ABSTRACT
Sleep disturbances are common among disorders associated with hypothalamic pituitary-adrenal (HPA) axis dysfunction, such as depression and anxiety. This comorbidity may partly be the result of the intersection between the role of the HPA axis in mediating the stress response and its involvement in sleep-wake cyclicity. Our previous work has shown that following 20 h of sleep restriction, mice show a blunting of the HPA axis in response to an acute stressor. Furthermore, these responses differ in a sex-dependent manner. This study sought to examine the effect of sleep restriction on corticotropin-releasing factor (CRF)-containing neurons in the paraventricular nucleus (PVN) of the hypothalamus. Male and female Crf-IRES-Cre: Ai14 (Tdtomato) reporter mice were sleep restricted for 20 h daily for either a single or three consecutive days using the modified multiple platform method. These mice allowed the visualization of CRF+ neurons throughout the brain. Animals were subjected to acute restraint stress, and their brains were collected to assess PVN neuronal activation via c-Fos immunohistochemistry. Analyses of cell counts revealed an ablation of the restraint-induced increase in both CRF/c-Fos colocalization and overall c-Fos expression in female mice following both a single day and three days of sleep restriction. Males showed an overall decrease in restraint-induced c-Fos levels following a single day of sleep restriction. However, male mice examined after three days of sleep restriction showed a recovery in PVN-CRF and overall PVN neuronal activation. These data suggest the sex dependent dysregulation in CRF function following sleep restriction.
