N-METHYL-DL-ASPARTIC ACID LESIONS OF THE MEDIAL PREOPTIC AREA DISRUPTONGOING PARENTAL BEHAVIOR IN MALE-RATS

The effects of axon-sparing, neurotoxic lesions of the medial preoptic area (MPOA) with N-methyl-DL-aspartic acid (NMA) on previously establ ished parental behavior in male rats were investigated. Adult, sexuall y-inexperienced male rats were gonadectomized and seven days later imp lanted sc with a single estradiol (E-2)-filled Silastic capsule on tre atment Day 1. Three progesterone (P-4) capsules were implanted sc on t reatment Day 3 and removed on Day 21, one day prior to the start of be havioral testing. Males were tested daily with foster pups in order to induce parental behavior, i.e., contacting the test pups, pup retriev al, grouping, and crouching over three foster pups. Full parental beha vior appeared in these males after an average of 3 days. After testing on the third consecutive day of parental behavior, parental males wer e infused bilaterally with either NMA or vehicle into the MPOA. NMA in fusions resulted in a significant decline in all components of parenta l behavior by the next test session, a deficit which persisted through out the 5 days of post-infusion testing. In contrast, parental care co ntinued to be displayed in animals given vehicle infusions. These find ings demonstrate that the cells in the MPOA play an important role in regulating ongoing parental care in male rats and indicate that the ne ural substrates controlling parental behavior in male and female rats are similar. (C) 1997 Elsevier Science Inc.