Site of origin of the pulsatile secretion of luteinizing hormone in long-term ovariectomized rats.
If long-term ovariectomized rats are treated with the long-acting barbiturate, sodium phenobarbitone, the well-known pulsatile secretion of LH is depressed, resulting in a constant, still raised, plasma LH level. This indicates that in all probability ovariectomized rats secrete LH in both a tonic and a pulsatile way, only the latter being sensitive to phenobarbitone treatment. Constant infusions of synthetic LH-RH into phenobarbitone-treated ovariectomized rats induced a steadily increasing plasma LH concentration without pulsations, whereas pulsatile infusions of the releasing hormone, following a constant infusion, resulted in a pulsatile secretion of LH. This indicates that the pulsatile secretion of LH in ovariectomized rats is the result of a pulsatile secretion of the hypothalamic releasing hormone; the pituitary gland itself is not the site of origin of the phenomenon.
D000818:Animals; D002369:Castration; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007031:Hypothalamus / Q000378:metabolism; D007986:Luteinizing Hormone / Q000378:metabolism*; D010053:Ovary / Q000502:physiology; D010634:Phenobarbital / Q000494:pharmacology; D051381:Rats; D012636:Secretory Rate / Q000187:drug effects
D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D010634:Phenobarbital