THE EFFECT OF CHOLINERGIC BLOCKADE ON THE ACTH, β‐ENDORPHIN AND CORTISOL RESPONSES TO INSULIN‐INDUCED HYPOGLYCAEMIA

Abstract

To assess the effect of cholinergic blockade on the ACTH, β‐endorphin and cortisol responses to insulin‐induced hypoglycaemia, six healthy male volunteers each underwent two insulin tolerance tests in random order, separated by at least 1 week with and without atropine. ACTH levels were significantly greater at + 45 min (mean ± SEM, 223 ± 21 pg/ml vs 148 ± 15 pg/ml, P > 0·01) and at + 120 min (54 ± 11 pg/ml vs 29 ± 10 pg/ml, P > 0·05). β‐endorphin levels were significantly greater at + 30 min (170 ± 45 pg/ml vs 96 ± 32 pg/ml, P > 0·05) and at + 105 min (81 ± 14 pg/ml vs 54 ± 7 pg/ml, P > 0·01). Cholinergic blockade had no effect on plasma glucose or cortisol concentrations. This study demonstrates that cholinergic blockade with atropine facilitates the ACTH and β‐endorphin responses to insulin‐induced hypoglycaemia without altering the cortisol responses.