title: Androgen and precursor levels in serum and testes of adult rats under basal conditions and after hCG stimulation.
abstract: In adult male Wistar rats, serum and testicular concentration of testosterone (T), estradiol (E2), dihydrotestosterone (DHT), 5 alpha-androstane 3 alpha, 17 beta-diol (Adiol), and their precursors were measured under basal conditions as well as 4 and 8 h respectively after i.m. injection of 100 I.U. of hCG. Under basal conditions T (203 +/- 30 (SE) ng/dl) was quantitatively by far the most important serum steroid, followed by progesterone (P) (76.5 +/- 12 ng/dl), 17-hydroxyprogesterone (170HP) (37.3 +/- 4.1 ng/dl), androstenedione (A) (24.6 +/- 2.5 ng/dl) and pregnenolone (P5) (22.9 +/- 4 ng/dl). Estradiol (E2) was present in a low concentration (1.06 +/- 0.26 ng/dl). In the testes, T was quantitatively the most important steroid (89 +/- 7.2 ng/g), followed by 5 alpha-androstane-3 alpha-17 beta-diol (Adiol) (26.5 +/- 2.8 ng/g) whereas 170HP (11.8 +/- 1.0 ng/g), P (11.5 +/- 1.0 ng/g) and P5 (16.6 +/- 1.8 ng/g) were present in roughly the same concentration, concentrations of A, DHT, dehydroepiandrosterone (DHEA), 17 hydroxy-pregnenolone (170HP5) and androst-5-ene-3 beta-17 beta-diol (D5diol) being much lower; E2 (0.06 +/- 0.01 ng/g) was hardly detectable. Within 4-8 h after hCG stimulation, serum androgen concentrations increased by a factor of 4-12, except for DHEA and D5diol (X2), and E2 (X 1.5). Intratesticular androgens and delta 4 steroid precursors increased by a factor of 5-10, delta 5 precursors by a factor of 2-4 and E2 by a factor of 2, the data tending to confirm that the delta 4 pathway is preferred over the delta 5 pathway. After hCG the relative increase of T precursors was the most important for P, suggesting that 17 hydroxylation might be the rate limiting step in T biosynthesis.
mesh_terms: D000728:Androgens / Q000097:blood / Q000378:metabolism*; D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013737:Testis / Q000378:metabolism*
chemical_list: D000728:Androgens; D006063:Chorionic Gonadotropin