PUB - Publikationen an der Universität Bielefeld

Current investigations on hippocampal neurogenesis and plasticity are usually performed with animals from standard laboratory rearing and housing. Yet, it is still unclear whether standard rearing conditions may destabilize those individual brain transmitters during peri- and postnatal development which control neurogenesis for life. The objective of the present study was to quantify cell proliferation rates and synaptic remodeling in the dentate gyrus of: male gerbils reared and housed either grouped under enriched (ER) or isolated under impoverished (IR) environmental conditions. Bromodeoxyuridine (BrdU) labeling was in young adults (90 days postpartum, pp 90), and animals survived 1 day, 1 week or 6 weeks, in order-to separate short-term cell proliferation from long-term survival rates of the progeny. The cell proliferation proved. to be significantly elevated in the IR as compared with the ER group in 1 week post-labelings, and attained similar low values in the 6 week survivals. No useful data could be obtained from the 1 day survivors because of clustering. Lysosomal accumulation (LA) in degrading synapses was quantified at pp 90 in selected fields of the hippocampal gyrus dentatus, of both ER and IR specimens. LA was significantly lowered in all molecular layers along the septo-temporal hippocampal axis of the IR as compared with the ER group, which indicates a reduced synapse remodeling under IR conditions. Results suggest that IR conditions during peri- and postnatal life cause morphogenetic effects that interfere with neurogenesis and synaptogenesis throughout life. Based on our results, recent publications on experience induced elevations and stress induced suppression of neurogenesis in the mammalian hippocampus demand a reinterpretation in view of the fact that rearing conditions set brain predispositions for life.