[3H]-dopamine release from the rabbit retina.
[3H]-Dopamine was found to be released from the rabbit retina in vitro by light stimulation, by 40 mM K+, and by alpha-MSH (alpha-Melanocyte-Stimulating Hormone) down to about 10(-7) M. The effect of alpha-MSH was dose-dependent. A number of known and putative retinal neurotransmitters and agonists (GABA, muscimol, glutamic acid, kainic acid, glycine, and carbachol, all 10(-4) M) were without significant effect. The results show that it is unlikely that there are excitatory receptors on the retinal dopaminergic neurons to any of the conventional transmitters. Further, alpha-MSH seems of interest as a possible neuroactive retinal substance, which was previously not been suspected.
D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010775:Photic Stimulation; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D012160:Retina / Q000378:metabolism*; D014316:Tritium
D018377:Neurotransmitter Agents; D014316:Tritium; D009074:Melanocyte-Stimulating Hormones; D011188:Potassium; D004298:Dopamine