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

Abstract

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.

Keywords: Acetylcholinesterase Optic tectum Cholinergic Stratum marginale Teleost.

Fig. 1, 2:

Microphotographs of 30 µm thick cryocut transverse sections passing through OT of 1 - Channa Punctatus 2 - Heteropneustes fossilis showing laminar AChE distribution IOX (Scale bar - 100 µm)