Effect of continual light deprivation and alpha-2u-globulin replacement therapy on serum concentration of gonadotropins and testicular activity in rats

Summary. Prolonged darkness caused a fall in testicular 17 β-hydroxysteroid dehydrogenase (17β-HSD) activity and diminished spermatogenesis, serum levels of gonadotropins, testosterone and α_2u-globulin.
Administration of α_2u-globulin at a dose of 1.5 mg rat⁻¹ per day for 7 days after 68 days of light deprivation, reversed the 17β-HSD activity and serum levels of gonadotropins, testosterone and α_2u-globulin, while spermatogenesis was restored to normal.
The animals kept in prolonged darkness for 68 days and then received saline (7 days in light-dark cycle, 14 L: 10 D), showed no significant changes of testicular activity, serum levels of gonadotropins, testosterone and α_2u-globulin, when compared with dark-exposed animals (68 days) receiving rabbit serum (7 days in light-dark cycle, 14 L: 10 D). These results suggest that α_2u-globulin plays an important role in testicular function in dark-exposed rats by inducing gonadotropins and testosterone secretion.