Effects of the eye enucleation on the activity of monoamine oxidase and acetylcholinesterase in the superior colliculus of the rat.

Changes in the activity of monoamine oxidase (MAO) and acetylcholinesterase (AChE) following unilateral eye enucleation were measured for the superior colliculus (SC), lateral geniculate body (LGB), and nucleus suprachiasmaticus (NSC) in the rat by means of microspectrophotometry. The most conspicuous change of high significance was the decrease of MAO activity in the superficial strata of the SC contralateral to the enucleated eye. The other layers of SC, such as the stratum opticum, the intermediate strata, the deep strata and the central gray did not show significant postoperative changes in MAO acitivity. MAO activity of the LGB and the NSC was also not affected to a significant degree. The site of decrease of MAO activity in the superficial strata of the SC sould be degenerating optic nerve terminals. The strong AChE activity in the superficial strata may be derived from the horizontal cells. AChE activity in the SC showed only slight postoperative changes. The possible roles of the monoaminergic and cholinergic systems in the process of visual information are discussed.