نقش هسته آكومبانس در پاسخ به استرس مزمن در موش كوچك آزمايشگاهي نر نژاد NMRI

Role of Nucleus Accumbens in Response to Chronic Stress in Small Male NMRI Mouse

زمينه و هدف: نقش بخش‌هاي مختلف مغز، به خصوص هسته آكومبانس (NAc)، در مديريت استرس به‌خوبي شناخته نشده است. در اين مطالعه نقش NAc در پاسخ به استرس مزمن در موش‌هاي نر بررسي شد. مواد و روش‌ها: در اين مطالعه تجربي، NAc به كمك دستگاه استريوتكس به‌صورت يك‌طرفه و دوطرفه كانول‌گذاري شد. پنج دقيقه قبل از القاء استرس، ليدوكائين 2% به داخل آكومبانس حيوانات تزريق شد. استرس توسط دستگاه Communication Box به‌مدت چهار روز متوالي بين ساعات 9 تا 11 به حيوانات (8 گروه 6 تايي) القاء شد. ميزان كورتيكوسترون پلاسما، آب و غذاي دريافتي، تغييرات وزن و زمان تأخير در غذا‌ خوردن به عنوان معيارهاي متابوليكي استرس سنجيده شد. داده‌ها با آناليز واريانس دوطرفه تجزيه و تحليل شد. يافته‌ها: استرس باعث افزايش ميزان كورتيكوسترون پلاسما و تأخير در غذا خوردن (0/001

Background and Objectives: Role of different parts of the brain in stress management, especially nucleus accumbens (NAc), is not well known. In this study the role of NAc in response to chronic stress in male mice were evaluated. Materials and Methods: In this experimental study, intra-accumbal uni- and bi-lateral cannulation was performed by stereotaxic instrument. Five minutes before stress induction, 2% lidocaine solution was administered to the animals intra-accumbally. Stress by Communication Box induced to the animals between 9- 11 am for 4 consecutive days (8 groups of 6). Plasma corticosterone, food and water intake, animals’ weight gain, and delay time in food intake were measured as stress metabolic signs. Data were analyzed using two-way analysis of variance. Results: Stress increased plasma corticosterone and delayed the eating time (p<0.001) and had no significant impact on weight changes and water intake. Lidocaine administration could not completely inhibit the plasma corticosterone levels and delays to eating time, compared with the control group. NAc transient inactivation inhibited stress in animals’ food intake (p<0.001) and weight (p<0.05), significantly. As well as, lidocaine administration either unilateral of right or left side or bilateral decreased water intake (p<0.05). Conclusion: It seems that NAc, as a brain structure, plays a role in mediation of chronic stress effects on metabolic functions. There are also some differences between the right and left sides of the NAc which may reflect a kind of side bias in the functions of the NAc.