Abstracts

It has been reported that female rats exposed to lithium-pilocarpine (li-pilo) status epilepticus (SE) and exhibiting spontaneous recurrent seizures (SRS) display a complete absence of maternal behavior. This lack of maternal behavior was partly attributed to the neuronal damage induced by SE. Therefore, in the present study we explored the neurobehavioral maturation of rat offspring born from control dams and dams rendered epileptic by li-pilo SE using different behavioral tasks. Nine adult female rats were subjected to li-pilo SE and 28 control rats received lithium and saline instead of pilocarpine. Li-pilo-exposed rats were observed until the occurrence of the first spontaneous seizure. All rats were mated and 8 and 27 viable litters corresponding to 61 and 257 pups were obtained from li-pilo and li-saline females, respectively. Then, the litters were cross-fostered to obtain control pups raised by li-pilo (control/li-pilo) or control dams (control/control), li-pilo pups raised by li-pilo (li-pilo/li-pilo) or control dams (li-pilo/control). Pups were tested for the following performance: static righting reflex at P4 and P5, antigravity reaction at P9, suspension duration at P10, locomotor coordination at P18 and open field at P19. The frequency of seizures of li-pilo dams was quite similar before and during pregnancy, i.e. 2-10 per week. In the group of pups raised by li-pilo dams, almost none survived because of the lack of maternal behavior and feeding, leading to undernutrition and dehydration. In the three other groups of rats, the weight of pups was similar in control/control and li-pilo/control pups while the lack of maternal behavior of li-pilo dams induced a delay in weight gain of control/li-pilo pups until weaning. In all tests, the performance of li-pilo/control pups was highest followed by control/control pups and by control/li-pilo pups. In the static righting reflex, the antigravity reaction, suspension test and locomotor coordination, li-pilo/control pups performed significantly better than the two other groups. In the open field, the spontaneous locomotion of the two groups of pups raised by control dams was faster while activity of control/li-pilo pups was reduced in this test. The data of this study emphasize the cardinal role of the mother-pup interaction in the development of neurobehavioral abilities of the rats. Indeed, control pups raised by li-pilo dams do not develop as well as control congeners raised by control dams while li-pilo pups are able not only to perform and develop as well as control pups raised by control dams but even better than the latter group. This difference may originate in the stress that these animals are exposed to in utero as a result of the spontaneous seizures of the pregnant dam. Indeed, prenatal stress was shown to alter neurotransmitter systems and brain development and to be counteracted by cross-fostering. (Supported by INSERM U 398)