Clinical Endocrinology (1990), 33, 605-61 2

PYRIDOSTIGMINE DOES NOT REVERSE DEXAMETHASONE-INDUCED GROWTH HORMONE INHIBITION P . D E L BALZO, R. SALVATORI, M . C A P P A *

AND

J. M . G E R T N E R

Division of Pediatric Endocrinology, The New York Hospital-Cornell University Medical College, New York, N Y , USA and *Department of Endocrinology, Bambino GesG Hospital, Research Institute, Rome, Italy (Received 5 February 1990; rerurned for revision 16 March 1990:finally revised 5 June 1990; accepted 26 June 1990)

SUMMARY

Glucocorticoids inhibit the growth hormone (GH) response to a variety of stimuli, including GH-releasing hormone (GHRH) in vivo, but they increase GHRH-stimulated G H secretion when added, in vitro, to animal and human pituitary cells. This discrepancy has led to the hypothesis that glucocorticoids act in vivo by increasing somatostatin secretion from the hypothalamus. To examine this hypothesis, we used a cholinergic drug, pyridostigmine (PD), which reduces hypothalamic somatostatin secretion. Eight normal volunteers were studied. They underwent four tests: (1) G H R H test; (2) Dex+GHRH (GHRH test after treatment the night before, with dexamethasone (Dex)); (3) PD + GHRH; (4) Dex + PD GHRH. Dex significantly inhibited the G H response to GHRH expressed as area under the GH/time curve (AUC, pg/l/ min) (mean 2 SEM = 895.2 & 196.6 vs 1970.9& 600.1, P < 0.05). PD significantly increased the AUC of G H secretion in P D + G H R H compared with G H R H alone (3541.2f571.3 us 1970.9+600.1, P

Pyridostigmine does not reverse dexamethasone-induced growth hormone inhibition.

Glucocorticoids inhibit the growth hormone (GH) response to a variety of stimuli, including GH-releasing hormone (GHRH) in vivo, but they increase GHR...
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