The overall goals of this research are to identify the neurotransmitters used by subgroups of the retina's neurons, and to learn the specific roles of those neurons in the retina's function.
The first aim i s to learn the shape and function of a subset of retinal neurons defined by their release of acetylcholine. The cholinergic neurons of the rabbit retina appear to be amacrine cells; they bracket the inner plexiform layer symmetrically, about half of them located in the conventional position of amacrine cells and half """"""""displaced"""""""" to the ganglion cell layer. The displaced cholinergic amacrine cells will be studied by intracelular recording and injection of fluorescent or enzymatic markers. The functional activity of the cholinergic cells will be further characterized by measurements of the retina's release of acetylcholine made with fast temporal resolution: acetycholine release will be measured in the dark, during application of Co++, during steady light, and at stimulus onset and cessation. Finally, at neuronal terminals contained within the two main sublaminae of the inner plexiform layer. This will be done by autoradiography of retinas preloaded with radioactive acetylcholine and then stimulated under conditions dominated by either On or Off transients.
A second aim i s to identify the cells responsible for the apparent presence of the renin-angiotensin system in the retina. Renin, angiotensin I, angiotensin II, and converting enzyme will be assayed biochemically. The cellular location of renin and the angiotensins will be established immunohistochemically. Because renin-containing neurons were found in preliminary experiments only in the ganglion cell layer, biochemical and histochemical analysis will be carried out both in normal retinas and retinas whose optic nerves had been sectioned 6 months previously; immunohistochemistry will be done after marking of the ganglion cell bodies by fluorescent dyes applied to the optic tract; and the renin and angiotensin content of ganglion cells purified by fluorescence-activated cell sorting will be determined.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY001075-12
Application #
3255669
Study Section
(VID)
Project Start
1977-04-01
Project End
1987-03-31
Budget Start
1985-04-01
Budget End
1986-03-31
Support Year
12
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
Peters, B N; Masland, R H (1996) Responses to light of starburst amacrine cells. J Neurophysiol 75:469-80
Strettoi, E; Masland, R H (1996) The number of unidentified amacrine cells in the mammalian retina. Proc Natl Acad Sci U S A 93:14906-11
Masland, R H (1996) Processing and encoding of visual information in the retina. Curr Opin Neurobiol 6:467-74
Masland, R H; Cassidy, C (1987) The resting release of acetylcholine by a retinal neuron. Proc R Soc Lond B Biol Sci 232:227-38
Sellner, P A (1986) The blood-retinal barrier: leucine transport by the retinal pigment epithelium. J Neurosci 6:2823-8
Sellner, P A (1986) The movement of organic solutes between the retina and pigment epithelium. Exp Eye Res 43:631-9
Sandell, J H; Masland, R H (1986) A system of indoleamine-accumulating neurons in the rabbit retina. J Neurosci 6:3331-47
Masland, R H; Tauchi, M (1985) A possible amacrine cell substrate for the detection of stimulus motion. Neurosci Res Suppl 2:S185-99
Tauchi, M; Masland, R H (1985) Local order among the dendrites of an amacrine cell population. J Neurosci 5:2494-501