Effect of acute administration of pyridostigmine and pirenzepine on ACTH, growth hormone and cortisol secretion in Cushing's and in obese patients

The effects of pyridostigmine (PD) (120 mg p.o.) and pirenzepine (PZ) (75 mg p.o.) on GH and ACTH/cortisol secretion were studied in 12 obese and 5 Cushing's patients. PD did not alter plasma ACTH and cortisol levels while inducing, in the obese but not in Cushing's patients, a small but appreciable GH rise (p <0.05 between GH values in the two groups). PZ was completely ineffective. These data seem to indicate that: a) both in Cushing's and in obese patients there is an impaired central cholinergic neurotransmission, the alteration being more pronounced in the former, b) cholinergic neuroregulation is not crucial for basal ACTH secretion in man.