Fathers Behaving Badly: The Role of Progesterone Receptors

This chapter examines the role of progesterone receptors on the father behavior. Male mammals display a wide range of complex social behaviors toward young that can range from aggression to indifference to parental care. Results are consistent with observations in primates in which treatment with progesterone inhibits reproductive behavior in male cynomolgus monkeys, but has been observed to increase male-on-male aggression independently of male-on-female aggression, while testosterone levels remained unchanged. In humans the progesterone agonist medroxyprogesterone acetate (MPA) is used clinically to suppress sexual activity in male sex offenders. MPA is reported to reduce pedophilia, incest, and rape; however, the reported theoretical basis for these treatments relies on the "antiandrogenic" function of progestins rather than other functions of progestins and their receptors. Despite its long history as a female hormone, progesterone is emerging as a hormone of importance in male reproductive physiology and behavior. The activation of progesterone receptors either by ligand-dependent or ligand-independent mechanisms may influence organizational and activational aspects of the male reproductive system. These effects include the propensity to mount females, the propensity to care for young, and the propensity to commit acts of aggression toward infants. The deletion or blockade of the progesterone receptor enhances the anticipatory components of sexual activity and promotes parental behavior in male mice. © 2008