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EFFECTS OF INTRANASAL CALCITONIN ADMINISTRATION ON PITUITARY GH RESPONSE TO hGHRH (1–29)NH 2 IN NORMAL ADULT SUBJECTS
Author(s) -
GIUSTINA ANDREA,
ROMANELLI GIUSEPPE,
DOGA MAURO,
PIZZOCOLO GIUSEPPE,
GIUSTINA GIANNI
Publication year - 1989
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1989.tb00276.x
Subject(s) - medicine , endocrinology , stimulation , bolus (digestion) , calcitonin , growth hormone–releasing hormone , pituitary gland , hormone , peptide hormone , nasal administration , growth hormone , pharmacology
SUMMARY Studies in man demonstrated that intramuscular salmon (s) calcitonin (CT) administration blunted pituitary GH response to hypothalamic stimuli such as arginine infusion and insulin‐induced hypoglycaemia. However, the mechanisms underlying this inhibiting action of CT are still unclear. The aim of our study was to investigate the effects of intranasal (i.n.) and i.m. sCT administration on GH secretion elicited by direct pituitary stimulation in man with human GH‐releasing hormone (GHRH) (1–29)NH 2 . Seven healthy non‐obese volunteers (five men, two women; mean age ± SDM 25 ± 2) underwent a bolus intravenous injection of GHRH, 100 pg , alone or associated with sCT, administered either i.n., 300 IU, or i.m., 100 IU. Our data demonstrate a significant decrease in GH secretion after GHRH when either i.n. or i.m. sCT is administered. GH peak (mean ± SDM); GHRH alone 22.9 ± 2.5 i s GHRH plus i.n. sCT, 8.9 ± 1.5 μg/l, P > 0.001; or vs GHRH plus i.m. sCT 12.3 ± 2.5 μg/l, P > 0.001. Area under the curve of GH secretion: GHRH alone 1211 ± 196 vs GHRH plus i.n. sCT 551 ± 116 μg 120 min/l, P > 0.001; or vs GHRH plus i.m. sCT 700 ± 167 μg 120 min/l, P > 0.001. We conclude that sCT is able to inhibit GHRH‐stimulated GH secretion in man.