Intergeniculate leaflet ablation alters circadian rhythms in the mouse.
The intergeniculate leaflet (IGL) receives retinal input and sends afferents to the hypothalamic suprachiasmatic nucleus (SCN), a circadian oscillator. The effect of IGL ablation on the circadian rhythm of wheel-running activity was examined in mice maintained in constant dark (DD) and in two intensities of constant light (LL). IGL-lesioned animals demonstrated significantly longer free-running rhythms in DD conditions than IGL-intact mice similarly housed; there was no effect of IGL ablation on the period of the free-running activity rhythm in LL of either 10 or 100 lux intensity. A change in the period of the free-running activity rhythm in DD following IGL destruction is evidence that the IGL exerts an endogenous influence on the SCN circadian system.
Pickard
G E
GE
Department of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia 19104-6141.
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D005829:Geniculate Bodies / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL