Alteration of fear behaviors in sleep-deprived adolescent rats: increased fear expression and delayed fear extinction

Anim Cells Syst (Seoul). 2021 Mar 22;25(2):83-92. doi: 10.1080/19768354.2021.1902854. eCollection 2021.

Abstract

Disruption of sleep due to acute or chronic stress can lead to changes in emotional memory processing. Sleep disturbances are highly prevalent in post-traumatic stress disorder (PTSD), but still, the contribution of sleep deprivation on the susceptibility to PTSD has received little attention. To determine whether rapid eye movement sleep deprivation (SD) alters the development of fear expression or fear-associated memory impairment in adolescent rats, we performed animal emotional behavior tests using an SD animal model with the flowerpot technique. SD rats showed an increase in locomotor activity frequency and a decrease in sucrose consumption compared to control rats. An increase in freezing behavior during shock trials was observed in SD rats. Noticeably, it was observed that when applying the SD condition after fear stimuli exposure, fear extinction was delayed more in SD rats than in control rats. Overall, these results indicate that SD in adolescent rats leads to increased locomotor activity and anhedonic behavior, as well as increased fear expression and delayed fear extinction, suggesting that SD would lead to increased severity of PTSD-like phenotype.

Keywords: Adolescence; fear conditioning; fear extinction; hyperactivity; sleep.

Grants and funding

This work was supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea [grant number NRF-2017S1A5A2A01026454].