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BioMed Research International
Volume 2014, Article ID 170795, 5 pages
Research Article

The Effect of Different Photoperiods in Circadian Rhythms of Per3 Knockout Mice

1Departamento de Psicobiologia, Universidade Federal de São Paulo (UNIFESP), Rua Napoleão de Barros 925, 3º Andar, 04024-002 São Paulo, SP, Brazil
2Faculty of Health and Medical Science, University of Surrey, Guildford, UK
3Departamento de Fisiologia, Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN, Brazil
4Instituto Federal Sudeste de Minas Gerais, Campus Barbacena, Barbacena, MG, Brazil
5Escola de Artes, Ciências e Humanidades, Universidade de São Paulo (USP), São Paulo, SP, Brazil

Received 26 January 2014; Revised 24 March 2014; Accepted 19 April 2014; Published 8 May 2014

Academic Editor: Martin Fredensborg Rath

Copyright © 2014 D. S. Pereira et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of this study was to analyse the circadian behavioural responses of mice carrying a functional knockout of the Per3 gene ( ) to different light : dark (L : D) cycles. Male adult wild-type (WT) and mice were kept under 12-hour light : 12-hour dark conditions (12L : 12D) and then transferred to either a short or long photoperiod and subsequently released into total darkness. All mice were exposed to both conditions, and behavioural activity data were acquired through running wheel activity and analysed for circadian characteristics during these conditions. We observed that, during the transition from 12L : 12D to 16L : 8D, mice take approximately one additional day to synchronise to the new L : D cycle compared to WT mice. Under these long photoperiod conditions, mice were more active in the light phase. Our results suggest that mice are less sensitive to light. The data presented here provides further evidence that Per3 is involved in the suppression of behavioural activity in direct response to light.