Gender-specific effect of maternal deprivation on anxiety and corticotropin-releasing hormone mRNA expression in rats

The long-term behavioral and neurochemical effects of 24 h maternal separation were assessed in rats of both genders. Maternal deprivation was applied at the age of 9 days, whereas consequences were assessed 3 months later. Deprived rats (irrespective of gender) showed a considerable growth retardation that disappeared till adulthood. The plus-maze performance of control and deprived males did not differ under normal conditions, but deprived males showed more anxiety when the test was applied shortly after stress exposure. CRH mRNA expression in the amygdala, but not in the hypothalamus, was more intense in deprived as compared with control males. Deprived females were not affected. These data suggest that (i) the maternal deprivation induced changes are larger in males than in females, (ii) maternal deprivation induces a latent behavioral disposition towards anxiety that is precipitated by acute stressors, and (iii) the changes noticed in amygdalar CRH expression may serve as mechanisms for the behavioral changes noticed. (C) 2003 Elsevier Inc. All rights reserved.