The effects of delta-sleep-inducing peptide (DSIP) on wakefulness and sleep patterns in the cat.

The effect of a single injection of synthetic delta-sleep-inducing peptide (DSIP, 7 nmol/kg) into the lateral ventricle of 10 cats was investigated by monitoring the sleep-wake cycle during an 8 h period. A significant decrease in sleep latency and a significant increase in total sleep and in total slow wave sleep (SWS) was found following DSIP administration. The increase in sleep resulted exclusively from a significant increase in deep slow wave sleep (S2), while light slow wave sleep (S1) was significantly decreased. Neither the total amount of REM sleep, nor hourly values of REM sleep were affected by DSIP application. Additional measures of REM sleep, like REM sleep latency, mean episode number and mean episode length were not different from those found in control conditions. DSIP was immediately effective since the amount of S2 increased to more than 50% in the first postinjection hour and the difference from the control value was highly significant. The increase in S2 was maintained over 7 h, and disappeared by the eighth hour. The increase in S2 was caused by a prolongation of S2 episodes and not by their more frequent occurrence. The results obtained suggest a sleep-facilitating property of DSIP.

Sleep patterns in the Mongolian gerbil, Meriones unguiculatus.

Sleep patterns were studied in Mongolian gerbils and normative values were derived from 48 hour recordings, during a 24-hr light-dark cycle (LD 12:12). Behavioral and electrographic observations confirmed the existence of well defined sleep states: slow-wave sleep (SWS) and paradoxical sleep (PS). During the light period, sleep occupied slightly more than half of the 12 hour period, 57.13 +/- 0.002% out of which 49.64 +/- 0.007% was occupied by SWS and 8.07 +/- 0.007% by PS. There were 23 +/- 0.01 episodes of PS with a mean duration of 2.32 +/- 0.01 min. During the dark period, sleep occupied slightly less than half of the recording time (51.75 +/- 0.01%). They spent 41.62 +/- 0.006% in SWS and 10.12 +/- 0.02% in PS. The number of PS episodes was 32 +/- 0 with a mean duration of 2.28 +/- 0.01 min. Sleep cycle duration was 7.80 +/- 3.76 min. The ratio day/night sleep was 1.17 +/- 0.002 min. We found that the gerbil in captivity, unlike most rodents that are nocturnal, is a crepuscular animal, being more active at the transitions between light and dark.

Effects of delta sleep inducing peptide on sleep cycle of cats deprived of paradoxical sleep.

The effect of synthetic delta sleep inducing peptide (DSIP) on sleep was investigated in cat. DSIP (7 nmol/kg was administered intracerebroventricularly to cats deprived of paradoxical sleep (PS) for 72 h and immediately after termination of PS deprivation an injection of either Ringer or DSIP solution was given. Eight h of recovery sleep was then recorded. DSIP failed to affect the duration of slow-wave sleep, PS and total sleep time. There was, however, significant decrease of wakefulness and light slow-wave sleep (S1) while deep slow-wave sleep (S2) was significantly increased. There was also no change in the latency to the first episode of S2 sleep and PS. Thus, we conclude that DSIP altered the relative amounts of S1 and S2 sleep, causing more S2 (delta) sleep at the time when pressure for sleep was at its highest due to prior sleep deprivation.

Effects of dihydroergotoxine methane sulphonate (Redergine) on sleep in cats deprived of paradoxical sleep.

Dihydroergotoxine methane sulphonate (DHET 1.0 mg/kg i.p.) was administered to cats deprived of paradoxical sleep (PS) for 72 h and 23 h of recovery sleep were recorded. During the first 12 h of recovery sleep slow-wave sleep (SWS) was significantly increased. There were no significant changes in the amounts of wakefulness (W), PS and several sleep indices. Analysis of the entire 23 h of recording period revealed no significant changes in any of the parameters studied. The results suggest that DHET has SWS enhancing property in the condition where "pressure" for PS was increased.

Effects of repeated administrations of dihydroergotoxine (Redergine) on the sleep-wakefulness cycle in the cat.

Investigations with dihydroergotoxine methane sulfonate (DHET, the active substance of Redergine) indicate that DHET acts on the sleep-wakefulness cycle of the cat by increasing wakefulness and slow-wave sleep and decreasing rapid eye movement sleep. DHET was administered intraperitoneally at a dose of 1.0 mg/kg for 5 successive days. The effects were fairly stable, although with a tendency to diminish with time. Such alterations in the sleep-wakefulness cycle are discussed as possible indices of the beneficial effects seen in elderly patients treated with DHET.

Sleep-waking cycle and behaviour after diethyldithiocarbamate in the rat.

Young adult Louis rats were implanted for chronic sleep recording to test the effect of diethyldithiocarbamate (DDC) on sleep. Recordings of EEG and EMG were done continuously for 12 h during the 12 consecutive days. There were 2 days of baseline recording, 3 days of recording with a single daily injection of placebo, 3 days of recording with a single daily injection of DDC (500 mg/kg i.p.), and 3 days of DDC withdrawal recording with placebo injection. Placebo injections did not change the proportion of time spent in different behavioural states. With daily injection of DDC there was an increase in wakefulness, no change in slow-wave sleep and elimination or drastic reduction in paradoxical sleep (PS). There was no PS rebound during the DDC withdrawal days. These results suggest that the reduction of PS produced by DDC and the absence of PS rebound may be due to a lowering in norepinephrine in the brain. In other experiments rats were injected with DDC (500 mg/kg i.p.) daily for 3 days and whole brains were analysed chemically. Norepinephrine was significantly decreased, while 5-hydroxytryptamine, 5-hydroxyindolacetic acid, dopamine and homovanilic acid were unchanged. Seizure activity appeared during relaxed wakefulness in all rats treated with DDC. Taken together it seems that lowering of brain NE is responsible for the appearance of seizure activity and also, for PS reduction. PS reduction might, per se, produce seizure activity.

Effects of dihydroergotoxine (Redergine) on the sleep-wakefulness cycle in the cat.

Investigations with dihydroergotoxine (DHE 1.0; 3.0 and 5.0 mg/kg i.p.) indicate that DHE exerts effect on the sleep-wakefulness cycle of the cat. In doses of 3.0 and 5.0 mg/kg i.p. DHE has a suppressant effect on sleep, and in particular on REM sleep, while wakefulness was increased. With a dose of 1.0 mg/kg, wakefulness and REM sleep were decreased, while slow-wave sleep was increased.

Effects of clozapine (Leponex) on sleep patterns in the cat.

This study examined the effects of clozapine on sleep-wakefulness profile in cats prepared for chronic recording of sleep. Clozapine in single dose (i.p.) of 5 mg/kg drastically reduced slow-wave sleep (SWS) and paradoxical sleep (PS), while wakefulness and drowsy pattern were increased. These changes lasted approximately 24 h and were followed by sleep recovery. PS had a priority of recovery. Some similarities between clozapine effects on sleep in cat and human were mentioned.

Paradoxical sleep deprivation: effects on brain energy metabolism.

A study was made of brain nucleotides and glycolytic intermediates in paradoxical sleep (PS)-deprived and recovery-sleeping rats. It was observed that PS deprivation of 24 h produced a fall in glucose, glucose 6-phosphate and pyruvate in cerebral frontal lobes. After three hours of recovery sleep all values returned toward their predeprivational levels. In cerebellar hemispheres ATP was increased, while glucose 6-phosphate and pyruvate were decreased. After three hours of recovery sleep, glucose 6-phosphate was increased and pyruvate decreased, indicating restoration of glycogen and creatine phosphate respectively.