How Different Light Colors Affect Melatonin Reduction in the Zebrafish Pineal Gland

The spectral sensitivity of melatonin suppression in zebrafish pineal glands shows the most efficient response to light around 512 nm.

• Melatonin production in zebrafish pineal glands is rhythmic, peaking at night and dropping during the day.
• Nocturnal light exposure acutely suppresses melatonin synthesis in photoreceptor cells.
• Exposure to seven wavelengths of light revealed multiple photopigments are likely involved in melatonin suppression.
• The action spectrum indicates a peak sensitivity at 512 nm, with additional sensitivity at middle to long wavelengths.
• Opsin analysis shows expression of exo-rhodopsin and visual red-sensitive opsin in the pineal gland, while other visual opsins are absent.
• Dartnall monograms for the identified opsins explain most spectral sensitivity, suggesting additional photopigments may also play a role.

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