Effect of Temporary Inactivation of Nucleus Accumbens on Chronic Stress Induced by Electric Shock to the Sole of the Foot in Female NMRI Mice

J Babol Univ Med Sci; 18(4); Apr 2016; PP: 21-8 Received: Mar 14 2015, Revised: Jun 17 2015, Accepted: Jan 4 2016. ABSTRACT BACKGROUND AND OBJECTIVE: Activity changes in the neurons of nucleus accumbens during stress have been previously identified. However, the role of nucleus accumbens in diminishing stress-induced side-effects is not fully understood. In this study, we aimed to evaluate the effects of temporary inactivation of nucleus accumbens on stressinduced metabolic changes in female mice. METHODS: This experimental study was performed on 48 female NMRI mice with an average 27±3 g. The nucleus accumbens was unilaterally and bilaterally cannulated. After one week of recovery, 2% lidocaine or saline was administered in mice for four consecutive days (5 min per day) before inducing electric shock to the sole of the foot. Plasma corticosterone level, food and water intake, and delay in eating were assessed as stress-induced metabolic parameters. FINDINGS: Stress lonely, caused an increase in plasma corticosterone (17±0.8) compared with the control group (4.5±0.3) (p<0.001). It also, caused an increase delay in eating (%218±9.8, p<0.01) and, decrease water (%80±4.5) and food (%84±5.5) intake (p<0.05). Temporary inactivation of nucleus accumbens did not affect the stress-induced changes in plasma corticosterone, and it suppressed the effect of stress on the amount of water intake; inactivation of the left nucleus accumbens was more effective (%195±7.6, p<0.01). Temporary inactivation of nucleus accumbens neutralized the effect of stress on the amount of food intake. Temporary inactivation of the right nucleus accumbens augmented the effect of stress on delay in eating (%264±10.8, p<0.01), and inactivation of the left nucleus accumbens could suppress this effect. CONCLUSION: It seems that temporary inactivation of nucleus accumbens can be effective in diminishing stressinduced metabolic changes. However, this influence is indicative of asymmetry in the function of right and left nucleus accumbens.