Tyrosine Hydroxylase Activity Research Articles

Effects on Dopaminergic Neurons are Secondary in COX-Deficient Locomotor Dysfunction in <i>Drosophila</i>

Dopaminergic (DA) neurons have been implicated as key targets in Parkinson's disease (PD) and other neurological disorders, and are considered to be highly vulnerable to mitochondrial dysfunction, a common feature of such diseases. Here we investigated a Drosophila model of PD in which locomotor impairment is brought about by pan-neuronal RNAi knockdown of subunit COX7A of cytochrome oxidase (COX). Despite minimal neuronal loss by apoptosis, the expression and activity of tyrosine hydroxylase was decreased by half. Surprisingly, COX7A knockdown specifically targeted to DA neurons did not produce locomotor defect. Instead, using various drivers, we found that COX7A knockdown in specific groups of cholinergic and glutamatergic neurons underlay the phenotype. The vulnerability of DA neurons to mitochondrial dysfunction as a cause of impaired locomotion should be reassessed.

Effects of silybin, flavonolignans, on catecholamine secretion and tyrosine hydroxylase activity in cultured bovine adrenal medullary cells

Effects of silybin, flavonolignans, on catecholamine secretion and tyrosine hydroxylase activity in cultured bovine adrenal medullary cells

Glucagon-Like Peptide-1 Receptor Controls Exocytosis in Chromaffin Cells by Increasing Full Fusion Events

Glucagon-like peptide-1 receptor (GLP-1R) agonists’ ability to increase insulin secretion and promote satiety have led to their development for the treatment of type 2 diabetes and obesity; while these beneficial effects have been attributed to receptors in the pancreas and hypothalamus, the function and importance of extra-pancreatic GLP-1Rs in other organ systems is not well understood despite the possibilities for targeting these receptors for other indications. We have analysed the contribution of GLP-1R to the secretory responses of adrenal medulla, a key player in stress responses. Exendin-4 (Ex-4), a synthetic analogue of GLP-1, increased the synthesis and the release of catecholamines (CA) by increasing cAMP production, without the participation of EPAC (Exchange Proteins Activated by cAMP). Ex-4 increased CA synthesis by promoting the activation of tyrosine hydroxylase (TH), and moreover increased the quantum size of exocytotic events by switching exocytosis from partial to full fusion. Our results give a strong support to the role of GLP-1 in the fine control of glycaemia and blood pressure by sympathetic tissues.

Histidine residues at the copper-binding site in human tyrosinase are essential for its catalytic activities

Tyrosinase is a copper-binding enzyme involved in melanin biosynthesis. However, the detailed structure of human tyrosinase has not yet been solved, along with the identification of the key sites responsible for its catalytic activity. We used site-directed mutagenesis to identify the residues critical for the copper binding of human tyrosinase. Seven histidine mutants in the two copper-binding sites were generated, and catalytic activities were characterised. The tyrosine hydroxylase activities of the CuA site mutants were approximately 50% lower than those of the wild-type tyrosinase, while the dopa oxidation activities of the mutants were not significantly different from that of wild-type tyrosinase. By contrast, mutations at CuB significantly decreased both tyrosine hydroxylation and dopa oxidation activities, confirming that the catalytic sites for these two activities are at least partially distinct. These findings provide a useful resource for further structural determination and development of tyrosinase inhibitors in the cosmetic and pharmaceutical industries.

A targeted neurotransmitter quantification and nontargeted metabolic profiling method for pharmacometabolomics analysis of olanzapine by using UPLC-HRMS.

Neurotransmitters (NTs) are specific endogenous metabolites that act as “messengers” in synaptic transmission and are widely distributed in the central nervous system. Olanzapine (OLZ), a first-line antipsychotic drug, plays a key role in sedation and hypnosis, but, it presents clinical problems with a narrow therapeutic window, large individual differences and serious adverse effects, as well as an unclear mechanism in vivo. Herein, a simultaneous targeted NT quantification and nontargeted metabolomics method was developed and validated for pharmacometabolomics analysis of OLZ by using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UPLC-HRMS). Considering the low physiological concentrations of NTs, a full MS scan and target selective ion monitoring (tSIM) scan were combined for nontargeted metabolomics and targeted NT quantification, respectively. By using this strategy, NTs at a very low physiological concentration can be accurately detected and quantified in biological samples by tSIM scans. Moreover, simultaneously nontargeted profiling was also achieved by the full MS scan. The newly established UPLC-HRMS method was further used for the pharmacometabolomics study of OLZ. Statistical analysis revealed that tryptophan, 5-hydroxytryptophan, 5-hydroxytryptamine, γ-aminobutyric acid etc. were significantly downregulated, while tyrosine was significantly upregulated, which suggested that OLZ could promote the downstream phase II reaction of 5-hydroxytryptamine, inhibit tyrosine hydroxylase activity, and increase the activity of γ-aminobutyric acid transaminase. In conclusion, this method could provide novel insights for revealing the pharmacodynamic effect and mechanism of antipsychotic drugs.

Muscle-derived Dpp regulates feeding initiation via endocrine modulation of brain dopamine biosynthesis.

In animals, the brain regulates feeding behavior in response to local energy demands of peripheral tissues, which secrete orexigenic and anorexigenic hormones. Although skeletal muscle is a key peripheral tissue, it remains unknown whether muscle-secreted hormones regulate feeding. In Drosophila, we found that decapentaplegic (dpp), the homolog of human bone morphogenetic proteins BMP2 and BMP4, is a muscle-secreted factor (a myokine) that is induced by nutrient sensing and that circulates and signals to the brain. Muscle-restricted dpp RNAi promotes foraging and feeding initiation, whereas dpp overexpression reduces it. This regulation of feeding by muscle-derived Dpp stems from modulation of brain tyrosine hydroxylase (TH) expression and dopamine biosynthesis. Consistently, Dpp receptor signaling in dopaminergic neurons regulates TH expression and feeding initiation via the downstream transcriptional repressor Schnurri. Moreover, pharmacologic modulation of TH activity rescues the changes in feeding initiation due to modulation of dpp expression in muscle. These findings indicate that muscle-to-brain endocrine signaling mediated by the myokine Dpp regulates feeding behavior.

ASL Metabolically Regulates Tyrosine Hydroxylase in the Nucleus Locus Coeruleus

SummaryPatients with germline mutations in the urea-cycle enzyme argininosuccinate lyase (ASL) are at risk for developing neurobehavioral and cognitive deficits. We find that ASL is prominently expressed in the nucleus locus coeruleus (LC), the central source of norepinephrine. Using natural history data, we show that individuals with ASL deficiency are at risk for developing attention deficits. By generating LC-ASL-conditional knockout (cKO) mice, we further demonstrate altered response to stressful stimuli with increased seizure reactivity in LC-ASL-cKO mice. Depletion of ASL in LC neurons leads to reduced amount and activity of tyrosine hydroxylase (TH) and to decreased catecholamines synthesis, due to decreased nitric oxide (NO) signaling. NO donors normalize catecholamine levels in the LC, seizure sensitivity, and the stress response in LC-ASL-cKO mice. Our data emphasize ASL importance for the metabolic regulation of LC function with translational relevance for ASL deficiency (ASLD) patients as well as for LC-related pathologies.

Neurorestorative effects of sub-chronic administration of ambroxol in rodent model of Parkinson's disease.

Disease-modifying agents are unmet medical need for Parkinson's disease (PD). Drugs are under clinical trial to halt its progression, such as ambroxol due to its glucocerebrosidase (GCase)-stimulating activity. However, the neurorestorative effect of ambroxol is not yet investigated in any of the well-established PD models in vivo. Ambroxol was administered as 400 mg/kg orally twice a day from D-28 to D-70 after the unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA) in male rats. Behavioral parameters were observed every week, and at last, tyrosine hydroxylase (TH), dopamine transporter (DAT), glucocerbrosidase (GCase) enzymatic and mitochondrial complex-I activity, α-synuclein levels, and Nissl's staining were performed. Behavioral functions were progressively recovered. Ambroxol restored TH and DAT levels on D-71 as the markers of dopaminergic cell and extracellular DA concentration respectively, indicating the recovery of dopaminergic system. Factors involved in PD pathogenesis such as GCase enzymatic and mitochondrial complex-I activity were restored, and α-synuclein pathology was decreased by ambroxol. GCase deficiency is involved in mitochondrial impairment and formation of oligomeric α-synuclein aggregates which negatively affect mitochondrial function. Nissl bodies were also normalized. Therefore, both the GCase-stimulating and α-synuclein pathology-diminishing effects of ambroxol may be responsible for increment in mitochondrial function and restoration of dopaminergic system. These may act as significant mechanisms for disease-modifying potential of ambroxol. The current study provides the preclinical evidence to support the neurorestorative potential of ambroxol in 6-OHDA-induced hemiparkinson's rat model and indicates its possible use as disease-modifying agent in PD.

Tyrosinemia Type 1 and symptoms of ADHD: Biochemical mechanisms and implications for treatment and prognosis.

Hereditary tyrosinemia Type 1 (HT-1) is a rare metabolic disease where the enzyme catalyzing the final step of tyrosine breakdown is defect, leading to accumulation of toxic metabolites. Nitisinone inhibits the degradation of tyrosine and thereby the production of harmful metabolites, however, the concentration of tyrosine also increases. We investigated the relationship between plasma tyrosine concentrations and cognitive functions and how tyrosine levels affected enzyme activities of human tyrosine hydroxylase (TH) and tryptophan hydroxylase 2 (TPH2). Eight Norwegian children between 6 and 18 years with HT-1 were assessed using questionnaires measuring Attention Deficit Hyperactivity Disorder (ADHD)-symptoms and executive functioning. Recent and past levels of tyrosine were measured and the enzyme activities of TH and TPH2 were studied at conditions replicating normal and pathological tyrosine concentrations. We observed a significant positive correlation between mean tyrosine levels and inattention symptoms. While TH exhibited prominent substrate inhibition kinetics, TPH2 activity also decreased at elevated tyrosine levels. Inhibition of both enzymes may impair syntheses of dopamine, noradrenaline, and serotonin in brain tissue. Inattention in treated HT-1 patients may be related to decreased production of these monoamines. Our results support recommendations of strict guidelines on plasma tyrosine levels in HT-1. ADHD-related deficits, particularly inattention, should be monitored in HT-1 patients to determine whether intervention is necessary.

Novel protein kinase C participates catecholamine biosynthesis and immunocompetence modulation in haemocytes of Litopenaeus vannamei

The catecholamine biosynthesis is required for physiological and immunological responses against stress, and the neuroendocrine-immune regulatory network plays a crucial role in immunocompetence of shrimp. A novel protein kinase C of Litopenaeus vannamei (LvnPKC) is involved in immune defense and signaling transduction in haemocytes, and in the present study, the gene silence technique is conducted to identify the role of LvnPKC on catecholamine biosynthesis and immunocompetence modulation in haemocytes of L. vannamei. The results show that tyrosine significantly increases in haemocytes of LvnPKC-silenced shrimp, and in the meantime, the obvious decrease of L-3, 4-dihydroxyphenylalanine and increase of dopamine as well as the consistent norepinephrine levels are detected. Tyrosine hydroxylase and dopamine β-hydroxylase activities are significantly reduced in haemocytes of LvnPKC-silenced shrimp. Total haemocyte count, hyaline cells and granulocytes insignificantly differ among treatments, and the obvious increase of phenoloxidase activity, respiratory bursts, superoxide dismutase and glutathione peroxidase activities are observed in haemocytes of LvnPKC-silenced shrimp, and furthermore, the downregulated phagocytic activity was observed. It is therefore concluded that the LvnPKC mediates catecholamine biosynthesis and immunocompetence in haemocytes, and plays a crucial role in the neuroendocrine-immune regulatory network.

Neuroprotective effects of docosahexaenoic acid against sub-acute manganese intoxication induced dopaminergic and motor disorders in mice

Manganese (Mn) is an essential metallic trace element involved in several vital biological functions. Conversely, exposure to excessive levels of Mn induces manganism, causing neurodegeneration and symptoms similar to those seen in Parkinson's disease (PD). Docosahexaenoic acid (DHA) is a long-chain polyunsaturated fatty acid exhibiting neuroprotective properties against neurodegenerative diseases and brain injuries and is known to easily incorporate into membrane phospholipids of brain cells and meditates its corrective actions. In the present study, mice were used for a sub-acute Mn intoxication model to investigate DHA neuroprotective potential against Mn neurotoxicity. We also seek to understand the mechanism by which Mn intoxication induces these motor impairments at 30 mg/kg, by pretreatment with DHA at 200 mg/kg and assessment of changes in spontaneous locomotor behavior by open field test (OF), motor coordination using the rotarod test (RR) and strength by mean of weights test (WT). To highlight these effects on brain neurotransmission, we evaluated the tyrosine hydroxylase immunoreactivity (TH-IR) within substantia nigra compacta (SNC) and striatum (St). Results showed that Mn intoxication significantly altered motor behavior parameters including, decreased of traveled distance by 46%, decreased mean speed by 36%, reduced the ability to sustain the rotarod test to 42%; Moreover, a drop score was obtained using weights test and reflecting affected strength in Mn-intoxicated animals. Pretreatment by DHA prevents mice from Mn toxicity and maintain normal spontaneous activity, motor coordination and strength. Data also showed the ability of Mn to disrupt dopamine neurotransmission by altering tyrosine hydroxylase activity in the nigrostriatal pathway while in pretreated animals, DHA prevented this disruption. Data approved the potential neurotoxic effect of Mn as a risk factor of the Parkinsonism onset, and then demonstrated for the first time the neuroprotective and nutraceutical outcomes of DHA in the sub-acute Mn-intoxication animal model.

In vivo long-lasting alterations of central serotonin transporter activity and associated dopamine synthesis after acute repeated administration of methamphetamine

BackgroundMethamphetamine (METH)-associated alterations in the striatal dopamine (DA) system or dopamine transport (DAT) have been identified in clinical and preclinical studies with positron emission tomography (PET) imaging but have not been well correlated with in vivo serotonin transporter (SERT) availability due to the lack of appropriate imaging agents to assess SERTs. N,N-dimethyl-2-(2-amino-4-[18F]-fluorophenylthio) benzylamine (4-[18F]-ADAM) has been developed by our group and validated for its high affinity and selectivity for SERTs, allowing the in vivo examination of SERT density, location, and binding function. The aims of this study were to investigate the potential of SERT imaging using 4-[18F]-ADAM PET to estimate the long-lasting effects of METH-induced serotonergic neurotoxicity, and further determine whether a correlative relationship exists between SERT availability/activity and tyrosine hydroxylase (TH) activity in various brain regions due to the long-lasting consequences of METH treatment.ResultsMale rats received four administrations of METH (5 or 10 mg/kg, s.c.) or saline (1 ml/kg, s.c.) at 1-h intervals. At 30 days post-administration, in vivo SERT availability and activity were measured by 4-[18F]ADAM PET imaging. In contrast to the controls, the uptake of 4-[18F]ADAM in METH-treated mice was significantly reduced in a dose-dependent manner in the midbrain, followed by the hypothalamus, thalamus, striatum, hippocampus, and frontal cortex. The regional effects of METH on TH activity were assessed by quantitative immunohistochemistry and presented as integrated optical density (IOD). A significant decrease in TH immunostaining and IOD ratios was seen in the caudate, putamen, nucleus accumbens, substantia nigra pars compacta, and substantia nigra pars reticulata in the METH-treated rats compared to controls.ConclusionThe present results suggested that the long-lasting response to METH decreased the uptake of 4-[18F]-ADAM and varied regionally along with TH immunoreactivity. In addition, 4-[18F]ADAM PET could be used to detect serotonergic neuron loss and to evaluate the severity of serotonergic neurotoxicity of METH.

Methyl jasmonate ameliorates rotenone-induced motor deficits in rats through its neuroprotective activity and increased expression of tyrosine hydroxylase immunopositive cells.

Decreased tyrosine hydroxylase (TH) activity, due to degeneration of dopaminergic neurons contributes to the low dopamine content and the motor deficits that characterized Parkinson's disease (PD). This study examines the effect of methyl jasmonate (MJ), a neuroprotective bioactive compound isolated from jasminum grandiflorum, on motor functions, immunopositive cells of TH, dendritic neurons and dopamine contents in rotenone (Rot)-treated rats. Rats pretreated daily with MJ (100mg/kg, i.p) for 21days also received Rot (2.5mg/kg, i.p.) 30min after each pretreatment for every 48h for 21days. Motor functions were assessed on day 22. The specific brain regions of the rats were processed for determination of dopamine contents, immunopositive cells of TH, neuronal cell morphology and dendritic aborizations. Rot impaired locomotion and rearing behavior, and decreased dopamine content in the striatum, prefrontal cortex and midbrain. It further reduced the expression of TH in the substantia nigra and striatum relative to vehicle-control (p < 0.05). Histopathologic studies revealed that Rot-treated rats had degenerated neurons with pyknotic nuclei and loss of nigrostriatal neuronal cells. Rot also altered the nigrostriatal dendritic neuronal networks, decreased the dendritic length and spine density. However, pretreatment with MJ improved motor deficits, increased TH activity and dopamine contents in the specific brain regions of Rot-treated rats. MJ also attenuated the cyto-architectural distortions, loss of neuronal cells and dendritic aborizations of the striatum of Rot-treated rats. These findings suggest that MJ may reverse the motor deficits associated with PD by modifying the key pathological abnormalities involved in the disease progression.

Kidney dopamine D1-like receptors and angiotensin 1–7 interaction inhibits renal Na+ transporters

The role of dopamine D1-like receptors (DR) in the regulation of renal Na+ transporters, natriuresis, and blood pressure is well established. However, the involvement of the angiotensin 1-7 (ANG 1-7)-Mas receptor in the regulation of Na+ balance and blood pressure is not clear. The present study aimed to investigate the hypothesis that ANG 1-7 can regulate Na+ homeostasis by modulating the renal dopamine system. Sprague-Dawley rats were infused with saline alone (vehicle) or saline with ANG 1-7, ANG 1-7 antagonist A-779, DR agonist SKF38393, and antagonist SCH23390. Infusion of ANG 1-7 caused significant natriuresis and diuresis compared with saline alone. Both natriuresis and diuresis were blocked by A-779 and SCH23390. SKF38393 caused a significant, SCH23390-sensitive natriuresis and diuresis, and A-779 had no effect on the SKF38393 response. Concomitant infusion of ANG 1-7 and SKF38393 did not show a cumulative effect compared with either agonist alone. Treatment of renal proximal tubules with ANG 1-7 or SKF38393 caused a significant decrease in Na+-K+-ATPase and Na+/H+ exchanger isoform 3 activity. While SCH23390 blocked both ANG 1-7- and SKF38393-induced inhibition, the DR response was not sensitive to A-779. Additionally, ANG 1-7 activated PKG, enhanced tyrosine hydroxylase activity via Ser40 phosphorylation, and increased renal dopamine production. These data suggest that ANG 1-7, via PKG, enhances tyrosine hydroxylase activity, which increases renal dopamine production and activation of DR and subsequent natriuresis. This study provides evidence for a unidirectional functional interaction between two G protein-coupled receptors to regulate renal Na+ transporters and induce natriuresis.

The Protective Effect of Korean Red Ginseng Against Rotenone-Induced Parkinson's Disease in Rat Model: Modulation of Nuclear Factor-κβ and Caspase-3.

Korean red ginseng was reported to have many biological effects like the antioxidant and the anti-inflammatory activities. Oxidative stress and neuro-inflammation play major roles in the pathogenesis of Parkinson's disease (PD). The current study aimed to investigate the protective effects of ginseng on rotenone-induced PD in rats. Rats were randomly allocated into 4 groups: normal rats, rotenone control, ginseng+rotenone and ginseng only treated rats. The severity of PD was evaluated through locomotor activity perceived in the open field test, histological examination and immunohistochemical detection of amyloid-β in brain tissues, in addition to the biochemical assessment of tyrosine hydroxylase activity in brain tissues. Moreover, the following parameters were investigated for studying the possible mechanisms of ginseng neuroprotective effect: nuclear factor-κβ (NF-κβ), tumor necrosis factor-alpha (TNF-α), caspase- 3, lipid peroxides and reduced glutathione (GSH). Ginseng exhibited potent neuroprotective effect that was reflected upon the histopathological examination, marked improvement in the locomotor activity and through its ability to suppress the amyloid- β deposition in the cortex and striatum along with significant increase in the tyrosine hydroxylase activity. Ginseng successfully inhibited the NF-κβ inflammatory pathway in brain tissues beside the inhibition of other oxidative stress and inflammatory mediators. Furthermore, it exhibited antiapoptotic effect via the inhibition of caspase-3 expression. Ginseng could be a promising treatment in PD. It can suppress dopaminergic neuron degeneration through variable mechanisms mainly via inhibition of NF-κβ pathway in addition to inhibition of oxidative stress and apoptosis.

Role of endothelin receptor type A on catecholamine regulation in the olfactory bulb of DOCA-salt hypertensive rats: Hemodynamic implications

Increasing evidence shows that the olfactory bulb is involved in blood pressure regulation in health and disease. Enhanced noradrenergic transmission in the olfactory bulb was reported in hypertension. Given that endothelins modulate catecholamines and are involved in the pathogenesis of hypertension, in the present study we sought to establish the role of the endothelin receptor type A on tyrosine hydroxylase, the rate limiting enzyme in catecholamine biosynthesis, in the olfactory bulb of DOCA-salt hypertensive rats.Sprague-Dawley male rats, randomly divided into Control and DOCA-Salt hypertensive groups, were used to assess endothelin receptors by Western blot and confocal microscopy, and their co-localization with tyrosine hydroxylase in the olfactory bulb. Blood pressure and heart rate as well as tyrosine hydroxylase expression and activity were assessed following BQ610 (ETA antagonist) applied to the brain. DOCA-Salt hypertensive rats showed enhanced ETA and decreased ETB expression. ETA co-localized with tyrosine hydroxylase positive neurons. Acute ETA blockade reduced blood pressure and heart rate and decreased the expression of total tyrosine hydroxylase and its phosphorylated forms. Furthermore, it also diminished mRNA tyrosine hydroxylase expression and accelerated the enzyme degradation through the proteasome pathway as shown by pretreatment with MG132, (20s proteasome inhibitor) intracerebroventricularly applied.Present findings support that the brain endothelinergic system plays a major role through ETA activation in the increase of catecholaminergic activity in the olfactory bulb of DOCA-Salt hypertensive rats. They provide rationale evidence that this telencephalic structure contributes in a direct or indirect way to the hemodynamic regulation in salt dependent hypertension.

Moxibustion Exerts a Neuroprotective Effect through Antiferroptosis in Parkinson's Disease.

The objective of this study was to explore the neuroprotective effect of moxibustion on rats with Parkinson's disease (PD) and its mechanism. A Parkinson's disease model was established in rats using a two-point stereotactic 6-hydroxydopamine injection in the right substantia nigra (SN) and ventral tegmental area. The rats received moxibustion at the Baihui (GV20) and Sishencong (EX-HN1) acupoints for 20 minutes, six times a week, for 6 weeks. The right SN tissue was histologically and immunohistochemically examined. Differentially expressed genes (DEGs) were identified through RNA sequencing. In addition, the levels of tyrosine hydroxylase (TH), glutathione peroxidase 4 (GPX4), and ferritin heavy chain 1 (FTH1) in SN were measured. In comparison to the model group, the moxibustion group showed a significantly greater TH immunoreactivity and a higher behavioural score. In particular, moxibustion led to an increase in the number and morphological stability of SN neural cells. The functional pathway analysis showed that DEGs are closely related to the ferroptosis pathway. GPX4 and FTH1 in the SN were significantly overexpressed in the moxibustion-treated rats with PD. Moxibustion can effectively reduce the death of SN neurons, decrease the occurrence of ferroptosis, and increase the TH activity to protect the neurons in rats with PD. The protective mechanism may be associated with suppression of the ferroptosis.

Identification by nano-LC-MS/MS of NT5DC2 as a protein binding to tyrosine hydroxylase: Down-regulation of NT5DC2 by siRNA increases catecholamine synthesis in PC12D cells

Tyrosine hydroxylase (TH), which catalyzes the conversion of l-tyrosine to l-DOPA, is the rate-limiting enzyme in the biosynthesis of catecholamines. It is well known that both α-synuclein and 14-3-3 protein family members bind to the TH molecule and regulate phosphorylation of its N-terminus by kinases to control the catalytic activity. In this present study we investigated whether other proteins aside from these 2 proteins might also bind to TH molecules. Nano-LC-MS/MS analysis revealed that 5′-nucleotidase domain-containing protein 2 (NT5DC2), belonging to a family of haloacid dehalogenase-type (HAD) phosphatases, was detected in the immunoprecipitate of PC12D cell lysates that had been reacted with Dynabeads protein G-anti-TH antibody conjugate. Surprisingly, NT5DC2 had already been revealed by Genome-Wide Association Studies (GWAS) as a gene implicated in neuropsychiatric disorders such as schizophrenia, bipolar disorder, which are diseases related to the abnormality of dopamine activity in the brain, although the role that NT5DC2 plays in these diseases remains unknown. Therefore, we investigated the effect of NT5DC2 on the TH molecule. The down-regulation of NT5DC2 by siRNA increased the synthesis of catecholamines (dopamine, noradrenaline, and adrenaline) in PC12D cells. These increases might be attributed to the catalytic activity of TH and not to the intracellular stability of TH, because the intracellular content of TH assessed by Western blotting was not changed by the down-regulation of NT5DC2. Collectively, our results indicate that NT5DC2 inhibited the synthesis of dopamine by decreasing the enzymatic activity of TH.

ANGIOTENSIN II INDUCES UCP1 IN ADIPOSE TISSUE OF AN EXPERIMENTAL MODEL OF CARDIO-RENAL CACHEXIA

Objective: Cachexia is a severe complication of advanced heart failure and chronic kidney disease. We previously reported that high dose Angiotensin II infusion in rats determined body weight reduction, prevented by an AT-1 receptor blocker treatment and beta-adrenergic non selective antagonism. The possible role of Ang II on UCP1 in white and brown adipose tissue, as a possible mechanism, was investigated in this study. Design and method: Male Sprague-Dawley rats, were implanted subcutaneously in the dorsal region with osmotic minipumps delivering Ang-II at high doses (525 ng/Kg/min) for 12 days to mimic heart failure and the development of cachexia. Five concurrent groups of rats were evaluated: 1) vehicle–infused rats (CTR-rat, n = 9); 2) Ang-II infused rats (n = 7); Ang- II rats receiving by oral gavage 2 days before minipump implantation until the 12th day of Ang-II infusion, either 3) bisoprolol (BIS,β1-adrenergic antagonist, 35 mg/Kg/day, n = 5), or 4) carvedilol (CVD,α1-non-selective-β1,2,3-adrenergic blocker, 90 mg/kg/day, n = 5) or 5) bupranolol (BPR,β3-antagonist, 200 mg/day/kg, n = 4). White adipose tissue (WATs) from retroperitoneal (RWAT), epidydimal (EWAT), dorsal (DWAT) and brown interscapular (IBAT) depot were withdrawn in order to determine UCP1 mRNA expression, norepinephrine tissue level (TNE) and tyrosine hydroxylase activity (THA) Results: THA and TNE were higher in Ang-II infused rats in all the white adipose tissue depots analyzed. CVD prevented TNE increase in all WATs, while BPR and BIS were effective in RWAT and EWAT but not DWAT. All the three beta adrenergic blocker treatments significantly reduced THA increased activity related to Ang-II infusion in all the WATs. UCP1 mRNA was increased in IBAT (+39%, p < 0.05) of Ang II-infused rat, significantly prevented by CVD and BPR but not by BIS. UCP1 was also increased in all the three WATs of Ang-II infused rats, with all the three beta blockers able to reduce the effect in RWAT and DWAT. No effect of beta-blockers treatment was observed in EWAT. Conclusions: High dose angiotensin II infusion determined an increase in UCP1 trascription in brown and white adipose tissue in rats. CVD and BPR were able to prevent UCP1 increase in brown and white adipose tissue more than beta-1 selective antagonist BIS.

Active immunization against serum alcohol dehydrogenase normalizes brain dopamine metabolism disturbed during chronic alcohol consumption.

Chronic ethanol consumption in high doses is associated with constitutively elevated activity of the serum alcohol dehydrogenase I (ADH I) isoform, which demonstrates a high affinity not only for ethanol but also for a number of bioamine metabolites. Such excessive ADH activity is probably associated with disruptions in the metabolism of neurotransmitters (dopamine, serotonin, and norepinephrine) and subsequent long-term changes in the activity of their receptors. Ultimately, a stable depressive-like condition contributes to the development of patients' craving for ethanol intake, frequent disruptions during therapy, and low efficacy of treatment. We applied active immunization against ADH to investigate its efficacy in the reduction of excessive serum ADH activity and regulation of ethanol consumption by chronically ethanol-fed Wistar rats (15% ethanol, 4 months, free-choice method), and we analyzed its ability to influence the levels of bioamines in the brain. Immunization (2 injections, 2-week intervals) was performed using a combination of recombinant horse ADH isozyme as an antigen and 2% aluminum hydroxide-based adjuvant. The efficacy of immunization was demonstrated by the production of high titers of ADH-specific antibodies, which was consistent with the significantly reduced ADH activity in the serum of chronically ethanol-fed rats. On the 26th day after the first vaccine injection, we registered significantly lower levels of alcohol consumption compared to ethanol-fed control animals, and the difference reached 16% on the 49th day of the experiment. These observations were accompanied by data that showed reduced levels of ethanol preference in immunized rats. Chronic alcohol drinking led to a decrease in dopamine and DOPAL (a direct dopamine metabolite and a high-affinity ADH substrate) levels in the striatum,while immunization neutralized this effect. Additionally, we observed that inhibition of serum ADH activity caused a decrease in peak dopamine levels during acute alcohol intake in chronically ethanol-fed rats during ethanol withdrawal that was associated with reduced tyrosine hydroxylase activity in the striatum. The obtained data suggest a significant contribution of ADH to the changes in neurotransmitter systems during chronic alcohol consumption and make available new prospects for developing innovative strategies for treatment of excessive alcohol intake.