Increased extracellular release of hippocampal NE is associated with tetanization of the medial perforant pathway in the freely moving adult male rat

The induction of long-term potentiation (LTP) within the dentate gyrus of t he hippocampal formation is modulated by many afferent influences from a nu mber of subcortical structures known to be intimately involved in hippocamp al-dependent learning and memory. It has been demonstrated in slice and ane sthetized preparations that norepinephrine (NE) is one of these major neuro modulators involved in the induction of UP. However, the majority of these studies have not been conducted in the freely moving animal. Recently, we d eveloped surgical procedures and instrumentation techniques to simultaneous ly record electrophysiological and neurochemical data from the hippocampal formation. The present study uses these techniques to examine the underlyin g neurochemical changes in the hippocampus associated with the induction of hippocampal dentate LTP in the freely moving adult rat. These findings est ablish baseline levels of NE that can be used to evaluate the impact of var ious tetanization paradigms as well as the effect of a variety of insults o n hippocampal plasticity. Hippocampus 2001;11:423-429. (C) 2001 Wiley-Liss, Inc.