Biomedical subjects

Sergio Tufik

Publications and source records attributed to Sergio Tufik.

At least 55 records · Page 3Linked to original sources

PubMed2005

Noradrenergic system interacts with genital reflexes induced by cocaine in paradoxical sleep-deprived male rats.

Different doses of alpha-1, alpha-2, beta-1, and beta-2 adrenoceptor agonists or antagonists were administered to paradoxical sleep-deprived (PSD) rats prior to cocaine administration. Methoxamine reduced the percentage of rats displaying erection, whereas prazosin did not. Yohimbine significantly decreased this percentage. For beta-1 adrenoceptor drugs, both compounds reduced the percentage of rats displaying erection at the highest dose; beta-2 adrenoceptor drugs had no effect. Except for clonidine, all drugs significantly reduced the frequency of erection. Ejaculation was significantly decreased following yohimbine and beta-1 drugs, whereas it was completely abolished by prazosin. The results showed that noradrenergic drugs inhibited genital reflexes in PSD rats, with distinct responses in relation to their respective action over the adrenoceptor.

Adrenergic Agonists↗

PubMed2005

Cyclic alternating pattern in peripubertal children.

STUDY OBJECTIVES: The aim of this study is to complement the data on the expression and characteristics of cyclic alternating pattern (CAP) events in children, specifically in the peripubertal age group of 8 to 12 years and to analyze the association of CAP events with arousals. The study of CAP and arousal is a useful tool for assessing sleep instability and fragmentation in children. DESIGN: Descriptive study. PARTICIPANTS: Ten sex-matched healthy children, aged 8 to 12 years, underwent standard polysomnography after 1 adaptation night in the sleep laboratory. Sleep stages, CAP, and arousals were analyzed according to standard international rules. RESULTS: The mean CAP rate was 62.1% +/- 10.8% and the mean CAP cycle duration, 24.6 +/- 2.1 minutes. CAP A1 phase was the most numerous (85.5% +/- 3.9%), whereas the A2 phase was 9.1% +/- 4.7%, and the A3 phase as 5% +/- 2.3%, (P < .01). Differences between boys and girls were detected by analysis of variance, namely increases of phase A2 and A3 subtypes in girls (P < .001). Stronger phase A1 subtype expression in slow-wave sleep was verified in both sexes. Positive correlation between electroencephalogram arousals and the sum of phase A2 and A3 subtypes was also present. The overall CAP rate is higher in this age group than the rate previously reported in children aged 6 to 10 years (62.1% +/- 10.8% vs 33.4% +/- 5.3%). CONCLUSIONS: Our study provides normative data on CAP in children aged 8 to 12 years and indicates that age and Tanner stages must both be considered when investigating peripubertal children.

Child↗

PubMed2005

Head and neck physical examination: comparison between nonapneic and obstructive sleep apnea patients.

STUDY OBJECTIVES: The purpose of this study was to apply a systematic physical examination, used to evaluate obstructive sleep apnea (OSA) patients, in nonapneic patients. DESIGN: Study was prospective. SETTING: Patients were seen in the sleep laboratory and department of otorhinolaryngology. PATIENTS OR PARTICIPANTS: Nonapneic patients (n = 100) were involved in the study. INTERVENTIONS: Physical examination to evaluate facial skeleton, pharyngeal soft tissue, rhinoscopy, and body mass index. Data were compared with a previously published study (2003) on a group of OSA patients (n = 223). MEASUREMENTS AND RESULTS: Skeletal examination detected retrognathism in 6%, class II occlusion in 12%, and high-arched hard palate in 11%. The modified Mallampati classification showed 54% in class I to II and 46% in class III to IV. Only 1% of nonapneic patients had tonsils of degree III to IV. Oropharynx evaluation showed web palate in 38%, posterior palate in 19%, thick palate in 10%, thick uvula in 10%, long uvula 15%, voluminous lateral wall in 11%, and tongue edge crenations in 28%. Anterior rhinoscopy detected significant septal deviation in 1% and turbinate hypertrophy in 31% of patients. CONCLUSIONS: The head and neck physical examination, considering both skeletal and soft tissue alterations, illustrated significant differences between nonapneic and OSA patients. Body mass index, modified Mallampati classification, tonsils hypertrophy, and high-arched hard palate previously related to the presence of sleep apnea in the literature showed different outcomes in nonapneic patients. Nonapneic patients had less alterations in nasal anatomy (severe septal deviation and enlarged turbinate). Skeletal parameters, such as retropositioned mandible and angle class II occlusion, were less frequent in nonapneic patients.

Adolescent↗

PubMed2005

Endocrinological and catecholaminergic alterations during sleep deprivation and recovery in male rats.

Since previous data of our group showed increased concentrations in HPA axis hormones in sleep deprived rats, we hypothesized that this augmentation could produce effects in other hormonal systems, particularly in the sexual system. Considering that little is known about how the hormonal system changes during the recovery period after sleep deprivation (SD), our objective was to examine from what point SD alters sexual and stress-related hormones along with plasma catecholamine concentrations during 4 days. We also sought to verify the time course of their recovery after an equivalent period of recovery sleep. Rats were deprived of sleep by the platform technique for 1-4 days and were allowed to recover for the same period. Plasma catecholamines [dopamine (DA) and noradrenaline (NOR)], testosterone, estrone, progesterone, prolactin, corticosterone and adrenocorticotropic hormone (ACTH) concentrations were measured. Comparisons between groups showed that the SD procedure used in the present study produced marked alterations in almost all studied hormones from 24 h of SD, except for estrone and prolactin (which required 96 h of SD to become altered). Testosterone and estrone decreased, whereas progesterone, prolactin, corticosterone, ACTH, DA and NOR increased. During recovery period, progesterone, prolactin and corticosterone concentrations returned to control levels, whereas testosterone, estrone, NOR and DA did not. In addition, after 48 h of recovery ACTH and NOR decreased below control concentrations, remaining low until 96 h of sleep recovery. Thus, SD showed long lasting, differential effects upon these neurochemicals suggesting that each has its own pattern of responses to SD as well as variable periods of recovery.

Adrenocorticotropic Hormone↗

PubMed2005

Behavioral and histopathological analysis of domoic Acid administration in marmosets.

PURPOSE: To induce status epilepticus (SE) followed by the subsequent onset of spontaneous recurrent seizures, thus characterizing a new model of temporal lobe epilepsy in a nonhuman primate. METHODS: Male and female marmosets (Callithrix jacchus) (n = 18), ages between 2 and 8 years, were injected with domoic acid (0.5-4 mg/kg, i.p.) or saline, and behaviorally assessed with regard to the presence of acutely induced seizures and for < or = 6 months for spontaneous seizures. Injection of doses ranging from 3.5 to 4 mg/kg either did not induce SE or resulted in fatal SE. Even a 5-min SE duration (SE blockade resulting from diazepam injection) proved lethal to marmosets within 1 h of domoate administration, regardless of intensive care and monitoring of the animals. Animals injected with doses ranging from 0.5 to 3 mg/kg that developed only a few minor convulsive signs were allowed a 6-month survival period for the assessment of spontaneous epileptic events. At the end of the experiment, 6-month period, or acute intoxication associated with SE induction, animals were deeply anesthetized and had their brains subjected to histologic processing for Nissl and delta-FosB. RESULTS: For the animals injected with domoate that did not develop SE (i.e., those that survived), we could not detect any behavioral signs of spontaneous epileptic seizures in the 6-month observation period, and only minor indications of neuropathologic changes (i.e., neuronal death) over Nissl-stained sections, as well as some small changes in the staining for delta-FosB in a few of the animals. CONCLUSIONS: Systemic administration of domoic acid to marmosets is not effective for the generation of a model of chronic temporal lobe epilepsy. Administration of domoic acid at doses that do not lead to SE also did not lead to the development of temporal lobe epilepsy or clear-cut behavioral changes over a 6-month period.

Animals↗

PubMed2005

Consequences of prolonged caffeine administration and its withdrawal on pilocarpine- and kainate-induced seizures in rats.

PURPOSE: To investigate the consequences of caffeine consumption on epileptic seizures, we used the pilocarpine and the kainate models of epilepsy. We hypothesized that prolonged caffeine consumption or its withdrawal would alter adenosine levels and hence alter seizure susceptibility. METHODS: We administered a 0.1% caffeine solution in the drinking water of adult male Wistar rats over a 2-week period. We challenged another group of animals with the same doses of pilocarpine or kainate 12 h after the withdrawal of the same caffeine-administration protocol. RESULTS: This did not alter the threshold for the induction of seizures by a subconvulsant dose of pilocarpine (200 mg/kg, i.p.) or kainic acid (8 mg/kg, i.p.). Similarly, challenging another group of animals with the same doses of pilocarpine or kainate 12 h after the withdrawal of the same caffeine-administration protocol did not lead to any significant changes in seizures. CONCLUSIONS: With the pilocarpine model of epilepsy, we were not able to find any significant difference in seizure profile that could stem from either caffeine administration or its withdrawal. Despite the extensive laboratory evidence on the convulsant properties of xanthine derivatives in animal models of epilepsy, such strong evidence is lacking in clinical settings. Our current findings with the administration of caffeine at doses similar to those of daily life both support and confirm the clinical experience.

Adenosine↗

PubMed2005

Heart rate variability during sleep in patients with vasovagal syncope.

BACKGROUND: There are a few studies showing no significant heart rate variability (HRV) over a 24-hour period in vasovagal syncope (VVS) patients, but no research has examined HRV and its sympathetic and parasympathetic components during rapid eye movement (REM) and non-REM sleep. The authors hypothesized that REM sleep might be a critical state in which VVS patients would show abnormal responses. OBJECTIVES: To analyze the sympathetic and parasympathetic components of HRV during REM and SWS in patients with VVS compared to normal subjects, and in patients with positive HUTT compared to negative ones. METHODS: Thirty-seven VVS patients and 20 normal age-matched controls were submitted to polysomnography with 24-hour Holter monitoring to assess HRV. Time and frequency domain techniques were carefully performed for 24 hours and during Stages 3 and 4 of REM and non-REM sleep. Variation of sympathetic activity index (VSAI) was defined as the difference in the low frequency (LF) component of HRV between REM and Stages 3 and 4 of non-REM sleep. An analysis of variance was performed to compare patients and controls; patients with positive and negative head-up tilt testing. RESULTS: The LF component was lower in syncope compared to normal patients (1,769.54 +/- 1,738.17, 3,225.37 +/- 2,585.05, respectively, P = 0.03). There was a significant decrease in VSAI in the syncope group compared to the control group (-539.39 +/- 1,930.78, 1,268.10 +/- 2,420.20, respectively, P = 0.01). The other sleep variables analyzed including very LF, high frequency, low frequency/high frequency and time domain parameters did not reach statistical significance. Syncope patients also showed an increase in slow wave sleep (28.2 +/- 10.5, 19.7 +/- 7.8, P = 0.01). CONCLUSIONS: VVS patients exhibited sympathetic suppression during REM sleep. Possible mechanisms are discussed in this article.

Adolescent↗

PubMed2005

Association of the length polymorphism in the human Per3 gene with the delayed sleep-phase syndrome: does latitude have an influence upon it?

STUDY OBJECTIVES: The objective of this study is to analyze the influence of a previously reported hPer3 gene-length polymorphism in the delayed sleep-phase syndrome and in morningness-eveningness tendencies at low latitudes in the southern hemisphere. DESIGN: We have genotyped a length polymorphism in the hPer3 gene characterized by a short repeat allele (4-repeat) and a long repeat allele (5-repeat). PARTICIPANTS: Seventeen patients with delayed sleep-phase syndrome; 156 volunteers chosen according to Horne-Ostberg questionnaire to have morning, intermediate, or evening preference; and 110 volunteers with no Horne-Ostberg score as a sample of the general population. RESULTS: We have found a higher frequency of 5-repeat allele in the delayed sleep-phase syndrome group and an association of this polymorphism with diurnal preference. CONCLUSION: Our results suggest that latitude has a role in the influence of hPer3 gene polymorphism on delayed sleep-phase syndrome and confirm previous data showing its association with morningness-eveningness tendencies.

Adult↗

PubMed2004

Acute cocaine effects in paradoxical sleep deprived male rats.

Cocaine is a psychomotor drug known to cause behavioural alterations. This study was conducted to characterize behavioural response to acute cocaine injection (7 mg/kg, ip) in paradoxical sleep deprived (PSD) male rats since sleep deprivation is also associated with several behavioural alterations. Cocaine or vehicle was administered to rats at the end of a 4-day period of sleep deprivation, and in home-cage control animals. Cocaine administration in control and PSD rats induced a significant increase in stereotyped behaviour in relation to saline-injected rats. PSD induced significant but heterogeneous effects in animals by increasing grooming while it had effect neither on stereotyped behaviours, locomotion nor on anxiety-like behaviours but significantly decreased rearing behaviour. PSD potentiates the action of cocaine on stereotyped behaviours suggesting supersensitivity of dopaminergic receptors. Thus, the present study indicated that the behavioural effects of cocaine could be modified by PSD. This in turn may have relevant implications in the cocaine effect in abusers under sleep deprived condition.

Analysis of Variance↗

PubMed2004

Involvement of dopamine receptors in cocaine-induced genital reflexes after paradoxical sleep deprivation.

Previous work has demonstrated that paradoxical sleep deprivation (PSD) potentiates cocaine-induced genital reflexes in male rats. To examine the possibility that this effect might involve alterations in binding to the DA transporter (DAT), we examined [3H] WIN 35,248 binding in brain after 96 h of PSD. No changes were found in any of the 11 brain regions examined. Since we had previously identified changes in D2 receptor binding after PSD, we next examined the effects of DA receptor subtype antagonists on cocaine-induced reflexes in sleep-deprived rats. Separate groups of PSD rats received saline, haloperidol (0.4, 0.8 or 1.6 mg/kg), SCH 23390 (0.25, 0.5, 1 mg/kg) or sulpiride (50, 100, 200 mg/kg) 60 min prior to acute cocaine (7 mg/kg). In saline pretreated rats, cocaine-induced penile erection (PE) in 100% of SD rats. This percentage was not significantly reduced by haloperidol at any dose, but was significantly reduced in rats pretreated with SCH 23390 (1 mg/kg) or sulpiride (100 or 200 mg/kg). In addition, acute cocaine-induced ejaculation in 80% of SD rats. This effect was not affected by haloperidol at any dose, but was significantly reduced by all doses of SCH 23390 and by the 200 mg/kg dose of sulpiride. These results suggest that the potentiating effects of cocaine on penile erection and ejaculation are likely due to PSD-induced changes in DA postsynaptic receptor sensitivity rather than alterations in DA transporter. They further suggest that both D1 and D2 receptors may play a role in these effects.

Analysis of Variance↗

PubMed2004

Distinct effects of sleep deprivation on binding to norepinephrine and serotonin transporters in rat brain.

There is evidence to suggest that the antidepressant activity of sleep deprivation may be due to an enhancement of serotonergic and/or noradrenergic neurotransmission in brain. In the present study we examined the possibility that such changes may occur at the level of the norepinephrine (NET) and serotonin (SERT) and transporters. Rats were deprived of sleep for 96 h using the modified multiple platform method and then sacrificed for autoradiographic assessments of NET and SERT binding throughout the brain. [3H]Nisoxetine binding to the NE transporter was generally decreased in 44 of 45 areas examined, with significant reductions occurring in the anterior cingulate cortex (-16%), endopiriform n. (-18%), anterior olfactory n. (-19%), glomerular layer of olfactory bulb (-18%), ventral pallidum (-14%), medial preoptic area (-16%), retrochiasmatic/arcuate hypothalamus (-18%), anteromedial thalamic n. (-15%), and rostral raphe (-17%). In contrast, SERT binding measured with [11C]DASB showed no clear directional trends in 61 brain areas examined, but was significantly reduced in subdivisions of the anterior olfactory nucleus (-22%) and substantia nigra (-18%). Thus, sleep deprivation induced widespread decreases in NET binding, and fewer and well-localized decreases in SERT binding. Significant down-regulation in one brain region, the anterior olfactory nucleus, was observed in the case of both transporters. These results suggest that mechanisms involved in the antidepressant action of sleep deprivation may involve generalized NET down-regulation as well as decreased SERT binding in specific areas. Insofar as these changes may be associated with increased levels of serotonin (5-HT) and norepinephrine (NE) in the synapse, they suggest that sleep deprivation may share some basic mechanisms of action with several current antidepressant medications.

Animals↗

PubMed2004

The effects of dopaminergic agonists on genital reflexes in paradoxical sleep-deprived male rats.

Dopamine (DA) agonists provide evidence that different receptor subtypes in the central nervous system (CNS) have influence in sexual behavior. Sleep deprivation induces supersensibility of DA receptors and previous work has shown that the DA agonist apomorphine enhances spontaneous genital reflexes (penile erection-PE and ejaculation-EJ) in rats deprived of paradoxical sleep. The present study sought to extend the latter finding by assessing the effects of other DA agonists in paradoxical sleep-deprived (PSD) male rats. The DA drugs (bromocriptine and piribedil) were acutely administered to rats that had been deprived of sleep for 4 days and to normal controls. Sleep deprivation alone induced PE and this effect was potentiated by piribedil, with maximal effects occurring with the 8 mg/kg dose, whereas only one dose of bromocriptine (8 mg/kg) induced more PE in PSD rats than in non-deprived treated controls. EJs were increased in piribedil PSD groups but this response was absent after bromocriptine treatment in the dose range tested. Our data show the genital reflexes that occurred in PSD rats are potentialized by piribedil and not by bromocriptine. These DA agonists showed distinct effects in sexual response suggesting that these effects are probably due to PSD-induced DA receptor supersensitivity even though different mechanisms are involved.

Analysis of Variance↗

PubMed2004

Diurnal variation in the genital reflexes and hormone levels induced by paradoxical sleep deprivation and cocaine in male rats.

The purpose was to ascertain whether the genital reflexes induced by paradoxical sleep deprivation (PSD) in male rats show diurnal variation, and whether the hormonal rhythm of testosterone and progesterone is involved in these behaviors. Genital reflexes (penile erection -- PE, and ejaculation -- EJ) and hormone levels were assessed during a 24 h period at four testing times (0900, 1600, 2100 and 0400 h) in PSD rats injected with saline or cocaine. Results indicated that PE in PSD rats given saline or cocaine did not show diurnal variation while EJ responses were significantly reduced at 0400 h in the PSD-cocaine group. The home-cage control group testosterone concentrations were lower at 1600, 2100 and 0400 h than at 0900 h. At 0900 h, testosterone levels were significantly lower in the PSD groups than in the control group. In contrast, progesterone levels were significantly higher in PSD groups in relation to the control group at the four testing times. Thus, we observed strong diurnal variation in testosterone and progesterone in control rats whereas only EJ responses in PSD-cocaine seemed to be influenced by the time of day. These results suggest that progesterone may influence the modulation of male genital reflexes displayed by sleep-deprived rats.

Animals↗

PubMed2004

Different criteria of sleep latency and the effect of melatonin on sleep consolidation.

OBJECTIVES: Since there is no consensus definition of sleep onset, we studied different aspects of initial sleep periods in healthy volunteers taking melatonin. Two criteria for sleep latency were used: 10 minutes of uninterrupted sleep and 1.5 minutes of stage 1 sleep. PARTICIPANTS: Forty healthy male volunteers (mean age 28 +/- 5 years) were assigned to 2 groups: 30 ingested melatonin and 10 placebo. DESIGN: All volunteers underwent an initial polysomnogram (baseline) after a 1-night adaptation period. The next day, the placebo or a 10-mg dose of melatonin was administered for 28 days, 1 hour before sleep time, in double-blind fashion. The second polysomnogram was recorded on day 14. SETTING: Sleep laboratory RESULTS: Chronic melatonin administration led to a significant reduction in sleep latency, using only the criterion 10 minutes of uninterrupted sleep. This effect suggests that melatonin may have a hypnotic effect, and the use of melatonin may lead to better sleep consolidation. CONCLUSIONS: These results show differences that have clinical implications, since the criteria used to diagnose initial insomnia were based on sleep onset.

Adaptation, Physiological↗

PubMed2004

Effects of maternal separation on baseline sleep and cold stress-induced sleep rebound in adult Wistar rats.

STUDY OBJECTIVES: To evaluate the influence of early life environments on basal and cold stress-induced sleep patterns in rats. DESIGN: The design was a 3 (Groups [control, early handling, maternal separation]) x 2 (Situations [basal, poststress]) x 11 (Time-blocks) factorial design. From postnatal days 2 to 14, whole litters were either submitted to early handling (15 minutes per day away from the mother) or maternal separation (180 minutes per day away from the mother). At 75 to 90 days of age, sleep was recorded for 22 hours (beginning at 9:00 AM) before and after 1 hour of cold stress (4 degrees C). SUBJECTS: Wistar male rats (n = 7-10 animals per group). MEASUREMENTS AND RESULTS: Sleep was analyzed in blocks of 2 hours, in 30-second epochs, separately in the daytime and nighttime sleep recordings. Maternally separated rats exhibited more paradoxical sleep at baseline, compared to both control and early-handled rats. In the first 2 hours following the end of cold stress, all groups showed a decrease in paradoxical sleep, whereas slow-wave sleep was reduced only in the control group. The highest corticosterone plasma concentration was observed immediately after stress. Sleep rebound after stress was equally manifested in all groups in the dark part of the light-dark cycle. CONCLUSIONS: Maternal separation during early infancy resulted in permanent changes of the sleep architecture reflected by augmented time spent in paradoxical sleep. Although these findings were not expected in light of the literature, they emphasize the importance of the early familiar environment on future behavior of rats.

Animals↗

PubMed2004

Occurrence of limb movement during sleep in rats with spinal cord injury.

Several studies have shown the occurrence of Periodic Leg Movement (PLM) in spinal cord injury patients. The aim of this study was to identify the occurrence of limb movements during sleep in spinal cord injury rats and the possible involvement of the spinal cord in causing these movements. The animals were allocated to spinal cord injury (SCI) and SHAM groups. The two groups were submitted to surgery and electrodes inserted to analyze sleep patterns (electroencephalogram-ECoG) and muscular activity patterns (eletromyogram-EMG). After baseline sleep recording (24 h), the spinal cord injury surgery (level T9) was performed on the SCI group rats and sleep was recorded for seven consecutive days. After spinal cord injury, 10 of the 11 rats began to present limb movements during sleep, while the SHAM group showed no limb movements during the 8-day sleep-recording period. In relation to sleep efficiency, the SCI group presented alterations during the first few days after spinal cord injury but returned to normal values at the end of the 7-day experimental period. The data suggest that spinal cord injury rats may be used as models to study PLM in paraplegic patients, and that these movements may be generated in the spinal cord itself, without the involvement of the cortical structures.

Animals↗

PubMed2004

Anxiogenic effect of sleep deprivation in the elevated plus-maze test in mice.

RATIONALE: Several clinical studies demonstrate that the absence of periods of sleep is closely related to occurrence of anxiety symptoms. However, the basis of these interactions is poorly understood. Studies performed with animal models of sleep deprivation and anxiety would be helpful in the understanding of the mechanisms underlying this relationship, but some animal studies have not corroborated clinical data, reporting anxiolytic effects of sleep deprivation. OBJECTIVES: The aim of the present study was to verify the effects of different protocols of sleep deprivation in mice tested in the elevated plus-maze and to assess the effect of chlordiazepoxide and clonidine. METHODS: Three-month-old male mice were sleep-deprived for 24 or 72 h using the methods of single or multiple platforms in water tanks. Mice kept in their home cages were used as controls. Plus-maze behavior was observed immediately after the deprivation period. RESULTS: Mice that were sleep-deprived for 72 h spent a lower percent time in the open arms of the apparatus than control animals. This sleep deprivation-induced anxiety-like behavior was unaffected by treatment with chlordiazepoxide (5.0 and 7.5 mg/kg IP), but reversed by an administration of 5 or 10 microg/kg IP clonidine. CONCLUSION: The results indicate that under specific methodological conditions sleep deprivation causes an increase in anxiety-like behavior in mice exposed to the elevated plus-maze.

Animals↗

PubMed2004

Sleep deprivation induced by the modified multiple platform technique: quantification of sleep loss and recovery.

Vigilance status was continually monitored in socially stable groups of rats exposed to the modified multiple platform (MMP) technique for sleep deprivation. For comparison, sleep parameters were also monitored in socially isolated rats deprived of sleep by the single platform (SP) method. In all cases, sleep was continuously recorded during baseline, during 96 h of sleep deprivation and during 4 days of recovery. Both multiple- and single-platform techniques completely abolished paradoxical sleep (PS) during the deprivation period, but also resulted in significant decreases in slow wave sleep (SWS) (-31% and -37%, respectively). Unexpectedly, animals on large platforms, which are normally intended as controls, also showed significant reductions in PS and SWS, and these effects were more pronounced in rats deprived in groups than in animals deprived in isolation. Another control preparation, rats placed on wire-mesh grids in the deprivation tank, also showed PS reduction (-39%) but no loss of SWS during the 4 test days. Paradoxical sleep rebound was observed in the first 24 h in all groups, except for grid controls. Overall, no significant differences were found between single- and multiple-platform procedures during the 4 days of deprivation. However, sleep rebound was more pronounced in MMP-deprived rats than in SP-deprived rats. Sleep loss in both control groups may reflect residual effect of stress that remain in the platform technique. These findings indicate that the MMP technique is effective in inducing PS deprivation (PSD). However, the fact that SWS is also affected may have implications for conclusions on paradoxical sleep function based upon paradoxical sleep deprivation.

Animals↗