Stress-induced activation of the hippocampal cholinergic system and the pituitary-adrenocortical axis.

The septo-hippocampal cholinergic system in rats undergoes rapid activation after acute stress. This is expressed by rapid increases both in high affinity choline uptake and newly synthesized acetylcholine release. Administration of ACTH or corticosterone at a high dose led 10 min later to changes comparable to those observed after acute stress. Choline uptake and acetylcholine release were also elevated 2 days after adrenalectomy. The effects of adrenalectomy could be attenuated by corticosterone, but not by ACTH treatment. The results demonstrate that (a) after short term stress the septo-hippocampal cholinergic system is activated secondary to activation of the pituitary-adrenocortical axis and (b) major changes in circulating corticosterone can modulate the activity of the hippocampal cholinergic synapse.