Fig. 2
From: Caloric restriction in female reproduction: is it beneficial or detrimental?
The interaction between peripheral hormones and HPO axis. The anorexigenic factors such as leptin, insulin, estradiol (E2) and insulin-like growth factor (IGF-1) activate HPO axis while the orexigenic ghrelin inhibits HPO axis. CR downregulates the expressions of leptin, insulin, E2 and IGF-1, which will lead to the inhibition of HPO axis. Ghrelin expression is upregulated during fasting but it is downregulated during chronic CR. Solid arrow indicates the promotion. Dotted arrow indicates the inhibition