نقش سيستم نور آدرنرژيك مغز در بروز الگوهاي رفتاري ناشي از استرس

The Effects of Brain Noradrenergic System on Stress-Induced Behavioural Responses

Background and Objectives: Today, stress and related complications have gained special importance. Stress is a nonspecific input resulting in an output called behavior. In this process, the neurotransmitter system is involved. This study aimed to evaluate the effects of brain noradrenergic system on stress-induced behavioral responses. Materials and Methods: Four groups of Albinowistar male rats (with 250-300 g weight) were selected. Control group were exposed to tail pinch stress for 5 minutes. Tail pinch stress causes a variety of behavioral responses in rats, including gnawing, licking and aggression. In this study, duration of gnawing was measured. Since implantation of micro dialysis prob in locus coeruleus causes more damage and impairs results, in other groups microdialysis probes were implanted in the lateral ventricle under cloral hydrate (500 mg/kg i.p) anesthesia. In the sham group, ringer solution was perfused (2^mol/min) and tail pinch stress (5 min) was introduced. In exam group, clonidine and noradernaline were added in ringer solution and rats were exposed to stress. Results compared with control and sham groups. Results: Sham group showed no significant difference compared with control group. In clonidine group, a statistically significant reduction was observed (p< 0.001) and noradrenalin group showed significant increase in behavioural responses (p< 0.001). Conclusion: Our results suggest that brain noradrenergic system is involved in special stress-induced behaviors and in a2-presynaptic autoreceptor regulation of noradrenergic system activity. Furthermore, the role of monoamines in stress, is more elucidated. This results show that, for avoiding adverse effects of drugs, treatment of stress-induced diseases must be more specific.