Acetylcholinesterase activity in several hypothalamic and brain stem nuclei after acute and chronic immobilization stress in rats.

Acute and repeated immobilization stress increased acetylcholinesterase (AChE) specific activity in the nucleus supraopticus and median eminence of the rat and this increase was still present 24 hours after the 7th or 45th day of immobilization. The increase of AChE activity in those nuclei was probably related to the neuronal activation of the hypothalamic-pituitary axis during stress conditions. Acute and repeated immobilization was not accompanied by the change of AChE activity in A1 area and locus coeruleus. 46 days of immobilization periods produced a significant increase of AChE specific activity in the raphae dorsalis nucleus only which returned to normal values 24 hours after the last day of immobilization.