Premium
Effect of atropine and pyridostigmine on growth hormone response to GH‐releasing peptide‐2 and GH‐releasing hormone in swine
Author(s) -
NOU Vonika,
TOMOSHI Kyouko,
INOUE Hiroaki,
KUWAYAMA Hideto,
HIDARI Hisashi
Publication year - 2003
Publication title -
animal science journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.606
H-Index - 38
eISSN - 1740-0929
pISSN - 1344-3941
DOI - 10.1046/j.1344-3941.2003.00097.x
Subject(s) - pyridostigmine , endocrinology , medicine , somatostatin , atropine , growth hormone–releasing hormone , pyridostigmine bromide , chemistry , hormone , muscarinic acetylcholine receptor , biology , growth hormone , receptor , myasthenia gravis
To investigate the effects of high and low somatostatinergic tone on GH‐releasing peptide‐2 (GHRP‐2) and GH‐releasing hormone (GHRH)‐induced growth hormone (GH) secretion in swine, we examined GHRP‐2‐ and GHRH‐induced GH secretion after pretreatment with atropine or pyridostigmine. Pretreatment of swine with atropine (80 µg/kg bodyweight (BW), intravenous (i.v.)) 15 min before i.v. administration of saline, GHRP‐2 (30 µg/kg BW), GHRH (1 µg/kg BW) or a combination of GHRP‐2 and GHRH, reduced plasma GH area under the curve ( P < 0.05), completely blocked GH response to GHRH, and attenuated GH response to GHRP‐2 and GHRH combined ( P < 0.05), without affecting GH response to GHRP‐2 only. A synergistic effect of GHRP‐2 and GHRH was not observed. In contrast, pretreatment of swine with pyridostigmine (100 µg/kg BW, i.v.), under the same pretreatment conditions as above, increased plasma GH concentration ( P < 0.01), augmented GH response to GHRP‐2 ( P < 0.05), and GHRP‐2 and GHRH combined ( P < 0.05), but did not affect GH response to GHRH. These results suggest that the cholinergic muscarinic agents atropine and pyridostigmine modulate the GH response to GHRP‐2 and GHRH, and that GHRP‐2 acts antagonistically on the inhibitory effect of somatostatin in swine.