Influence of hypothalamic arcuate nucleus lesion with monosodium glutamate on plasma corticosterone in neonatal rats

The purpose of present experiment was to assess the role of hypothalamic arcuate nucleus (ARC) in regulation of pituitary-adrenocortical system. The plasma corticosterone was determined by competitive protein-binding radioassay. The number of ARC neurons in monosodium glutamate (Msg)-treated rats showed a decrease of 60%, and the pituitary gland in Msg-treated group was smaller than that of control group (P<0.01), but there was no obvious difference in the weights of adrenal glands. No significant difference in corticosterone levels was seen between Msg-treated group and the control one, even after electrical foot-shock. These results indicate that the neurons in ARC do not play an essential role in the regulation of pituitary-adrenocortical system.