Abstract: (10770 Views)
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.