Drugs and the frog retina. Effect of dopaminergic agents on the pigment screening of light- and dark-adapted frogs.
This is a study, using the light and electron microscope, of the action of a dopamine agonist (apomorphine) and of a dopamine antagonist (haloperidol) on the retinal pigment screening (PS) of light- and dark-adapted frogs. Pigment screening is a phenomenon which consists of the migration of melanin granules into processes of the pigment epithelium that extend between photoreceptors, in response to changes in the conditions of illumination. In the light the pigment migrates vitreally , in the dark it aggregates sclerally . A single intravenous injection of apomorphine (0.15 mg/kg) and of haloperidol (1 mg/kg) did not induce substantial modifications in the pattern of pigment screening which was similar to that of controls both in light- and dark-adapted frogs. This suggests that dopamine is probably not directly involved in the phenomenon of pigment screening in the retina of the frog.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D003623:Dark Adaptation; D006220:Haloperidol / Q000494:pharmacology*; D008027:Light; D008543:Melanins / Q000502:physiology; D008854:Microscopy, Electron; D010857:Pigment Epithelium of Eye / Q000502:physiology* / Q000648:ultrastructure; D011893:Rana esculenta; D012160:Retina / Q000502:physiology* / Q000648:ultrastructure
D008543:Melanins; D006220:Haloperidol; D001058:Apomorphine