Gonadotropin secretion and porcine pituitary cell proliferation under the influence of cortisol

The investigations have been performed to clarify the influence of cortisol on gonadotropin secretion and porcine pituitary cell proliferation in vitro. Pituitary cells isolated from 3-4-year-old sows at the follicular phase of the oestrous cycle were cultured in McCoy5A medium with various concentrations of cortisol (10(-10), 10(-9), 10(-8), 10(-7) and 10(-6) M/l) and the ovarian steroid hormones 17beta-oestradiol (E-2; 1.8 x 10(-11) M/l) and progesterone (P-4; 2.3 x 10(-10) M/l). Treatment with cortisol caused significant (pless than or equal to0.05) suppression of FSH secretion after 12, 24, 36 and 48 h of the experiment. LH secretion was also suppressed by cortisol, but this was dose and time dependent. All utilized doses, except for one, decreased LH secretion after 24, 36 and 48 h. At the highest dose of 10(-6) M/l cortisol caused a significant suppression also after 12 h of the experiment. Almost all the utilized doses of cortisol led to the inhibition of proliferation after 48 h. Only 10(-6) M/l of cortisol inhibited proliferation of pituitary cells in the culture throughout the experiment. Under the influence of high doses of cortisol, considerably lesser numbers of secretory granules with E-2 and P-4 were observed in comparison to the non-stimulated and those stimulated only with oestradiol and progesterone cells.