The involvement of NMDA receptor/NO/cGMP pathway in the antidepressant like effects of baclofen in mouse force swimming test

In the current study, the involvement of N-methyl-d-aspartate receptor (NMDAR) and nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) system in the antidepressant-like effects of baclofen was evaluated by using animal model in forced swimming test. Followed by an open field test for the evaluation of locomotor activity, the immobility time for mice in force swimming test was recorded. Only the last four min was analyzed. Administration of Baclofen (0.5 and 1 mg/kg, i.p.) reduced the immobility interval in the FST. Prior administration of l-arginine (750 mg/kg, i.p.,) a nitric oxide synthase substrate or sildenafil (5 mg/kg, i.p.) a phosphodiesterase 5 into mice suppressed the antidepressant-like activity of baclofen (1 mg/kg, i.p.).Co-treatment of 7-nitroindazole (50 mg/kg, i.p.,) an inhibitor of neuronal nitric oxide synthase, L-NAME (10 mg/kg, i.p.,) a non-specific inhibitor of nitric oxide synthase or MK-801 (0.05 mg/kg, i.p.) an NMDA receptor antagonist with subeffective dose of baclofen (0.1 mg/kg, i.p.), reduced the immobility time in the FST as compared to the drugs when used alone. Co-administrated of lower doses of MK-801 (0.01 mg/kg) or l-NAME (1 mg/kg) failed to effect immobility time however, simultaneous administration of these two agents in same dose with subeffective dose of baclofen (0.1 mg/kg, i.p.), minimized the immobility time in the FST. Thus, our results support the role of NMDA receptors and l-arginine-NO-GMP pathway in the antidepressant-like action of baclofen. © 2015 Elsevier Ireland Ltd

Evaluation of the relationship between the gene expression level of orexin-1 receptor in the rat blood and prefrontal cortex, novelty-seeking, and proneness to methamphetamine dependence: A candidate biomarker

Background: previous studies have suggested that methamphetamine (METH) abuse may affect orexin regulation. However, the data regarding the relationship between the current level of orexin and the vulnerability to METH abuse are minimal. Here, we have investigated the correlation between the gene expression level of the orexin-1 receptor (OX1R) in the rat prefrontal cortex (PFC) and blood lymphocytes and susceptibility to METH dependence and its impact on novelty-seeking behavior. Methods: male Wistar rats were first examined for novelty-seeking behavior by the novel object recognition test, and the expression level of OX1R in their blood lymphocytes was evaluated by real-time PCR. Then, the susceptibility to METH abuse was investigated by voluntary METH oral consumption test. According to the amounts of METH consumption, the animals were divided into two groups of METH preferring and non-preferring. Half of the rats in each group were sacrificed, and the level of OX1R in their blood lymphocytes and PFC tissue was measured. The other half were sacrificed for the same reason after two weeks of drug abstinence. Results: The indexes of novelty-seeking behavior were significantly higher in the METH- preferring group compared to the non-preferring animals. Furthermore, the expression level of OX1R in the blood lymphocytes and PFC in the preferring group was considerably higher than the non-preferring group. Conclusion: Up-regulation of the mRNA expression level of OX1R in the lymphocytes and PFC may predict vulnerability to the METH consumption and novelty-seeking, which may serve as a potential biomarker for METH abuse. © 2020 Elsevier Inc

The Neuroprotective Effect of Lithium in cannabinoid Dependence is Mediated through Modulation of Cyclic AMP, ERK1/2 and GSK-3β Phosphorylation in Cerebellar Granular Neurons of Rat

Lithium (Li), a glycogen synthase kinase-3β (GSK-3β) inhibitor, has used to attenuate the cannabinoid-induced dependence/withdrawal signs, but molecular mechanisms related to this are unclear. Recent studies indicate the involvement of upstream extracellular signal kinase1/2 (ERK1/2) and downstream GSK-3β pathways in the development of cannabinoid-induced dependence. This is mediated through cannabinoid receptor 1 (CB1) enriched in cerebellar granular neurons (CGNs). Accordingly, the present study aimed to investigate the mechanism of modulatory/neuroprotective effects of Li on a cannabinoid agonist (WIN 55,212-2 (WIN))-induced dependence, through quantitative analysis of some involved proteins such as ERK1/2, GSK-3β and related signaling pathways including their phosphorylated forms; and cAMP level as the other molecular mechanisms leading to dependence, in CGNs model. The CGNs were prepared from 7-day-old Wistar rat pup in a 12-well plate, pretreated with Li (1mM) and an ERK1/2 inhibitor SL327 (SL, 10 µM). The WIN (1 µM) was added 30 minutes prior to treatment and AM251 (AM, 1 µM), as a cannabinoid antagonist was co-treated with WIN. The cAMP level, as an indicator of cannabinoid-induced dependence, was measured by ELISA following forskolin (FSK) stimulation. Western blot analyses determined the phosphorylated forms of ERK1/2 (p-ERK1/2), GSK-3β (p-GSK-3β) as well as their total expressions in various treatment times and doses in CGNs. WIN alone could down regulate the cAMP/p-ERK1/2 cascade compared to AM treatment. However, P-GSK-3β was up-regulated with Li and WIN or with SL and Li pretreatment to AM-induced cellular response, which was the highest 60 minutes after CGNs exposure. Results further suggested the potential role of Li pretreatment to diminish the development of cannabinoid-induced dependence/neuronal injury through possible mechanisms of modulating the cAMP/p-ERK1/2 cascade independent of p-GSK-3β signaling pathway in-vitro

IN VITRO MEIOTIC MATURATION OF MOUSE OOCYTES: ROLE OF NITRIC OXIDE

In this experiment we used cultured mouse cumulus cell-enclosed oocytes (CEOs) and denuded oocytes (DOs) to study the function of nitric oxide (NO) in mouse oocyte meiotic maturation. CEOs and DOs were cultured in a medium containing 4 mM hypoxanthine (HX) to maintain meiotic arrest, in maturation medium (without HX) supplemented with different doses of sodium nitroprusside (SNP, a NO donor), and in N-omega-nitro-L-arginine methyl ester (L-NAME) (inhibitor of NO synthase). NOS inhibitor suppressed the formation of first polar body (PB1) of the oocytes in CEOs in a dose dependent manner, but no effect on germinal vesicle break down (GVBD) was observed. Treatments of low concentrations of SNP stimulated significantly the oocyte meiotic maturation of CEOs which were inhibited with HX, but had no effect on DOs in the same culture medium. The treatment with high concentrations of SNP (0.1-2 mM) during the CEOs cultured in maturation medium resulted in a lower percentage of oocytes at PB1 stage and a higher percentage of atypical oocytes. A dose of SNP at 1 mM exhibited significant inhibitory effect on the formation of PB1, and the number of atypical oocytes compared with control. The results showed that the treatment with 1 mM concentration of SNP could significantly delay GVBD during the first 5 h culture period. The concomitant addition of L-NAME with SNP did not reverse the inhibitory effect of SNP on CEOs. Pre-incubation use of SNP did not have any effect on oocyte maturation. These data support the idea that NO could act in mouse meiotic maturation depending on its concentration

Co-occurrence of anxiety and depressive-like behaviors following adolescent social isolation in male mice; possible role of nitrergic system

Approximately more than 50 of patients with depression have the co-occurrence of anxiety, which complicates the treatment of disease. Recently, social isolation stress (SIS) paradigm has been suggested as an animal model to investigate the underlying mechanism involved in depression-anxiety co-occurrence. In this study, applying six weeks of SIS to adolescent mice, we tested whether nitrergic system plays a role in co-occurrence of depression and anxiety. In this study, comparisons between socially and isolated conditioned (SC and IC) animals showed that SIS induces behaviors relevant to depression and anxiety in IC mice and in addition, nitrergic system is involved in mediating the negative outcomes of SIS. Administration of subeffective doses of aminoguanidine (a specific inducible nitric oxide synthase inhibitor or iNOS, 50. mg/kg) and L-NAME (non-specific inhibitor of NOS, 10. mg/kg) significantly reversed the negative effects of SIS on behavioral profile as well as nitrite levels in the cortex of IC mice, Although administration of subeffective dose of 7-nitroindazole (a specific neuronal NOS inhibitor, 25. mg/kg) decreased the nitrite levels in the hippocampus, but had no effect on depressant and anxiogenic effects of SIS. Results of this study confirmed that SIS is an appropriate animal model to investigate the potential mechanisms in depression-anxiety co-occurrence. We also showed that nitrergic system has contributed to co-occurrence of depression and anxiety in IC mice as an underlying mechanism. © 2015

Anti-inflammatory effect of AMPK signaling pathway in rat model of diabetic neuropathy

Abstract Diabetic neuropathy (DN) is characterized as Hyperglycemia activates thdisturbed nerve conduction and progressive chronic pain. Inflammatory mediators, particularly cytokines, have a determinant role in the pathogenesis of neuropathic pain. The activity of adenosine monophosphate protein kinase (AMPK), an energy charge sensor with neuroprotective properties, is decreased in diabetes. It has been reported that activation of AMPK reduces the systemic inflammation through inhibition of cytokines. In this study, we aimed to investigate the probable protective effects of AMPK on DN in a rat of diabetes. DN was induced by injection of streptozotocin (65 mg/kg, i.p.). Motor nerve conduction velocities (MNCV) of the sciatic nerve, as an electrophysiological marker for peripheral nerve damage, were measured. Plasma levels of IL-6, TNF-a, CRP were assessed as relevant markers for inflammatory response. Also, the expression of phosphorylated AMPK (p-AMPK) and nonphosphorylated (non-p-AMPK) was evaluated by western blotting in the dorsal root ganglia. Histopathological assessment was performed to determine the extent of nerve damage in sciatic nerve. Our findings showed that activation of AMPK by metformin (300 mg/kg) significantly increased the MNCV and reduced the levels of inflammatory cytokines. In addition, we showed that administration of metformin increased the expression of p-AMPK as well as decline in the level of non p-AMPK. Our results demonstrated that co-administration of dorsomorphin with metformin reversed the beneficial effects of metformin. In conclusion, the results of this study demonstrated that the activation of AMPK signaling pathway in diabetic neuropathy might be associated with the anti-inflammatory response