HYPOTHALAMIC PARAVENTRICULAR NUCLEUS MODULATES MATERNAL AGGRESSION INRATS - EFFECTS OF IBOTENIC ACID LESION AND OXYTOCIN ANTISENSE

Central oxytocin (OT) appears to be crucial for maternal behavior. OT: through the parvocellular neurons of the hypothalamic paraventricular nucleus (PVN), can exert its physiological and behavioral effects by acting on OT receptors in nonpituitary projections of the PVN. The pur pose of the present study was to analyze the role of the PVN and OT on maternal aggressive behavior in two different periods after delivery: on the fifth day (period of high aggressiveness) and on the eighteent h day postpartum (period of low aggressiveness). In the first experime nt, ibotenic acid was injected into the PVN in order to lesion the par vocellular neurons. A second experiment was designed to study more spe cifically the effects of OT using the antisense technique. On the fift h day postpartum, both the PVN lesion by the ibotenic acid and a possi ble acute reduction of OT synthesis by the antisense administration in that nucleus increased maternal aggressive behavior, while on the eig hteenth day postpartum no effect was recorded. We may conclude that ce ntral projections of the PVN modulate maternal aggression during a res tricted period after delivery, only when lactating females show natura lly high levels of aggressive behaviors. (C) 1998 Elsevier Science Inc .