Estrogen modulates ghrelin expression in the female rat stomach

Ghrelin was recently identified as an endogenous ligand for GH secretagogue receptor. In this study, we investigated the effects of ovariectomy on the numbers of ghrelin-immunopositive and -expressing cells, ghrelin mRNA levels, and plasma ghrelin concentrations in 4- and 9-week-old female rats. Three days after ovariectomy, the number of ghrelin cells and plasma ghrelin level significantly increased in both 4- and 9-week-old rats and the ghrelin mRNA level also increased in 4-week-old rats. These responses were reversed by 17β-estradiol replacement. We also found that ghrelin-immunopositive cells express estrogen receptor α. These results suggested that estrogen is involved in the regulation of ghrelin expression.