Modulatory influence of Parkia biglobosa protein isolate on testosterone and biomarkers of oxidative stress in brain and testes of streptozotocin-induced diabetic male rats.

Parkia biglobosa seed an important household spice commonly consumed in Nigeria is believed to possess antioxidant activity that may exert modulatory effects in diabetes and diabetic complications. This study investigated the modulatory potential of Parkia biglobosa protein isolate (PBPi) on serum testosterone (sTT) level as well as its influence on biomarkers of oxidative stress in brain and testes of streptozotocin-induced diabetic male rats. Animals were made diabetic by single intraperitoneal administration of streptozotocin (STZ; 60 mg/kg body weight). PBPi (200 or 400 mg/kg body weight) was given orally by gavage or insulin (5 U/kg, i.p.) was administered daily to STZ-induced diabetic rats for 28 days. The results revealed a significant elevation in thiobarbituric acid reactive substances (TBARS) levels in the brain and testes of diabetic rats. This was closely associated with a concomitant reduction in levels of sTT and reduced testes weight, a noticeable decline in the glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) as well as total glutathione (Total GSH) level in the brain and testes of diabetic rats. Interestingly, treatment with PBPi efficiently prevented the alterations witnessed in the serum sTT and also ameliorated various alterations in the biomarkers of oxidative stress (TBARS, Total GSH, GST, SOD and CAT) in brain and testes of diabetic rats. These results provide evidence that PBPi could protect the brain and testicular tissues against oxidative stress induced by STZ, via modulation of serum testosterone concentration and also by enhancing antioxidant defence system in STZ-diabetic rats.