Periodic maternal deprivation and lesion of anterodorsal thalami nuclei induce alteration on hypophyso adrenal system activity in adult rats

The hypothalamic-pituitary-adrenal (HPA) axis is normally regulated by extr ahypothalamic limbic structures, among these, the anterodorsal thalami nucl ei (ADTN), which exert an inhibitory influence on HPA, in basal and acute s tress conditions in rats. In the present work we have investigated whether neonatal maternal deprivation (MD) produces long-term changes in the ADTN r egulation of HPA activity, Maternal deprivation, in female rats, for 4,5 hs daily, during the first 3 weeks of life, produced at 3 months old, a signi ficant decrease in plasma ACTH concentration (p <0.001) and an increase in plasma corticosterone (C) (p <0.001), compared to control non-deprived rats (NMD). Also MD showed higher plasma epinephrine (E) and norepinephrine (NE ) levels than NMD rats. The increase of NE (66.6% p <0.001) was higher than that observed in E (19%). After 30 days of ADTN lesion, plasma ACTH values were higher than in sham lesioned rats, in both NMD and MD animals. ACTH r esponse was greater in MD rats. Plasma C, in NMD, was higher, whereas in MD lesioned animals, it was significantly lower than in sham lesioned. In MD rats, lesion produced a significant increase in plasma E and NE (p <0.001), and again, NE increase was higher than E increase. The more accentuated in crease of NE than E, suggests sympathetic nervous system hyperactivity. In summary, neonatal maternal deprivation induces long-term alterations on HPA axis sensitivity and medullo adrenal secretion; enhanced sympathetic nervo us system activity and, therefore affected the ADTN inhibitory influence on ACTH and adrenal glands secretion. (C) 2001 Elsevier Sciences Inc. All rig hts reserved.