cFOS and pCREB activation and maternal aggression in mice

Lactating mice exhibit a dramatic increase in aggression, termed maternal a ggression, only in association with the rearing and protection of their off spring. Previous work indicates that the neural mechanisms underlying mater ial and male aggression are different in rodents. In this study, we sought to examine possible neural regions involved in the control of maternal aggr ession by combining behavioral testing with immunohistochemistry for both c FOS and pCREB, two indirect markers of neuronal activity. All lactating fem ale mice were exposed to a male intruder for 20 min and those exhibiting ma ternal aggression were placed in one group and those that were non-aggressi ve were placed in a second group. Thus, the sensory stimuli were similar an d the main difference between the two groups was the behavior, cFOS express ion increased significantly in the claustrum, bed nucleus of the stria term inalis, medial preoptic nucleus, paraventricular nucleus, medial amygdala, and cortical amygdala in association with maternal aggression. In contrast, the number of pCREB-positive cells significantly increased only in the ven trolateral portion of the caudal periaqueductal gray and in the lateral sep tum in aggressive lactating mice. Due to large variance in the counts of pC REB-positive cells, the data were log transformed prior to statistical anal ysis. Thus, the sites of cFOS and pCREB increases do not overlap, but provi de complementary indirect information on neural regions active during mater nal aggression. These results complement previous studies of nitric oxide r elease during maternal aggression to create a possible map of the functiona l neural circuitry underlying maternal aggression. (C) 2001 Elsevier Scienc e B.V. All rights reserved.