Impaired Masking Responses to Light in Melanopsin-Knockout Mice

N. Mrosovsky, S. Hattar

Research output: Contribution to journalArticle

Abstract

There are two ways in which an animal can confine its behavior to a nocturnal or diurnal niche. One is to synchronize an endogenous clock that in turn controls the sleep-wake cycle. The other is to respond directly to illumination with changes in activity. In mice, high illumination levels suppress locomotion (negative masking) and low illumination levels enhance locomotion (positive masking). To investigate the role of the newly discovered opsin-like protein melanopsin in masking, we used 1h and 3h pulses of light given in the night, and also a 3.5: 3.5h light-dark (LD) cycle. Mice lacking the melanopsin gene had normal enhancement of locomotion in the presence of dim lights but an impaired suppression of locomotion in the presence of bright light. This impairment was evident only with lights in the order of 10 lux or brighter. This suggests that melanopsin in retinal ganglion cells is involved in masking, as it is in pupil contraction and phase shifts. Melanopsin is especially important in maintaining masking responses over long periods.

Original languageEnglish (US)
Pages (from-to)989-999
Number of pages11
JournalChronobiology International
Volume20
Issue number6
DOIs
StatePublished - 2003

Fingerprint

Locomotion
Knockout Mice
locomotion
Lighting
lighting
Light
mice
Opsins
opsin
Retinal Ganglion Cells
Photoperiod
Pupil
sleep
Sleep
niches
photoperiod
melanopsin
Genes
animals
Proteins

Keywords

  • Diurnality
  • Irradiance detection
  • Masking
  • Melanopsin
  • Retina
  • Rhythms

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Physiology
  • Physiology (medical)

Cite this

Impaired Masking Responses to Light in Melanopsin-Knockout Mice. / Mrosovsky, N.; Hattar, S.

In: Chronobiology International, Vol. 20, No. 6, 2003, p. 989-999.

Research output: Contribution to journalArticle

Mrosovsky, N. ; Hattar, S. / Impaired Masking Responses to Light in Melanopsin-Knockout Mice. In: Chronobiology International. 2003 ; Vol. 20, No. 6. pp. 989-999.
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