Gene expression in the CNS of lactating rats with different patterns of maternal behavior.

For most mammalian species, maternal behavior has an essential role in the development of the offspring. The frequency of licking/grooming (LG) the pups has been used as a parameter to evaluate maternal care, having mothers with high (HL) or low (LL) frequencies of LG. This study aimed to analyze the gene expression of the receptors for dopamine (Drd1a), prolactin (Prlr), serotonin (Htr1a, Htr1b), estrogen (Esr1, Esr2), and of Bdnf in the olfactory bulb (OB), hippocampus (HP), prefrontal cortex (PFC), and striatum (ST) of Wistar rats from three groups: LL (n = 8); HL (n = 8); virgin females in diestrus (D; n = 6). Maternal behavior was studied between the 1st and 7th postpartum days. Brain parts were analyzed by qRT-PCR. LL showed a decrease in the frequency of nursing, and an increase of remaining off the pups. There was an increase in gene expression of Drd1a, Prlr, Htr1a, Htr1b and Esr1 in the OB of HL, compared to LL. In the HP, Drd1a, Prlr and Htr1a were differently expressed when comparing HL, or LL, with D. The main finding is that HL had higher gene expression levels in the OB, which is a crucial structure to promote behavioral differences.