Effects of ghrelin and orexin A on aromatase gene expression in the ovaries of female rats androgenized in third day of birth

Introduction: Ghrelin and Orexin A exert inhibitory effects on gonadotropins secretion. Aromatase is a key enzyme in the steroidogenesis pathway which converts testosterone to the estradiol. Treatment of neonatal female rats with testosterone propionate (TP) alters gonadotropin secretion patterns in the adulthood. In the present study the effects of central injection of ghrelin or orexin A on the expression of aromatase gene in the ovaries of pubertal androgenized female rats. Methods: Forty two neonatal female rats were androgenized on the third day after birth by subcutaneous injection of 50μg TP and 6 neonatal female rats in one group received subcutaneous injection of olive oil as controls. After puberty, the animals in seven groups (n=6 in each group) received central injections of saline, different doses of ghrelin (2, 4 or 8μg) or Orexin A (2, 4 or 8μg). The ovaries were removed bilaterally and frozen. Aromatase gene expression levels was determined by semi quantitative RT-PCR. Results: The mRNA levels of aromatase (CYP19) increased significantly in the ovaries of the androgenized rats compared to the control group. Orexin A and ghrelin injections significantly decreased aromatase gene expression compared to the androgenized rats (P <0.05). Conclusion: Androgens may stimulate aromatase gene expression in the ovaries. Orexin A and ghrelin may exert inhibitory effects on reproductive axis partly via reducing the expression of genes involved in the steroidgenesis.