A galanin-like peptide coexists in putative cholinergic somata of the septum-basal forebrain complex and in acetylcholinesterase-containing fibers and varicosities within the hippocampus in the owl monkey (Aotus trivirgatus).

The putative cholinergic neurons of the basal forebrain and fibers in the hippocampus were studied in relation to galanin (GAL)-like immunoreactivity (LI) in the owl monkey by the use of acetylcholinesterase (AChE) histochemistry in combination with immunocytochemistry. Virtually all of the AChE-reactive somata within the medial septal nucleus, diagonal band and nucleus basalis and hippocampal AChE reactive fibers and varicosities co-contained GAL-LI. The more extensive distribution of GAL-like peptide in the cholinergic forebrain of the monkey (as compared to the rat) may reflect an increased importance of this peptide(s) in cotransmission processes in this region in higher animals.