Roles of the nucleus accumbens [shell] in the acquisition and expression of morphine-induced conditioned behavior in freely moving rats

The nucleus accumbens [NAc] is a part of the rewarding cortico mesolimbic dopamine [DA] pathway. This is a heterogeneous structure divided in two sub regions termed core and shell. DA function in the NAc is critical for goal oriented behaviors, including those motivated by drug and brain stimulation reward. In the conditioned-place preference [CPP] paradigm, a test assessing animal's ability to associate drug induced effects with environmental cause to quantify drug reward for example morphine. In the present study, we investigated the influence of electrical stimulation with different current intensities on [25 and 100 micro A] with and without an effective dose of morphine [0.5 and 5 mg/kg] on CPP. Subcutaneous administration of morphine 5 mg/kg produced significant CPP in comparison with saline group. Our findings also showed that electrical stimulation of NAc [100 micro A] significantly [P < 0.01] suppressed morphine-induced CPP that reveals impaired learning and memory formation in the process of conditioning. We found that morphine induced CPP can be successfully suppressed by current intensity [100 micro A]. It was probably due to decreasing of dopamine contents and its metabolites in the NAc. Current intensity [100 micro A] in combination with ineffective dose of morphine [0.5 mg/kg] increased morphine induced CPP probability via the prove reward system. Since stimulation of dopaminergic neurons increases tendency to dependence to morphine, therefore in the present study, the stimulation of the NAc suppressed morphine induced CPP that this shows impairment of learning and memory formation

effect of red grape juice and exercise, and their combination on parkinson's disease in rats

Parkinson's disease [PD] is one of the most common neurodegenerative disorders which is characterized by tremor, rigidity, bradykinesia and postural disturbances. Studies indicate that grape juice and exercise may have beneficial effects on neurodegenerative disorders. Therefore, in the present study, we evaluated the effects of red grape juice [GJ] together with treadmill running on animal model of PD. 30 male Wistar rats were divided randomly into Sham, PD, PD treated with GJ [PD-GJ], PD treated with exercise [PD-Ex], and PD treated with GJ associated with exercise [PD-GJ-Ex] groups with six rats in each. In order to obtain the PD model, 6-OHDA was infused into left substantia nigra pars compacta. In order to prove that the lesions are created and to estimate their extent, apomorphine was administered [i.p.] and total number of induced rotations was recorded during 60 minutes. Exercise was applied by treadmill and GJ was added into drinking water for 30 days and rotations test was performed again. Our results indicate that there was a significant difference in number of rotations between PD and Sham groups [p<0.05]. At the end of experiment, number of rotations decreased significantly in both PD-GJ and PD-GJ-Ex groups [p<0.05]. Exercise alone increased the number of rotations nonsignificantly. Grape juice reduced rotations probably via the antioxidant agents