Suppression of eltoprazine-induced REM sleep rebound by scopolamine

Protein kinase A in the pedunculopontine tegmental nucleus of rat contributes to regulation of rapid eye movement sleep

Intracellular signaling mechanisms within the pedunculopontine tegmental (PPT) nucleus for the regulation of recovery rapid eye movement (REM) sleep following REM sleep deprivation remain unknown. This study was designed to determine the role of PPT intracellular cAMP-dependent protein kinase A (cAMP-PKA) in the regulation of recovery REM sleep in freely moving rats. The results show that a brief period (3 h) of selective REM sleep deprivation caused REM sleep rebound associated with increased PKA activity and expression of the PKA catalytic subunit protein (PKA-CU) in the PPT. Local application of a cAMP-PKA-activation-selective inhibitor, RpCAMPS (0.55, 1.1, and 2.2 nmol/100 nl; n = 8 rats/group), bilaterally into the PPT, reduced PKA activity and PKA-CU expression in the PPT, and suppressed the recovery REM sleep, in a dose-dependent manner. Regression analyses revealed significant positive relationships between: PPT levels of PKA activity and the total percentages of REM sleep recovery (Rsqr = 0.944; n = 40 rats); PPT levels of PKA-CU expression and the total percentages of REM sleep recovery (Rsqr = 0.937; n = 40 rats); PPT levels of PKA-CU expression and PKA activity (Rsqr = 0.945; n = 40 rats). Collectively, these results provide evidence that activation of intracellular PKA in the PPT contributes to REM sleep recovery following REM sleep deprivation.

Rapid eye movement (REM) sleep homeostatic regulatory processes in the rat: changes in the sleep-wake stages and electroencephalographic power spectra

The aim of this study was to elucidate physiological processes that are involved in the homeostatic regulation of REM sleep. Adult rats were chronically instrumented with sleep-wake recording electrodes. Following post-surgical recovery, rats were habituated extensively for freely moving polygraphic recording conditions. On the first experimental recording day (baseline day, BLD), polygraphic signs of undisturbed sleep-wake activities were recorded for 4 h (between 11:00 AM and 3:00 PM). During the second experimental recording day (REM sleep deprivation day, RDD), rats were selectively deprived of REM sleep for the first 2 h and then allowed to have normal sleep-wake for the following 2 h. The results demonstrated that during the first 2 h, compared to BLD, RDD recordings exhibited 87.80% less time in REM sleep and 16% more time in non-REM (NREM) sleep. The total percentages of wakefulness remained comparable between the BLD and RDD. During the RDD, the mean number of REM sleep episodes was much higher than in the BLD, indicating increased REM sleep drive. Electroencephalographic (EEG) power spectral analysis revealed that selective REM sleep deprivation increased delta power but decreased theta power during the residual REM sleep. During the last 2 h, after REM sleep deprivation, rats spent 51% more time in REM sleep compared to the BLD. Also during this period, the number of REM sleep episodes with the shortest (5-30 s) and longest (>120 s) duration increased during the RDD. These findings suggest that the REM sleep homeostatic process involves increased delta- and decreased theta-frequency wave activities in the cortical EEG.

Sleep-wake effects of meta-chlorophenyl piperazine and mianserin in the behaviorally depressed rat

The present study examined the effects of meta-chlorophenyl piperazine (mCPP) and mianserin on the sleep-wake cycle of the clomipramine-induced behaviorally screened depressed rats. Six-hour polygraphic recordings were made between 06:00 and 12:00 h, after a single injection of either saline or mianserin or mCPP into the lateral cerebral ventricle (i.c.v.) of both the depressed (n=12) and control rats (n=12). The injection of mCPP in the depressed rats caused a significant reduction in the total duration and number of rapid eye movement (REM) sleep episodes while it increased the REM sleep onset latency compared to the control saline injections. The injection of mianserin in the depressed rats also caused a significant reduction in the total duration and number of REM sleep episodes without changing the REM sleep latency. These results demonstrate for the first time that the central administration of mCPP and mianserin could act as an antidepressant in the clomipramine-induced rat model of depression.

Role of the locus coeruleus in the sleep rebound following two different sleep deprivation methods in the rat

The aim of the present study was to assess the involvement of the locus coeruleus in the paradoxical sleep rebound following sleep deprivation in the rat. Animals were sleep-deprived for 10 h before, and after, specific N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) lesioning of the noradrenergic-locus coeruleus system. Sleep deprivation was produced using either an instrumental (water tank) or pharmacological (methylamphetamine) method. After lesioning, the rats submitted to the instrumental method showed a significant decrease in the paradoxical and slow-wave sleep rebounds (-54% and -78%, respectively), while animals receiving metamphetamine did not. Our results suggest that the noradrenergic system of the locus coeruleus is a relevant component of the sleep rebound mechanisms. However, the extent of involvement is dependent on the sleep deprivation method used.

Diurnal penile tumescence recording in the etiological diagnosis of erectile dysfunction

Rapid eye movement sleep occurs during napping. We investigated the appearance of penile tumescence during periods of day napping in a population of 18 impotent men who, in addition, underwent a comprehensive sleep investigation for impotence, including polysomnographic recording and nocturnal penile tumescence monitoring. Of the subjects 16 (88%) had rapid eye movement sleep during the night. Four patients who did not have erections on 2 separate sessions of nocturnal sleep recording also did not experience penile tumescence during the day. Of the 12 patients with documented erections at night 9 (75%) also exhibited erectile episodes during napping. Diurnal penile tumescence recording is less cumbersome, less expensive and more convenient to perform than its nocturnal counterpart. Diurnal penile tumescence appears to be a summary reflection of nocturnal penile tumescence episodes. The consistency between nocturnal and diurnal penile tumescence suggests that further study of this new technique is worthwhile. Validation of diurnal penile tumescence may offer a viable alternative to the comprehensive assessment of impotent men.