PRL and hyperprolactinemia: Several data appear to show that prolactin may be a major factor mediating the hyperphagia associated with both states.   23  In fact, there are reports indicating that prolactin can induce hyperphagia when administered systemically or intra-cerebro-ventricularly. 24,25  The hyperprolactinemia exhibited in both states likely plays an important role in regulating numerous brain functions, including feeding and appetite.   23  During the first three days of pregnancy, serum prolactin was higher than during the following day 18.