Food intake dependence on acute changes in light schedule.
The mechanism of the diurnal eating pattern in the rat (eating much more food at night than in the day) is not entirely clear. To further study the influence of environmental lighting on food intake, male rats were maintained in constant 12:12 light-dark cycle (daytime from 0800 to 2000) and subjected to short-time acute changes in the light schedule. The results show: (1) Lights on during the nighttime (30-min from 2230 to 2300 or from 2258 to 2328) suppress short-term food intake; (2) Lights off during the daytime (2-hr from 1000 to 1200) increase short-term food intake. Both responses (1 and 2) are independent of the age of the rat. These results are consistent with acute regulatory adjustment of feeding to abrupt light shifts, possibly by generation through the retino-hypothalamic pathway to the suprachiasmatic nucleus (supporting its action as a pacemaker in the endogenous circadian feeding rhythm in the rat), although other control mechanisms are not excluded.
Plata-Salamán
C R
CR
Department of Physiology, Faculty of Medicine, Kyushu University 60, Fukuoka, Japan.
Oomura
Y
Y
D000818:Animals; D002940:Circadian Rhythm; D005247:Feeding Behavior / Q000502:physiology*; D007031:Hypothalamus / Q000502:physiology; D008027:Light; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000502:physiology