Seasonal changes in circulating growth hormone (GH), hepatic GH-binding and plasma insulin-like growth factor-I immunoreactivity in a marine fish,gilthead sea bream,Sparus aurata |
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| Authors: | J Pérez-Sánchez H Marti-Palanca P-Y Le Bail |
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| Institution: | (1) Instituto Acuicultura de Torre de la Sal, CSIC, 12595 Torre de la Sal, Castellón, Spain;(2) Laboratoire de Physiologie des Poissons, INRA, Campus de Beaulieu, 35042 Rennes Cedex, France;(3) Instituto de Acuicultura de Torre de la Sal, CSIC, 12595 Torre de la Sal, Castellón, Spain |
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| Abstract: | We have studied the seasonal relationship between growth and circulating growth hormone (GH), hepatic GH-binding and plasma
insulin-like growth factor-I immunoreactivity in gilthead sea bream,Sparus aurata. The seasonal increase in plasma GH levels preceded by several weeks the summer increase in growth rates. In contrast, a
marked increase in hepatic GH-binding with a high degree of endogenous GH occupancy was found during the period of maximum
growth which suggests an enhanced sensitivity of liver to GH action. Thus, circulating levels of immunoreactive IGF-I, probably
derived from the liver in response to GH action, were positively correlated with growth throughout the experimental period
although a consistent relationship between growth and circulating GH was not found. In spite of this, we consider that, in
gilthead sea bream, as in several other teleosts, the availability of endogenous GH can limit growth. Thus, under environmental
conditions of suboptimal growth, a single intraperitoneal injection of recombinant rainbow trout GH (rtGH) induced over the
dose range tested (0.75, 1.5, 3 μg g BW−1) an increase in plasma IGF-I-like immunoreactivity comparable to that seen during the period of maximum growth. |
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| Keywords: | teleost gilthead sea bream seasonal growth growth hormone IGF-I-like immunoreactivity |
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