Angiotensin II-like immunoreactivity in the retina of some mammalian species.
The decapeptide angiotensin II (AngII) is a circulating hormone and the most important endogenous vasoconstrictor. In the central nervous system (CNS), AngII has been reported to have a transmitter-like function. In the retina angiotensin I (AngI), the precursor protein of AngII, and AngI-converting enzyme (ACE), the rate-limiting enzyme for AngII synthesis, are present. Both ACE inhibition and application of an AngII antagonist affect the b-wave of the electroretinogram. In the present study we used immunocytochemical techniques to identify putative AngII-containing cells in the bovine, cat, and rabbit retina. In the rabbit retina, faintly labeled amacrine cells were visible at the inner border of the inner nuclear layer. Preincubation with protease inhibitors (PI) resulted in an enhanced immunoreaction and in the labeling of ganglion cells and fibers in the inner plexiform layer. In the bovine retina, AngII-like immunoreactivity was detectable only after preincubation with PI. Under these conditions, ganglion cells and amacrine cells as well as cells in more distal parts of the inner nuclear layer were stained. In the cat retina, AngII-like immunoreactivity was detectable only after preincubation with PI and exogenous AngII. Photoreceptor and ganglion cells showed an enhanced AngII-like immunoreaction, and amacrine cells were stained preferably in clusters that were irregularly distributed within the retina. Our results demonstrate that AngII is a putative neurotransmitter in a subpopulation of mammalian amacrine cells.
Jurklies
B
B
Department of Pathophysiology of Vision and Neuroophthalmology, University Eye Hospital, Tübingen, Germany.
Kohler
K
K
Eikermann
J
J
Zrenner
E
E
D000804:Angiotensin II / Q000032:analysis*; D000818:Animals; D002415:Cats; D002417:Cattle; D005455:Fluorescent Antibody Technique; D007124:Immunoenzyme Techniques; D007395:Interneurons / Q000737:chemistry; D009412:Nerve Fibers / Q000737:chemistry; D010786:Photoreceptor Cells / Q000737:chemistry; D011817:Rabbits; D012160:Retina / Q000737:chemistry* / Q000166:cytology; D012165:Retinal Ganglion Cells / Q000737:chemistry; D013045:Species Specificity
D000804:Angiotensin II