Madsen S S, Bern H A
Department of Integrative Biology, University of California, Berkeley 94720.
J Endocrinol. 1993 Jul;138(1):23-30. doi: 10.1677/joe.0.1380023.
The effect of ovine GH (oGH) in vivo and recombinant bovine insulin-like growth factor-I (rbIGF-I) in vitro on gill Na+,K(+)-ATPase activity was investigated in two seasonal experiments conducted during the parr-smolt transformation period of coho salmon. In 1991, when fish were held under a photoperiod of 12 h light : 12 h darkness, the stimulatory effect of oGH (1 microgram/g) on gill Na+,K(+)-ATPase in vivo decreased at the time of expected parr-smolt transformation. Gill Na+,K(+)-ATPase from control fish was insensitive to rbIGF-I in vitro from February to June, whereas GH treatment induced sensitivity to rbIGF-I (100-1000 micrograms/l) in vitro in February and March, but not later in development. In 1992, when fish were held under natural conditions, oGH (4 micrograms/g) stimulated gill Na+,K(+)-ATPase in vivo from February to July. There was, however, of pronounced developmental change in sensitivity of gill Na+,K(+)-ATPase to rbIGF-I in vitro. In February, gills from control fish were insensitive, but oGH treatment in vivo induced sensitivity to rbIGF-I in vitro (100-1000 micrograms/l). In April and May, control fish were sensitive to rbIGF-I in vitro. This sensitivity was not further potentiated by oGH treatment in vivo. In June, gills from control or oGH-treated fish were not sensitive to rbIGF-I in vitro, but in July exogenous oGH again induced gill tissue sensitivity to rbIGF-I at 1000 micrograms/l. Both studies showed that rbIGF-I stimulates gill Na(+),K(+)-ATPase directly; an ability that may depend on priming by endogenous or exogenous GH. This supports the role of IGF-I as an endocrine mediator for GH action during parr-smolt transformation.
在银大麻哈鱼幼鱼向稚鱼转变阶段进行的两个季节性实验中，研究了体内注射绵羊生长激素（oGH）和体外添加重组牛胰岛素样生长因子-I（rbIGF-I）对鳃Na⁺,K⁺-ATP酶活性的影响。1991年，当鱼饲养在12小时光照：12小时黑暗的光周期条件下时，预期的幼鱼向稚鱼转变时，oGH（1微克/克）对鳃Na⁺,K⁺-ATP酶的体内刺激作用下降。2月至6月，对照鱼的鳃Na⁺,K⁺-ATP酶对体外rbIGF-I不敏感，而GH处理在2月和3月使鳃对体外rbIGF-I（100 - 1000微克/升）敏感，但在发育后期则不然。1992年，当鱼在自然条件下饲养时，oGH（4微克/克）在2月至7月刺激鳃Na⁺,K⁺-ATP酶的体内活性。然而，鳃Na⁺,K⁺-ATP酶对体外rbIGF-I的敏感性有明显的发育变化。2月，对照鱼的鳃不敏感，但体内GH处理使鳃对体外rbIGF-I（100 - 1000微克/升）敏感。4月和5月，对照鱼的鳃对体外rbIGF-I敏感。体内GH处理未进一步增强这种敏感性。6月，对照鱼或经GH处理的鱼的鳃对体外rbIGF-I不敏感，但7月外源oGH再次使鳃组织对1000微克/升的rbIGF-I敏感。两项研究均表明，rbIGF-I直接刺激鳃Na⁺,K⁺-ATP酶；这种能力可能取决于内源性或外源性GH的启动作用。这支持了IGF-I作为幼鱼向稚鱼转变过程中GH作用的内分泌介质的作用。
