Metabolism of testosterone in vivo in the pregnant rat.
The metabolism of testosterone (T) was examined during the second half of pregnancy in the rat to determine whether utilization of T for estradiol (E2) synthesis occurs via conversion of T to androstenedione (A). On Days 11, 16, and 21 of gestation (term = Day 23), rats (n = 7-9/group) were anesthetized and a constant infusion of [3H]T was initiated. At 60 min, blood was obtained from a jugular vein and the ovaries (Days 11, 16, and 21), and placentae and uterine tissue (Day 16 only) were removed. In a second study performed in rats on Day 16 of gestation (n = 8-10/group), the ovaries and/or gravid uterus were removed 15 min after initiation of [3H]T infusion, and blood was taken from a jugular vein 60 min later. Radiolabeled T and A were purified from serum and tissues by paper chromatography. In a third group of rats (n = 6), jugular vein samples were obtained sequentially on Days 11, 16 and 21 of gestation and serum concentrations of T were measured by radioimmunoassay. The metabolic clearance rate of T was constant during the study period (overall mean = 31 1/day). In contrast, the serum concentration of T (pg/ml) on Day 16 of gestation (863 +/- 108) exceeded (p less than 0.02) that on Day 11 (445 +/- 74); the latter was similar to that measured on Day 21 (592 +/- 109). Thus, the estimated production rate of T was greatest on Day 16 of gestation.(ABSTRACT TRUNCATED AT 250 WORDS)
Bassett
S G
SG
Department of Physiology, Eastern Virginia Medical School, Norfolk 23501.
Pepe
G J
GJ
D000735:Androstenedione / Q000096:biosynthesis; D000818:Animals; D004958:Estradiol / Q000096:biosynthesis; D005260:Female; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000378:metabolism*
D013739:Testosterone; D000735:Androstenedione; D004958:Estradiol