Electrochemical characterization of stimulated norepinephrine overflow in locus coeruleus-hippocampus double brain grafts grown in oculo.

Rat locus coeruleus-hippocampus double in oculo brain grafts were studied with high-speed electrochemical techniques to characterize stimulus-evoked overflow of norepinephrine. Local pressure ejections of KCl into the locus coeruleus (LC) portion of the double graft elicited electrochemical signals in the hippocampal portion that had NE-like reduction/oxidation current ratios. In contrast, electrical stimulation of the LC part of the double graft did not lead to consistently detectable signals in the hippocampal portion of the transplant. These data demonstrate that LC graft neurons are able to release NE in target tissues when stimulated in an appropriate manner, and that the time course and magnitude of the overflow of NE can be detected with sensitive high-speed electrochemical recording techniques.