Demanding pups improve maternal behavioral impairments in sensitized and haloperidol-treated lactating female rats.

The impairments in the maternal behavior of ovariectomized sensitized females, relative to lactating dams, resemble those deficits found in lactating females after treatment with the D1/D2 DA receptor antagonist haloperidol, which interferes with maternal motivation. Therefore, it could be speculated that these behavioral deficits found in sensitized females and haloperidol-treated dams are due to a reduced motivation to interact with pups. In support of this hypothesis, we have found that both sensitized and haloperidol-treated lactating females exhibited remarkably similar impairments in the expression of all active maternal behaviors relative to lactating dams. Furthermore, these deficits were overridden when they were allowed to interact with 12h-isolated pups (demanding pups). Interestingly, lactating dams also improved their maternal behavior in the presence of demanding pups, and clearly chose demanding more than non-demanding pups in a preference paradigm. These data support the idea that the behavioral deficits of sensitized and haloperidol-treated lactating females are due to a reduced behavioral activation in response to the incentive cues from pups compared to lactating dams, and not because of a motor inability to express maternal behavior. These findings ultimately suggest that pups modulate the activity of DA system involved in the regulation of maternal behavior.