Biomaterial Database

Effects of melatonin on the chick retinal pigment epithelium: membrane potentials and light-evoked responses. 1989

N Nao-i, and S E Nilsson, and R P Gallemore, and R H Steinberg

Department of Physiology, University of California, San Francisco 94143.

The indolamine hormone melatonin, synthesized in the retina, is thought to participate in modulating day-night cyclic variations in photoreceptor and retinal pigment epithelium (RPE) function. It has also been shown to alter the electrical activity of the RPE of the mammalian eye (Dawis and Niemeyer, 1985, Soc. Neurosci. 11, 1079:1988, Clin. Vis. Sci. 3, 109-118: Textorius and Nilsson, 1987, Doc. Ophthalmol, 65, 97-111). To determine the origin of such electrical effects studies were performed on in vitro preparations of both chick retina-RPE-choroid and RPE-choroid. In retina-RPE-choroid preparations choroidal perfusion with melatonin (2.10(-6) M) hyperpolarized the basal membrane, increased its apparent resistance, and diminished the amplitude of the c-wave of the electroretinogram (ERG). Retinal perfusion with melatonin (2.10(-6) M) first depolarized the RPE apical membrane and increased its apparent resistance and this gave way to a basal membrane hyperpolarization accompanied by an increase in basal membrane resistance. Both phases were accompanied by c-wave decreases. Experiments in RPE-choroid preparations suggested that the choroidal effect of melatonin was independent of the neural retina, while the retinal effect was more complex and probably included a neural retinal component. Retinal or choroidal melatonin (2.10(-6) M) had little or no effect on the amplitude of the light peak of the DC ERG. These results show that chick RPE membrane potentials and resistances at either the apical or basal membrane can be affected by melatonin directly, or indirectly via effects on other cells.

UI	MeSH Term	Description	Entries
D008550	Melatonin	A biogenic amine that is found in animals and plants. In mammals, melatonin is produced by the PINEAL GLAND. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of SLEEP, mood, and REPRODUCTION. Melatonin is also an effective antioxidant.
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D010857	Pigment Epithelium of Eye	The layer of pigment-containing epithelial cells in the RETINA; the CILIARY BODY; and the IRIS in the eye.	Eye Pigment Epithelium
D002645	Chickens	Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.	Gallus gallus,Gallus domesticus,Gallus gallus domesticus,Chicken
D002829	Choroid	The thin, highly vascular membrane covering most of the posterior of the eye between the RETINA and SCLERA.	Choriocapillaris,Haller Layer,Haller's Layer,Sattler Layer,Sattler's Layer,Choroids
D004596	Electroretinography	Recording of electric potentials in the retina after stimulation by light.	Electroretinographies
D005074	Evoked Potentials, Visual	The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways.	Visual Evoked Response,Evoked Potential, Visual,Evoked Response, Visual,Evoked Responses, Visual,Potential, Visual Evoked,Potentials, Visual Evoked,Response, Visual Evoked,Responses, Visual Evoked,Visual Evoked Potential,Visual Evoked Potentials,Visual Evoked Responses
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001485	Basement Membrane	A darkly stained mat-like EXTRACELLULAR MATRIX (ECM) that separates cell layers, such as EPITHELIUM from ENDOTHELIUM or a layer of CONNECTIVE TISSUE. The ECM layer that supports an overlying EPITHELIUM or ENDOTHELIUM is called basal lamina. Basement membrane (BM) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. BM, composed mainly of TYPE IV COLLAGEN; glycoprotein LAMININ; and PROTEOGLYCAN, provides barriers as well as channels between interacting cell layers.	Basal Lamina,Basement Lamina,Lamina Densa,Lamina Lucida,Lamina Reticularis,Basement Membranes,Densas, Lamina,Lamina, Basal,Lamina, Basement,Lucida, Lamina,Membrane, Basement,Membranes, Basement,Reticularis, Lamina