LACTATION REDUCES FOS INDUCTION IN THE PARAVENTRICULAR AND SUPRAOPTICNUCLEI OF THE HYPOTHALAMUS AFTER URETHANE ADMINISTRATION IN RATS

Both neuroendocrine and behavioral responses to stressors are reduced in lactating animals. In these studies we determined whether Fos induc tion following treatment with urethane would differ between nonlactati ng and lactating rats. Urethane treatment produced robust Fos expressi on in the central nucleus of the amygdala and the paraventricular and supraoptic nuclei of the hypothalamus 1 h after treatment. Fos express ion in both the paraventricular and supraoptic nuclei was attenuated i n lactating rats compared to that seen in nonlactating animals but Fos expression in the central nucleus of the amygdala did not differ betw een these two groups. Removing litters from lactating rats 48 h prior to urethane administration restored the Fos response in the parvocellu lar division of the paraventricular nucleus (PVN) to the level seen in nonlactating rats. (C) 1997 Elsevier Science B.V.