Genetically related rats with differences in hippocampal uptake of norepinephrine and maze performance

The spontaneously hypertensive rat (SHR) and its progenitor strain, the Wistar-Kyoto (WKY) display marked differences in brain catecholamines and behavior. The behavioral differences are suggestive of alterations in hippocampal function and, in particular, the noradrenergic input to the hippocampus. To test these hypotheses we have analyzed the performance of the SHR and WKY in a spatial memory maze task that is specific to hippocampal function and determined the kinetics of norepinephrine (NE) uptake in synaptosomal preparations of the hippocampus. We have found that WKYs exhibit an abnormally strong bias tendency in T-maze arm preference that influences the rate of acquisition and the final level of maze performance. We have also found differences in noradrenergic uptake in hippocampal synaptosomes. WKYs exhibit higher NE uptake rates and higher kinetic constants for NE uptake when compared with SHRs, suggesting that strain differences in noradrenergic function may contribute to the observed behavioral differences.