Effect of porcine follicular fluid on LH and FSH secretion in rats.

Abstract

Effect of Porcine Follicular Fluid on LH and FSH Secretion in Rats . Tohoku J. exp. Med., 1988, 156 (2), 157-163 -To investigate a mode and a site of action of inhibin on FSH and LH secretion , in vivo and in vitro effects of porcine follicular fluid (PFF) on FSH and LH secretion were studied in male rats . PFF administerd i.v. suppressed basal FSH levels for 1-8 hr , but did not alter LH levels. O n the contrary, PFF given either 1 or 6 hr in advance , suppressed LH-RH stimulated LH responses as well as LH-RH induced FSH responses . In cultured pituitary cells PFF exerted a partial suppressive effect on LH release. PFF suppressed LH release only under the maximal stimulation with 10-70 M LH-RH and 0.1 mM 3-isobutyl-1-metylxanthine (IBMX) to a lesser degree compared with uniform and greater suppression on FSH release regardless of the experimental conditions. Above results showed a selective suppressive effect of PFF on FSH release and synthesis with a less inhibitory effect on LH release mainly at the pituitary level.inhibin ; porcine follicular fluid ; FSH ; LH ; LH-RH It has been widely demonstrated that follicular or testicular preparations with definite inhibin activities suppressed FSH secretion in rats (Marder et al . 1977;Schwartz and Charming 1977) as well as in other species (Channing et al. 1981 ;Rettori et al. 1982). However, effects of inhibin on LH release are still controversial.To investigate the effect of inhibin on LH and FSH secretion, in vivo and in vitro effects of porcine follicular fluid (PFF) on LH and FSH secretion were studied in male rats under various conditions.

Inhibin .ALPHA., .BETA.A and .BETA.B Subunit Messenger Ribonucleic Acid Levels in Cultured Rat Pituitary: Studies by a Quantitative RT-PCR.

“…In accord with many previous reports [10][11][12][13][14] including ours [15], basal FSH secretion was increased by activin A and suppressed by inhibin A. No significant change was observed in 3 mRNA levels accompanying changes in FSH and LH secretion, though f subunit mRNA decreased to approximately half of the initial level when activin A was added, and a slight increase in a mRNA levels caused by both inhibin A and activin A. Bilezikjian et al [7] observed a significant decrease in activin f monomer and dimer production when activin A was added to rat anterior pituitary cells and proposed a local negative feedback by activin of its own production.…”