Divergent effects on LH and FSH synthesis and release from intact female rat pituitary glands in vitro by methylxanthines, cyclic AMP derivatives and sodium fluoride

FSH release from the female rat pituitary gland consists of an LH-like, LRH-dependent component and an autonomous, inhibin-sensitive component. It was investigated whether cyclic AMP mediated FSH release. BrcAMP, theophylline, MIX or NaF stimulated LH release but inhibited FSH release and synthesis. Although dbcAMP had no inhibitory effect on FSH release, it partly reversed the inhibitory action of theophylline. In view of previous and the present results it is concluded that cyclic AMP may mediate the LRHdependent LH and FSH release and, through a separate pathway, may mediate the inhibition of autonomous FSH release by the ovarian protein inhibin.

A procedure for the purification of somatotrophs isolated from rat anterior pituitary glands using Percoll density gradients

We have used fractionation on density gradients of Percoll to separate the cell types in the rat anterior pituitary gland and to produce a purified preparation of somatotrophs. The method differs from those described previously which used, for example, albumin or Ficoll gradients, in being more rapid and avoiding low temperatures, and therefore gives cells with improved viability. Anterior pituitary glands from male rats were dispersed with trypsin to produce 1·5 × 106–2·0 × 106 cells/gland. These were fractionated on hyperbolic density gradients of Percoll. Two bands of cells containing somatotrophs were detected, one of which (band A; density 1·075–1·082 g/cm3) contained approximately 90% somatotrophs, whereas the other (band B; density 1·055–1·068 g/cm3) contained about 70% somatotrophs mixed with other cells, especially lactotrophs. Cells in band A appeared more responsive to secretagogues than those in band B; growth hormone secretion was stimulated markedly by cyclic AMP derivatives and prostaglandin E2, and inhibited by somatostatin. Such purified somatotrophs are well suited to biochemical studies on the mechanism of the control of growth hormone secretion.