RIAs were developed for the two salmon gonadotropins (GTH I and GTH II) and used to measure plasma GTH throughout the life of the rainbow trout, Oncorhynchus mykiss. The RIA for GTH II was specific and sensitive (< 0.001% cross-reaction with GTH I, mean sensitivity = 0.26 +/- 0.02 ng/ml). The RIA for GTH I was less specific and less sensitive than the GTH II RIA (9.7% cross-reaction with GTH II...

The goldfish, a member of the carp family, is a widely used model for reproductive neuroendocrine studies of economically important fish. The two gonadotrophin (GTH) molecules released from the fish anterior pituitary, GTH-I and GTH-II, are structurally similar to tetrapod FSH and LH, respectively. Gonadotrophin II is the best studied, and in goldfish stimulates gonadal growth and steroidogenes...

Concentrations of brain salmon gonadotropin-releasing hormone (sGnRH), plasma gonadotropin I (GTH I), and pituitary GTH I and GTH II were determined in yearling chinook salmon (Oncorhynchus tschawytscha) during the parr-smolt transformation in two successive seasons. There were significant elevations in brain sGnRH content from February to March in 1988, and from February to April in 1989. Incr...

In order to determine the factors of ovarian origin which can modulate the postovulatory secretion of the FSH-like gonadotropin (GtH I) and the LH-like gonadotropin (GtH II), freshly ovulated female rainbow trout were divided into two groups. In the first group the fish were stripped in order to eliminate the eggs and ovarian fluid from the body cavity, while in the second group the eggs were k...

Insulin-like growth factor (IGF)-I has been suggested as a potential signal linking growth and puberty in mammals. Using the juvenile European eel as a model, we employed a long-term, serum-free primary culture of pituitary cells to study the direct effect of IGF-I on gonadotrophin (GtH-II=LH) production. IGF-I increased both cell content and release of GtH-II in a time- and dose-dependent mann...