Monoamine Levels Research Articles

Monosodium glutamate induces cortical oxidative, apoptotic, and inflammatory challenges in rats: the potential neuroprotective role of apigenin.

Monosodium glutamate (MSG) is used as a flavor, and a taste enhancer was reported to evoke marked neuronal impairments. This study investigated the neuroprotective ability of flavonoid apigenin against neural damage in MSG-administered rats. Adult male rats were allocated into four groups: control, apigenin (20mg/kg b.wt, orally), MSG (4g/kg b.wt, orally), and apigenin + MSG at the aforementioned doses for 30days. Regarding the levels of neurotransmitters, our results revealed that apigenin augmented the activity of acetylcholinesterase (AChE) markedly, and levels of brain monoamines (dopamine, norepinephrine, and serotonin) accompanied by lessening the activity of monoamine oxidase (MAO) as compared to MSG treatment. Moreover, apigenin counteracted the MSG-mediated oxidative stress by decreasing the malondialdehyde (MDA) levels together with elevating the glutathione (GSH) levels. In addition, pretreatment with apigenin induced notable increases in the activities of cortical superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR). Furthermore, apigenin attenuated the cortical inflammatory stress as indicated by lower levels of pro-inflammatory mediators such as interleukin-1 b (IL-1b), tumor necrosis factor-α (TNF-α), and nitric oxide (NO) as well as downregulated inducible nitric oxide synthase (iNOS) expression levels. Histopathological screening validated the abovementioned results and revealed that apigenin restored the distorted cytoarchitecture of the brain cortex. Thus, the present findings collectively suggest that apigenin exerted significant protection against MSG-induced neurotoxicity by enhancing the cellular antioxidant response and attenuating inflammatory machineries in the rat brain cortex.

RF22 | PMON03 Sex-specific Effects of Bisphenol-A and its Analogs on Monoamine Levels in the Paraventricular Nucleus

Abstract Bisphenol A (BPA) is known to produce adverse effects on fertility, cardiovascular, and metabolic health. The constraints placed on BPA production led companies to switch to BPA's structural analogs, Bisphenol S (BPS) and Bisphenol F (BPF). These chemicals are used in various equipment, food and drink cans, and paper, permitting widespread exposure. We recently found that prenatal exposure to low levels of these chemicals can increase blood pressure in the offspring. However, the underlying neurobiological mechanism is unclear. We hypothesized that these chemicals could alter the levels of monoamines, specifically in brain regions that regulate cardiovascular function such as the paraventricular nucleus (PVN) of the hypothalamus. Pregnant Sprague Dawley rats were exposed to saline, 5 µg/kg BW of BPA or BPS, or 1 µg/kg BW of BPF from gestation day 6 to 21. Their adult Male and Female offspring were implanted with a radiotelemetry device to measure blood pressure and heart rate levels. Following telemetry, animals were sacrificed, and the brains were collected, frozen and sectioned. The PVN was microdissected, and analyzed for monoamine levels using HPLC-EC. Males exposed to BPA had significant increases in the levels of serotonin (5HT) in the PVN compared to the control group, while a marked increase in 5HT levels were only observed in females exposed to BPF and not BPA (p = 0.0002). No significant changes were observed in Dopamine (DA) or norepinephrine (NE) levels. There were significant sex differences (p<0.0001) and treatment effects (p=0.0003) in the DOPAC/DA turnover ratio with males exposed to BPA, BPS, and BPF having markedly less turnover rates compared to control. No changes in DOPAC/DA turnover was apparent in females. There were significant sex (p<0.0001) and treatment effects (p<0.0001) in the 5HIAA/5HT turnover ratio, with males in the BPA and BPS groups having significantly less turnover compared to controls. In contrast, Females exposed to BPS and BPF had significantly lower 5HIAA/5HT turnover ratios but higher turnover ratios in the groups exposed to BPA. These results indicate that 5-HT production increases markedly in males exposed to BPA and in females exposed to BPF. This is associated with reduced metabolism of 5-HT. This suggests that the significant increases in 5-HT activity in the PVN could possibly contribute to the development of hypertension in these animals. Presentation: Sunday, June 12, 2022 12:30 p.m. - 12:35 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

RF22 | PMON04 Sex- and Dose-Dependent Effects of In Utero Endocrine Disruptor Exposure on Offspring Behavior and Brain Monoamines

Abstract Exposure to endocrine disruptors (EDs), including the well-known plasticizers bisphenol A (BPA) and di(2-Ethylhexyl) phthalate (DEHP), during the highly sensitive gestational period, can produce long-lasting behavioral changes in offspring. In this study, we hypothesized that gestational exposure to BPA and/or DEHP at various doses would alter stress-related behaviors and monoaminergic activity in a region-specific manner in exposed offspring. To test this, female Sprague-Dawley dams were orally administered saline (control group - 10 µL/kg BW), BPA (5 µg/kg body weight (BW)), DEHP (5 µg/kg BW or 7.5 mg/kg BW), a combination of BPA and low-dose (LD) DEHP (5 µg BPA + 5 µg DEHP/kg BW), or a combination of BPA and high-dose (HD) DEHP (5 µg BPA + 7.5 mg DEHP/kg BW) during days 6 through 21 of pregnancy. The male and female offspring of these dams underwent a battery of behavioral tests in adulthood. Brains collected from the offspring were microdissected to obtain the medial prefrontal cortex (mPFC), paraventricular hypothalamic nucleus (PVN), and hippocampus (HC), which were analyzed for monoamine and metabolite levels using High-Performance Liquid Chromatography (HPLC). While BPA and B+D (LD) female offspring demonstrated anxiolytic effects in the Open Field Test, DEHP (HD) male offspring showed feminized anxiety-like behavior in the Elevated Plus Maze. The offspring also displayed impaired fear responses in the Shock Probe Defensive Burying (SPDB) test. Males in most ED groups buried less than their control counterparts. Furthermore, low-dose ED treatments led to a robust preference for passive coping strategies in both male and female offspring. Within the brain, male offspring in the BPA, LD and HD DEHP, and B+D (HD) groups had diminished dopamine (DA) levels in the PVN, which corresponded with their reduced SPDB burying levels. Moreover, DEHP (LD) male offspring had elevated DA turnover in the mPFC, whereas B+D (LD) female offspring had enhanced norepinephrine levels in the HC, which may underlie their behavioral outcomes in the SDPB. The findings of this study have implications for sex differences in mood and anxiety disorders following prenatal exposures to BPA, DEHP, and their mixtures. Presentation: Sunday, June 12, 2022 12:36 p.m. - 12:41 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Anti-depressant-like effect of fermented Gastrodia elata Bl. by regulating monoamine levels and BDNF/NMDAR pathways in mice

Ethnopharmacological relevanceGastrodia elata Blume (GE) is a Chinese medicinal herb commonly used to treat central nervous system-related diseases, including headaches, dizziness, epilepsy, numbness of the limbs and depression. Aim of the studyMicrobial-based fermentation has been successfully used to increase the extract efficiency of medicinal herbs in recent years. However, no study has hitherto explored the anti-depressant-like effect of GE processed by microorganisms. Herein, this subject aimed to clarify the anti-depressant-like effect of fermented Gastrodia elata Bl. (FGE) and its active chemical constituents. Materials and methodsThe chronic unpredictable mild stress (CUMS) model, a well-established animal model of depression, was induced in Kunming (KM) mice. The mice were administrated with FGE for 3 weeks. The sucrose preference test (SPT), open field test (OFT) and tail suspension test (TST) were conducted. Moreover, the levels of serotonin (5-HT) and dopamine (DA) in brain tissue homogenates, the concentration of Ca2+ and the activity of MAO in serum, H&E and Nissl staining in the hippocampus, and the hippocampus protein expressions of BDNF, NMDAR1, NMDAR2A and NMDAR2B relevant to depression were detected. Furthermore, chemical constituents of FGE were further isolated, and the protective activity of the obtained compounds against NMDA-induced PC-12 cell damage was assessed. ResultsFGE could alleviate the depression state in CUMS-induced mice and reduce apoptosis of neuronal cells in the hippocampus. Furthermore, FGE could improve the contents of 5-HT, DA and decrease the concentration of Ca2+ and MAO activity in brain tissue and serum compared with the control group. It could reverse the decreased expression of BDNF, NMDAR2A and NMDAR2B and increase NMDAR1 protein expression. Investigation of the active constituents from FGE yielded two new compounds, (4-(((4-ethoxybenzyl) oxy)methyl)-phenol 1 and 3-((4-hydroxy benzyl)oxy)propane-1,2-diol) 2, with twelve known compounds (3–14). The compounds (3-((4-hydroxybenzyl)oxy)propane-1,2-diol 2, 4, 4′-dihydroxyd iphenyl methane 3, and bungein A 4) protected against NMDA-induced PC-12 cells damage. ConclusionThis study demonstrated that FGE could improve the depressive behavior of CUMS-induced mice and exert a protective effect on nerve cells in the brain. Importantly, compounds 2–4 are the active components of FGE. Overall, the above findings suggest that FGE has huge prospects for application in treating depression-related diseases.

Prenatal SAMe Treatment Induces Changes in Brain Monoamines and in the Expression of Genes Related to Monoamine Metabolism in a Mouse Model of Social Hierarchy and Depression, Probably via an Epigenetic Mechanism.

Reduction in the levels of monoamines, such as serotonin and dopamine in the brain, were reported in patients and animals with depression. SAMe, a universal methyl donor and an epigenetic modulator, is successfully used as an adjunct treatment of depression. We previously found that prenatal treatment with SAMe of Submissive (Sub) mice that serve as a model for depression alleviated many of the behavioral depressive symptoms. In the present study, we treated pregnant Sub mice with 20 mg/kg of SAMe on days 12–15 of gestation and studied the levels of monoamines and the expression of genes related to monoamines metabolism in their prefrontal cortex (PFC) at the age of 3 months. The data were compared to normal saline-treated Sub mice that exhibit depressive-like symptoms. SAMe increased the levels of serotonin in the PFC of female Sub mice but not in males. The levels of 5-HIAA were not changed. SAMe increased the levels of dopamine and of DOPAC in males and females but increased the levels of HVA only in females. The levels of norepinephrine and its metabolite MHPG were unchanged. SAMe treatment changed the expression of several genes involved in the metabolism of these monoamines, also in a sex-related manner. The increase in several monoamines induced by SAMe in the PFC may explain the alleviation of depressive-like symptoms. Moreover, these changes in gene expression more than 3 months after treatment probably reflect the beneficial effects of SAMe as an epigenetic modulator in the treatment of depression.

Vinpocetine restores cognitive and motor functions in Traumatic brain injury challenged rats.

Traumatic brain damage is common worldwide and the treatments are not well-defined. Vinpocetine is a synthetic derivative of the vinca alkaloid vincamine and is clinically being used for various brain disorders. Here in the current study, we have investigated the neuroprotective potential of vinpocetine against traumatic brain injury. TBI was induced by the Marmarou weight drop method in rats. Brain damage was evaluated using cognitive and motor functions and the alterations in biomolecules. Injured rats were treated with different doses of vinpocetine (2.5, 5, and 10mg/kg) for 4weeks. Traumatic brain injury in rats produced significant deterioration of cognition and motor functions, which was accompanied by increased oxidative stress and significant alterations in brain monoamine levels as compared with the sham control group (p < 0.05). Vinpocetine alleviated TBI-induced oxidative burden, altered neurochemistry, and improved the cognitive and motor functions as compared with that of the TBI control group (p < 0.05). The observed neuroprotective potential of vinpocetine may be due to the observed antioxidant potential and its ability to restore the levels of brain neurochemicals under stressed conditions. The outcomes of the current study may help the repositioning of vinpocetine for preventing or treating traumatic brain injuries.

Behavioral and neurochemical interactions of the tricyclic antidepressant drug desipramine with L-DOPA in 6-OHDA-lesioned rats. Implications for motor and psychiatric functions in Parkinson’s disease

RationaleThe pharmacological effects of antidepressants in modulating noradrenergic transmission as compared to serotonergic transmission in a rat model of Parkinson’s disease under chronic L-DOPA therapy are insufficiently explored.ObjectivesThe aim of the present study was to investigate the effect of the tricyclic antidepressant desipramine administered chronically alone or jointly with L-DOPA, on motor behavior and monoamine metabolism in selected brain structures of rats with the unilateral 6-OHDA lesion.MethodsThe antiparkinsonian activities of L-DOPA and desipramine were assessed behaviorally using a rotation test and biochemically based on changes in the tissue concentrations of noradrenaline, dopamine and serotonin and their metabolites, evaluated separately for the ipsi- and contralateral motor (striatum, substantia nigra) and limbic (prefrontal cortex, hippocampus) structures of rat brain by HPLC method.ResultsDesipramine administered alone did not induce rotational behavior, but in combination with L-DOPA, it increased the number of contralateral rotations more strongly than L-DOPA alone. Both L-DOPA and desipramine + L-DOPA significantly increased DA levels in the ipsilateral striatum, substantia nigra, prefrontal cortex and the ipsi- and contralateral hippocampus. The combined treatment also significantly increased noradrenaline content in the ipsi- and contralateral striatum, while L-DOPA alone decreased serotonin level on both sides of the hippocampus.ConclusionsThe performed analysis of the level of monoamines and their metabolites in the selected brain structures suggests that co-modulation of noradrenergic and dopaminergic transmission in Parkinson’s disease by the combined therapy with desipramine + L-DOPA may have some positive implications for motor and psychiatric functions but further research is needed to exclude potential negative effects.

Sex-specific behavioral, neurobiological, and cardiovascular responses to chronic social stress in mice.

Psychosocial stress promotes and links mood and cardiovascular disorders in a sex-specific manner. However, findings in animal models are equivocal, in some cases opposing human dimorphisms. We examined central nervous system (CNS), behavioral, endocrine, cardiac, and hepatic outcomes in male or female C57Bl/6 mice subjected to chronic social stress (56 days of social isolation, with intermittent social confrontation encounters twice daily throughout the final 20 days). Females exhibited distinct physiological and behavioral changes, including relative weight loss, and increases in coronary resistance, hepatic inflammation, and thigmotaxic behavior in the open field. Males evidence reductions in coronary resistance and cardiac ischemic tolerance, with increased circulating and hippocampal monoamine levels and emerging anhedonia. Shared CNS gene responses include reduced hippocampal Maoa and increased Htr1b expression, while unique responses include repression of hypothalamic Ntrk1 and upregulation of cortical Nrf2 and Htr1b in females; and repression of hippocampal Drd1 and hypothalamic Gabra1 and Oprm in males. Declining cardiac stress resistance in males was associated with repression of cardiac leptin levels and metabolic, mitochondrial biogenesis, and anti-inflammatory gene expression. These integrated data reveal distinct biological responses to social stress in males and females, and collectively evidence greater biological disruption or allostatic load in females (consistent with propensities to stress-related mood and cardiovascular disorders in humans). Distinct stress biology, and molecular to organ responses, emphasize the importance of sex-specific mechanisms and potential approaches to stress-dependent disease.

Deleting Snord115 genes in mice remodels monoaminergic systems activity in the brain toward cortico-subcortical imbalances.

The neuronal-specific SNORD115 has gathered interest because its deficiency may contribute to the pathophysiology of Prader-Willi syndrome (PWS), possibly by altering post-transcriptional regulation of the gene encoding the serotonin (HTR2C) receptor. Yet, Snord115-KO mice do not resume the main symptoms of PWS, and only subtle-altered A-to-I RNA editing of Htr2c mRNAs was uncovered. Because HTR2C signaling fine-tunes the activity of monoaminergic neurons, we addressed the hypothesis that lack of Snord115 alters monoaminergic systems. We first showed that Snord115 was expressed in both monoaminergic and non-monoaminergic cells of the ventral tegmental area (VTA) and the dorsal raphe nucleus (DRN) harboring cell bodies of dopaminergic and serotonergic neurons, respectively. Measuring the tissue level of monoamines and metabolites, we found very few differences except that the content of homovanillic acid-a metabolite of dopamine-was decreased in the orbitofrontal and prefrontal cortex of Snord115-KO mice. The latter effects were, however, associated with a few changes in monoamine tissue content connectivity across the 12 sampled brain regions. Using in vivo single-cell extracellular recordings, we reported that the firing rate of VTA dopaminergic neurons and DRN serotonergic neurons was significantly increased in Snord115-KO mice. These neural circuit dysfunctions were not, however, associated with apparent defects in binge eating, conditioned place preference to cocaine, cocaine-induced hyperlocomotion or compulsive behavior. Altogether, our multiscale study shows that the absence of Snord115 impacts central monoaminergic circuits to an extent that does not elicit gross behavioral abnormalities.

Effect of Mentone® on depression- and anxiety-like profiles and regional brain neurochemistry in the adolescent Wistar Kyoto rat, a putative model of endogenous depression

Objectives: Antidepressants, when prescribed to treat adolescent depression tend to induce adverse effects, including suicidal tendencies. This is because the adolescent brain circuitry is still maturing and is therefore extremely vulnerable. As such, the search is on for compounds for use in complementary/alternative medicine. Polyherbal formulations are widely used as therapeutic alternatives for the treatment of depression. Such formulations and plant extracts are being studied in adult rodent models using standard pharmacological parameters, but not much emphasis has been given to testing the same in adolescents and endogenous animal models of depression. Therefore, the present study was focused on testing out the effect of the polyherbal formulation Mentone® on depression- and anxiety-like profiles and brain neurochemistry in the adolescent Wistar Kyoto rat (WKY), a putative model of endogenous and treatment-resistant depression (TRD). Materials and Methods: Mentone®, a polyherbal formulation comprising of four different plant species: Centella asiatica (Brahmi), Evolvulus alsinoides (Shankapushpi), Tinospora cordifolia (Guduchi), and Glycyrrhiza glabra (Yashtimadhu) was tested at two (18 and 36 mg/kg body weight) doses from the post-natal day (pnd) 25 to pnd 42 using standard neurobehavioral paradigms. Vehicular controls were intubated with saline and positive controls with 10 mg/kg body weight of conventional antidepressant, Fluoxetine. From pnd 35 onwards, animals were tested on a battery of tests, including sucrose preference, novel open field, elevated plus maze, and forced swim or Porsolt’s learned helplessness test. On pnd 42, animals were sacrificed and brain regional tissues such as the Prefrontal cortex (PFC), Striatum (Str), Nucleus Accumbens (NAc), and Hippocampus were microdissected out and subjected to reverse phase HPLC for the separation and quantification of monoamines: Norepinephrine (NE), dopamine (DA), serotonin (5-HT) and their metabolites, 3,4-Dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) in reference to external standards. Results: Mentone® reversed anhedonia by increasing sucrose consumption in Mentone®-treated as compared to Fluoxetine-treated groups. However, there was no effect on anxiety-related parameters in the novel open field or elevated plus-maze. Mentone® exhibited significant anti-depressant-like effects as indicated by its ability to reduce swim stress-induced immobility in Porsolt’s behavioural despair test with a concomitant increase in climbing or struggling behaviour, signifying reversal of depressive-like symptomatology. HPLC-based separation and quantification of brain regional levels of monoamines and their metabolites revealed increased DA levels in NAc and Str in treated groups with decreased levels of metabolite DOPAC in Mentone®-treated groups indicating increased DA tone. Significantly reduced 5-HT metabolite 5-HIAA levels in both PFC and Str is indicative of increased 5-HT tone in both Mentone®- and Fluoxetine-treated groups. NE was variably affected. Conclusion: While no anxiolytic effects and differential neurochemical effects were observed in brain regional areas in relation to Mentone® and Fluoxetine treatment, anhedonia and forced swim test, which are gold-standard tests for assessing depressive-like profiles indicated an effect of Mentone® that was on par with Fluoxetine. Thus, studies on such Ayurvedic formulations would enable a teasing out or differentiation between anxiolytic-like and depressive-like symptomatology and could constitute a source that holds promise in the development of complementary/alternative therapies for the treatment of depression in general and TRD in particular.

Ferulic acid inhibits catamenial epilepsy through modulation of female hormones.

Approximately 40% of women with epilepsy experience perimenstrual seizure exacerbation, referred to as catamenial epilepsy. These seizures result from cyclic changes in circulating progesterone and estradiol levels and there is no effective treatment for this form of intractable epilepsy. We artificially increased progesterone levels and neurosteroid levels (pseudo-pregnancy) in adult Swiss albino female mice (19-23g) by injecting them with pregnant mares' serum gonadotropin (5 IU s.c.), followed by human chorionic gonadotropin (5 IU s.c.) after 46h. After this, ferulic acid (25, 50, 100mg/kg i.p.) treatment was given for 10 days. During treatment, progesterone, estradiol, and corticosterone levels were estimated in blood on days 1, 5, and 10. Neurosteroid withdrawal was induced by finasteride (50mg/kg, i.p.) on treatment day 9. Twenty-four hours after finasteride administration (day 10 of treatment), seizure susceptibility was evaluated with the sub-convulsant pentylenetetrazol (PTZ) dose (40mg/kg i.p.). Four to six hours after PTZ, animals were assessed for depression like phenotypes using tail-suspension test (TST). Four to six hours following TST, animals were euthanized, and discrete brain parts (cortex and hippocampus) were separated for estimation of norepinephrine, serotonin, and dopamine as well as glutamic acid decarboxylase (GAD) enzyme activity. PMSG and HCG treatment elevated progesterone and estradiol levels, assessed on days 1, 5, and 10 causing a state of pseudo-pregnancy. Treatment with finasteride increased seizure susceptibility and depression-like characteristics possibly due to decreased progesterone and elevated estrogen levels coupled with decreased monoamine and elevated corticosterone levels. Ferulic acid treatment, on the other hand, significantly decreased seizure susceptibility and depression like behavior, possibly because of increased progesterone, restored estradiol, corticosterone, monoamines, and GAD enzyme activity. We concluded anticonvulsant effect of ferulic acid in a mouse model of catamenial epilepsy, evidenced by favourable seizure attenuation and curative effect on the circulating progesterone, estradiol, and corticosterone levels along with restorative effect on GAD enzyme activity and monoamine levels.

Probiotics (Bacillus clausii and Lactobacillus fermentum NMCC-14) Ameliorate Stress Behavior in Mice by Increasing Monoamine Levels and mRNA Expression of Dopamine Receptors (D1 and D2) and Synaptophysin.

Stress is a physiological consequence of the body to adversity. The gut–brain axis and probiotics are gaining interest to provide better treatment for stress and other neurological disorders. Probiotic (Lactobacillus fermentum NMCC-14 and Bacillus clausii, 1010 colony-forming unit/day/animal, per oral) effects were investigated in acute (up to day 7) and subacute (days 8–14) restraint-stressed and normal mice through behavioral paradigms (elevated plus maze: EPM, light dark box/dark light box: LDB, and open field test: OFT). Time spent in the open arms of the EPM, time spent in the light compartment of the LDB, and movable time and time spent in the center of the OFT were significantly (p ≤ 0.05, n = 5) increased in probiotic-treated restraint-stressed mice. Enzyme-linked immunoassay determined blood cortisol and adrenocorticotropic hormone (ACTH) levels, which were reduced significantly (p < 0.05, n = 5) in probiotic-treated restraint-stressed mice. Hematoxylin and eosin-stained hippocampal slides also showed less or no neurodegeneration in the probiotic-treated animals. High-performance liquid chromatography and quantitative polymerase chain reaction were performed to determine the monoamine levels and mRNA expression of dopamine receptor subtypes (D1 and D2) and synaptophysin in the mice hippocampus (HC) and prefrontal cortex (PFC). The dopamine, serotonin, and norepinephrine levels were also significantly (p < 0.05, n = 5) increased in the HC and PFC of probiotic-treated animal brains. Fold expression of mRNA of D1 and D2 (except HC, LF-S, day 14) receptors and synaptophysin was also significantly (p < 0.05, n = 5) increased in the same brain parts of probiotic-treated restraint-stressed mice. Comparing mice in the Lactobacillus fermentum NMCC-14 and Bacillus clausii groups to mice in the normal group, only a significant (p < 0.05, n = 5) decrease was observed in the serum ACTH and cortisol levels on day 14 in Bacillus clausii-treated mice, where all other parameters also showed improvement. In comparison, Bacillus clausii showed greater stress suppressant activity than Lactobacillus fermentum NMCC-14. However, both probiotic bacteria can be a better and safer therapeutic alternative for ailments than currently available drugs.

Evaluating the neuroprotective activities of vinpocetine, punicalagin, niacin and vitamin E against behavioural and motor disabilities of manganese-induced Parkinson's disease in Sprague Dawley rats

The current study investigated the neuroprotective activity of some drugs and nutriceuticals with antioxidant and anti-inflammatory potential on the pathogenesis of Parkinson’s disease (PD). Rats were categorized into seven groups: Rats received tween80 daily for 5 weeks as a control group, MnCl2 (10 mg/kg, i.p) either alone (group II) or in combination with vinpocetine (VIN) (20 mg/kg) (group III), punicalagin (PUN) (30 mg/kg) (group IV), niacin (85 mg/kg) (group V), vitamin E (Vit E) (100 mg/kg) (group VI) or their combination (group VII). Motor activities was examined using open-field and catalepsy. Striatal monamines, acetylcholinesterase, excitatory/inhibitory neurotransmitters, redox status, pro-oxidant content, brain inflammatory, apoptotic and antioxidant biomarkers levels were assessed. Besides, histopathological investigations of different brain regions were determined. Groups (IV –GVII) showed improved motor functions of PD rats. Applied drugs significantly increased the brain levels of monoamines with the strongest effect to PUN. Meanwhile, they significantly decreased levels of acetylcholinesterase with a strongest effect to PUN. Moreover, they exhibited significant neuronal protection and anti-inflammatory abilities through significant reduction of the brain levels of COX2, TNF-α and Il-1β with a strongest effect to the PUN. Interestingly; groups (IV – GVII) showed restored glutamate/GABA balance and exhibited a pronounced decrease in caspase-3 content and GSK-3β protein expression levels. In addition, they significantly increased Bcl2 mRNA expression levels with a strongest effect for PUN. All these findings were further confirmed by the histopathological examinations. As a conclusion, we propose VIN and PUN to mitigate the progression of PD via their antioxidant, anti-inflammatory, anti-apoptotic, neurotrophic and neurogenic activities.

Activation and blockade of 5-HT4 receptors in the dorsal hippocampus enhance working and hippocampus-dependent memories in the unilateral 6-hydroxydopamine lesioned rats

Cognitive dysfunction is a common symptom in Parkinson’s disease (PD). Serotonin4 (5-HT4) receptors are richly expressed in the dorsal hippocampus (dHIPP) and play an important role in cognitive activities. However, the mechanism underlying the role of dHIPP 5-HT4 receptors in PD-related cognitive dysfunction remains unclear. Here we found that unilateral 6-hydroxydopamine lesions of the medial forebrain bundle increased the protein expression of 5-HT4 receptors in the dHIPP, decreased hippocampal theta rhythm, and impaired working memory and hippocampus-dependent memory in the T-maze and hole-board test, respectively. Both activation and blockade of dHIPP 5-HT4 receptors (agonist BIMU8 and antagonist GR113808) improved working memory and hippocampus-dependent memory in the lesioned rats, but not in sham rats. Activation of dHIPP 5-HT4 receptors increased hippocampal theta rhythm in the lesioned rats. The neurochemical studies showed that injection of BIMU8, GR113808 or GR113808/BIMU8 in the dHIPP increased the levels of dopamine in the medial prefrontal cortex (mPFC), dHIPP and amygdala, and the level of 5-HT in the amygdala in the lesioned rats, but not in sham rats. Injection of GR113808 or GR113808/BIMU8 into the dHIPP also increased the levels of noradrenaline in the mPFC, dHIPP and amygdala only in the lesioned rats. These results suggest that activation or blockade of dHIPP 5-HT4 receptors may improve the cognitive impairments in parkinsonian rats, which may be due to the increase of hippocampal theta rhythm, up-regulated expressions of 5-HT4 receptors in the dHIPP and the changes in the levels of monoamines in the relative brain areas.

Chronic rapid eye movement sleep restriction during juvenility has long-term effects on anxiety-like behaviour and neurotransmission of male Wistar rats

Modernity imposes a toll on the sleep time of young population, with concomitant increase in symptoms of anxiety and depression. Whether there is a causal relationship between these events are only now being experimentally tested in humans and rodents. In a previous study, we showed that chronic sleep deprivation in juvenile-adolescent male rats led to increased anxiety-like behaviour and changes in noradrenaline and serotonin in the amygdala and hippocampus. In the present study we investigated whether early chronic sleep restriction affects emotional behaviour, stress response and neurochemistry in adulthood. From 21 to 42 days of age, Wistar male rats were submitted to sleep restriction by the multiple platform method or allowed to sleep freely. Forty-five days after this period, rats were tested in the elevated plus maze (EPM) and blood samples were collected from non-tested rats or 30 and 60 min after the EPM for determination of plasma corticosterone levels. Levels of monoamines were determined in the frontal cortex, hippocampus, amygdala and hypothalamus 60 min after the EPM. Sleep restriction resulted in increased anxiety-like behaviour, decreased noradrenaline levels in the amygdala and dopamine levels in the ventral hippocampus. Anxiety index was positively correlated with increased serotonin metabolism in the frontal cortex and greater dopamine metabolism in the ventral hippocampus, and negatively correlated with dopamine levels in the ventral hippocampus. These results suggest that sleep restriction in juvenility and adolescence induces persistent changes in emotional behaviour in adult male rats and that levels of anxiety are correlated with increased serotonin and dopamine metabolism in specific brain areas.

SSRIs treatment did not completely restore affective state in patients with the initial clinically confirmed major depressive disorder/generalized anxiety disorder after COVID-19 disease

IntroductionThe major clinical outcomes of COVID-19 in the brain are associated with its deleterious neurological and mental health actions.Today, there are limited findings concerning the studying of neuropsychiatric action for SARS-Cov-2 in humans after COVID-19 disease.ObjectivesThe aim of the present study was to compare the efficacy of SSRIs (escitalopram, sertraline and fluoxetine) for 6 months therapy on the affective profile of man and women with the clinically confirmed Major Depressive Disorder (MDD) or Generalized Anxiety Disorder (GAD) cases following COVID-19 disease.Methods. For the assessment of affective profile in man and women (30-55 years) with the initial clinically confirmed MDD or GAD cases after COVID-19 disease, we used the different tests: Montgomery-Asberg Depression Rating Scale (MADRS) and anxiety scale (ShARS Scale). The hormonal and monoamines levels in the serum blood were measured by ELISA tests before and after SSRIs therapy.Results After 6 months of SSRIs therapy, MADRS Scale showed a incomplete disappearance of the depressive/anxiety manifestations in both men and women with the initial clinically confirmed MDD case after COVID-19 (p&lt;0,05). We found that SSRIs were able to reduce depression/anxiety levels only on 20% in man or on 30% in women with the initial MDD case after COVID-19 before treatment.ConclusionsSSRIs treatmet alone failed to produce the decrease of depression/anxiety in the patients of both gender with the initial MDD or GAD diagnosis after COVID-19. The further randomized clinical trials involving new pharmacological therapies for psychiatric pations after COVID-19 disease are needed.DisclosureNo significant relationships.

Activation of Estrogen Receptor β in the Lateral Habenula Improves Ovariectomy-Induced Anxiety-Like Behavior in Rats.

BackgroundLoss of estrogen due to menopause or ovarian resection is involved in the development of anxiety, which negatively impacts work productivity and quality of life. Estrogen modulates mood by binding to estrogen receptors in the brain. Estrogen receptor beta (ERβ) is highly expressed in the lateral habenula (LHb), a key site for controlling the activities of dopaminergic neurons in the ventral tegmental area (VTA) and serotoninergic neurons in the dorsal raphe nucleus (DRN) that are known to be involved in anxiety.MethodsIn this study, we examined the role of LHb in the anxiolytic-like effect of estrogen in ovariectomized (OVX) rats. The establishment of OVX anxiety model was validated in behavioral tests, including elevated plus maze (EPM) and mirror chamber maze (MCM) tasks. The expression of c-Fos in the LHb neurons was analyzed by immunohistochemistry, and monoamine neurotransmitter levels in related nuclei were analyzed using high-performance liquid chromatography (HPLC).ResultsEstrogen-treated OVX rats showed a lower degree of anxiety-like behavior than OVX rats. OVX rats showed anxiety-like behavior and low monoamine levels in the DRN and VTA compared with sham operated and estrogen-treated OVX rats. c-Fos expression in the LHb was higher than that in the sham operated and estrogen-treated OVX rats. Intra-LHb injection of the ERβ-selective agonist diarylprepionitrile (DPN) reduced expression of c-Fos (a neuronal activity marker) and anxiety-like behavior in OVX rats, but not in normal rats, as evidenced by increased time spent in EPM open areas and the MCM mirror chamber. These changes coincided with higher levels of serotonin and dopamine in the DRN and higher dopamine levels in the VTA in OVX rats receiving intra-LHb DPN compared with those receiving vehicle injection.ConclusionThese results suggest that OVX-induced anxiety-like behavior may be associated with increased LHb activity. DPN may inhibit LHb activity to improve anxiety-like behavior in OVX rats by increasing monoamine neurotransmitter levels in the DRN and VTA.

Deficiency of the ywhaz gene, involved in neurodevelopmental disorders, alters brain activity and behaviour in zebrafish.

Genetic variants in YWHAZ contribute to psychiatric disorders such as autism spectrum disorder and schizophrenia, and have been related to an impaired neurodevelopment in humans and mice. Here, we have used zebrafish to investigate the mechanisms by which YWHAZ contributes to neurodevelopmental disorders. We observed that ywhaz expression was pan-neuronal during developmental stages and restricted to Purkinje cells in the adult cerebellum, cells that are described to be reduced in number and size in autistic patients. We then performed whole-brain imaging in wild-type and ywhaz CRISPR/Cas9 knockout (KO) larvae and found altered neuronal activity and connectivity in the hindbrain. Adult ywhaz KO fish display decreased levels of monoamines in the hindbrain and freeze when exposed to novel stimuli, a phenotype that can be reversed with drugs that target monoamine neurotransmission. These findings suggest an important role for ywhaz in establishing neuronal connectivity during development and modulating both neurotransmission and behaviour in adults.

Ethanol Inhibits Dopamine Uptake and Augments Rewarding Effects of Cocaine via Organic Cation Transporter 3

Concurrent use of cocaine and alcohol is a major cause of emergency hospitalization, underscoring a vital need to understand the mechanistic basis of this highly addictive and dangerous drug combination. Both cocaine (blocker of dopamine (DA), norepinephrine and serotonin transporters, DAT, NET and SERT, respectively) and ethanol (EtOH) increase extracellular levels of these monoamines. However, we and others find no evidence for EtOH interacting with DAT, NET, or SERT, suggesting that EtOH may be acting elsewhere to inhibit uptake of these monoamines. Organic cation transporter 3 (OCT3) is emerging as a key player in the regulation of monoamine signaling. Whether EtOH acts at OCT3 to increase extracellular levels of monoamines is unknown. To this end, we first conducted studies to determine the ability of EtOH to inhibit uptake of [3H]MPP+ into cultured HEK293 cells stably overexpressing human OCT3. We found the IC50 to be 4 mM, showing that concentrations of EtOH reaching brain following behaviorally relevant doses may be sufficient to engage OCT3. We also found that cocaine does not have activity at OCT3 (Mayer et al., 2018, PMID: 29773909), raising the possibility that EtOH may interact with OCT3 to inhibit monoamine uptake, potentially increasing the addictive properties of cocaine and propagating the concurrent use of these drugs. Next, we assessed the effect of EtOH on DAT, NET, and SERT mediated uptake in real‐time by microsuperfusing fluorescent substrate (APP+ or ASP+) onto HEK293 cells stably expressing DAT, NET, or SERT (APP+) or OCT3 (ASP+) before the addition of EtOH. We found that while EtOH did not affect APP+ uptake by DAT, NET, or SERT, it did inhibit accumulation of ASP+ via OCT3 in a concentration‐dependent manner. To further parse out the relationship between EtOH and OCT3, we used high‐speed chronoamperometry to interrogate the effects of local application of EtOH, cocaine, and their combination on clearance of exogenously applied DA from extracellular fluid in striatum of male and female OCT3+/+ and constitutive OCT3‐/‐ mice in vivo. EtOH inhibited DA clearance and enhanced the ability of cocaine to inhibit DA clearance in both male and female OCT3+/+ mice, effects that were lost in OCT3‐/‐ mice. Finally, we conducted behavioral experiments to assess conditioned place preference (CPP) in response to administration of EtOH, cocaine, or both, to determine if coadministration of EtOH and cocaine enhanced place preference compared to administration of each drug individually. The combination of EtOH (1000 mg/kg) and cocaine (3.2 mg/kg), doses which by themselves did not induce CPP, produced robust CPP. CPP studies in OCT3‐/‐ mice are ongoing (n = 7M &amp; 7F/dose) but so far demonstrate no development of CPP, regardless of treatment. Taken together, results suggest that potentiation of the neurochemical and behavioral effects of cocaine by EtOH are OCT3 dependent. OCT3 may be a putative target for therapeutic intervention in the treatment of EtOH and cocaine co‐abuse.

Single Molecule Analysis Reveals Dimer Formation of the Norepinephrine Transporter at the Plasma Membrane of Live Cells

BackgroundMonoamine transporters are the principal regulators of extracellular monoamine levels in the brain. At the plasma membrane, monoamine transporters form oligomers, which may play an important role in transporter trafficking, drug‐induced monoamine efflux, and drug tolerance development. Using single molecule microscopy, we previously reported that the serotonin transporter (SERT) co‐exists as monomers, dimers, and higher‐order oligomers, while the dopamine transporter (DAT) forms monomers and dimers only. Furthermore, whereas SERT oligomers are kinetically trapped at the plasma membrane by the phospholipid phosphatidylinositol (4,5)‐bisphosphate (PIP2), DAT dimerization is PIP2 independent. The subunit stoichiometry of the norepinephrine transporter (NET) is currently unknown. Based on a high degree of sequence homology between DAT and NET, we aimed to test the hypothesis that NET oligomerization resembles the one of DAT.MethodsWe fused monomeric green fluorescent protein (mGFP) to the N‐terminus of human NET and expressed the construct in Chinese hamster ovary cells. We assessed NET oligomerization using single molecule total internal reflection fluorescence (TIRF) microscopy in live cells. In order to determine the role of cell membrane lipids in NET oligomerization, we pharmacologically depleted the cell membrane of cholesterol and PIP2 before imaging.ResultsSingle molecule brightness analysis revealed that NET co‐exists as monomers (~60%) and dimers (~40%) at the plasma membrane. NET oligomerization displayed signs of transporter density dependence and subunit exchange. Cholesterol depletion did not affect NET dimerization, whereas PIP2 depletion resulted in a small but significant decrease in the average oligomeric state (Student's t‐test, P&lt;0.05).ConclusionNET forms monomers and dimers but no higher‐order oligomers, thereby resembling the oligomerization of DAT. However, unlike DAT, NET dimers exchange subunits over time and dimerization is affected by the transporter density and PIP2 concentrations. This study therefore demonstrates that the oligomerization behavior of each monoamine transporters has unique features.