NICOTINAMIDE-ADENINE DINUCLEOTIDE PHOSPHATE DIAPHORASE ACTIVITY MATCHES ACETYLCHOLINESTERASE-RICH PATCHES IN THE MEDIAL THALAMIC NUCLEI OF THE CAT

Patches of high nicotinamide-adenine dinucleotide phosphate diaphorase (NADPH-d) activity were found in the mediodorsal and midline thalamic nuclei of cats. These patches matched acetylcholinesterase (AChE)-ric h patches within the medial thalamus, whereas other AChE-rich patches were NADPH-d negative. There were also patches of NADPH-d activity in the lateral habenula, but these did not match the AChE staining. These results suggest that the functional role of discrete thalamic regions may require the joint presence of AChE and NADPH-d enzymatic activiti es.