Complete sleep and local field potential analysis regarding estrus cycle, pregnancy, postpartum and post-weaning periods and homeostatic sleep regulation in female rats

Abstract

Sleep and local field potential (LFP) characteristics were addressed during the reproductive cycle in female rats using long-term (60–70 days) recordings. Changes in homeostatic sleep regulation was tested by sleep deprivation (SDep). The effect of mother-pup separation on sleep was also investigated during the postpartum (PP) period. First half of the pregnancy and early PP period showed increased wakefulness (W) and higher arousal indicated by elevated beta and gamma activity. Slow wave sleep (SWS) recovery was suppressed while REM sleep replacement was complete after SDep in the PP period. Pup separation decreased maternal W during early-, but increased during middle PP while did not affect during late PP. More W, less SWS, higher light phase beta activity but lower gamma activity was seen during the post-weaning estrus cycle compared to the virgin one. Maternal sleep can be governed by the fetuses/pups needs and their presence, which elevate W of mothers. Complete REM sleep- and incomplete SWS replacement after SDep in the PP period may reflect the necessity of maternal REM sleep for the offspring while SWS increase may compete with W essential for maternal care. Maternal experience may cause sleep and LFP changes in the post-weaning estrus cycle.

Many faces of sleep regulation: beyond the time of day and prior wake time

“…Pregnancy‐related sleep changes have also been reported in rodents, although the exact nature of the sleep alterations is unclear. Studies have found a reduction in REM and non‐REM (NREM) sleep during the light phase [103,104]. However, two studies showed that pregnancy generally increase NREM and REM sleep [104,105], whereas a third study found decreased sleep [103].…”

“…Studies have found a reduction in REM and non‐REM (NREM) sleep during the light phase [103,104]. However, two studies showed that pregnancy generally increase NREM and REM sleep [104,105], whereas a third study found decreased sleep [103]. The mechanisms underlying these changes are not yet known but may involve hormones [106–108].…”

“…In dolphins and killer whales, both mothers and offspring suppress rest behavior for several months after birth [121,122]. The early postpartum period in rodents is also associated with increased wakefulness and decreased NREM sleep [103,105], in part due to the external stimuli stemming from the pups [103]. Interestingly, maternal nursing in rabbits acts as a synchronizing factor on their offspring through brain regions that are not part of the central circadian oscillator, resembling the findings of the FEOs and suggesting that reproductive demands recruit novel neuronal substrates to regulate rest–activity patterns [123–125].…”

Modulation and Neural Correlates of Postmating Sleep Plasticity inDrosophilaFemales

“…On the other hand, females exhibit changes in sleep patterns during pregnancy and after the birth of the offspring. Pregnancy-related sleep changes have been observed in humans and rodents 60,61 . Notably, female rats exhibit sleep changes after mating with vasectomized males 62 .…”

Sleep- and sleep deprivation-related changes of vertex auditory evoked potentials during the estrus cycle in female rats

“…Estrus (EST) cycle was found to affect a variety of physiological functions in female rats including social- and sexual behavior 16 , 17 , anxiety 18 , 19 and sleep 20 . EST cycle is under strict and complex hormonal control with gonadal hormones playing a major role 21 .…”