Streptozotocin diabetes and insulin resistance impairment of spermatogenesis in adult rat testis: central Vs local mechanism

Mammalian reproduction is dynamically regulated by the pituitary gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones are synthesized in the pituitary gland following stimulation by the gonadotropin-releasing hormone (GnRH) and act by stimulating steroid production and gametogenesis in both males and females. Male adult Sprague-Dawley rats (120 – 140 g) were randomly divided into 7 groups. Group 1 > Control group; fed on normal rat pellets. Group 2 > Streptozotocin group; received a single dose IP injection of streptozotocin 45 mg/kg BW in Na⁺ citrate buffer pH 4.5. Group 3 > Streptozotocin-insulin treated group; received a single dose IP injection of streptozotocin as in group 2 above and treated with insulin sub-cutaneously. Group 4 > Streptozotocin-ginger treated group; received a single dose IP injection of streptozotocin as in group 2 above and treated with 500 mg/Kg Ginger extract orally. Group 5 > Insulin resistant group; fed ad libitum on a special diet containing 25% fructose mixed with 75% normal rat chow (w/w). Group 6 > Insulin resistant-pioglitazone treated group; fed ad libitum on a special diet as in group 5 above and treated with Pioglitazone 15 mg/kg orally. Group 7 > Insulin resistant-ginger treated group; fed ad libitum on a special diet as in group 4 above, and also treated with 500 mg/Kg Ginger extract orally. Hormonal and tissue biochemistry analyses revealed that both central and local mechanisms are implicated in the impairment of spermatogenesis by diabetes but the hypothalamo-pituitary testicular axis alteration might not likely have a major impact as the local defect on steroidogenesis in the testis. This local defect could also predispose to male hypogonadism, i.e. failure of gonadal function.

Keywords
Diabetes mellitus, Insulin resistance, LH, FSH, Testosterone, Cholesterol.