Postnatal maternal deprivation produces long-lasting modifications of the stress response, feeding and stress-related behaviour in the rat

The hypothalamo-pituitary-ad renal (HPA) axis plays a central role both in the regulation of the stress response, and in the control of feeding behavi our. Sensitivity of the HPA axis to respond to stress varies both during on togeny and between individuals, and can be altered by neonatal events. The aim of our experiments was to determine whether early events that affect th e HPA axis could also induce persistent modifications in food intake (quant itatively and qualitatively), as well as alterations of anxiety-related beh aviour. Twenty-four-hour maternal deprivation was introduced at two differe nt periods of HPA maturation, on day 5 (DEP5) or day 14 (DEP14) after birth . Sequential measurements of plasma levels of adrenocorticotropin hormone ( ACTH) and corticosterone showed that this deprivation altered the HPA axis of adults; the response to restraint stress was prolonged in DEP5 and a hig her ACTH peak appeared in DEP14. The neonatal stress also produced long-las ting modifications of rat behaviour, as DEP14 adults became more anxious. S tandard food intake decreased in both groups of deprived rats. Diet prefere nces also changed, as carbohydrate intake decreased in DEP5 rats. Corticost eroid receptor binding did not vary in the hippocampus of the deprived rats . The modifications of the stress response and the behaviour parameters cou ld be due to the alteration of corticosteroid receptors in the hypothalamic paraventricular nucleus and/or corticotropin-releasing hormone or vasopres sin function, but these parameters have yet to be determined. This early st ress paradigm altering feeding behaviour could become an interesting model for research into human eating disorders.