Gonadotropic Hormone Treatment of Rainbow Trout (Salmo gairdneri): Plasma Hormone Profile Following a Single Injection

Abstract

Immature rainbow trout (Salmo gairdneri) were treated with salmon gonadotropic hormone to determine the presence of this hormone in circulation, to describe the plasma profile with time after exogenous hormone treatment, and to determine the difference in plasma gonadotropin levels resulting from treatment with two different hormone doses. The effect of three selected temperatures on the plasma hormone profile was also studied. The plasma concentration of the injected hormone following a low dose (0.02 μg/g) and a high dose (0.2μg/g) suggested that plasma hormone levels were directly related to the hormone quantity injected. For fish maintained at 6 C, plasma gonadotropin values declined over a period of 7 days reaching low but detectable levels. Lower plasma gonadotropin profiles were observed for fish held at 6 and 15 compared with fish at 2 C ambient temperature. These data suggest the plasma gonadotropin levels and ambient temperature are related in an inverse manner.