Histochemical and cytochemical localization of acetylcholinesterase in retina and optic tectum of teleost fish

Abstract

The activity of cholinesterase and its cellular and subcellular localization were investigated in the retina and optic tectum of Eugerres plumieri and in the retina of Carassius carassius by means of radiometric, histochemical, and cytochemical procedures. In both fishes only the presence of acetylcholinesterase could be demonstrated. This study, besides confirming previous findings that acetylcholinesterase is located in the ganglion and amacrine cells of the retina as well as in the inner plexiform layer, in addition provides evidence that the enzyme is also present at the region of photoreceptor synapses between the cell bodies and apposing extensions of the horizontal cells of the same layer. The latter localization may indicate the involvement of a cholinergic mechanism at the functional contacts (transferapses) between the horizontal cells. In the optic tectum of Eugerres plumieri, histochemistry reveals fine distinguishable bands of acetylcholinesterase activity; two of the bands are quite sharply defined, whereas three others have rather a more diffuse appearance. The presence of these bands and their distribution may suggest a widespread distribution of cholinergic elements in the optic tectum.

Histochemical Localization of Dopamine and Acetylcholinesterase Activity in the Carp Retina

“…The cellular localization of AchE activity in the carp retina was consistent with earlier findings (4,9,29,31). AchE activity was found in a certain group of amacrine cells and in some ganglion cells, diffusely in the IPL and weakly in the external horizontal cell layer.…”

“…The cellular localization of AchE and the Ach metabolism in the retina have been also extensively investigated (4,9,29,31). It has been commonly described that AchE activity is predominantly positive in amacrine and ganglion cells and at the IPL.…”

The physiology of the teleostean optic tectum

“…However, it is unlikely that AChE is confined to presynaptic elements. Electron microscope (EM) histochemistry of the tectum of the Mojarra (Eugerres plumieri) shows reaction product on dendritic and axonal membranes as well as on nerve terminals (Drujan et al, 1979);Villani et al (1979), using similar methods, also concluded that all neuronal types in the optic tectum synthesized AChE.…”

Ultrastructural localization of acetylcholinesterase activity in the developing chick retina.

“…A number of investigators have also studied the enzyme distribution within the retina during its development (5,30,31). These studies have revealed that AChE activity localizes in ganglion and amacrine cells, and in the inner plexiform layer of almost all species so far examined (5,10,12,19,20,25,28). In addition, the presence of enzyme activity has been reported within the horizontal cells of the rat (31), rabbit (28), chick (30) and fish (10), and within the outer plexiform layer of the frog (5), newt (8) and fish (10).…”