Release and synthesis of FSH by pituitary glands of female rats in vitro

Abstract

Anterior hemi-pituitary glands from intact female and ovariectomized (OVX) rats were incubated with or without a maximally effective dose of LRH. During an 8 h incubation, LRH-stimulated release of FSH by pituitary glands from intact rats was biphasic: an initial slow rate of release and, from 2 to 8 h, an enhanced rate of release. Basal release was low up to 4 h, after which a marked increase of the rate of release was measured: from 6 to 8 h there was no difference between the rates of basal and LRH-stimulated release. Basal and LRH-stimulated release of FSH by pituitary glands from OVX rats were high and approximately constant during an 8 h incubation.Both basal and LRH-stimulated release by glands from intact as well as OVX rats were protein synthesis dependent. During the incubations an LRH-independent synthesis of FSH was measured. The results suggest that this synthesis is involved, either directly or indirectly, in increasing the rate of basal release of FSH after 4 h. A comparison of release and synthesis of FSH with those of LH reveals characteristic differences.

Effect of pre-treatment of long-term ovariectomized rats with anti-LRH on the response of the pituitary gland in vitro to the analogue of LRH D-ser-(tBu)6-des-gly10-ethylamide-LRH (Buserelin®)

“…The expla¬ nation put forward by Valk et al (1980) Whereas plasma levels of both LH and FSH were lowered by anti-LRH, basal release in vitro of LH did not but that of FSH did reflect the changes of plasma levels. In agreement with previous results (Jenner et al 1982) basal release of FSH in vitro reflects synthesis and release of FSH in vivo to a far greater extent than is the case for LH.…”

“…J. Uilenbroek and J. Dullaart and described by Welschen et al (1975). With regard to the measurement of LH and FSH in incubation media slight modifications were used as described by Jenner et al (1982). In order to avoid interference by injected rabbit globulins plasma LH and FSH were estimated using a further modification in that the anti¬ body-antigen complex was separated by adsorption to an increased amount of protein A.…”

Cyclic Nucleotides and Suppression of Follicle-Stimulating Hormone Release by Inhibin

“…Simpson et al [6] have demon strated that the FSH response to GnRH can be suppressed by inhibition of calcium mo bilization from either extracellular or intra cellular stores. Jenner et al [7], however, report that basal FSH release is independent of extracellular calcium. Antagonism of cal cium mobilization and calmodulin (CAM) activity failed to restore FSH responsiveness in the presence of IBN [8], Stimulation of gonadotropes with GnRH is associated with an increase in cellular 3',5'-cyclic AMP (cAMP) [9].…”

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

“…The following agents were dissolved in the media at final concentrations of 1 to 10 mM: 8-bromoadenosine-3':5'-mono-phosphoric acid (BrcAMP; Boeh¬ ringer), N6 -2' -0 -dibutyryl -adenosine -3',5'-monophos¬ phate (dbcAMP; Boehringer), l-methyl-3-isobutyl-xanthine (MIX; Sigma), NaF (Merck) and theophylline (DBH Chemicals Ltd.). The LH and FSH contents of the media and of saline-extracted pituitary glands were esti¬ mated by radioimmunoassay (Welschen et al 1975;De Koning et al 1982;Jenner et al 1982). Since in one case (10 mM NaF treatment) pituitary wet weight was signifi¬ cantly higher, the results are expressed as µg LH-RP-1 or pg FSH-RP-1/pituitary tissue (mean ± SEM; = 4) instead of per mg pituitary wet weight (see e.g.…”

“…Many reports deal with a possible role for cyclic AMP as an intracellular mediator for LRH-induced LH release, but only few of them also include FSH release (for review see Tixier-Vidal & Gourdji 1981;De Koning et al 1981). Furthermore, secre¬ tion of FSH apparently is more complex than that (Welschen et al 1975;De Koning et al 1982;Jenner et al 1982). Since in one case (10 mM NaF treatment) pituitary wet weight was signifi¬ cantly higher, the results are expressed as µg LH-RP-1 or pg FSH-RP-1/pituitary tissue (mean ± SEM; = 4) instead of per mg pituitary wet weight (see e.g.…”