Constant light uncovers behavioral effects of a mutation in the schizophrenia risk gene Dtnbp1 in mice.

TitleConstant light uncovers behavioral effects of a mutation in the schizophrenia risk gene Dtnbp1 in mice.
Publication TypeJournal Article
Year of Publication2015
AuthorsBhardwaj SK, Stojkovic K, Kiessling S, Srivastava LK, Cermakian N
JournalBehav Brain Res
Volume284
Pagination58-68
Date Published2015 May 01
ISSN1872-7549
KeywordsAnimals, Anxiety, Circadian Rhythm, Corticosterone, Darkness, Disease Models, Animal, Dystrophin-Associated Proteins, Exploratory Behavior, Feces, Genetic Predisposition to Disease, Light, Mice, Inbred C57BL, Mice, Inbred DBA, Motor Activity, Mutation, Photic Stimulation, Prepulse Inhibition, Reflex, Startle, Risk Factors, Running, Schizophrenia
Abstract

Various psychiatric disorders, including schizophrenia, are comorbid with sleep and circadian rhythm disruptions. To understand the links between circadian rhythms and schizophrenia, we analyzed wheel-running behavior of Sandy (Sdy) mice, which have a loss-of-function mutation in the schizophrenia risk gene Dtnbp1, and exhibit several behavioral features of schizophrenia. While rhythms of Sdy mice were mainly normal under light-dark conditions (LD) or in constant darkness (DD), they had a significantly longer free-running period under constant light (LL) compared to wild-type (WT) littermates. The mutant mice also had a higher subjective day/subjective night ratio of activity under LL, indicating lower amplitude, and a lower precision of their onsets of activity under all three lighting conditions. These observations are reminiscent of the circadian disruptions observed in schizophrenia patients. This prompted us to assess schizophrenia-relevant behavioral abnormalities in Sdy mice following alteration of the circadian rhythms by presentation of constant light. Spontaneous locomotor activity, prepulse inhibition (PPI) of acoustic startle and anxiety-like behavior were assessed under baseline LD conditions, then in LL, and then again in LD. Under LL, the Sdy mice showed significantly increased spontaneous locomotion as well as deficits in PPI compared to WT mice. Strikingly, these behavioral deficits persisted even after the mice were returned in LD conditions. While LL led to an increase in anxiety-like behavior in WT animals that was fully reversed after 3 weeks in LD, this effect was not observed in the Sdy mutants. Overall, these results suggest that Dtnbp1 deficiency may lead to increased vulnerability to schizophrenia under environmental conditions where circadian rhythms are altered.

DOI10.1016/j.bbr.2015.01.048
Alternate JournalBehav. Brain Res.
PubMed ID25677649
Grant ListMOP-81123 / / Canadian Institutes of Health Research / Canada