Regulation of murine alpha 1-pregnancy-associated protein by gonadal steroids during the acute-phase response

A pregnancy-associated serum protein of the mouse (alpha 1-PAP) has recently been reported to be also synthesized by the non-pregnant female, but not the untreated male, in response to injury. The role of gonadal hormones in this phenomenon has been investigated. Ovariectomy abolished the ability of injury to induce synthesis of alpha 1-PAP. Although administration to ovariectomized animals of oestradiol alone resulted in the appearance of low concentrations of alpha 1-PAP after injury, injection of either progesterone or oestradiol plus progesterone permitted injury to induce concentrations of alpha 1-PAP similar to those observed in intact injured females. Castrated mice, like intact males, failed to produce alpha 1-PAP in response to injury, but administration of either oestradiol or oestradiol plus progesterone caused injury to induce concentrations of alpha 1-PAP similar to those in injured intact females. Administration of testosterone to intact females abolished the alpha 1-PAP response to injury and administration of oestradiol plus progesterone in intact males failed to induce the same response as in castrated males. These findings suggest that testosterone can inhibit the synthesis of alpha 1-PAP in response to injury in both sexes whereas oestradiol and progesterone exhibit different abilities in males and females to facilitate the induction of alpha 1-PAP synthesis by injury.