Glucose and free fatty acid modulation of growth hormone and luteinizing hormone secretion by cultured porcine pituitary cells.

The influence of glucose and free fatty acids (FFA) on LH and GH secretion from porcine pituitary cells was examined in culture. Cells were challenged with 10(-9), 10(-8), or 10(-7) M GnRH; 10(-9), 10(-8), or 10(-7) M [Ala15]-h growth hormone-releasing factor-(1-29)NH2 (GRF); 10(-3) or 10(-5) M forskolin; glucose (100, 300, or 600 mg/dL); and oleic or linoleic acid (10(-11) to 10(-5) M) individually or in combinations of glucose, oleic, and linoleic acid with GnRH, GRF, or forskolin. Relative to control (medium alone), GnRH increased (P < .003) LH secretion. Glucose at 100 mg/dL enhanced (P < .05) basal LH release, whereas the 600-mg/dL dose suppressed (P < .05) LH response to GnRH. Except for 10(-7) M, all doses of linoleic acid increased (P < .05) basal LH release, whereas only 10(-5) M linoleic acid suppressed (P < .02) LH response to GnRH. All doses of oleic acid enhanced (P < .05) basal LH release and suppressed (P < .03) the LH response to GnRH. In contrast, neither FFA suppressed the forskolin-induced LH secretion compared to forskolin alone. Growth hormone-releasing factor stimulated (P < .02) GH release in a dose-dependent manner. Glucose did not alter basal GH release but suppressed (P < .01) GRF-induced GH release. Only 300 mg/dL of glucose suppressed (P < .05) forskolin-induced GH release.(ABSTRACT TRUNCATED AT 250 WORDS)