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

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

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