase promotor-driven expression of A53T/A30P mutant alpha-synuclein in dopamine neurons provide a useful preclinical model of these conditions by virtue of developing behavioral deficits. Here, we report a lack of replication of this finding. Despite detecting robust overexpression of A53T/A30P mutant alpha-synuclein in dopamine neurons, we did not observe decreased tyrosine hydroxylase immunofluorescence or behavioral deficits in these mice. Our results demonstrate that preclinical models of synucleinopathy need careful validation in the field.

Postnatal Exposure to the Endocrine Disruptor Dichlorodiphenyltrichloroethane Affects Adrenomedullary Chromaffin Cell Physiology and Alters the Balance of Mechanisms Underlying Cell Renewal.

Dichlorodiphenyltrichloroethane (DDT) is a wide-spread systemic pollutant with endocrine disrupting properties. Prenatal exposure to low doses of DDT has been shown to affect adrenal medulla growth and function. The role of postnatal exposure to DDT in developmental disorders remains unclear. The aim of the present investigation is to assess growth parameters and the expression of factors mediating the function and renewal of chromaffin cells in the adult adrenal medulla of male Wistar rats exposed to the endocrine disruptor o,p'-DDT since birth until sexual maturation. The DDT-exposed rats exhibited normal growth of the adrenal medulla but significantly decreased tyrosine hydroxylase production by chromaffin cells during postnatal period. Unlike the control, the exposed rats showed enhanced proliferation and reduced expression of nuclear β-catenin, transcription factor Oct4, and ligand of Sonic hedgehog after termination of the adrenal growth period. No expression of pluripotency marker Sox2 and absence of Ascl 1-positive progenitors were found in the adrenal medulla during postnatal ontogeny of the exposed and the control rats. The present findings indicate that an increase in proliferative activity and inhibition of the formation of reserve for chromaffin cell renewal, two main mechanisms for cell maintenance in adrenal medulla, in the adult DDT-exposed rats may reflect a compensatory reaction aimed at the restoration of catecholamine production levels. The increased proliferation of chromaffin cells in adults suggests excessive growth of the adrenal medulla. Thus, postnatal exposure to DDT alters cell physiology and increases the risk of functional insufficiency and hyperplasia of the adrenal medulla.

Aqueous leaf extract of Phyllanthus amarus protects against oxidative stress and misfiring of dopaminergic neurons in Paraquat-induced Parkinson’s disease-like model of adult Wistar rats

Background of the studyPhyllanthus amarus has high nutritional value and is beneficial in managing and treating diverse ailments. This study assessed the role of aqueous leaf extract of Phyllanthus amarus on Paraquat (PQ) induced neurotoxicity in the substantia nigra of Wistar rats. Materials and methodsThe role of aqueous leaves extract of Phyllanthus amarus was assessed using an open field test (OFT) for motor activity, oxidative stress biomarkers [Catalase (CAT), and Superoxide Dismutase (SOD)], histological examination (H and E stained) for cytoarchitectural changes and immunohistochemical studies using tyrosine hydroxylase (TH) as a marker for dopaminergic neurons. Forty-two (42) rats were categorized into six groups (n = 7); group 1: control was administered 0.5 ml/kg distilled water, group 2: received 10 mg/kg PQ + 10 mg/kg L-dopa as reference drug, group 3; received 10 mg/kg PQ, while group 4: received 10 mg/kg PQ + 200 mg/kg P. amarus, group 5: received 10 mg/kg PQ + 300 mg/kg P. amarus, and group 6: received 10 mg/kg PQ + 400 mg/kg P. amarus respectively, for 14 days. All administrations were done orally; a significant difference was set at p < 0.05. Results and discussionThe study's open field test (OFT) revealed no motor activity deficit with Paraquat (PQ) exposure. Also, cytoarchitectural distortions were not observed with Paraquat (PQ) only treatment group compared to the control and other groups pretreated with P. amarus and L-dopa. Moreover, the Paraquat (PQ) only treatment group showed oxidative stress by significantly decreasing the antioxidant enzyme (SOD) compared to the control and L-dopa pretreated group. A significant decrease in tyrosine hydroxylase (TH) expressing dopaminergic neurons was also observed in Paraquat (PQ) only treatment. However, P. amarus treatment showed therapeutic properties by significantly increasing tyrosine hydroxylase (TH) expressing dopaminergic neuron levels relative to control. ConclusionAqueous leaf extract of Phyllanthus amarus possesses therapeutic properties against Paraquat (PQ) induced changes in the substantia nigra of Wistar rats.

The gut microbiota metabolite butyrate mitigates MPTP/MPP+ -induced Parkinson's disease by inhibiting the JAK2/STAT3 signaling pathway.

Butyrate (BU), a gut microbiota-derived metabolite, has been reported to play a neuroprotective role in Parkinson's disease (PD). However, the specific molecular mechanism of BU has not been fully interpreted. This work aimed to verify the protective effects of BU against MPTP/MPP+ -induced neurotoxicity and explore the mechanisms involved. The results showed that BU protected against MPTP-induced motor dysfunction and decreased tyrosine hydroxylase (TH) and dopamine transporter (DAT) levels. Additionally, BU pretreatment improved PC12 cell viability and reduced MPP+ -induced PC12 cell apoptosis. BU treatment also attenuated MPP+ -stimulated oxidative stress and inflammatory response in PC12 cells. Furthermore, BU inhibited MPTP/MPP+ -induced hyperactivation of the JAK2/STAT3 signaling in mice and PC12 cells. Besides, a JAK2 agonist, Coumermycin A1 (C-A1), substantially reversed BU-mediated inhibition on JAK2/STAT3 phosphorylation in MPP+ -challenged PC12 cells and abated BU-induced repression on MPP+ -triggered apoptosis, oxidative stress, and inflammatory response in PC12 cells. To sum up, BU might exert neuroprotective effects against MPP+ /MPTP-induced neurotoxicity by inactivating the JAK2/STAT3 signaling.

Myeloid-specific blockade of notch signaling alleviates dopaminergic neurodegeneration in Parkinson's disease by dominantly regulating resident microglia activation through NF-κB signaling.

Yolk sac-derived microglia and peripheral monocyte-derived macrophages play a key role during Parkinson's disease (PD) progression. However, the regulatory mechanism of microglia/macrophage activation and function in PD pathogenesis remains unclear. Recombination signal-binding protein Jκ (RBP-J)-mediated Notch signaling regulates macrophage development and activation. In this study, with an 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) hydrochloride-induced acute murine PD model, we found that Notch signaling was activated in amoeboid microglia accompanied by a decrease in tyrosine hydroxylase (TH)-positive neurons. Furthermore, using myeloid-specific RBP-J knockout (RBP-JcKO) mice combined with a PD model, our results showed that myeloid-specific disruption of RBP-J alleviated dopaminergic neurodegeneration and improved locomotor activity. Fluorescence-activated cell sorting (FACS) analysis showed that the number of infiltrated inflammatory macrophages and activated major histocompatibility complex (MHC) II+ microglia decreased in RBP-JcKO mice compared with control mice. Moreover, to block monocyte recruitment by using chemokine (C-C motif) receptor 2 (CCR2) knockout mice, the effect of RBP-J deficiency on dopaminergic neurodegeneration was not affected, indicating that Notch signaling might regulate neuroinflammation independent of CCR2+ monocyte infiltration. Notably, when microglia were depleted with the PLX5622 formulated diet, we found that myeloid-specific RBP-J knockout resulted in more TH+ neurons and fewer activated microglia. Ex vitro experiments demonstrated that RBP-J deficiency in microglia might reduce inflammatory factor secretion, TH+ neuron apoptosis, and p65 nuclear translocation. Collectively, our study first revealed that RBP-J-mediated Notch signaling might participate in PD progression by mainly regulating microglia activation through nuclear factor kappa-B (NF-κB) signaling.

SYNJ1 rescues motor functions in hereditary and sporadic Parkinson's disease mice by upregulating TSP-1 expression

This study aimed to explore the role of SYNJ1 in Parkinson's disease (PD) and its potential as a neuroprotective factor. We found that SYNJ1 was decreased in the SN and striatum of hSNCA*A53T-Tg and MPTP-induced mice compared to normal mice, associated with motor dysfunction, increased α-synuclein and decreased tyrosine hydroxylase. To investigate its neuroprotective effects, SYNJ1 expression was upregulated in the striatum of mice through injection of the rAdV-Synj1 virus into the striatum, which resulted in the rescue of behavioral deficiencies and amelioration of pathological changes. Subsequently, transcriptomic sequencing, bioinformatics analysis and qPCR were conducted in SH-SY5Y cells following SYNJ1 gene knockdown to identify its downstream pathways, which revealed decreased expression of TSP-1 involving extracellular matrix pathways. The virtual protein-protein docking further suggested a potential interaction between the SYNJ1 and TSP-1 proteins. This was followed by the identification of a SYNJ1-dependent TSP-1 expression model in two PD models. The coimmunoprecipitation experiment verified that the interaction between SYNJ1 and TSP-1 was attenuated in 11-month-old hSNCA*A53T-Tg mice compared to normal controls. Our findings suggest that overexpression of SYNJ1 may protect hSNCA*A53T-Tg and MPTP-induced mice by upregulating TSP-1 expression, which is involved in the extracellular matrix pathways. This suggests that SYNJ1 could be a potential therapeutic target for PD, though more research is needed to understand its mechanism.

Effects of sensory deprivation on glomerular interneurons in the mouse olfactory bulb: differences in mortality and phenotypic adjustment of dopaminergic neurons.

Neurogenesis persists in the mammalian subventricular zone after birth, producing various populations of olfactory bulb (OB) interneurons, including GABAergic and mixed dopaminergic/GABAergic (DA) neurons for the glomerular layer. While olfactory sensory activity is a major factor controlling the integration of new neurons, its impact on specific subtypes is not well understood. In this study we used genetic labeling of defined neuron subsets, in combination with reversible unilateral sensory deprivation and longitudinal in vivo imaging, to examine the behavior of postnatally born glomerular neurons. We find that a small fraction of GABAergic and of DA neurons die after 4 weeks of sensory deprivation while surviving DA-neurons exhibit a substantial decrease in tyrosine hydroxylase (TH) expression levels. Importantly, after reopening of the naris, cell death is arrested and TH levels go back to normal levels, indicating a specific adaptation to the level of sensory activity. We conclude that sensory deprivation induces adjustments in the population of glomerular neurons, involving both, cell death and adaptation of neurotransmitter use in specific neuron types. Our study highlights the dynamic nature of glomerular neurons in response to sensory deprivation and provide valuable insights into the plasticity and adaptability of the olfactory system.

Vitamin E Analog Trolox Attenuates MPTP-Induced Parkinson's Disease in Mice, Mitigating Oxidative Stress, Neuroinflammation, and Motor Impairment.

Trolox is a potent antioxidant and a water-soluble analog of vitamin E. It has been used in scientific studies to examine oxidative stress and its impact on biological systems. Trolox has been shown to have a neuroprotective effect against ischemia and IL-1β-mediated neurodegeneration. In this study, we investigated the potential protective mechanisms of Trolox against a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease mouse model. Western blotting, immunofluorescence staining, and ROS/LPO assays were performed to investigate the role of trolox against neuroinflammation, the oxidative stress mediated by MPTP in the Parkinson's disease (PD) mouse model (wild-type mice (C57BL/6N), eight weeks old, average body weight 25-30 g). Our study showed that MPTP increased the expression of α-synuclein, decreased tyrosine hydroxylase (TH) and dopamine transporter (DAT) levels in the striatum and substantia nigra pars compacta (SNpc), and impaired motor function. However, Trolox treatment significantly reversed these PD-like pathologies. Furthermore, Trolox treatment reduced oxidative stress by increasing the expression of nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Lastly, Trolox treatment inhibited the activated astrocytes (GFAP) and microglia (Iba-1), also reducing phosphorylated nuclear factor-κB, (p-NF-κB) and tumor necrosis factor-alpha (TNF-α) in the PD mouse brain. Overall, our study demonstrated that Trolox may exert neuroprotection on dopaminergic neurons against MPTP-induced oxidative stress, neuroinflammation, motor dysfunction, and neurodegeneration.

Effects of sodium oxybate on hypocretin/orexin and locus coeruleus neurons.

Long-term use of sodium oxybate (SXB), (also called gamma-hydroxybutyrate [GHB]) attenuates the cataplexy and sleepiness of human narcolepsy. We had previously found that chronic opiate usage in humans and long-term opiate administration to mice significantly increased the number of detected hypocretin/orexin (Hcrt) neurons, decreased their size, and increased Hcrt level in the hypothalamus. We also found that opiates significantly decreased cataplexy in human narcoleptics as well as in narcoleptic mice and that cessation of locus coeruleus neuronal activity preceded and was tightly linked to cataplectic attacks in narcoleptic dogs. We tested the hypothesis that SXB produces changes similar to opiates and now report that chronic SXB administration significantly increased the size of Hcrt neurons, the reverse of what we had seen with opiates in humans and mice. Levels of Hcrt in the hypothalamus were nonsignificantly lower, in contrast to the significant increase in hypothalamic Hcrt level after opiates. SXB decreased tyrosine hydroxylase levels in the locus coeruleus, the major descending projection of the hypocretin system, also the reverse of what we saw with opioids. Therefore despite some similar effects on narcoleptic symptomatology, SXB does not produce anatomical changes similar to those elicited by opiates. Analysis of changes in other links in the cataplexy pathway might further illuminate SXB's mechanism of action on narcolepsy.

Neuroprotective Effects of Nicotinamide against MPTP-Induced Parkinson's Disease in Mice: Impact on Oxidative Stress, Neuroinflammation, Nrf2/HO-1 and TLR4 Signaling Pathways.

Nicotinamide (NAM) is the amide form of niacin and an important precursor of nicotinamide adenine dinucleotide (NAD), which is needed for energy metabolism and cellular functions. Additionally, it has shown neuroprotective properties in several neurodegenerative diseases. Herein, we sought to investigate the potential protective mechanisms of NAM in an intraperitoneal (i.p) 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) mouse model (wild-type mice (C57BL/6N), eight weeks old, average body weight 25-30 g). The study had four groups (n = 10 per group): control, MPTP (30 mg/kg i.p. for 5 days), MPTP treated with NAM (500 mg/kg, i.p for 10 days) and control treated with NAM. Our study showed that MPTP increased the expression of α-synuclein 2.5-fold, decreased tyrosine hydroxylase (TH) 0.5-fold and dopamine transporters (DAT) levels up to 0.5-fold in the striatum and substantia nigra pars compacta (SNpc), and impaired motor function. However, NAM treatment significantly reversed these PD-like pathologies. Furthermore, NAM treatment reduced oxidative stress by increasing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) between 0.5- and 1.0-fold. Lastly, NAM treatment regulated neuroinflammation by reducing Toll-like receptor 4 (TLR-4), phosphorylated nuclear factor-κB, tumor (p-NFκB), and cyclooxygenase-2 (COX-2) levels by 0.5- to 2-fold in the PD mouse brain. Overall, these findings suggest that NAM exhibits neuroprotective properties and may be an effective therapeutic agent for PD.

Mepirapim, a novel synthetic cannabinoid, induces Parkinson's disease-related behaviors by causing maladaptation of the dopamine system in the brain.

Mepirapim is a novel synthetic cannabinoid that first appeared on the illicit drug market in 2013. In recent years, recreational abuse of Mepirapim has caused serious emergencies, posing a threat to public health. However, there are no legal regulations to prohibit the use of Mepirapim, as there is no scientific evidence for the dangerous pharmacological effects of the drug. In the present study, we investigated the dangerous neurotoxic effects of Mepirapim through behavioral and molecular experiments in mice (ICR/CD1, male, 25-30g). In particular, based on a previous study that Mepirapim activates the dopamine system, we evaluated whether high-dose Mepirapim [single (15, 30, or 60mg·kg-1, i.p.) or multiple (8, 15, or 30mg·kg-1, i.p. × 4 at 2h intervals)] treatment causes Parkinson's disease-related symptoms through damage to the dopamine system. In the result, we found that Mepirapim treatment caused comprehensive Parkinson's disease-related symptoms, including motor impairment, cognitive deficits and mood disorders. Furthermore, we confirmed the maladaptation in dopamine-related neurochemicals, including decreased dopamine levels, decreased tyrosine hydroxylase expression, and increased α-synuclein expression, in the brains of mice treated with Mepirapim. Taken together, these results indicate that Mepirapim has dangerous neurotoxic effects that induces Parkinson's disease-related behaviors by causing maladaptation of the dopamine system in the brain. Based on these findings, we propose the strict regulation of recreational abuse and therapeutic misuse of Mepirapim.

Prenatal Morphine Exposure Differentially Alters Addictive and Emotional Behavior in Adolescent and Adult Rats in a Sex-Specific Manner.

The effects of prenatal opioid exposure in adult animals has been widely studied, but little is known about the effects of prenatal opioid on adolescents. Most of the risk behaviors associated with drug abuse are initiated during adolescence. The developmental state of the adolescent brain makes it vulnerable to initiate drug use and susceptible to drug-induced brain changes. In this study, pregnant rats were subcutaneously injected with an increasing dose of morphine (5mg/kg, 7mg/kg, 10mg/kg) for 9 days since the gestation day 11. The effects of prenatal morphine (PNM) on learning and memory, anxiety- and depressive- like behavior, morphine induced conditioned place preference (CPP) as well as locomotor sensitization were tested in both adolescent and adult rats. The results showed that: (1) PNM decreased anxiety-like behavior in both adolescent and adult female rats, but not males; (2) PNM decreased depressive-like behavior in adolescent but increased depressive -like behavior in adult females; (3) PNM increased low dose morphine induced locomotor sensitization in females; (4) PNM decreased tyrosine hydroxylase (TH) expression in the prefrontal cortex but decreased dopamine D1 receptor expression in the nucleus-accumbens (NAc) in female rats. These results suggested that PNM altered the emotional and addictive behavior mainly in female rats, with female rats being less anxiety and depressive during adolescence, but more depressive in adult, and more sensitive to low dose morphine induced locomotor activity sensitization, which might be mediated in part by the differential expression of the TH, dopamine D1 receptors in the female brain.

210-LB: Central Regulation of Peripheral Adiposity by Nos1PVHNeurons

Within the CNS, the paraventricular nucleus of the hypothalamus (PVH) is critical for energy homeostasis, as developmental or mechanical lesions targeting the PVH lead to massive obesity. The PVH is composed of multiple cell types expressing an assortment of neuropeptides, receptors, and enzymes, including a subset of neurons expressing nitric oxide synthase-1 (Nos1PVH) . Nos1PVH neurons project to the nucleus of the solitary tract and the intermediolateral column of the spinal cord suggesting a neural substrate through which Nos1PVH neurons might directly modulate sympathetic output and energy balance [1]. To understand the necessity of Nos1PVH neurons in basal energy balance regulation, we bilaterally injected the PVH of Nos1-iCre mice with an AAV expressing a Cre-dependent tetanus toxin (Nos1TT) . Chronic silencing of the Nos1PVH resulted in acute onset of subcutaneous and visceral obesity without changes in food intake. Surprisingly, metabolic analyses indicated no significant changes in energy expenditure, although Nos1TT treated animals preferred to utilize fat as the predominant fuel source. Pair feeding experiments also confirmed that the obesity observed in Nos1TT animals was not secondary to increased caloric intake. Adipose tissues receive input from CNS cell groups that are part of the general SNS outflow from the brain [2, 3]. Analysis of subcutaneous white adipose tissue of Nos1TT animals revealed a significant decrease in tyrosine hydroxylase (TH) immunoactivity within WAT suggesting decreased capacity for sympathetic activation of lipolysis. These data indicate that Nos1PVH neurons regulate energy homeostasis possibly through changes in peripheral aspects of energy balance without the influence of energy consumption. Therefore, the main goal of this project is to clarify the physiological roles of Nos1PVH neurons in the regulation of peripheral adiposity, which may lead to the development of more refined anti-obesity therapies. 1. PMID: 25392498 2. PMID: 9688991 3. PMID: 15142857 Disclosure L. D. Faulkner: n/a. K. Lewis: None. T. H. Meek: Employee; Novo Nordisk. A. J. Mercer: Employee; Novo Nordisk. O. A. Macdougald: None. D. Olson: Research Support; AstraZeneca, Novo Nordisk A/S. Funding American Diabetes Association (7-21-PMF-020) ; Novo Nordisk A/S; National Institutes of Health (5R01DK104999-05)

1398-P: Lactobacillus rhamnosus Attenuates Depressive-Like Behavior in High-Fat Diet Fed Mice and Regulates Tyrosine Hydroxylase

Prevalence of depression is higher in diabetic patients compared to healthy humans due to a shared pathogenesis including insulin resistance and inflammation. These factors are also linked to intestinal dysbiosis. Interestingly, preventive intake of probiotic lactobacilli has been shown to improve dysbiosis along with mood and metabolism. Yet, a potential therapeutic role and underlying mechanism of Lactobacillus rhamnosus GG (LGG, ATCC 53103) to improve emotional behavior in diet-induced obesity is unknown. Male C57BL/6N mice were fed a low-fat diet (LFD, 10% kcal from fat) or high-fat diet (HFD, 45% kcal from fat) for 6 weeks and followed by daily oral gavage of vehicle or 1x108 CFU of LGG. Dark-Light Box Test was used to evaluate anxiety, Mousetail Suspension Test (MST) and Splash Test were used to assess depressive-like behavior and motivation for self-care. Cecal microbiome composition was analyzed using 16S rRNA Sequencing. Plasma and CSF were collected for metabolomic analysis, and gene expression was analyzed using qPCR. We observed that 12 weeks of HFD feeding increased anxiety and depressive-like behavior. Strikingly, LGG decreased specifically depressive-like behavior in the MST which was confirmed by the Splash Test. Metagenomics analysis revealed that HFD but not LGG alters cecal microbiome composition, indicating a transient effect. Moreover, HFD feeding significantly altered plasma lipid metabolism whereas LGG decreased branched chain amino acids which associated with improved emotional behavior. In dopaminergic brain regions, LGG restored the HFD-induced decrease of tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, while not altering enzymes responsible for dopamine degradation. Our data indicate that LGG attenuates specifically depressive-like behavior in HFD-fed mice with a molecular signature of restored dopamine synthesis. Disclosure M.Schell: Other Relationship; Novozymes A/S, Denmark. K.Wardelmann: None. R.Hauffe: None. M.Rath: None. S.Chopra: None. A.Kleinridders: Other Relationship; Novozymes. Funding German Ministry of Education and Research (BMBF) and the State of Brandenburg (DZD grant 82DZD00302 and BMBF grant 031B0569) .

Glycogen synthase kinase-3 inhibition affects dopamine metabolism by decreasing tyrosine hydroxylase activity

Glycogen synthase kinase-3 inhibition affects dopamine metabolism by decreasing tyrosine hydroxylase activity