Growth hormone inhibits growth hormone secretion from the rainbow trout pituitary in vitro |
| |
Authors: | Agústsson T Björnsson B T |
| |
Affiliation: | Department of Zoology, G?teborg University , Sweden. t.agustsson@zool.gu.se |
| |
Abstract: | Growth hormone (GH) secretion in salmonids and other fish is under the control of a number of hypothalamic factors, but negative feed-back regulation by circulating hormones can also be of importance for the regulation of GH secretion. Mammalian studies show that GH has a negative feed-back effect on its own secretion. In order to elucidate if GH levels present a direct ultra-short negative feedback loop at the pituitary level GH secretion was studied in intact pituitaries from 50 g fish in an in vitro perifusion system. Following an initial equilibrium period pituitaries were exposed to five increasing concentrations (1-1,000 ng ml(-1)) of ovine GH (oGH) in 20-min steps, before being returned to a GH-free perifusion. Ovine GH caused a significant dose-dependent inhibition of GH secretion and it is concluded that GH can exert a direct negative feedback control on GH secretion at the pituitary level. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|