Influência da exposição pré-natal ao LPS na seleção entre predação e cuidado materno de ratas na lactação

Resumo (EN)

In the natural environment, animals need to make rapid decisions when exposed to conflicting situations. Particularly, after delivery, mothers have to choose feeding or take care of their offspring, and these behaviors could affect both, the mother and pups survival. In mammals, maternal behavior is essential for the perpetuation of the species, since their offspring born immature and dependent on the mother's ability to divide their time taking care of offspring and feed. Thus, postpartum females have to express other behaviors linked to their survival such as hunting and feeding. A common problem in the postpartum are maternal infections induced by gram negative bacteria. In this condition the mother is faced with the conflict of caring their puppies, even sick, or abandon it and seach for food to, in more propitious occasion, have new offspring. This behavioral flexibility depends on the existence of neuroplasticity. Based in these observations, the first question of in this study invetigated the effects of an acute inflammation in postpartum behavioral selection of lactating rats between maternal and predatory behaviors was examined. LPS, an endotoxin present on the walls of gram-negative bacteria, was employed to induce inflammatory agent and activates the immune system. Thus, the results showed the effects on behavioral selection in lactating females exposed to LPS. The LPS was administered between 5/6 days of lactation and the behavioral selection observed 2 hours after administration of endotoxin. The results showed that in the paradigm of care the offspring or hunting insects the female treated with LPS showed preference for the predation relative to maternal behavior. Despite these females presented increased immobility, one of the sickness behavior signs, they contacted, hunted and ate more insects that control group than female of control group. In addition, these females had increased plasma levels of TNF-alpha, which corroborates with the presence of maternal inflammation. We conclude that acute exposure to LPS to lactating females, probably prioritized the predatory behavior towards the maternal behavior to ensure its survival, since their offspring might be sick. Thus, in more favorable conditions, it could generate new offspring and keep her species. Previous study showed that prenatal administration of LPS reduced the maternal behavior of rats. Since it was observed that acute administration to LPS led to the selection of the predatory behavior instead of maternal behavior arose the second question of this study: prenatal administration of LPS modify this selection in the face of a challenge dose of LPS? The second experimente investigated this issue. The behavioral selection in females prenatally treated with LPS and challenged between 5/6 days of lactation with the same endotoxin was observed. First, female rats exposed to prenatally endotoxin challenged with saline showed few effects on behavioral selection, ie looked over the pups and hunted less insects. However, prenatal LPS treatment and a challenge with LPS revealed that females showed reductions in both maternal behavior as predation with greater immobility. It was concluded that the absence of behavioral flexibility of these females may have implications for the survival of mothers and offspring.