CHOLINE-ACETYLTRANSFERASE AND NADPH-DIAPHORASE LOCALIZATION IN THE GOLDFISH HABENULO-INTERPEDUNCULAR SYSTEM

The habenular nuclei are the major sources of projections to the inter peduncular nucleus. The habenular neurons of the goldfish are ChAT and NADPH-diaphorase positive. The localization of these two enzymes in t he habenulae suggests the involvement of acetylcholine and nitric oxid e (the product of NADPH-diaphorase activity in the nervous tissue) in the habenulo-interpeduncular connection. This finding is supported by the presence of ChAT and NADPH-diaphorase activity in the neuropilar a rea of the interpeduncular nucleus. This activity was depleted 12 days after habenular ablation. The overlap of ChAT and NADPH-diaphorase lo calization in goldfish habenular neurons is consistent with previous o bservations on the co-localization of these two enzymes in some brains tem neurons of other vertebrates. It is, however, not identical to the localization of NADPH-diaphorase in the habenulae and in the interped uncular nucleus of the rat.