DA) And Its Metabolites 3,4-dihydroxyphenylacetic Acid Research Articles

Chrysin for Neurotrophic and Neurotransmitter Balance in Parkinson's Disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has a direct impact on the dopaminergic neurons in the substantia nigra pars compacta (SNpc), dopamine in the striatum (ST), homovanillic acid (HVA), neurotrophic factors of the SNpc, and ST regions leading to Parkinson's disease (PD). Dopaminergic neuron atrophy in the SNpc and dopamine degradation in the ST have an explicit link to disrupted homeostasis of the neurotrophic factor brain-derived neurotrophic factor (BDNF) of the SNpc and ST regions. Chrysin is a flavonoid with a pharmacological potential that directly influences neurotrophic levels as well as neurotransmitters. As a result, analysis of the altering levels of neurotransmitters such as dopamine and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), are observed via high-performance liquid chromatography (HPLC) and the confirmation of the influential role of BDNF and glial-derived neurotrophic factor (GDNF) in the homeostasis of dopamine, DOPAC, and HAV via examination of gene expression. The observation confirmed that chrysin balances the altering levels of neurotransmitters as well as neurotrophic factors. The protocols for reverse transcription-polymerase chain reaction (RT-PCR) and HPLC analysis for neurotransmitter levels from the SNpc and ST regions of acute PD mice brain-induced MPTP are described in this chapter.

Protective effects of Auranofin on the 6-hydroxydopamine model of Parkinson's disease in rats

Auranofin (AU) presents anti-inflammatory effects and was shown to have a neuroprotective action. The objectives were to investigate the actions of AU in the 6-OHDA model of Parkinson’s disease (PD). Methods: Male Wistar rats were distributed into sham-operated (SO, control), untreated 6-OHDA lesioned and 6-OHDA lesioned, and treated with AU (3 and 10 mg/kg, p.o. for 2 weeks) groups. Then, animals were euthanized, the striatum dissected and processed for measurements of dopamine (DA) and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), as well as immunohistochemical assays for inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and the Nuclear factor erythroid 2-related factor 2 (Nrf2). The influence of AU on the activation of the brain NrF2 was also pursued by molecular docking experiments. Results: While the 6-OHDA lesioned rats presented a decrease in the striatal DA and DOPAC concentrations, these effects were prevented after AU treatment. The 6-OHDA group showed increased expressions of iNOS and COX-2 and these effects were highly prevented by AU. While Nrf2 expression was significantly decreased in the 6-OHDA lesioned animals, values came back to those close to the SO group after AU treatment. Auranofin may bind to the Kelch domain of the Kelch-like ECH-associated Protein 1 (Keap1) and possibly inhibit Keap1/Nrf2 interaction. Significance: AU by decreasing iNOS and COX-2 expressions and by increasing the expression of Nrf2, emerge as a potential neuroprotective drug for the treatment of PD.

Establishment and measurement of myopia in mice with ON‐bipolar cell defects

AbstractPurpose: Myopia is a multifactorial eye disorder caused by genetic and environmental factors and is inhibited by light exposure. Complete congenital stationary night blindness (cCSNB) a group of genetically and clinically heterogeneous retinal disorders associated with high myopia in patients. Mutations in cCSNB‐associated genes have been found to disrupt the transmission of ON‐bipolar cells (ON‐BC) in the retina. As ON‐BCs are responsible for the retinal integration of the perception of surrounding light intensity, which is disrupted in myopia, we seek to determine whether cCSNBs models are more susceptible to develop myopia.Methods: We evaluated the levels of retinal Dopamine (DOPA) and its metabolite 3,4‐Dihydroxyphenylacetic acid (DOPAC), commonly used markers of myopia, in three cCSNB mouse models lacking Grm6, Gpr179 or Lrit3. Using an eccentric infrared photorefractometer, we measured the refractive development of two cCSNB mouse models lacking Gpr179 or Lrit3. To assess the sensitivity of cCSNB mouse lines to myopia induction, we developed a lens‐induced myopia (LIM) model and measured the induced refractive error in mice lacking Gpr179 or Lrit3.Results: Our preliminary data revealed decreased levels of both retinal DOPA and DOPAC in all tested cCSNB mouse models. All tested groups presented the same kinetic of refractive development. Mice lacking Gpr179 displayed a higher sensitivity to LIM as shown by an increase in the mean interocular shift compared to wild‐type littermates. Mice lacking Lrit3 with LIM will be measured to document the refractive errors induced by the ON‐BC defect.Conclusions: These results suggest that disruption of the ON‐BC pathway contributes to the development of myopia and that mouse models of cCSNB represent good models to study myopia. Our data strengthen the hypothesis of an impact of ON‐BC dysfunction upon the onset of myopia. These findings provide the basis for the development of pharmacological and optical therapies.

Adult health and transition stage-specific rotenone-mediated Drosophila model of Parkinson's disease: Impact on late-onset neurodegenerative disease models.

Parkinson’s disease (PD) affects almost 1% of the population worldwide over the age of 50 years. Exposure to environmental toxins like paraquat and rotenone is a risk factor for sporadic PD which constitutes 95% of total cases. Herbicide rotenone has been shown to cause Parkinsonian symptoms in multiple animal models. Drosophila is an excellent model organism for studying neurodegenerative diseases (NDD) including PD. The aging process is characterized by differential expression of genes during different life stages. Hence it is necessary to develop life-stage-matched animal models for late-onset human disease(s) such as PD. Such animal models are critical for understanding the pathophysiology of age-related disease progression and important to understand if a genotropic drug/nutraceutical can be effective during late stages. With this idea, we developed an adult life stage-specific (health and transition phase, during which late-onset NDDs such as PD sets in) rotenone-mediated Drosophila model of idiopathic PD. Drosophila is susceptible to rotenone in dose-time dependent manner. Rotenone-mediated fly model of sporadic PD exhibits mobility defects (independent of mortality), inhibited mitochondrial complex I activity, dopaminergic (DAergic) neuronal dysfunction (no loss of DAergic neuronal number; however, reduction in rate-limiting enzyme tyrosine hydroxylase (TH) synthesis), and alteration in levels of dopamine (DA) and its metabolites; 3,4-Dihydroxyphenylacetic acid (DOPAC) and Homovanilic acid (HVA) in brain-specific fashion. These PD-linked behaviors and brain-specific phenotypes denote the robustness of the present fly model of PD. This novel model will be of great help to decipher life stage-specific genetic targets of small molecule mediated DAergic neuroprotection; understanding of which is critical for formulating therapeutic strategies for PD.

Biomarkers of Cerebral Glucose Metabolism and Neurodegeneration in Parkinson's Disease: A Cerebrospinal Fluid-Based Study.

Several biomarkers have been evaluated in Parkinson's disease (PD); cerebrospinal fluid (CSF) levels of lactate may reflect cerebral metabolism function and CSF amyloid-β42 (Aβ42), total tau (t-tau) and phosphorylated tau (p-tau) concentrations may detect an underlying neurodegenerative process. CSF levels of lactate, Aβ42, t-tau, and p-tau were measured in patients with mild to moderate PD. CSF levels of dopamine (DA) and its metabolite 3,4-Dihydroxyphenylacetic acid (DOPAC) were also assessed, exploring their relations with the other CSF biomarkers. 101 drug-naive PD patients and 60 controls were included. Participants underwent clinical assessments and CSF biomarker analysis. Patients were divided into subgroups according to their Hoehn & Yahr stage (PD-1, PD-2, PD-3). PD patients showed higher lactate levels (M = 1.91; p = 0.03) and lower Aβ42 (M = 595; p < 0.001) and DA levels (M = 0.32; p = 0.04) than controls (Mlactate = 1.72; MAβ42 = 837; MDA = 0.50), while no significant differences were found in t-tau, p-tau and DOPAC concentrations. Considering the subgroup analysis, PD-3 group had higher lactate (M = 2.12) and t-tau levels (M = 333) than both PD-1 (Mlactate = 1.75, p = 0.006; Mt-tau = 176, p = 0.008) and PD-2 groups (Mlactate = 1.91, p = 0.01; Mt-tau = 176, p = 0.03), as well as the controls (Mlactate = 1.72, p = 0.04; Mt-tau = 205, p = 0.04). PD-2 group showed higher lactate levels than PD-1 group (p = 0.04) and controls (p = 0.03). Finally, CSF lactate levels negatively correlated with DA (r = -0.42) and positively with t-tau CSF levels (r = 0.33). This CSF-based study shows that lactate levels in PD correlated with both clinical disease progression and neurodegeneration biomarkers, such as tau proteins and DA. Further studies should explore the clinical potential of measuring CSF biomarkers for better understanding the role of brain energy metabolism in PD, for research and therapeutic options.

The effect of mitragynine on extracellular activity of brain dopamine and its metabolites

Kratom, derived from the plant Mitragyna speciosa (M. speciosa) Korth is a traditional psychoactive preparation widely used in Southeast Asia and increasingly in the rest of the world. Use and abuse of Kratom preparations can be attributed to mitragynine (MIT), the main psychoactive compound isolated from its leaves. While MIT may have beneficial effects as a recreational drug, for pain management, and for opiate withdrawal, it may have an addiction potential at higher doses. However, its action in the reward system of the brain is currently unknown. This study investigated how mitragynine (10 mg/kg, i.p.) affects extracellular activity of dopamine (DA) and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the prefrontal cortex (PFC), nucleus accumbens (NAc) and caudate putamen (CPu) of the brain, compared to morphine (MOR; 10 mg/kg, i.p.) and methamphetamine (METH; 10 mg/kg, i.p.). Using in-vivo microdialysis in freely moving rats, we found a significant increase of extracellular DA after MOR and METH, but not after MIT in all three brain regions. MIT led to a significant increase of DOPAC and/or HVA in these brain regions while MOR and METH had only moderate effects. These findings suggest a strong and prolonged effect of MIT on DA synthesis/metabolism, but not on extracellular DA activity, which may limit the addiction risk of MIT, in contrast to MOR and METH.

Vertical exposition to Luffa operculata extract deregulates behavior and hypothalamus neurotransmitters in juvenile rats

Ethnopharmacological relevanceLuffa operculata (L.) Cogn (Cucurbitaceae) is a traditional plant popularly used in the abortion induction, against sinusitis and is toxic. Aim of the studyTo verify the influence of the aqueous extract obtained from the dry fruit of L. operculata (BNE) on the male rats vertically exposed to a subabortive dose of BNE, by evaluating alterations in behavior and neurochemical features in hypothalamus, striatum and frontal cortex, at a juvenile age, after receiving a stress challenge given by the use of the “New York subway stress” technique (NYS). Materials and methodsPregnant female rats (F0 generation) received 1.0 mg/kg BNE, or distilled water (100 mL/kg), by gavage, between gestation days GD17 and GD21. The pups were weaned at PND21 and were kept up to PND60 (juvenile age) in controlled environmental conditions. Four groups were obtained: control (CG), experimental (EG), stress control (SCG) and stress experimental (SEG) After being stressed, the animals were behavioral screened for in the open field (OF) and in light-dark box (LDB) apparatuses. They were euthanized, and the liver, kidneys and brain were removed for both macroscopic and microscopic analyses, and for quantification of vanillylmandelic acid (VMA), norepinephrine (NE), dopamine (DA) and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC) and the serotonin (5-HT) and its metabolite 5-hydroxyindolylacetic acid (5-HIAA) were accessed in the hypothalamus, frontal cortex and striatum. Results and discussionalthough most of the behavior changes were due to the stress challenge, the rats spent more time in the dark side of the LDB and were less likely to explore the light side, indicating that the treatment with BNE induced to fear. Interferences of BNE over behavior were due to impairment of VMA, NE, 5-HT and DA and increasing of DOPAC in the hypothalamus, and an increase of 5-HIAA in the frontal cortex, indicating alterations in the hypothalamic-hypophysis-adrenal axis (HHAA). No macroscopic or histopathological changes were observed in the liver, kidneys, or brain, although GFAP was diminished in the SCG, as expected for stressed rats. Conclusionthe vertical exposition of juvenile rats to BNE led to the manifestation of fear and to a down regulation of the hypothalamic-hypophysis-adrenal axis.

Chronic Administration of Fipronil Heterogeneously Alters the Neurochemistry of Monoaminergic Systems in the Rat Brain.

Fipronil (FPN), a widely used pesticide for agricultural and non-agricultural pest control, is possibly neurotoxic for mammals. Brain monoaminergic systems, involved in virtually all brain functions, have been shown to be sensitive to numerous pesticides. Here, we addressed the hypothesis that chronic exposure to FPN could modify brain monoamine neurochemistry. FPN (10 mg/kg) was chronically administered for 21 days through oral gavage in rats. Thereafter, the tissue concentrations of dopamine (DA) and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid; serotonin (5-HT) and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA); and noradrenaline (NA) were measured in 30 distinct brain regions. FPN significantly decreased DA and its metabolite levels in most striatal territories, including the nucleus accumbens and the substantia nigra (SN). FPN also diminished 5-HT levels in some striatal regions and the SN. The indirect index of the turnovers, DOPAC/DA and 5-HIAA/5-HT ratios, was increased in numerous brain regions. FPN reduced the NA content only in the nucleus accumbens core. Using the Bravais–Pearson test to study the neurochemical organization of monoamines through multiple correlative analyses across the brain, we found fewer correlations for NA, DOPAC/DA, and 5-HIAA/5-HT ratios, and an altered pattern of correlations within and between monoamine systems. We therefore conclude that the chronic administration of FPN in rats induces massive and inhomogeneous changes in the DA and 5-HT systems in the brain.

Development of a PC12 Cell Based Assay for Screening Catechol-O-methyltransferase Inhibitors.

The male rat adrenal pheochromocytoma cell-derived PC12 cell line can synthesize and release catecholamine neurotransmitters, and it has been widely used as a model system in cell biology and toxicology research. Catechol-O-methyltransferase (COMT) is involved in the inactivation of the catecholamine neurotransmitters, and it is particularly important for the regulation of dopamine. In this study, we explored the feasibility of using PC12 cells as an in vitro drug screening platform to compare the activity of multiple COMT inhibitors. Incubation of PC12 cells with tolcapone, a highly potent and selective COMT inhibitor, increased the concentrations of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) while reducing the metabolites 3-methoxytyramine (3-MT) and homovanillic acid (HVA) in the cell culture medium. LIBD-3, a novel, non-nitrocatechol COMT inhibitor, produced similar effects compared to tolcapone. LIBD-4, a less potent inhibitor, exhibited the expected right-shift in functional inhibition in the assay. These results match the known in vivo effects of COMT inhibition in rodents. Together, these data support the continued use of PC12 cells as an in vitro screen that bridges cell-free enzyme assays and more costly in vivo assays.

Ameliorative effects of Radix rehmanniae extract on the anxiety- and depression-like symptoms in ovariectomized mice: A behavioral and molecular study

BackgroundMenopause is closely associated with the risk of anxiety and depression in a woman's life. Despite the numerous reports on the effects of Radix rehmanniae extract (RRE) on various types of depression, there are few studies exploring the effects of RRE on the menopausal anxiety and depression. PurposeTo investigate whether RRE could alleviate the menopausal anxiety and depression in ovariectomized (OVX) mice submitted to chronic unpredictable mild stress (CUMS). MethodsOVX mice were treated with 2.6 g/kg RRE for 5 weeks. After a series of behavior tests, serum, uterus, and brain tissues were collected for the measurement of neurotransmitters and their related biomarkers, neurotrophins, and estrogen receptor α (ERα) and β (ERβ). ResultsRRE showed antidepressant and anxiolytic effects through these behavior tests, but had no effects on the OVX-induced weight gains, uterine shrinkage and drop of serum estrogen level. RRE restored the levels of serotonin (5-HT), dopamine (DA) and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC), Glutamate (Glu), gamma-Aminobutyric acid (GABA) and their related biomarkers in different brain regions. RRE also reversed OVX-induced decrease in the expression levels of neurotrophins in uterus and brain regions except for uterine nerve growth factor (NGF). Moreover, RRE restored and even enhanced ERβ expression levels in uterus and brain without affecting uterine, hippocampal and cortical ERα. ConclusionThis study demonstrated the antidepressant and anxiolytic effects of RRE in OVX mice, which were possibly mediated via their modulation of brain neurotransmitters, and regulation of neurotrophins and activation of ERβ.

Melatonin pretreatment attenuates acute methamphetamine-induced aggression in male ICR mice

Aggression is one of the symptoms of methamphetamine (MA) use and withdrawal, which can exacerbate MA addiction and relapse. Many studies have demonstrated that poor sleep is significantly associated with aggression. Melatonin has been indicated to be effective in treating sleep disorders induced by MA, and it can also protect neuronal cells against MA-induced neurotoxicity. However, the underlying effects of melatonin on MA-reduced aggression remain unclarified. This study was designed to evaluate the effects of melatonin on acute MA-induced aggressive behavior in male ICR mice and the effects on neurotransmitters related to aggression. Fifty male ICR mice were randomly assigned to control and treatment groups pretreated with MA (3 mg/kg) or melatonin (2.5, 5, 10 mg/kg) plus MA. Aggressive behaviors were observed through isolation-induced aggression in the resident-intruder model. High-performance liquid chromatography combined with electrochemical detection (HPLC-ECD) was used to anatomize the levels of dopamine (DA) and its metabolites, 3,4-dihydroxyphenyl acetic acid (DOPAC) and homovanillic acid (HVA), and the concentrations of serotonin (5-HT) and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), in the hippocampus involved in behavior processing. The results showed that acute MA administration decreased latency to initial attacks and thereby increased the number and total duration of attacks. Furthermore, HVA level as well as 5-HIAA and 5-HT turnover estimated by 5-HIAA/5-HT ratios declined compared to those in the vehicle group. The medium melatonin pretreatment dose (5 mg/kg) could significantly reverse acute MA-induced aggressive behavior in the form of prolonging latency to initial attacks and thereby attenuating the number of attacks and total duration of attacks. HVA and 5-HIAA levels, 5-HT turnover estimated by 5-HIAA/5-HT ratios, and DA turnover estimated by HVA/DA ratios and (DOPAC + HVA)/DA ratios were elevated compared to those in the MA group. These results indicate that the DA and 5-HT systems are involved in the processes of MA-induced aggressive behaviors and that melatonin has the capacity to reverse MA-induced aggressive behaviors.

L-Dopa treatment during perinatal development leads to different behavioral alterations in female vs. male juvenile Swiss mice

Alterations in dopaminergic signaling and neurodevelopment are associated with many neuropsychiatric disorders, such as attention deficit and hyperactivity disorder (ADHD), autism, and schizophrenia. Imbalances in dopamine levels during prenatal development are associated with behavioral alterations later in life, like hyperactivity and addiction, and it is possible that dopaminergic imbalances may have diverse effects during different neurodevelopmental windows. In this study, we investigate whether an increase in dopamine levels during the perinatal developmental window affects behavior of juvenile male and female Swiss mice. In order to do so, we intraperitoneally administered daily doses of l-Dopa to mice pups beginning from postnatal day 1 (PD1) to PD5, which increased the levels of dopamine and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), in the striatum of the pups. At the age of 4 weeks, we submitted the juvenile males and females to the open field test, elevated plus maze, forced swimming test, and sucrose preference test. We observed that increase of dopamine levels during the perinatal developmental window increased exploratory behavior in juvenile females, but not males. We observed no changes in anxiety- and depressive-like behaviors. In contrast, we observed that increased dopamine levels during the perinatal period lead to hedonic alterations in juvenile males, but not females. Our results show that dopamine signaling is important for behavioral development and that transient imbalance of dopamine levels causes juvenile behavioral alterations, which are different in males than in females. These data may help in better understanding the spectrum of symptoms associated with different neuropsychiatric disorders.

Monoaminergic impairment in Down syndrome with Alzheimer's disease compared to early-onset Alzheimer's disease

IntroductionPeople with Down syndrome (DS) are at high risk for Alzheimer's disease (AD). Defects in monoamine neurotransmitter systems are implicated in DS and AD but have not been comprehensively studied in DS. MethodsNoradrenaline, adrenaline, and their metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG); dopamine and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid; and serotonin and its metabolite 5-hydroxyindoleacetic acid were quantified in 15 brain regions of DS without AD (DS, n = 4), DS with AD (DS+AD, n = 17), early-onset AD (EOAD, n = 11) patients, and healthy non-DS controls (n = 10) in the general population. Moreover, monoaminergic concentrations were determined in cerebrospinal fluid (CSF)/plasma samples of DS (n = 37/149), DS with prodromal AD (DS+pAD, n = 13/36), and DS+AD (n = 18/40). ResultsIn brain, noradrenergic and serotonergic compounds were overall reduced in DS+AD versus EOAD, while the dopaminergic system showed a bidirectional change. For DS versus non-DS controls, significantly decreased MHPG levels were noted in various brain regions, though to a lesser extent than for DS+AD versus EOAD. Apart from DOPAC, CSF/plasma concentrations were not altered between groups. DiscussionMonoamine neurotransmitters and metabolites were evidently impacted in DS, DS+AD, and EOAD. DS and DS+AD presented a remarkably similar monoaminergic profile, possibly related to early deposition of amyloid pathology in DS. To confirm whether monoaminergic alterations are indeed due to early amyloid β accumulation, future avenues include positron emission tomography studies of monoaminergic neurotransmission in relation to amyloid deposition, as well as relating monoaminergic concentrations to CSF/plasma levels of amyloid β and tau within individuals.

Effects of bifenthrin exposure on the estrogenic and dopaminergic pathways in zebrafish embryos and juveniles.

Bifenthrin is a pyrethroid insecticide used in urban and agricultural applications. Previous studies have shown that environmentally relevant (ng/L) concentrations of bifenthrin increased plasma concentrations of 17β-estradiol (E2) and altered the expression of dopaminergic pathway components. The dopaminergic neurons can indirectly regulate E2 biosynthesis, suggesting that bifenthrin may disrupt the hypothalamic-pituitary-gonadal (HPG) axis. Because embryos do not have a complete HPG axis, the hypothesis that bifenthrin impairs dopamine regulation was tested in embryonic and 1-mo-old juvenile zebrafish (Danio rerio) with exposure to measured concentrations of 0.34 and 3.1 µg/L bifenthrin for 96 h. Quantitative reverse transcriptase polymerase chain reaction was used to investigate transcripts of tyrosine hydroxylase (TH), dopamine receptor 1 (DR1) and 2A (DR2A), dopamine active transporter (DAT), estrogen receptor α (ERα), ERβ1, ERβ2, luteinizing hormone β (LHβ), follicle-stimulating hormone β (FSHβ), vitellogenin (VTG), cytochrome P450 cyp19a1a, and cyp19a1b. Levels of E2 were measured by enzyme-linked immunosorbent assay (ELISA). Dopamine and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) concentrations were measured by liquid chromatrography-tandem mass spectrometry (LC-MS/MS). Significant decreases in TH and DR1 transcripts and HVA levels, as well as ratios of HVA/dopamine and HVA+DOPAC/dopamine, in zebrafish embryos were observed after bifenthrin treatment. In juveniles, a significant increase in the expression of ERβ1 and the DOPAC to dopamine ratio was noted. These results show a possible antiestrogenic effect of bifenthrin in embryos, and estrogenicity in juveniles, indicating life-stage-dependent toxicity in developing fish. Environ Toxicol Chem 2018;37:236-246. © 2017 SETAC.

Timed Release of Cerebrolysin Using Drug-Loaded Titanate Nanospheres Reduces Brain Pathology and Improves Behavioral Functions in Parkinson's Disease.

Previous studies from our laboratory show that intraperitoneal injections of 1-metyl-4-phenyl-1,2,3,6-tetrahydropyridin (MPTP, 20mg/kg) daily within 2-h intervals for 5days in mice induce Parkinson's disease (PD)-like symptoms on the 8th day. A significant decrease in dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) along with a marked decrease in the number of tyrosine hydroxylase (TH)-positive cells in the substantia nigra pars compacta (SNpc) and striatum (STr) confirms the validity of this model for studying PD. Since cerebrolysin (CBL) is a well-balanced composition of several neurotrophic factors and active peptide fragments, in the present investigation we examined the timed release of CBL using titanate nanospheres (TiNS) in treating PD in our mouse model. Our observations show that TiNS-CBL (in a dose of 3ml/kg, i.v.) given after 2days of MPTP administration for 5days resulted in a marked increase in TH-positive cells in the SNpc and STr as compared to normal CBL. Also, TiNS-CBL resulted in significantly higher levels of DA, DOPAC, and HVA in SNpc and STr on the 8th day as compared to normal CBL therapy. TiNS-CBL also thwarted increased α-synuclein levels in the brain and in the cerebrospinal fluid (CSF) as well as neuronal nitric oxide synthase (nNOS) in the in PD brain as compared to untreated group. Behavioral function was also significantly improved in MPTP-treated animals that received TiNS-CBL. These observations are the first to demonstrate that timed release of TiNS-CBL has far more superior neuroprotective effects in PD than normal CBL.

Early increase in dopamine release in the ipsilateral striatum after unilateral intranigral administration of lactacystin produces spontaneous contralateral rotations in rats

Since the discovery of the role of the ubiquitin–proteasome system (UPS) in the pathogenesis of Parkinson’s disease, UPS inhibitors, such as lactacystin have been used to investigate the relationship between UPS impairment and degeneration of dopamine (DA) neurons. However, mostly long-term neurotoxic effects of lactacystin have been studied in animal models. Therefore, the aim of our study was to investigate behavioral and biochemical changes related to the DA system during the first week following unilateral intranigral injection of lactacystin to rats. We found that lactacystin produced early spontaneous contralateral rotations which were inhibited by combined administration of DA D1 and D2 receptor antagonists. Simultaneously, an increase in the extracellular level of DA and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA) was found in the ipsilateral striatum. In contrast, one week after lesion, when turning behavior was no longer visible, a decrease in the extracellular level of DA, DOPAC and HVA was demonstrated. It was accompanied by a substantial reduction in the tissue levels of DA and its metabolites in the lesioned substantia nigra and striatum. We concluded that unilateral intranigral administration of lactacystin produces an early increase in DA neurotransmission which precedes a decrease in the striatal and nigral tissue DA content. It is manifested by the appearance of spontaneous contralateral rotations and an elevation of the extracellular DA level in the ipsilateral striatum. Since similar behavior was previously observed after intranigral administration of rotenone and MPP+ but not 6-hydroxydopamine (6-OHDA), it may indicate a common mechanism of action shared by these neurotoxins.

Ursolic acid attenuates oxidative stress in nigrostriatal tissue and improves neurobehavioral activity in MPTP-induced Parkinsonian mouse model

Parkinson's disease (PD) is characterized by a slow and progressive degeneration of dopaminergic neurons in substantia nigra pars compacta (SNpc) region of brain. Oxidative stress and inflammation plays important role in the neurodegeneration and development of PD. Ursolic Acid (UA: 3β-hydroxy-urs-12-en-28-oic acid) is a natural pentacyclic triterpenoid found in various medicinal plants. Its anti-inflammatory and antioxidant activity is a well-established fact. In this paper, the neuroprotective efficiency of UA in MPTP induced PD mouse model has been explored. For this purpose, we divided 30 mice into 5 different groups; first was control, second was MPTP-treated, third, fourth and fifth were different doses of UA viz., 5mg/kg, 25mg/kg, and 50mg/kg body weight (wt) respectively, along with MPTP. After 21 days of treatment, different behavioral parameters and biochemical assays were conducted. Tyrosine hydroxylase (TH) immunostaining of SN dopaminergic neurons as well as HPLC quantification of dopamine and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA) were also performed. Our results proved that, UA improves behavioral deficits, restored altered dopamine level and protect dopaminergic neurons in the MPTP intoxicated mouse. Among three different doses, 25mg/kg body wt was the most effective dose for the PD. This work reveals the potential of UA as a promising drug candidate for PD treatment.

MK-801 increases locomotor activity in a context-dependent manner in zebrafish

Zebrafish have become a popular animal model for behavioral neuroscience with an increasing number of studies examining the effects of pharmacological compounds targeting the brain. Exposure to MK-801, a non-competitive N-methyl-d-aspartate receptor antagonist has been shown to increase locomotor activity in zebrafish. However, others have failed to replicate this finding as several contradicting studies report no changes in locomotor activity following exposure to similar doses. In the current study we reconcile these behavioral reports by demonstrating that zebrafish do not exhibit changes in locomotor activity during exposure to non-sedative doses of MK-801. Interestingly, zebrafish do exhibit significant increases in locomotion if pre-treated with MK-801 followed by subsequent testing in a novel environment, which suggests the effects of MK-801 are context-dependent. In addition, we examine the potential role of the dopaminergic system in mediating MK-801’s locomotor stimulant effect by quantifying the levels of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the brains of zebrafish following a 30min exposure to 10μM of MK-801 (the dose found to induce the largest increase in locomotor activity). Our findings indicate that the MK-801-induced increase in locomotor activity is not accompanied by changes in whole-brain levels of dopamine or DOPAC. Overall, our results suggest that MK-801's context-dependent locomotor stimulant effect may be independent of whole-brain dopaminergic activation.

Differential effects of acute administration of SCH-23390, a D₁ receptor antagonist, and of ethanol on swimming activity, anxiety-related responses, and neurochemistry of zebrafish.

The zebrafish has become an increasingly popular animal model for investigating ethanol's actions in the brain and its effects on behavior. Acute exposure to ethanol in zebrafish has been shown to induce a dose-dependent increase of locomotor activity, to reduce fear- and anxiety-related behavioral responses, and to increase the levels of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC). The objective of the present study was to investigate the role of dopamine D1 receptors (D1-R) in ethanol-induced locomotor activity in zebrafish. Zebrafish were pre-treated with SCH-23390 (0 or 1 mg/L bath concentration), a D1-R antagonist, and subsequently exposed to ethanol (0, 0.25, 0.5, 1.0 % v/v). To explore potential underlying mechanisms, we quantified levels of dopamine, DOPAC, serotonin, and 5-HIAA from whole-brain tissue using high-precision liquid chromatography. We found pre-treatment with the D1-R antagonist to attenuate locomotor activity independent of ethanol concentration. Furthermore, unlike ethanol, D1-R antagonism did not alter behavioral responses associated with fear and anxiety. Pre-treatment with SCH-23390 decreased levels of dopamine and DOPAC, but this effect was also independent of ethanol concentration. The D1-R antagonist also reduced serotonin and 5-hydroxyindole acetic acid (5-HIAA) levels. These results suggest a multifaceted and at least partially independent role of dopamine D1 receptors in ethanol-induced locomotor activity and anxiety-related responses as well as in the functioning of the dopaminergic and serotoninergic neurotransmitter systems in zebrafish.

Comparison of Opioid Antagonist Modulation of Buprenorphine‐Induced Neurochemical Changes

ObjectiveEvaluate differences in onset and duration of action of µ‐opioid antagonists on buprenorphine (BUP)‐induced elevations of nucleus accumbens shell (NAc‐sh) neurotransmitters.Methods: Studies utilized male Wistar rats (275 ‐ 375g) with microdialysis probes inserted into the NAc‐sh (A/P +1.70; M/L ±0.8; D/V ‐7.8 from bregma). Bioanalytical analyses of dopamine (DA) and its metabolites 3,4‐dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were performed using HPLC‐EC. Data were converted to percent change from baseline and analyzed using a repeated measures two‐way ANOVA and mechanistic pharmacodynamic modeling.Results: BUP (0.1 mg/kg) elevated extracellular concentrations of DA, DOPAC and HVA in the NAc‐sh for approximately 20 hours after subcutaneous administration. Co‐administration of either samidorphan (SAM) or naltrexone (NTX) (0.3 ‐ 3.0 mg/kg) dose dependently attenuated BUP‐induced dopaminergic activity. However, the temporal pattern of this attenuation was different for NTX and SAM. NTX displayed a rapid Kon and Koff resulting in an immediate but short‐lived (~4 hours) attenuation of BUP's effects. SAM displayed a longer Kon and Koff resulting in a protracted but longer‐lasting (~8‐10 hours) attenuation of BUP's effects.ConclusionsDifferences observed between SAM and NTX in onset and duration of action were not predicted by in‐vitro pharmacology or pharmacokinetic profiles. Importantly, the duration of action reported previously in humans for both antagonists is much longer than in rats. These data illustrate the importance of understanding the duration of action when assessing the activity of different opioid antagonists in nonclinical models.