Distribution pattern of acetylcholinesterase in the optic tectum of two Indian air breathing teleosts

BACKGROUND: A histoenzymological study has been carried out on the distribution of enzyme acetylcholinesterase in the optic tectum of two Indian air breathing teleosts by employing a histochemical technique to visualize acetylcholinesterase containing neurons described by Hedreen, JC (1985). PURPOSE: Data available on enzyme localizaton in the brain of fishes, particularly Indian teleosts is inadequate and scattered. METHODS: AChE distribution in the optic tectum shows a prevalent pattern characterized by precise laminar distribution of enzyme which shows alternatively strong, weak or negative reaction in the different layers. RESULTS: Layers with maximum enzyme activity most likely correspond to areas where cholinergic mechanism is prevailing whereas layers with mild activity may be considered to be non-chalinergic/cholinoceptive having some cholinergic innervations from other layers. CONCLUSION: The present investigation suggests some possible connections between enzyme localization and functional and anatomical organization of optic tectum.