Reversal of the increase in apomorphine-induced stereotypy and aggression in REM sleep deprived rats by dopamine agonist pretreatments

Insomnia Complaints and Perceived Immune Fitness in Young Adults with and without Self-Reported Impaired Wound Healing

Background and Objectives: Adequate sleep and an effective immune system are both essential to maintain a good health status. The current study aimed to determine the nature of insomnia complaints and perceived immune fitness among Dutch young adults with and without self-reported impaired wound healing. Materials and Methods: A total of (n = 2033) Dutch students (83.8% women) completed an online survey. Perceived immune fitness was assessed with a single-item scale and insomnia complaints with the SLEEP-50 insomnia subscale. The sample comprised a control group without self-reported impaired wound healing (n = 1622), a wound infection (WI) group (n = 69), a slow healing wounds (SHW) group (n = 250), and a COMBI group that experienced both WI and SHW (n = 92). Results: Comparisons with the control group revealed that individuals of the SHW and COMBI groups reported significantly poorer perceived immune functioning, increased insomnia complaints and daytime fatigue, and poorer sleep quality. Conclusions: Individuals with self-reported impaired wound healing have a poorer perceived immune functioning, increased insomnia complaints, daytime fatigue, and poorer sleep quality.

Maternal sleep deprivation affects extinction and reinstatement of methamphetamine reward memory in male offspring: role of the D1-like and D2-like dopamine receptors

Maternal sleep-deprivation (MSD) has been shown to induce stress, hyperactivity, and risk taking behavior in the offspring; howbeit, it is not yet clear whether it may also affect vulnerability to psychostimulant abuse in the offspring. We aimed to determine whether MSD affects extinction and reinstatement of methamphetamine (METH) reward memory in the offspring and also to evaluate the possible role of dopamine D1-like and D2-like receptors in these processes. Thirty-day-old male offspring born to control and sleep-deprived dams (during the third week of pregnancy) were trained to acquire METH-induced place preference (2 mg/kg., i.p.). METH reward memory was then reinstated following an 8-day period of extinction. The offspring received SCH 23390 (0.03 or 0.1 mg/kg, i.p.) or sulpiride (20 or 60 mg/kg, i.p.) as antagonists of dopamine D1-like and D2-like receptors, respectively, either immediately after each daily extinction session or prior to the reinstatement session. MSD postponed METH extinction and facilitated METH reinstatement in the offspring. SCH 23390 facilitated METH extinction and decreased reinstatement of the extinguished METH preference. Sulpiride in the offspring from sleep-deprived dams facilitated METH extinction, but it did not affect reinstatement of the extinguished METH place preference. It seems that MSD may enhance vulnerability to METH abuse in the offspring. Furthermore, both dopamine D1-like and D2-like receptors may mediate METH extinction in the offspring born to the sleep-deprived dams; however, only the dopamine D1 receptor may play an important role in reinstating the extinguished METH reward memory in the offspring.

REM sleep deprivation before extinction or reinstatement alters methamphetamine reward memory via D1-like dopamine receptors

We aimed to determine whether REM sleep deprivation (RSD) affects extinction and reinstatement of methamphetamine (METH) reward memory in male rats and also to evaluate the possible role of dopamine D1-like and D2-like dopamine (DA) receptors in these processes. Male rats were trained to acquire METH-induced place preference (2 mg/kg, i.p.). METH reward memory was then reinstated following a 10-day extinction period. The animals underwent a 72-hour sleep deprivation episode by multiple platforms method (in separate groups), either before the extraction or before the reinstatement of METH reward memory. The animals received SCH 23390 (0.01 or 0.05 mg/kg, i.p.) or sulpiride (20 or 60 mg/kg, i.p.) as antagonists of D1-like and D2-like DA receptors, respectively, either immediately following each daily extinction session or before the reinstatement of METH-seeking behavior. The RSD episode postponed extinction and facilitated reinstatement of METH reward memory. Administration of SCH 23390, but not sulpiride, facilitated METH extinction and decreased reinstatement of the extinguished METH-seeking behavior. Moreover, locomotor activity was not affected by METH and/or the RSD paradigm. The results would seem to suggest that the D1-like, but not the D2-like, DA receptors may be involved in the extinction and reinstatement of the extinguished METH reward memory in RSD animals. Nonetheless, more investigations are needed to elucidate the exact mechanisms involved.

REM sleep deprivation impairs retrieval, but not reconsolidation, of methamphetamine reward memory in male rats

Susceptibility to interference can be a result of memory retrieval and reconsolidation. Given the fact that addiction develops through the neural mechanisms of learning and memory, it would not be surprising that a consolidated drug reward memory may also be susceptible to interference following retrieval/reconsolidation. Due to the critical role of sleep in memory consolidation, sleep deprivation (SD) has been shown to impair memory. Therefore, the major objective of this study was to investigate the effect of rapid eye movement (REM) sleep deprivation (RSD) on the retrieval and reconsolidation of methamphetamine (METH) reward memory in male rats. The animals were trained to acquire METH-induced CPP (2 mg/kg, i.p.). METH reward memory was then reactivated/retrieved in the drug-paired chamber during a drug-free (memory reactivation) session. A period of 48-h RSD paradigm using the multiple platform technique resulted in persistent deficits in the retrieval of METH reward memory. Nevertheless, the same protocol of RSD, which was conducted immediately after the memory reactivation, did not affect the reconsolidation of METH reward memory. Additionally, the RSD episode induced a temporary potentiation of METH-induced hyperlocomotion. Our findings would seem to suggest that sleep is involved in the retrieval, but not reconsolidation, of METH reward memory. The results may also demonstrate that RSD mimics the effects of METH on locomotor activity. The results of this study, therefore, support the idea that sleep is involved in the processing of METH reward memory which can be considered for further investigations to manage the relapse associated with drug-related memory.

The effects of paradoxical sleep deprivation on amphetamine-induced behavioral sensitization in adult and adolescent mice

Drug-induced behavioral sensitization (BS), paradoxical sleep deprivation (PSD) and adolescence in rodents are associated with changes in the mesolimbic dopaminergic system. We compared the effects of PSD on amphetamine-induced BS in adult and adolescent mice. Adult (90 days old) and adolescent (45 days old) Swiss mice were subjected to PSD for 48h. Immediately after PSD, mice received saline or 2.0mg/kg amphetamine intraperitoneally (i.p.), and their locomotion was quantified in activity chambers. Seven days later, all the animals were challenged with 2.0mg/kg amphetamine i.p., and their locomotion was quantified again. Acute amphetamine enhanced locomotion in both adult and adolescent mice, but BS was observed only in adolescent mice. Immediately after its termination, PSD decreased locomotion of both saline- and amphetamine-treated adolescent mice. Seven days later, previous PSD potentiated both the acute stimulatory effect of amphetamine and its sensitization in adolescent mice. In adult animals, previous PSD revealed BS. Our data suggest that adolescent mice are more vulnerable to both the immediate and long-term effects of PSD on amphetamine-induced locomotion. Because drug-induced BS in rodents shares neuroplastic changes with drug craving in humans, our findings also suggest that both adolescence and PSD could facilitate craving-related mechanisms in amphetamine abuse.

Does sleep deprivation and morphine influence wound healing?

The contrast between present-day sleep habits and those of the pre-industrial era are quite evident. One study recent has shown that the amount of sleep has decreased 2 h per night over the past 50 years. Such sleep curtailment, ubiquitous in the modern lifestyle, inflicts adverse repercussions upon health and well being. Investigations examining the relationship between stress and the skin have shown that different types of stress affect the healing process. Morphine is an immunosuppressive drug, and when it is used chronically, it can lead to an increased incidence of infections and a delay in the healing process. Therefore, our hypothesis is that the lack of sleep associated with chronic treatment with morphine is detrimental to the healing of the skin in the animal model we have adopted. Thus, it is important that future studies consider the paradigm of sleep curtailment when investigating the mechanisms involved in the process of skin healing in individuals who are dependent on morphine.

Sleep deprivation amplifies reactivity of brain reward networks, biasing the appraisal of positive emotional experiences

Appropriate interpretation of pleasurable, rewarding experiences favors decisions that enhance survival. Conversely, dysfunctional affective brain processing can lead to life-threatening risk behaviors (e.g., addiction) and emotion imbalance (e.g., mood disorders). The state of sleep deprivation continues to be associated with maladaptive emotional regulation, leading to exaggerated neural and behavioral reactivity to negative, aversive experiences. However, such detrimental consequences are paradoxically aligned with the perplexing antidepressant benefit of sleep deprivation, elevating mood in a proportion of patients with major depression. Nevertheless, it remains unknown how sleep loss alters the dynamics of brain and behavioral reactivity to rewarding, positive emotional experiences. Using functional magnetic resonance imaging (fMRI), here we demonstrate that sleep deprivation amplifies reactivity throughout human mesolimbic reward brain networks in response to pleasure-evoking stimuli. In addition, this amplified reactivity was associated with enhanced connectivity in early primary visual processing pathways and extended limbic regions, yet with a reduction in coupling with medial frontal and orbitofrontal regions. These neural changes were accompanied by a biased increase in the number of emotional stimuli judged as pleasant in the sleep-deprived group, the extent of which exclusively correlated with activity in mesolimbic regions. Together, these data support a view that sleep deprivation not only is associated with enhanced reactivity toward negative stimuli, but imposes a bidirectional nature of affective imbalance, associated with amplified reward-relevant reactivity toward pleasure-evoking stimuli also. Such findings may offer a neural foundation on which to consider interactions between sleep loss and emotional reactivity in a variety of clinical mood disorders.

Effects of sleep deprivation on memory in mice: role of state-dependent learning

STUDY OBJECTIVES

A considerable amount of experimental evidence suggests that sleep plays a critical role in learning/memory processes. In addition to paradoxical sleep, slow wave sleep is also reported to be involved in the consolidation process of memories. Additionally, sleep deprivation can induce other behavioral modifications, such as emotionality and alternations in locomotor activity in rodents. These sleep deprivation-induced alterations in the behavioral state of animals could produce state-dependent learning and contribute, at least in part, to the amnestic effects of sleep deprivation. The aim of the present study was to examine the participation of state-dependent learning during memory impairment induced by either paradoxical sleep deprivation (PSD) or total sleep deprivation (TSD) in mice submitted to the plus-maze discriminative avoidance or to the passive avoidance task.

DESIGN

Paradoxical sleep deprivation (by the multiple platform method) and total sleep deprivation (by the gentle handling method) were applied to animals before training and/or testing.

CONCLUSIONS

Whereas pre-training or pre-test PSD impaired retrieval in both memory models, pre-training plus pre-test PSD counteracted this impairment. For TSD, pre-training, pre-test, and pre-training plus pre-test TSD impaired retrieval in both models. Our data demonstrate that PSD- (but not TSD-) memory deficits are critically related to state-dependent learning.

Paradoxical sleep deprivation: neurochemical, hormonal and behavioral alterations. Evidence from 30 years of research

Sleep comprises approximately one-third of a person's lifetime, but its impact on health and medical conditions remains partially unrecognized. The prevalence of sleep disorders is increasing in modern societies, with significant repercussions on people's well-being. This article reviews past and current literature on the paradoxical sleep deprivation method as well as data on its consequences to animals, ranging from behavioral changes to alterations in the gene expression. More specifically, we highlight relevant experimental studies and our group's contribution over the last three decades.

Neuroleptic drugs revert the contextual fear conditioning deficit presented by spontaneously hypertensive rats: a potential animal model of emotional context processing in schizophrenia?

Schizophrenia, bipolar disorder, and attention deficit/hyperactivity disorder (ADHD) present abnormalities in emotion processing. A previous study showed that the spontaneously hypertensive rats (SHR), a putative animal model of ADHD, present reduced contextual fear conditioning (CFC). The aim of the present study was to characterize the deficit in CFC presented by SHR. Adult male normotensive Wistar rats and SHR were submitted to the CFC task. Sensitivity of the animals to the shock and the CFC performance after repeated exposure to the task were investigated. Pharmacological characterization consisted in the evaluation of the effects of the following drugs administered previously to the acquisition of the CFC: pentylenetetrazole (anxiogenic) and chlordiazepoxide (anxiolytic); methylphenidate and amphetamine (used for ADHD); lamotrigine, carbamazepine, and valproic acid (mood stabilizers); haloperidol, ziprasidone, risperidone, amisulpride, and clozapine (neuroleptic drugs); metoclopramide and SCH 23390 (dopamine antagonists without antipsychotic properties); and ketamine (a psychotomimmetic). The effects of paradoxical sleep deprivation (that worsens psychotic symptoms) and the performance in a latent inhibition protocol (an animal model of schizophrenia) were also verified. No differences in the sensitivity to the shock were observed. The repeated exposure to the CFC task did not modify the deficit in CFC presented by SHR. Considering pharmacological treatments, only the neuroleptic drugs reversed this deficit. This deficit was potentiated by proschizophrenia manipulations. Finally, a deficit in latent inhibition was also presented by SHR. These findings suggest that the deficit in CFC presented by SHR could be a useful animal model to study abnormalities in emotional context processing related to schizophrenia.

Prenatal nicotine exposure changes natural and drug-induced reinforcement in adolescent male rats

Clinical studies have demonstrated an increased incidence of substance misuse and obesity in adolescents whose mothers smoked during pregnancy. Although dopamine systems that mediate natural and drug-induced reinforcement have been shown in animal studies to be altered by gestational nicotine treatment, it is not clear whether there are concomitant changes in reinforcement sensitivity. To test whether prenatal nicotine exposure influences sensitivity to natural and drug rewards, timed pregnant rats were implanted with osmotic minipumps delivering saline or nicotine (3 mg/kg/day) from gestational day 4 to 18. Male offspring were tested as adolescents, on postnatal day 32, for operant responding maintained by sucrose pellets or i.v. cocaine (200 or 500 mug/kg per injection). Cocaine-induced stereotypy and c-fos mRNA expression in cortex and striatum were also examined. Complex changes in reward circuitry were observed in the offspring of nicotine-exposed dams. Nicotine-exposed adolescents did not self-administer the low dose of cocaine, but, at the higher dose, exhibited significantly greater cocaine intake and c-fos mRNA expression in nucleus accumbens than did controls. In contrast, control animals showed significantly greater drug-induced stereotypy at both cocaine doses. Operant responding maintained by sucrose was also influenced by gestational nicotine exposure. At a fixed ratio (FR) 1 schedule, although the number of pellets eaten by the two experimental groups was equivalent, more pellets were left uneaten by nicotine-exposed offspring. At FR2 and FR5 schedules, the responding maintained by sucrose pellets was lower in nicotine-exposed offspring. These findings suggest that nicotine exposure during gestation may induce changes in both natural and drug reward pathways.

Privação de sono e exercício físico

A privação do sono é a remoção ou supressão parcial do sono, e esta condição pode causar diversas alterações: endócrinas, metabólicas, físicas, cognitivas, neurais e modificações na arquitetura do sono, que em conjunto comprometem a saúde e a qualidade de vida do sujeito nestas condições. Já o exercício físico praticado regularmente promove benefícios como melhora do aparato cardiovascular, respiratório, endócrino, muscular e humoral, além disso, pode melhorar a qualidade do sono. Entretanto, a associação desses dois parâmetros não tem sido bem explorada, em parte pela dificuldade conseguir voluntários que se submetam a essa condição principalmente sem nenhum tipo de compensação financeira. A maioria dos estudos que investigaram o binômio exercício físico e privação de sono focou os efeitos no desempenho aeróbio. Embora ainda haja controvérsias, os estudos apontam para pequena ou nenhuma alteração desse parâmetro quando as duas situações se fazem presentes. Em relação à potência anaeróbia e força não tem sido encontrados alterações significativas, mas para eventos prolongados, parece haver uma interação entre a privação de sono e o exercício físico, o que sugere um mecanismo de proteção. Entretanto, é importante considerar que uma das alterações mais importantes causadas pela privação do sono é o aumento na percepção subjetiva, que por si só já representa um fator para diminuição e comprometimento do desempenho físico e pode representar um elemento de "mascaramento" dos efeitos deletérios da privação. Assim, o objetivo da presente revisão é o de discutir os diferentes aspectos da relação entre o exercício físico e a privação de sono, evidenciando seus efeitos e reflexos no desempenho físico.

Sleep deprivation-induced gnawing—relationship to changes in feeding behavior in rats

We have recently reported that food spillage increases during sleep deprivation in rats, which may lead to an overestimation of food intake in this condition. The objective of this study was to verify whether sleep deprivation induces an increase in gnawing behavior that could account for increased food spillage and apparent increase in food intake. We introduced wood blocks as objects for gnawing and determined the effects of their availability on food consumption and food spillage during sleep deprivation. Wood block availability reduced the amount of food removed from hoppers and decreased the amount of food spilled. However, weight loss still occurred during the sleep deprivation period, especially in the first 24 h, and it was related to a reduction in food intake. Sleep deprivation causes an increase in stereotyped gnawing behavior which largely accounts for increased food spillage observed during deprivation. Specifically, the observed increase in food removed from feeders seems to be due to an increase in gnawing and not to increased hunger. However, even when appropriately corrected for spillage, food intake decreased in the first 24 h of sleep deprivation, which accounted for most of the body weight loss seen during the 96 h of sleep deprivation.

Effects of environmental enrichment and paradoxical sleep deprivation on open-field behavior of amphetamine-treated mice

BACKGROUND

Environmental enrichment or paradoxical sleep deprivation (PSD) has been shown to modify some responses elicited by drugs of abuse. The aims of the present study were to examine the effects of environmental enrichment and PSD, conducted separately or in association, on open-field behavior elicited by amphetamine (AMP) in mice.

METHODS

Male C57BL/6 mice were randomly assigned to live in either an enriched environmental condition (EC) or a standard environmental condition (SC) for 12 months since weaning. Some of the EC and SC mice were sleep deprived for 48 h, while others were maintained in their home-cages. Immediately after PSD or home-cage stay, the animals received an ip injection of saline, 2.5 mg/kg AMP or 5.0 mg/kg AMP. Fifteen minutes later, their open-field behavior was quantified.

RESULTS

Whereas PSD enhanced total and peripheral locomotor activity of acutely AMP-treated mice, environmental enrichment presented only a trend toward enhancement. When PSD and environmental enrichment were combined, an increase in the total and peripheral locomotion frequencies of AMP-treated animals, similar to that observed after PSD, was revealed. In addition, PSD, environmental enrichment or their combination did not modify the effects of AMP on the other open-field behavioral parameters that were analyzed.

CONCLUSION

The present findings demonstrate that some (but not all) of the behavioral effects caused by AMP acute administration can be similarly and specifically enhanced by both environmental enrichment and PSD in C57BL/6 mice.

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.

The effect of venlafaxine on behaviour, body weight and striatal monoamine levels on sleep-deprived female rats

Partial sleep deprivation is clinically associated with fatigue, depressive symptoms and reduced memory. Previously, it has been demonstrated that venlafaxine, an atypical antidepressant, increases the levels of noradrenaline and serotonin in rat hippocampus. The aim of this study was to evaluate the effects of venlafaxine on depression, anxiety, locomotor activity and memory in a model of REM sleep (REMs) deprivation in rats. We have also studied the influence of venlafaxine on monoamine levels in the striatum. Six groups of animals (N=20 each) were treated with saline or venlafaxine (1 or 10 mg/kg) during 10 days, submitted or not to REMs deprivation and studied with the forced swimming test of Porsolt (STP), plus-maze, passive avoidance and open-field tests right after sleep deprivation. Animals were also studied for passive avoidance 24 h later (rebound period). Brain samples for monoamine measurements were collected either immediately after REMs deprivation or after 24 h. Both REMs deprivation and venlafaxine showed an antidepressant effect. An anxiolytic effect was also observed after REMs deprivation. Previous treatment with venlafaxine blocked the antidepressant and anxiolytic effects of REMs deprivation. REMs deprivation alone and treatment with venlafaxine 10 mg/kg increased locomotor activity, and this effect was inhibited by venlafaxine in REMs deprived rats. Both venlafaxine treatment and REMs deprivation induced weight loss. Venlafaxine treatment, but not REMs deprivation, induced an increase in striatal dopamine (DA) levels. The combination of REMs deprivation and venlafaxine treatment was associated with an increase in serotonin turnover 24 h after rebound sleep. In this study, venlafaxine treatment hindered most behavioral effects of REMs deprivation and was associated with an interference on dopamine and serotonin systems in the striatum.

Paradoxical sleep deprivation potentiates amphetamine-induced behavioural sensitization by increasing its conditioned component

The effects of paradoxical sleep deprivation (PSD-48 h) on the conditioned and unconditioned components of behavioural sensitization to amphetamine (two injections of 2.0 mg/kg, separated by 7 days) were studied using locomotion frequency of mice observed in an open-field as experimental parameter. Behavioural sensitization only occurred in PS deprived mice that were exposed to the open-field after the first amphetamine injection. The possible involvement of PSD in the development of a Pavlovian association between the stimulant effect of amphetamine and environmental as well as interoceptive drug cues is discussed.

Cocaine-induced genital reflexes during paradoxical sleep deprivation and recovery

Paradoxical sleep deprivation (PSD) for 96 h together with cocaine administration elicits genital reflexes (penile erection [PE] and ejaculation [EJ]) in rats. Our objective was to examine genital reflexes after periods of 24, 48, 72, 96, 120, and 144 h of PSD and during a 4-day recovery period in acute cocaine-administered rats. After 24 h of PSD followed by cocaine administration, animals started to display PE and EJ, peaking in the 96th h of PSD, whereas PE and EJ were absent in control animals. The effects of more than 96 h of PSD decrease genital reflexes as observed after 120 and 144 h. Genital reflexes were present in the recovery periods but diminished gradually during the period evaluated. Even short periods of PSD probably cause supersensitivity of dopamine (DA) receptors and exacerbate the effects of cocaine on dopaminergic pathways to induce frequent PE and EJ.

The effects of flumazenil, Ro 154513 and beta-CCM on the behaviour of control and stressed mice in the staircase test

The effects of flumazenil, Ro 154513 and beta-CCM in the staircase test were studied in control and small platform (SP) stressed mice. SP stress was induced by placing mice on small platforms (3.5 cm in diameter) surrounded by water for 24 h. This model contains several factors of stress, such as rapid eye movement sleep deprivation, isolation, immobilization and falling into the water. The staircase test consisted of placing a mouse in an enclosed staircase with five steps and recording: (i) the number of rearings and (ii) steps made during 3 min. SP stress increased the exploratory activity of mice in the staircase test as demonstrated by an increase in the number of rearings and steps made. In control mice flumazenil (2.0 and 10.0 mg/kg), Ro 15-4513 (1.0 and 3.0 mg/kg) and beta-CCM (1.0 and 2.0 mg/kg) exerted an anxiogenic effect that was demonstrated by an increase in the number of rearings without significant changes in the number of steps. Similar to control mice, flumazenil induced an anxiogenic effect in SP stressed mice as demonstrated by an increase in the number of rearings. However, the sedative effect of flumazenil as demonstrated by a decrease in the number of steps made was more pronounced in SP stressed mice. In the SP stressed mice, the anxiogenic effect of Ro 15-4513 and beta-CCM was masked by their strong sedative effect and a decrease in both measures of exploratory activity (number of rearings and number of steps). These data suggest that SP stress induces hypersensitivity to the sedative effect of flumazenil, Ro 15-4513 and beta-CCM in the staircase test.

Cholecystokinin modulation of apomorphine- or amphetamine-induced stereotypy in rats: opposite effects

Stereotyped behavior can be induced by the dopamine agonist apomorphine or by the releasing agent amphetamine. Cholecystokinin influence on dopamine-mediated behaviors has been extensively studied but a real controversy remains. Our purpose was to further characterize the dopamine-cholecystokinin interaction in apomorphine- and amphetamine-induced stereotyped behavior using sulphated cholecystokinin octapeptide (CCK8) and cholecystokinin tetrapeptide (CCK4) treatments. The results showed that CCK8 decreases apomorphine-induced stereotyped behavior and CCK4 has no effect. CCK4 and CCK8 increased the amphetamine-induced stereotyped behavior; CCK4 was more effective. The results confirm the opposite modulation of apomorphine or amphetamine-induced stereotyped behavior by CCK. These data suggest that this modulation is mediated by both CCK receptors on apomorphine-induced and only by CCK(2) receptors on amphetamine-induced stereotyped behavior.

Effect of sleep deprivation on motor performance in patients with Parkinson's disease

Animal research provides evidence that sleep deprivation influences the dopamine system. Knowledge about the effect of sleep deprivation on motor performance in patients with Parkinsons disease is scarce. This study examines the influence of total and partial sleep deprivation compared to normal sleep on motor state and performance in Parkinson's disease. Fifteen nondepressed patients with Parkinson's disease underwent one night of total sleep deprivation (TSD), one night of partial sleep deprivation (PSD) after 3 a.m., and one control night of normal sleep (S), performed in a random, nonconsecutive order. Over a period of 3 hours the following morning, motor evaluations (United Parkinson's Disease Rating Scale, [UPDRS] and tapping rate) were performed before and every 30 minutes after intake of the usual morning dopaminergic drug dose. All patients underwent polysomnography apart from the sleep deprivation protocol. Mean UPDRS motor scores and tapping velocities did not differ significantly after each of the schedules, but a subgroup of four patients improved their motor score after partial sleep deprivation. These data do not confirm previous findings of an overall positive influence of sleep deprivation on motor function in Parkinson's disease. However, the results indicate that different response types to sleep deprivation may exist and that a subgroup of patients could benefit from partial sleep deprivation.

Reproductive experience modulates dopamine-related behavioral responses

Reproductive experience (RE), i.e., mating, pregnancy, parturition and lactation, has long-term physiological effects. It reduces the basal levels of circulating prolactin in parous women, decreases the intensity of nocturnal and diurnal prolactin surges in multigravid rats during early pregnancy, as well as the hormonal and neurochemical responses to the dopamine receptor antagonists metoclopramide and haloperidol. In the present study, we evaluated the possible influences of RE on some dopaminergic-related behaviors: (1) acute responses to a new environment represented by an open-field arena plus injection stress; (2) modulation of behavior after a short-term withdrawal subsequent to 7 days amphetamine (AMPH) pretreatment; (3) stereotypy elicited by AMPH and apomorphine (APO); and (4) APO-induced hypothermia. In the 3-min open-field test, there was a decrease in locomotor activity as a function of RE. Behavioral depression was mild and AMPH pretreatment revealed RE alterations. APO-induced stereotyped behavior was slightly more intense in primiparous animals, although no significant differences were found in AMPH-induced stereotyped behavior. No differences were observed between intact and ovariectomized primiparous and nulliparous animals in APO-induced hypothermia. Our data suggest that RE modifies some DA-related behavioral responses. The physiological relevance of the phenomenon is discussed.

The effects of acute cocaine administration in paradoxical sleep-deprived rats

Recent studies demonstrate the action of cocaine on reward pathways, which are activated by pleasant stimuli. Cocaine's mechanism of action involves the blockade of dopamine and norepinephrine reuptake by the presynaptic terminal. Paradoxical sleep (PS) deprivation is known to induce several behavioural alterations most of which suggest the occurrence of supersensitivity of D₂ and a subsensitivity of β₁and β₂receptors.The present study sought to examine the effects of PS deprivation on the actions of cocaine on the erection and ejaculation behaviours in rats. Four different doses of cocaine (3.5, 7.0, 15.0 and 30.0 mg/kg) were acutely administered to Wistar male rats, at the end of a 4-day period of PS deprivation or at the equivalent time-point to control animals. Moreover, 15 mg/kg of cocaine were administered in animals submitted to immobilization, footshock and forced swimming. The data were analysed by the Chi-square test, and revealed that only PS-deprived animals exhibited penile erections and ejaculation behaviours, which were absent in control animals. PS deprivation increases the sexual behaviour of male rats, probably due to its action on dopaminergic systems. However, further studies need to be carried out in order to clarify the mechanisms involved between PS deprivation and cocaine.

Opposite modulation of apomorphine- or amphetamine-induced stereotypy by antagonists of CCK receptors

Stereotyped behavior is elicited by activation of dopaminergic systems with drugs such as apomorphine and amphetamine. In previous studies, we have reported that the sulfated cholecystokinin octapeptide (CCK-8) decreased apomorphine-induced stereotypy in animals with normal and supersensitive dopamine receptors. The aim of the present study was to evaluate the effects of CCK(1) and CCK(2) receptor antagonists on stereotyped behavior induced by apomorphine or amphetamine. Rats were pretreated with the CCK(1) (SR 27897B; 1-[[2-(4-(2-chlorophenyl) thiazol-2-yl) aminocarbonyl]indolyl]acetic acid; 500 microg/kg; i.p.) or CCK(2) (L-365,260; 3R-(+)-N-(2,3-dihydro-1-methyl-2-oxo-5 phenyl-1H-1, 4-benzodiazepine-3-yl)-N'-(3-methyl phenyl)-urea; 500 microg/kg; i.p. ) receptor antagonists or saline 15 min before apomorphine (0.6 mg/kg; s.c.) or amphetamine (9.0 mg/kg; i.p.) injection. Both CCK(1) and CCK(2) receptor antagonists significantly increased apomorphine-induced stereotypy. In contrast, only the blockade of CCK(2) receptors significantly decreased amphetamine-induced stereotypy. The results suggest a dual opposite mechanism for CCK-dopamine interactions. These data also suggest that both apomorphine- and amphetamine-induced stereotypy should be used whenever effects of drugs acting on dopaminergic systems are being assessed.

Decreased activity of striatal monoamine oxidase B after rapid eye movement (REM) sleep deprivation in rats

The striatum seems to be the main brain region involved in stereotyped behavior induced by dopaminergic agonists. Rapid eye movement (REM) sleep deprivation increases dopaminergic agonist-induced stereotypy and produces biochemical changes in striatal dopaminergic neurotransmission. However, the mechanism underlying the increased dopaminergic sensitivity induced by REM sleep deprivation has not been elucidated. In an attempt to determine some of the biochemical changes in striatal dopaminergic neurotransmission that could contribute to REM sleep deprivation effects, we measured the activity of monoamine oxidase (MAO) A and B, the enzymes responsible for dopamine and beta-phenylethylamine (beta-PEA) deamination in striatum. Male adult rats were deprived of REM sleep for 96 h by the flower-pot technique. MAO A and B were assayed radioisotopically in the mitochondrial fraction by standard laboratory procedures, using [14C]-5-hydroxytryptamine (5-HT) and [14C]-beta-phenylethylamine (beta-PEA), as substrates for MAO A and MAO B, respectively. The results showed no significant statistical differences in striatal MAO A activity, whereas a significant decrease in MAO B activity was observed. The results are discussed in terms of the possible involvement of beta-PEA, a striatal endogenous trace amine, which potentiates dopaminergic neurotransmission and may participate in the increased dopaminergic sensitivity observed after REM sleep deprivation.

Modulation of apomorphine-induced stereotyped behavior by cholecystokinin

1. The goal was to verify if central or peripheral sulphated cholecystokinin octapeptide (CCK8) injections can modulate apomorphine (APO)-induced stereotyped behavior. Experiments were designed to determine the involvement of cholecystokinin receptor subtypes as well. 2. Animals which received CCK8 (0.0725, 0.145 and 14.5 nmol, icv) showed a significant (p < 0.05) decrease in APO (0.6 mg/kg, sc)-induced stereotyped behavior. 3. No other statistically significant difference was observed among groups. Since ip CCK8 (1.16 or 2.32 nmol/kg) injections did not interfere with APO-induced stereotypy, the results suggest that the CCK8 modulatory effects have a central action. 4. The results also suggest that the effects of icv CCK8 were not due to the stimulation of CCK8 receptors alone since central CCK4 (14.5 or 29.0 nmol) injections did not interfere with the expression of stereotypy.

Atropine increases pilocarpine-induced yawning behavior in paradoxical sleep deprived rats

Paradoxical sleep (PS) deprivation has been suggested to induce supersensitivity of postsynaptic dopamine (DA) receptors and subsensitivity of acetylcholine (ACh) receptors. Yawning behavior is reduced after PS deprivation and is believed to result from an interaction between ACh and DA systems. Concomitant treatment of PS deprived animals with DA agonists reverses PS deprivation effects on stereotypy and aggressiveness. To examine this possibility on yawning behavior, rats were treated, during the deprivation period, with atropine, methamphetamine, haloperidol or distilled water. Following PS deprivation, rats were injected with apomorphine or pilocarpine and number of yawns was recorded. Atropine increased yawning of PS deprived rats induced by pilocarpine, but not by apomorphine. Treatment with methamphetamine and haloperidol did not change PS deprivation effect on pilocarpine- and apomorphine-induced yawning. The data suggest that reversal of PS deprivation-induced yawning inhibition is mediated distinctly by both acetylcholine and dopamine systems.

Paradoxical sleep deprivation in female rats alters drug-induced behaviors

Paradoxical sleep deprivation (PSD) induces changes in behaviors induced by dopaminergic and cholinergic agonists, including increased aggressive behavior and stereotypy, decreased number of yawns, and shedding of bloody tears in male rats. In female rats, however, very little is known about the relationship between PSD and the effect of these drugs. The present study sought to examine this issue. As in males, PSD in females resulted in increased apomorphine-induced stereotypy, decreased pilocarpine-induced chromodacryorrhea, and hyperthermia. Unlike males, however, no apomorphine-induced aggressiveness or apomorphine- and pilocarpine-induced yawning were observed in PSD females. These findings suggest that female sexual hormones may affect the expression of some behaviors and not the neurotransmission as a whole, because drug-induced behaviors in PSD females were partly similar to those observed in PSD males.

The effects of drugs acting at GABA-benzodiazepine-barbiturate receptor complex on the behaviour of sleep-deprived mice

The effects of the benzodiazepine receptor agonist diazepam, the benzodiazepine receptor antagonist flumazenil and the benzodiazepine receptor inverse agonist ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo-[1,5-a][1-4] benzodiazepine-3-carboxylate (RO 15-4513) on the locomotor activity and the behaviour of animals in the plus-maze test were studied in sleep-deprived mice. The effects of convulsants acting at GABA-benzodiazepine-barbiturate receptor complex-bicuculline, picrotoxin and pentylenetetrazole, were also studied. Sleep deprivation of mice for 24 hr using the platform technique caused behavioural excitation that was reflected by an increase in the locomotor activity. Administration of diazepam (0.5 and 2.0 mg/kg), flumazenil (5.0 and 10.0 mg/kg) and RO 15-4513 (1.0, 2.0 and 3.0 mg/kg) either did not affect (in low doses) or inhibited (in high doses) locomotions of control animals. The inhibition of locomotor activity by these drugs was greater in sleep-deprived animals. In the plus-maze test, diazepam in a dose of 2.5 mg/kg had an anxiolytic effect in control mice that was reflected by an increase in the percentage of entries onto and the percentage of time spent on the open arms of the plus-maze. In contrast, in sleep-deprived animals, diazepam did not induce anxiolytic action at any dose tested. In the highest dose (2.5 mg/kg) diazepam produced a sedative effect that was reflected by a decrease in the total number of entries made onto the open and into the closed arms of the plus-maze.(ABSTRACT TRUNCATED AT 250 WORDS)

Single photon emission computerized tomography assessment of cerebral dopamine D2 receptor blockade in depression before and after sleep deprivation--preliminary results

The antidepressant properties of total sleep deprivation (TSD) have been well established. There is some evidence that TSD may improve depression by altering central dopamine (DA) function. We therefore studied five depressed TSD responders and five TSD nonresponders after sleep and after TSD and five controls after sleep with IBZM single photon emission computerized tomography (SPECT). Responders showed a significant decrease (Wilcoxon--test p < 0.05) of relative basal ganglia D2 receptor occupancy after TSD compared to nonresponders (change score responders versus nonresponders p < 0.05, U-test). The data are interpreted as a sign of an enhanced DA release in responders. The results confirm previous hypotheses of dopaminergic involvement in the therapeutic action of TSD and indirectly support a dopamine hypotheses of depression.

Sodium diclofenac inhibits hyperthermia induced by paradoxical sleep deprivation: the possible participation of prostaglandins

Sodium diclofenac inhibits hyperthermia induced by paradoxical sleep deprivation (PSD), which suggests the participation of prostaglandins. The temperature of paradoxical sleep-deprived rats increased from the first to the fourth day of deprivation. This hyperthermia was blocked on the second, third, and fourth days by daily administration, twice a day, of 10 mg/kg of sodium diclofenac, a potent prostaglandin synthesis inhibitor. In the dose of 10 mg/kg, a decrease of temperature was observed only on the second and third days of PSD. These data suggest the participation of prostaglandins in modulating the increase in temperature during PSD.

REM sleep deprivation decreases apomorphine-induced stimulation of locomotor activity but not stereotyped behavior in mice

1. Effects of rapid eye movement (REM) sleep deprivation on central dopaminergic system were investigated by testing the behavioral responses to apomorphine and brain dopamine metabolism in mice. 2. REM sleep deprivation for 48 hr significantly suppressed apomorphine.HCl (3.0 and 6.0 mg/kg, i.p.)-stimulated spontaneous locomotor activity without affecting the intensity of stereotyped behavior. 3. Neither the latency of nociceptive response in a hot-plate test nor the duration of pentobarbital-induced sleep was changed by REM sleep deprivation. 4. Dopamine turnover in the striatum and the nucleus accumbens of REM sleep-deprived mice was significantly higher than that of control animals. 5. These results suggest that REM sleep deprivation may decrease the function of postsynaptic dopamine receptor in the mesolimbic but not nigrostriatal dopaminergic system.