Pituitary Follicle-Stimulating Hormone in Immature Female Rats Treated with Drugs that Inhibit the Synthesis or Antagonise the Actions of Catecholamines and 5-Hydroxytryptamine

Abstract

Drugs that inhibit the synthesis or antagonise the actions of catecholamines and 5-hydroxytryρtamine (5-HT) were tested in rats in relation to: (1) the acute depletion of pituitary follicle-stimulating hormone (FSH) occurring during the after- noon at the age of 35 or 37 days; (2) the depletion of pituitary FSH occurring between the ages of 34 and 39 days; (3) the increase in ovarian weight in immature rats treated with human chorionic gonadotrophin; this increase probably involves endogenous FSH. The acute depletion (1) was prevented by barbitone, reserpine, p-chlorophenylalanine (CPA), methysergide, and α-methyl-p-tyrosine (MPT). The slower fall in FSH (2) was inhibited by reserpine, CPA, thymoxamine and methallibure. Ovarian weight in the third situation (3) was reduced by CPA but increased by thymoxamine. From these results, it is suggested that 5-HT may have an excitatory role in the control of FSH secretion.