Localization of putative dopamine D2-like receptors in the chick retina, using in situ hybridization and immunocytochemistry.
The actions of dopamine are mediated by 5 or more receptor subtypes, any of which may be coupled by G-proteins to adenylate cyclase (D1-family: stimulatory, D2-family: inhibitory or no action). Postnatal ocular growth in the chick is a vision-dependent mechanism which involves D2-type receptors in either the retina or the retinal pigment epithelium (RPE). Although the dopaminergic amacrine cells are well described in the chick retina, only D2-receptors, but not D3- and D4-receptors have been clearly localized, and the cells that express them have not been identified. In this study we showed that immunoreactive D2/3-receptor protein is localized to the photoreceptor inner segments, outer and inner plexiform layer and ganglion cell layer, as described previously (Wagner et al., J. Comp. Neurol., 330 (1993) 1-13). D2-receptor mRNA was localized to cell bodies in all nuclear layers of the retina, whereas D4-receptor mRNA was restricted to the inner half of the retina. Immunoreactive D2-type receptors and their mRNA were observed also in the basal region of the RPE. Because of the widespread distribution of both D2- and D4-receptor mRNA in the chick retina and RPE and the lack of D3- and D4-receptor-specific antibodies, we were unable to identify which of the D2/3/4-receptor-bearing cells are involved in controlling ocular growth.
Rohrer
B
B
Department of Anatomy, University of Calgary, AB, Canada.
Stell
W K
WK
D000818:Animals; D002645:Chickens / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D010786:Photoreceptor Cells / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D017448:Receptors, Dopamine D2 / Q000096:biosynthesis / Q000378:metabolism*; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4; D012160:Retina / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism
D012333:RNA, Messenger; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4