Effect of gonadotropins and alpha 2u-globulin on testicular steroidogenesis and spermatogenesis in melatonin-treated rats

Abstract

IntroductionA sex-dependent urinary protein, alpha 2u-globulin is synthesized in the liver and due to its small molecular size it is cleared by the kidneys in the adult male rats. 1,2 Sexually mature male rats show diurnal rhythm of alpha 2u-globulin synthesis.3 Similar diurnal rhythm also occurs in melatonin synthesis from the pineal gland in rats. 4 On the other hand melatonin treatment causes a substantial decrease in FSH together with testicular atrophy. 5 While perfusion of the third cerebroventricle with melatonin lowers the plasma concentration of both FSH and LH in the adult rats. 6 Melatonin treatment also decreases serum level of gonadotropins and alpha 2u-globulin along with the inhibition of testicular activity in the adult rats. 7The purpose of the present investigation was to determine whether external administration of FSH, LH or alpha 2u-globulin can prevent testicular degeneration in melatonin-treated rats. Materials and methodsAnimal-Adult male rats of Sprague Dawley (Rattus norvegcus) strain weighing 150-200g were used in this experiment. A standard laboratory chow and water were available ad-libitum. Preparation of alpha 2u-globulinAlpha 2u globulin was isolated from male rat urine according to the method of Roy, Neuhaus and AbstractAdministration of melatonin (400µg/100g bd.wt.) for 14 days caused a fall in weights of the testes and accessory sex organs and testicular 17β-hydroxysteroid dehydrogenase (17β-HSD) but rise in 3β-hydroxysteroid dehydrogenase (3β-HSD) activity, decreased spermatogenesis, serum level of gonadotropins, testosterone and alpha 2u-globulin, The animals treated with melatonin when received gonadotropins or alpha 2u-globulin for the last seven days reversed the weight of testis and accessory sex organs, 3β-HSD, 17β-HSD activities, serum level of gonadotropins, testosterone and alpha 2u-globulin when compared with melatonin-treated rats. It is concluded that alpha 2u-globulin prevents testicular degeneration in melatonin-treated rats by stimulating the synthesis of gonadotropins.