Opioid modulation of LH secretion by pig pituitary cells in vitro.
The effects of naloxone and beta-endorphin on LH secretion by pig pituitary cells were studied in primary cultures. On Day 4 of culture, cells (10(5) seeded/well) were challenged with 10(-9), 10(-8) or 10(-7) M gonadotrophin-releasing hormone (GnRH), 10(-10), 10(-9), 10(-8) or 10(-7) M-beta-endorphin or 10(-6) M-naloxone individually or in combinations. Secreted LH was measured at 4 h and 24 h after treatment and cellular content of LH was measured after 24 h. Basal LH secretion (control) was 23.5 +/- 7.6 and 36.9 +/- 10.3 ng/well at 4 h and 24 h, respectively. Relative to control at 4 h, 10(-9), 10(-8) or 10(-7) M-GnRH stimulated (P less than 0.05) LH secretion 140%, 210% and 250%, respectively. At 24 h, LH secretion was increased (P less than 0.05) by GnRH compared to control, but the dose-response to GnRH was absent. Naloxone increased (P less than 0.01) LH secretion 166 +/- 13% at 4 h and 141 +/- 13% (P less than 0.06) at 24 h. Secretion of LH after simultaneous addition of 10(-8) M-GnRH plus naloxone was greater (P less than 0.01) than after GnRH alone at 4 h but not at 24 h. beta-Endorphin at 10(-10), 10(-9), 10(-8) or 10(-7) M failed to alter basal LH secretion at 4 h but decreased secretion at 24 h, while cellular LH content was similar to control at 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)
Barb
C R
CR
USDA-ARS, Russell Research Center, Athens, GA 30612.
Barrett
J B
JB
Wright
J T
JT
Kraeling
R R
RR
Rampacek
G B
GB
D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D007986:Luteinizing Hormone / Q000378:metabolism*; D009270:Naloxone / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology; D013552:Swine; D013997:Time Factors; D001615:beta-Endorphin / Q000494:pharmacology*
D010906:Pituitary Hormone-Releasing Hormones; D009270:Naloxone; D001615:beta-Endorphin; D007986:Luteinizing Hormone