Serotonergic and cholinergic stimulation of inositol phosphate formation in the rabbit retina. Evidence for the presence of serotonin and muscarinic receptors.
A direct assay which involves prelabelling with [3H]inositol has been performed to characterize receptor-mediated breakdown of inositol phospholipids in the rabbit retina. In the presence of 10 mM lithium, the receptor agonists, carbachol and serotonin (5-HT), evoked an increase in the accumulation of tritiated inositol phosphates in a dose-dependent manner. A variety of 5-HT and other antagonists were used to show that at least part of the 5-HT-induced response is mediated by 5-HT2 receptor sites, adding weight to the theory that 5-HT plays a neurotransmitter role in the mammalian retina. The very high rate of carbachol-stimulated inositol phosphate accumulation observed in retinas from young animals (10 days) decreases significantly during development of the rabbit to the adult stage. In contrast 5-HT only induces significant stimulation of inositol phosphate accumulation in retinas of animals matured to at least 17 days. Separation of total accumulated inositol phosphates (after stimulation with both carbachol and 5-HT) showed that the vast majority of tritium label was associated with the monophosphate fraction.
Nuffield Laboratory of Ophthalmology, University of Oxford, U.K.
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Cutcliffe
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Osborne
D000367:Age Factors; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism*; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology* / Q000502:physiology; D013403:Sugar Phosphates / Q000378:metabolism*
D007295:Inositol Phosphates; D011976:Receptors, Muscarinic; D011985:Receptors, Serotonin; D013403:Sugar Phosphates; D012701:Serotonin; D001285:Atropine; D002217:Carbachol; D009638:Norepinephrine