Role of Catecholamine Pathways in Action of Orexin B Induced Open Field Activity by Nucleus Accumbens in Wistar Rats

Aims: To elucidate whether exploratory behaviour changes following Orexin B infusion in NAc is mediated through catecholamines in male Wistar rats. Methods: Inbred male Wistar rats (n= 24) were divided into three groups. Control, Treated 1 (Orexin B) and Treated 2 (Orexin B antagonist) groups. Using stereotaxic method, guide cannula was set in place bilaterally to reach Nucleus Accumbens. Orexin B and its antagonist, TCS-OX2-29 were infused in separate groups of overnight fasted rats. Following open field activity, catecholamines (Dopamine, Adrenaline, and Noradrenaline) were estimated in brain tissue homogenate by ELISA. Data were expressed as mean±SEM (ANOVA; Student-Newman Keuls test,).p<0.05 were considered as statistically significant. Results: Orexin B infusion significantly increased noradrenaline levels in Nucleus accumbens when compared to controls. TCS-OX2-29 significantly decreased noradrenaline in Nucleus accumbens during open field exploration activity. Adrenaline was not altered significantly during open field activity. Conclusion: These results suggest that Orexin B, which plays a role in the regulation of motor and exploratory behaviour when infused in NAc mediates these actions through noradrenergic neurotransmission in Nucleus Accumbens.