Acetyl- and butyrylcholinesterase activities in the rat retina and retinal pigment epithelium

✍ Scribed by G. Sánchez-Chávez; C. J. Vidal; R. Salceda

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 792 KB
• Volume: 41
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490410512

✦ Synopsis

Abstract

The acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities in the neural retina and retinal pigment epithelium (RPE) of adult rats were determined. The tissues were extracted with a saline buffer to release the soluble enzymes (S~1~) and the pellet re‐extracted with Triton X‐100 to detach the membrane‐bound enzymes (S~2~). Less than 5 % of the cholinesterase activity measured in retina and almost 30% of that assayed in RPE was due to BChE. About 20% and 10% of the AChE in retina and RPE was brought into solution with a saline buffer and the rest with a detergent‐containing buffer. Main AChE molecular forms of 10.5S (hydrophilic G4^H^), 9.5S (amphiphilic G4 ^A^) and 3.OS (amphiphilic G1^A^) were identified in retina by subjecting the supernatant S~1~ to sedimentation analysis in sucrose gradients made with Brij 96. Amphiphilic G~4~ and G~1~ AChE were found in S~2~. Analysis of the soluble fractions obtained from RPE in the gradients made with Brij 96 revealed 16.OS (asymmetric A~12~), 10.5–10.0S (globular G~4~^H^ + G~4~^A^), 4.5S (G~2~^A^), and 3.0S (G~1~^A^) AChE forms in S~1~, whereas G~4~^A^, G~2~^A^, and G~1~^A^ enzyme molecules predominated in S~2~. Our results show that amphiphilic tetramers and monomers of AChE are abundant in neural retina, and enzyme tetramers, dimers, and monomers in RPE. The AChE in the neural retina might be involved in cholinergic actions. The enzyme function in the retinal pigment epithelium remains to be established. © 1995 Wiley‐Liss, Inc.