The paradox of growth acceleration in fish

摘要

Growth is a complex and tightly regulated process in fish. The growth hormone (GH) is a polypeptide playing a key role in the process of growth and is synthesized mainly by somatotrophos in the anterior pituitary gland. Release of GH from the pituitary gland is thought to be controlled primarily by hypothalamic factors. Once in the circulation, a substantial proportion of the GH appears to bind to a specific binding protein, probably responsible for the control of the hormone half life in the circulation. After binding to specific cell receptors, GH stimulates, primarily in the liver, Insulin-like growth factor (IGF-I and IGF-II) synthesis and secretion to elicit the growth promoting action in an autocrine and paracrine fashions. IGF also elicits a negative feedback on the secretion of GH in the pituitary gland in tilapia (Guillen et al., in press).