The effects of cholinergic blockade on the growth hormone and prolactin response to insulin hypoglycaemia

The effect of cholinergic blockade on growth hormone (GH) and prolactin (PRL) secretion during insulin-induced hypoglycaemia was assessed in six normal male volunteers (mean age 23, age range 21-25). Each subject underwent two insulin tolerance tests with and without atropine. GH responses were significantly lower 45 min after insulin administration with atropine (17.5 +/- 2.5 mU/l (mean +/- SEM) than with placebo (37.6 +/- 3.6 mU/l, P less than 0.0006). In contrast PRL responses were higher (P less than 0.01) at 45 and 90 min after insulin during treatment with atropine. These data demonstrate that cholinergic mechanisms are involved in stimulatory and inhibitory pathways in the medication of the respective GH and PRL responses to insulin induced hypoglycaemia in man.