Interactions of Porcine Follicular Fluid with Ovarian Steroids and Luteinizing Hormone-Releasing Hormone on the Secretion of Luteinizing Hormone and Follicle-Stimulating Hormone by Cultured Pituitary Cells

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Abstract
Basal and LHRH-stimulated FSH secretion were suppressed by the addition of porcine follicular fluid extract (pffl) to cultured rat anterior pituitary cells. Pig serum had no effect on basal or LHRH-induced LH or FSH secretion. The suppressive effects of pffl were quantitatively and temporally cumulative, since an increase in both the dosage and the length of exposure to pffl resulted in an increased inhibition of basal and LHRH-stimulated FSH secretion. The presence of steroids (estradiol and progesterone or estradiol-progesterone and testosterone) or pretreatment of cell cultures with LHRH enhanced basal 24-h FSH secretion. However, the addition of 0.5% or 0.1% pffl suppressed FSH secretion by 66–75%, whereas 0.02% pffl reduced FSH secretion by only 17%. The greatest suppression of LHRH-induced LH and FSH secretion by pffl occurred when cells were preincubated with pffl for 24 vs. 2 h. Further, higher concentrations of LHRH (2.1 × 10−8m) overcame the inhibitory effect of 2-h but not 24-h treatment with pffl (0.5%) on LH and FSH release. The inhibitory effects of pffl on basal secretion of FSH were reversible, since removal of pffl and reincubation of cell cultures for an additional 24 h in growth media with pig serum resulted in FSH concentrations equivalent to those obtained in cultures not previously exposed to pffl (Endocrinology106: 237, 1980)