Neuropeptide Y modulates growth hormone but not luteinizing hormone secretion from prepuberal gilt anterior pituitary cells in culture.
Pituitary cells, from seven 160- to 170-day-old pigs, were studied in primary culture to determine the affects NPY on LH and GH secretion at the level of the pituitary. On day 4 of culture, medium was discarded, plates were rinsed twice with serum-free medium and cells were cultured in 1 ml fresh medium without serum and challenged individually with 10(-10), 10(-8) or 10(-6) M [Ala(15)]-h growth hormone-releasing factor-(1-29)NH(2) (GRF); 10(-9), 10(-8) or 10(-7) M GnRH or 10(-9), 10(-8), 10(-7) or 10(-6) M NPY individually or in combinations with 10(-9) or 10(-8) M GnRH or 10(-8) or 10(-6)M GRF. Cells were exposed to treatment for 4 h at which time medium was harvested and quantified for LH and GH. Basal LH secretion (control; n = 7 pituitaries) was 12 +/- 6 ng/well. Relative to control at 4 h, 10(-9), 10(-8) and 10(-7) M GnRH increased (P < 0.01) LH secretion by 169, 176 and 197%, respectively. Neuropeptide-Y did not alter (P > 0.4) basal LH secretion nor 10(-8) M GnRH-induced increase in LH secretion but 10(-9) M GnRH-stimulated LH secretion was reduced by NPY and was not different from control or GnRH alone. Basal GH secretion (control; n = 7 pituitaries) was 56 +/- 12 ng/well. Relative to control at 4 h, 10(-10), 10(-8) and 10(-6) M GRF increased GH secretion by 111%, 125% (P < 0.01) and 150% (P < 0.01), respectively. Only 10(-6) M (134%) and 10(-7) M (125%) NPY increased (P < 0.04) basal GH secretion. Addition of 10(-9), 10(-8) and 10(-7) M NPY in combination with 10(-8) M GRF suppressed (P < 0.04) GRF-stimulated GH secretion. However, 10(-9) M NPY enhanced (P < 0.06) the GH response to 10(-6) M GRF. These results demonstrate that NPY may directly modulate GH secretion at the level of the pituitary gland.
Barb
C R
CR
USDA-ARS, Animal Physiology Research Unit, Russell Agricultural Research Center, Athens, GA 30604-5677, USA. rbarb@saa.ars.usda.gov
Barrett
J B
JB
D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage / Q000502:physiology; D007986:Luteinizing Hormone / Q000378:metabolism*; D009478:Neuropeptide Y / Q000008:administration & dosage / Q000502:physiology*; D010446:Peptide Fragments / Q000008:administration & dosage / Q000502:physiology; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D012741:Sexual Maturation / Q000502:physiology; D013552:Swine
D009478:Neuropeptide Y; D010446:Peptide Fragments; D007986:Luteinizing Hormone; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; C059148:somatotropin releasing hormone (1-29)