Effects of restricted feeding cycle on the locomotor activity rhythm in the mouse Mus booduga

Author(s): Chidambaram, R., Subbaraj, R., Chandrashekaran, M. K.

Journal/Book: Physiol Behav. 2000; 70: the Boulevard Langford Lane, Kidlington, Oxford Ox5 1GB, England. Pergamon-Elsevier Science Ltd. 81-87.

Abstract: The effect of restricted feeding (RF) cycles on the circadian locomotor activity rhythm was studied in the nocturnal field mouse Mus booduga. Mice were presented with a 2-h meal schedule every 24 h in continuous darkness (DD), in continuous light (LL), and in a light-dark (LD) cycle. Additionally, in DD, two groups of mice were subjected to RF cycles of periodicities 22 (T22) and 26 h (T26), respectively, in order to assess the limits of entrainment. The T22 and T26 RF cycles failed to produce any entrainment of the locomotor activity rhythm, whereas some of the animals that had a free-running period (tau) close to 24 h showed stable entrainment or ''relative coordination'' to daily (T24) RF cycle. In LD, the locomotor activity rhythm phase advanced under the influence of the daily RF cycle when the food presentation preceded the light to dark (L to D) transition by 5-6 h. However, when the timing of food presented in the RF cycle coincided with the L to D transition, locomotor activity rhythm dissociated into two components. Some of the mice whose locomotor activity rhythm disappeared in LL showed prominent meal-AA. These results suggest that RF modifies the expression of the light-entrainable pacemaker (LEP) directly and also that in the absence of the expression of the LEP, RF can induce meal-AA.

Note: Article Sharma VK, Jawaharlal Nehru Ctr Adv Sci Res, Evolutionary & Organismal Biol Unit, Chronobiol Lab, POB 6436, Bangalore 560064, Karnataka, INDIA

Keyword(s): circadian rhythms; non-photic entrainment; restricted feeding; meal anticipatory activity; food-entrainable pacemaker (FEP); light entrainable pacemaker (LEP); CIRCADIAN ACTIVITY RHYTHMS; RUNNING ACTIVITY RHYTHMS; FOOD ACCESS; SUPRACHIASMATIC NUCLEUS; ANTICIPATORY ACTIVITY; SMINTHOPSIS-MACROURA; LIGHT-DARK; RATS; LESIONS; ENTRAINMENT

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