Cholecystokinin-like immunoreactivity in frog retina: localization, characterization, and biosynthesis.
We sought to localize and characterize cholecystokinin-like immunoreactivity (CCK-LI) in frog retinal tissues, CCK-LI was present in concentrations of 2.20 +/- 0.19 pmol/g wet weight (mean +/- SE, n = 6) in water extracts of frog retina and 0.23 +/- 0.04 pmol/g in acid extracts. The predominant form of CCK-LI co-eluted with the octapeptide of CCK on Sephadex G50 column chromatography. A minor form which eluted as a molecule larger than the 39 amino acid form of CCK was found only in the acid extracts. By immunohistochemistry, CCK-LI was localized to amacrine cells which give rise to processes ramifying in the distal 2/3 of the inner plexiform layer. Time dependent uptake of 35S-methionine into CCK-LI was observed in cultured frog retinas and this uptake was blocked with 0.2 mM cycloheximide. Our findings suggest that the retina may be a useful system for further characterization of the neural function of CCK-LI.
D000818:Animals; D002766:Cholecystokinin / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D006651:Histocytochemistry; D006863:Hydrogen-Ion Concentration; D008715:Methionine / Q000378:metabolism; D009924:Organ Culture Techniques; D010446:Peptide Fragments / Q000378:metabolism; D011894:Rana pipiens; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D012844:Sincalide; D014018:Tissue Distribution
D010446:Peptide Fragments; D002766:Cholecystokinin; D003513:Cycloheximide; D008715:Methionine; D012844:Sincalide