Measurement of inhibin concentrations in men: study of changes after castration and comparison with androgen levels in testicular tissue, spermatic venous blood, and peripheral venous blood

• Published in: The journal of clinical endocrinology and metabolism Vol. 70; no. 4; p. 1019
• Main Authors: Ishida, H, Tashiro, H, Watanabe, M, Fujii, N, Yoshida, H, Imamura, K, Minowada, S, Shinohara, M, Fukutani, K, Aso, Y
• Format: Journal Article
• Language: English
• Published: United States 01-04-1990
• Subjects: Aged; Aged, 80 and over; Androgens - analysis; Androgens - blood; Humans; Inhibins - analysis; Inhibins - blood; Male; Orchiectomy; Prostatic Neoplasms - blood; Prostatic Neoplasms - surgery; Radioimmunoassay; Spermatic Cord - blood supply; Spermatic Cord - metabolism; Testis - metabolism; Testosterone - analysis; Time Factors
• ISSN: 0021-972X
• DOI: 10.1210/jcem-70-4-1019

We measured serum inhibin levels in eight untreated patients with prostatic cancer undergoing castration by RIA using an antiserum against 31-kDa bovine follicular fluid inhibin. The inhibin concentrations in testicular tissue and spermatic venous blood were also measured in six of these patients. Serum inhibin levels (mean +/- SD, 377.8 +/- 212.1 U/L), declined rapidly after castration (15 min after, 233 +/- 171.4; 30 min, 224.6 +/- 156.6; 1 h, 181.5 +/- 95.9; 2 h, 174.3 +/- 69.4; 4 h, 122 +/- 6.4; 6 h, less than 120). High concentrations of inhibin were detected in testicular tissue (31,360 +/- 15,180 U/kg), and the levels in spermatic venous blood (3,178.3 +/- 1,386.8 U/L) were approximately 10 times greater than those in peripheral blood (385.5 +/- 233.1 U/L). Testosterone levels were 1,968.2 +/- 992.3 nmol/kg in testicular tissue and approximately 100 times greater in spermatic venous blood (1,631.6 +/- 389.7 nmol/L) than in peripheral blood (18.0 +/- 4.4 nmol/L). These results suggest that circulating inhibin in men mainly originates from testis and that one of the routes of secretion is via the bloodstream.