Growth hormone secretion in response to surgery. Effects of cholinergic blockade and octreotide

Cholinergic blockade markedly reduces the growth hormone (GH) response to most stimuli, with the exception of insulin induced hypoglycaemia. We have administered the cholinergic antagonist, atropine, known to cross the blood brain barrier, to eight healthy female patients prior to elective surgery in order to investigate the role of cholinergic pathways in the GH response to surgery. Additionally, eight patients received the octapeptide analogue of somatostatin, octreotide, known to suppress GH secretion. A control group matched for age and weight received no injection. The GH response to surgery was assessed by peak values and areas under curves. Octreotide resulted in a significant inhibition of GH secretion compared with the control group (p < 0.01 for both parameters). In contrast, atropine did not significantly inhibit the GH response to surgery. In conclusion, octreotide completely suppressed GH secretion during surgery, whereas cholinergic blockade was ineffective. Thus surgery is similar to insulin induced hypoglycaemia poglycaemia in that the GH response is not decreased by cholinergic blockade.