Progesterone facilitates the LRH releasing action of oestrogen.
The effects of progesterone (P) on the release of LRH and LH were examined in a sequential double chamber superfusion system by superfusing the medial basal hypothalamus (MBH) and/or pituitaries excised randomly from cycling female rats. Addition of 10 microliters of 10(-6) M oestradiol (E2) to the first chamber resulted in a gradual and significant (60-160%) increase in LH release above the pre-injection level from the pituitary in series with MBH. Administration of 10(-8) M P after 10(-6) M E2 caused a prompt and marked increase (300%) of LH (P less than 0.05), whereas 10(-8) M P alone had no effect. Administration of 10(-6) M E2, 10(-8) M P or E2 plus P did not significantly change LH secretion from the pituitary superfused alone. The concentration of LRH in the efflux was significantly increased (150-200%) 150 min after 10(-6) M E2 administration. P administration after E2 injection produced a prompt and significant increase of LRH and the increase of LRH (300-600%) was 2-3-fold that produced by E2. P alone had no effect. These data clearly indicate that P enhances E2-induced LH release by increasing LRH secretion from the MBH.
D000818:Animals; D002478:Cells, Cultured; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism*; D010477:Perfusion; D010902:Pituitary Gland / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone