“INHIBITION” OF PITUITARY ACTH RELEASE AFTER ADMINISTRATION OF RESERPINE OR EPINEPHRINE¹

Effects of Single and Repeated Doses of Reserpine on the Secretion of Adrenocorticotrophic Hormone

“…The decrease in corticosterone level 16 hr after reserpine may be due to a reduction in its stimulating action on the hypophysis or to an exhaustion of ACTH in the gland (Kitay et al, 1959;Maickel et al, 1961). This was tested by applying the ether stimulus to the animals, 24 hr after reserpine.…”

“…Kitay et al (1959), Saifran &Vogt (1960), andMaiekel et al (1961) have reported that large doses of reserpine deplete the ACTH stores in the pituitary, and it was of interest to determine the effects of repeated large doses both on the adrenal ascorbic acid concentration and on the plasma corticosterone, before and after the ether stimulus. Rats were therefore given 2.5 mg/kg of reserpine daily for 4 days and used 24 hr after the last injection, by which time there was a marked loss in body weight (Table 1).…”

“…A single injection of reserpine promotes the release of ACTH from the pituitary gland as shown by the findings that both adrenocortical activation (Wells, Briggs & Munson, 1956;Kitay, Holub & Jailer, 1959;Khazan, Sulman & Winnik, 1961;Maickel, Westermann & Brodie, 1961) and depletion of ACTH stores in the hypophysis (Kitay et al, 1959;Saffran & Vogt, 1960;Maickel et al, 1961) have been reported. According to Maickel et al (1961), reserpine produces these effects by depressing inhibitory pathways in the hypothalamus which control the secretion of a humoral factor influencing ACTH discharge.…”

“…It has also been reported that chronic treatment with reserpine prevents the ether stimulus from lowering the adrenal ascorbic acid. This latter effect has been ascribed either to an inhibitory effect of reserpine on the pituitary (Wells et al, 1956) or to the exhaustion of the ACTH stores in the gland (Kitay et al, 1959).…”

The Effect of Carbon Tetrachloride on Plasma Corticosterone Level

“…The repeated administration of morphine, reserpine and cortisone for 2 days, or sur gical trauma, was found to eliminate the elevation of plasma corticosterone levels normally induced by CC14, and CC14 likewise inhibited the morphine or histamine-induced rise in the circulating hormone. These treatments are well-known to evoke hypersecretion of ACTH, so a reduction of ACTH in the hypophysis caused by a large dose or prolonged treatment of the drugs has been reported (18)(19)(20)(21). Brodie et al have proposed that the rate of ACTH discharge following reserpine is greater than the rate of its synthesis and the discharge results in a condition in which animals can not respond to an additional pituitary stimulus (22).…”