The regulatory effects of thyrotropin-releasing hormone on growth hormone secretion from the pituitary of common carp in vitro

• Published in: Fish physiology and biochemistry 1993-07, Vol.11 (1-6), p.71-76
• Main Authors: Lin, X W, Lin, H R, Peter, R E
• Format: Article
• Language: English
• Subjects: Cyprinus carpio; Freshwater
• ISSN: 0920-1742; 1573-5168
• DOI: 10.1007/BF00004552

The effects of thyrotropin-releasing hormone (TRH) on growth hormone (GH) and gonadotropin (GtH) release, and the influences of somatostatin (SRIF), the dopamine agonist apomorphine (APO) and extracellular calcium on basal and TRH-induced GH release were examined using an in vitro perifusion system for pituitary fragments of common carp (Cyprinus carpio). Five minute pulses of different dosages of TRH stimulated a rapid and dose-dependent increase in GH release from the perifused pituitary fragments with an ED50 of 9.7 ± 2.3 nM. TRH was ineffective on GtH release. SRIF significantly inhibited basal and TRH-induced GH release from the perifused pituitary fragments, and the effects of SRIF were dose-dependent. APO induced a dose-dependent increase in basal and TRH-stimulated GH release from the perifused pituitary fragments. Increasing the concentrations of extracellular calcium from 0 mM to 1.25 mM resulted in an increase in basal and TRH-induced GH release. The high dose of calcium (6.25 mM) caused a slight decrease in basal and TRH-induced GH release compared with those at a concentration of 1.25 mM.