Early pubertal exposure of vaspin elevates testicular steroidogenesis in mice

Vaspin, a novel adipokine expressed in the testis and ovary, is known to regulate ovarian steroidogenesis in rats, porcine, and humans. Recently, adipokines like visfatin have been shown to modulate testicular steroidogenesis in early pubertal and adult mice, however, effects of vaspin on testicular steroidogenesis in early pubertal is still unknown.

Male mice at postnatal day 21 were selected and divided into three groups: control (n = 6), vaspin low (0.1 µg/kg) (n = 6), and vaspin high (1 µg/kg) (n = 6). Control group received saline as a vehicle, and other two groups were administered with vaspin at a dose of 0.1 µg/kg and 1 µg/kg (IP). The treatment was given for 15 days (PND21 to PND35).

Vaspin treatment at a dose of 0.1 and 1 µg/kg elevated the circulating testosterone, androstenedione, and estrogen, with no change in progesterone levels. StAR and CYP11A1 expression showed a significant increase at both doses of vaspin, while 3β-HSD immunostaining showed a decline only at higher doses of vaspin. 17β-HSD and CYP17A1 showed increased expression at lower doses of vaspin, and aromatase showed a significant decrease at higher doses. AR expression was unaffected; moreover, ERα and β showed a dose-dependent decreased expression in testis. The results indicate that elevated levels of vaspin enhance the secretion of testicular steroids by differential regulation of steroidogenic markers.

In conclusion, excess of vaspin stimulates the testicular testosterone, estrogen, and androstenedione secretion in early pubertal mice. However, its functional significance on the testicular functions needs further investigation.