Glycoprotein gonadotropin in the plasma and its cellular origin in the adenohypophysis of sham-operated and ovariectomized rainbow trout, salmo gairdneri

Abstract

Among the cells of the pituitary generally believed to produce glycoprotein gonadotropin (GTH) five forms were distinguished, based on the amount and the diameter of granules and globules and the appearance of the rough endoplasmic reticulum. In sham-operated trout so-called "globular" cells predominated, whereas after ovariectomy these were replaced by so-called "cisternal" cells, suggesting that both belong to one GTH-cell type. In addition, ovariectomy caused a strong increase in plasma GTH-levels. This indicates that the transition from globular to cisternal cells is accompanied by extrusion of GTH, and thus points to a storage of GTH in the granules and globules. It is argued that one of the five forms has the morphological characteristics of thyrotropic cells and may not produce glycoprotein GTH.

Internal and external factors controlling reproduction in the African catfish,Clarias gariepinus

“…Castration also resulted in increascd plasma GTH levels. In the rainbow trout, Oncor/zynchu.s mykiss (Billard et al, 1977;Van Putten et al, 1981) and the three spined stickleback, Ga.stero.steus aculeutus (Borg et al, 1985), this was accompanied by a partial degranulation of GTH cells. Billard (1978) and Bommelaer et al (1981) showed that the increase in GTH levels could be prevented by testosterone and estradiol, and to soine extent, by Il-ketotcstosterone.…”

Aromatase activity in brain and pituitary of immature and mature atlantic salmon (Salmo salar L.) parr

“…In the stickleback morphological studies indicate that methyltestosterone stimulates the GTH cells in winter (Borg et al, 1986) and have an inhibitory effect when the breeding season has already started (Borg et al, 1985). The feedback from the gonads to the pituitary is largely negative in adult salmonids (e.g., van Putten et al, 1981;Billard et al, 1977). One might speculate that an increased aromatase activity in the brain in the maturing parr might change the general androgen effect on the GTH cells from a positive accelerating to a negative stabilizing feedback.…”

Steroid hormone secretion by testicular tissue from African catfish, Clarias gariepinus, in primary culture: identification and quantification by gas chromatography — mass spectrometry

“…In rainbow trout, Oncorhynchus mykiss, plasma GTH levels increase after castration (Billard et al 1977;Van Putten et al 1981). Billard (1978) and Bommelaer et al (1981) found that this GTH increase could be prevented by testosterone (T) and estradiol (E 2 ) and also partially by 11-ketotestosterone (11KT).…”