Tryptamine and some related molecules block the accumulation of a light-sensitive pool of cyclic AMP in the dark-adapted, dark-incubated mouse retina.
Dark-adapted retinas of mice (C57BL/6J) incubated in the dark in media containing 1 mM 3-isobutylmethylxanthine (IBMX) or 5 mM Co2+ accumulate cyclic AMP (cAMP). A portion of this pool is light sensitive, as light can prevent or reverse its accumulation. Similarly, tryptamine, serotonin, 5-methoxytryptamine, bufotenine, and 5-methoxydimethyltryptamine can block the accumulation of the light-sensitive pool of cAMP, whereas tryptophan, melatonin, N-acetylserotonin, 5-methoxytryptophol, and tetrahydro-beta-carbolines are inactive. The phenomenon is not seen with mutant mouse retinas (rd/rd), which lack most photoreceptors, but persists in abnormal retinas containing photoreceptors but with extensive neuronal depletion in the inner retina. Tryptamine also inhibits cAMP accumulation in either dark or light-adapted retinas exposed to forskolin alone but not in media containing high levels of forskolin plus 1 mM IBMX. There is some suggestion that serotonin 5-HT-2 antagonists can partially reverse the action of the tryptamines, but hitherto undescribed receptors may be involved. Current data suggest that photoreceptors are the target for the action of the tryptamines.
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D008735:5-Methoxytryptamine / Q000494:pharmacology; D000818:Animals; D003035:Cobalt / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D003623:Dark Adaptation; D008027:Light; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D010786:Photoreceptor Cells / Q000502:physiology; D012160:Retina / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D014363:Tryptamines / Q000494:pharmacology*
D012702:Serotonin Antagonists; D014363:Tryptamines; D005576:Colforsin; D012701:Serotonin; D003035:Cobalt; D008735:5-Methoxytryptamine; C030820:tryptamine; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine