Tetrahydrobiopterin Administration Restores Sex Hormones Imbalance in Streptozotocin-induced Diabetic Rats

Introduction: Diabetes mellitus results in the state of imbalance in oestrogen and testosterone; more so, females exhibit increased circulating testosterone along with decreased in oestrogen level in diabetes mellitus. It is suggested that, sex hormones are important regulators of glucose and lipid metabolism. Tetrahydrobiopterin bioavailability which is an important modulator of these metabolites may be involved in sex hormones metabolism. In current work we investigated the effect of tetrahydrobiopterin administration on sex-hormones levels in diabetes mellitus.

Materials and Methods: Thirty (30) albino Westar rats (15 males and 15 females) weighing 100-120 g was divided into three groups: Controls (5 males and 5 female), diabetics (5 males and 5 females) and diabetics supplemented with tetrahydrobiopterin (5 males and 5 female). Diabetic groups received a single intra venous injection of Streptozotocin (STZ, 60 mg/ kg) while the control group were injected with a similar volume of citrate buffer. Tetrahydrobiopterin 20 mg/kgbw/day was supplemented for two weeks. Fasting Plasma Glucose, oestrogen and testosterone were estimated in all the groups.

Results: The mean Fasting plasma glucose concentration was significantly lower (p<0.05) in controls males (5.24±0.15 mmol/l) and females (5.43±0.15 mmol/l) and treated males (7.66±0.22 mmol/l) and females (7.20±0.36 mmol/l) compared to untreated males (15.68±2.84 mmol/l) and females (19.40±4.13 mmol/l). The mean plasma oestrogen concentration in control males (12.75±4.52 g/ml) and females (111.72±6.42 pg/ml) and treated males (15.16±2.08 pg/ml) and females (103.74±2.41 pg/ml) were significantly higher (p<0.05) than untreated males (5.33±1.36 g/ml) and females (66.84±20.88 pg/ml). The mean plasma testosterone concentration for females in control and treated groups were significantly lower (p<0.05) than untreated while there is no significant difference in mean values for males across the groups (p>0.05).

Conclusion: Diabetes resulted in oestrogen and testosterone imbalance and tetrahydrobiopterin administration restores level to near normal.