Acetylcholinesterase and choline acetyltransferase activity in some hypothalamic nuclei under immobilization stress in rats.

Rats were subjected to acute immobilization (IMO) for 1 or 2 h and killed by decapitation. The hypothalamic supraoptic and paraventricular nuclei were isolated by dissection technique and the activity of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) was assayed. A period of 1 or 2 h of IMO resulted in a significant increase of AChE activity only in the supraoptic nucleus, while no change of ChAT activity occurred. Acute IMO of 1 or 2 h duration resulted in an increase of AChE activity in supraoptic nucleus.