STRESS-INDUCED DECREASES IN THE SERUM CONCENTRATION OF PROGESTERONE IN THE PREGNANT BABOON

Abstract

Pregnancy Research Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20014, U.S.A. (Received 4 January 1978) During preliminary studies on the rate of production of progesterone in pregnant baboons, an apparent decline was noted in the serum concentration of progesterone during ketamine sedation. Ketamine (Elvidge, Challis, Robinson, Roper & Thorburn, 1976) and phencyclidine (Setchell, Shackleton & Himsworth, 1975) reduce the plasma concentration of cortisol in rhesus monkeys. The present study determined the effect of no sedation, sedation with ketamine or phencyclidine and tranquillization with chlordiazepoxide on the serum concentrations of progesterone and cortisol during serial bleeding of pregnant baboons. Nine pregnant baboons (Papiopapio) were mated and maintained as described previously (Townsley, 1974) and studied between days 60 and 172 of gestation (term = 184 days). Between 11.00 and 13.00 h baboons were restrained in a squeeze cage and bled (4 ml) via a 21-gauge needle from the saphenous vein; the