Periodic maternal separation of neonatal rats produces region- and gender-specific effects on biogenic amine content in postmortem adult brain

Early environment exerts profound effects on mammalian behavioral and neura l development. The aim of this study was to describe changes in adult neuro chemistry in the rat following repeated neonatal maternal separation (RMS) during the preweaning period, a procedure known to induce enduring behavior al effects. Following RMS, rats show an attenuated locomotor response to no velty, to D-amphetamine, and attenuated behavioral responses for conditione d incentives as adults. These behavioral effects are broadly opposite in di rection to those found following postweaning isolation rearing. Isolation r earing-induced behavioral changes are associated with profound changes in c entral monoamine function. Following RMS, adult rats had increased tissue l evels of dopamine in both dorsal and ventral striatum. The turnover of dopa mine, as determined by the ratio of DOPAC to dopamine, was decreased in the mPFC of RMS subjects. Serotonin levels were reduced in dorsal hippocampus of RMS rats of both sexes and in the mPFC of male RMS rats. Noradrenaline l evels were increased in the dorsal hippocampus in female, but not in male, RMS rats. These data provide evidence that, in addition to the adult behavi oral consequences, RMS leads to profound, region-, and gender-specific chan ges in brain monoamine content. The developmental specificity of these resu lts is discussed with respect to their possible role in altered behavioral development and psychopathology. (C) 2001 Wiley-Liss, Inc.