Regulation of circadian photic responses by nitric oxide.
A role for nitric oxide in circadian responses to light has been indicated in previous studies. To determine the specific function of NO-, the authors manipulated NO- and nitric oxide synthase (NOS) activity prior to light pulses that would normally induce phase shifts. The NOS inhibitor, L-NAME, selectively attenuated phase advances of locomotor rhythms and had no effect on phase delays. The NO- donor, SNAP, potentiated both photic responses, and phase delays were larger than the maximum responses that could be obtained with light alone. The date suggest a model in which NO- participates in the adaptation of the system to environmental lighting conditions by regulating in a phase-dependent manner responsiveness to light.
Melo
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Department of Zoology, University of Toronto, Ontario, Canada.
Golombek
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DA
Ralph
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MR
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D006224:Cricetinae; D006152:Cyclic GMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D008647:Mesocricetus; D009043:Motor Activity / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010775:Photic Stimulation
D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester