EFFECTS OF SOCIAL DEPRIVATION IN PREPUBESCENT RHESUS-MONKEYS - IMMUNOHISTOCHEMICAL ANALYSIS OF THE NEUROFILAMENT PROTEIN TRIPLET IN THE HIPPOCAMPAL-FORMATION

Social deprivation during early postnatal life has profound and long-l asting effects on the behavior of primates, including prolonged and ex aggerated responses to stress as well as impaired performance on a var iety of learning tasks. Although the cellular changes that underlie su ch alterations in behavior are unknown, environmentally induced psycho pathology may involve morphologic or biochemical changes in select neu ronal populations. The hippocampal formation of both socially deprived and socially reared prepubescent rhesus monkeys was selected for immu nocytochemical investigation because of its association with the behav ioral stress response and learning. Immunocytochemical analysis using antibodies specific for the neurofilament protein triplet was performe d since these proteins are modified within degenerating neurons in a v ariety of neurodegenerative disorders. Results from optical density me asurements indicate an increase in the intensity of non-phosphorylated neurofilament protein immunoreactivity in the dentate gyrus granule c ell layer of socially deprived monkeys in comparison with that of soci ally reared animals, suggesting that early social deprivation may resu lt in an increase in the amount of non-phosphorylated neurofilament pr otein in these cells. This phenotypic difference in dentate granule ce lls between differentially reared monkeys supports the notion that spe cific subpopulations of neurons in brain regions that subserve complex behaviors may undergo long-term modifications induced by environmenta l conditions. Furthermore, the data suggest that constitutive chemical components related to structural integrity may be as susceptible to e arly environmental manipulations as the more traditionally viewed meas ures of cellular perturbations, such as neurotransmitter dynamics, cel l density and the establishment of connectivity. The observed modifica tions may serve as an anatomical substrate for behavioral abnormalitie s that persist in later life.