Enzyme histochemical changes in some optic projection areas of the goldfish after optic nerve lesions

Enzyme histological changes have been studied in several optic projection areas after right optic nerve lesion in goldfish. An increase in acid phosphatase activity was found in the optic tectum, nucleus rotundus, nucleus geniculatus lateralis and area pretectalis between 2 and 15 days postoperatively. The enzymes glutamate dehydrogenase, lactate dehydrogenase, NADH tetrazolium reductase, cytochrome oxidase, succinate dehydrogenase and beta-hydroxybutyrate dehydrogenase showed a decrease in activity in all or some of these projection areas. No changes were found in acetylcholinesterase activity after optic nerve lesions. Three weeks postoperatively, all enzyme activities returned to the same level as on the normal side. The results are discussed in relation to possible neurotransmitters in goldfish optic terminals.