Melanopsin’s role in how the body’s internal clock responds to light

Knockout mice exhibited a 40% lower behavioral response magnitude to light compared to wild-type mice.

• Melanopsin is proposed as a key molecule in the mammalian circadian system.
• Both wild-type and melanopsin knockout mice showed entrainment to a light/dark cycle.
• Mice of both types phase-shifted after exposure to a light pulse.
• Increased light intensity resulted in a longer circadian period in both groups.
• Induction of the immediate-early gene c-fos occurred in response to nighttime light pulses in both mouse types.
• Melanopsin is associated with enhancing the strength of photic responses, though not essential for basic light input to the circadian clock.

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