Differential environment alters ontogeny of dopamine innervation of the orbital prefrontal cortex in gerbils

In the present study, the influence of postnatal environmental conditions o n the structural ontogeny of the orbital prefrontal cortex of adult gerbils (Meriones unguiculatus) was examined. The animals were bred and reared eit her isolated in standard laboratory cages or grouped in an object-filled en vironment. At the age of postnatal day 90, dopamine fibers were stained imm unocytochemically and innervation density was determined in the orbital pre frontal cortex. By comparison, restricted rearing produced a restraint of t he subsequent maturation of orbital prefrontal dopamine innervation, leadin g to adult fiber densities that were approximately 38% below those in semin aturally reared gerbils. Results are discussed in terms of activity-depende nt postnatal maturation of the cortex and adaptive neuroplasticity with reg ard to previously published data concerning diminished dopamine innervation in the medial prefrontal cortex (Winterfeld et al. [1998] J. Neurosci. Res . 63:209-213, 2001. (C) 2001 Wiley-Liss, Inc.