Licht-im-Terrarium: Literaturdatenbank
Licht-im-Terrarium: Literaturdatenbank |
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Cahill, G. M., Parsons, S. E., & Besharse, J. C. (1998). Spectral sensitivity of melatonin synthesis suppression in xenopus eyecups. Visual Neuroscience, 15, 499–592. Added by: Sarina (2009-08-24 15:31:52) |
| Resource type: Journal Article BibTeX citation key: Cahill1998 View all bibliographic details  |
Categories: Englisch = English Keywords: Chronobiologie = Chronobiology, Netzhaut = Retina, Reptilien = Reptiles Creators: Besharse, Cahill, Parsons Collection: Visual Neuroscience |
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| Abstract |
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Melatonin synthesis in retinal photoreceptors is stimulated at night by a circadian oscillator and suppressed acutely by light. To identify photoreceptor mechanisms involved in the acute suppression of melatonin synthesis, an action spectrum was measured for dark-adapted Xenopus laevis eyecups at night. Intensity–response curves at six wavelengths from 400 to 650 nm were parallel, suggesting that a single photopigment predominates in melatonin suppression. Half-saturating intensities at 400, 440, 480, and 533 nm were not significantly different from one another, at 1–2 × 108 quanta cm[minus sign]2 s[minus sign]1. Significantly higher intensities of 580- and 650-nm light were required for melatonin suppression. These results indicate a predominant role for the principal green-absorbing rods in acute regulation of retinal melatonin synthesis in response to light, and argue against an important role for the red-absorbing cones. Higher than expected sensitivity at short wavelengths suggests that photoreceptors sensitive to blue and/or violet light may also contribute to melatonin suppression. Key Words: Action spectrum; Retina; Photoreceptors; Circadian Added by: Sarina |