Ovarian aging and the activation of the primordial follicle reserve in the long-lived Ames dwarf and the short-lived bGH transgenic mice

- GH deficient mice had increased ovarian follicle reserve, while in mice overexpressing GH the reserve was decreased.
- GH treatment at adult age can reduce the primordial follicle reserve in both df/df and N/df mice.
- Reduced ovarian reserve is associated to increased presence of pFoxO3a in oocytes enclosed in primordial follicles.

The aim of this study was to evaluate the effect of growth hormone (GH) in the maintenance of the ovarian primordial follicle reserve. Ovaries from 16 mo old GH-deficient Ames Dwarf (df/df) and Normal (N/df) mice were used. A subgroup of df/df and N mice received GH or saline injections for six weeks starting at 14 mo of age. In addition, ovaries from 12 mo old mice overexpressing bovine GH (bGH) and controls were used. df/df mice had higher number of primordial and total follicles than N/df mice (p < 0.05), while GH treatment decreased follicle counts in both genotypes (p < 0.05). In addition, bGH mice had lower number of primordial and total follicles than the controls (p < 0.05). pFoxO3a levels were higher in mice treated with GH and in bGH mice (p < 0.05) when comparing with age match controls. These results indicate that increased circulating GH is associated with a reduced ovarian primordial follicle reserve and increased pFoxO3a content in oocytes.