Cellular prion protein is present in dopaminergic neurons and modulates the dopaminergic system.

Cellular prion protein (PrP(C) ) is widely expressed in the brain. Although the precise role of PrP(C) remains uncertain, it has been proposed to be a pivotal modulator of neuroplasticity events by regulating the glutamatergic and serotonergic systems. Here we report the existence of neurochemical and functional interactions between PrP(C) and the dopaminergic system. PrP(C) was found to co-localize with dopaminergic neurons and in dopaminergic synapses in the striatum. Furthermore, the genetic deletion of PrP(C) down-regulated dopamine D1 receptors and DARPP-32 density in the striatum and decreased dopamine levels in the prefrontal cortex of mice. This indicates that PrP(C) affects the homeostasis of the dopaminergic system by interfering differently in different brain areas with dopamine synthesis, content, receptor density and signaling pathways. This interaction between PrP(C) and the dopaminergic system prompts the hypotheses that the dopaminergic system may be implicated in some pathological features of prion-related diseases and, conversely, that PrP(C) may play a role in dopamine-associated brain disorders.

Surgical treatment of patients with chronic rupture of the pectoralis major muscle tendon. Prospective comparative study with 2 years of follow-up.

To compare outcomes between autologous fascia lata and autologous hamstring grafts for chronic pectoralis major muscle (PMM) rupture repair, and perform histological, and imaging analyses. Forty male patients with chronic PMM ruptures (time since injury ranging from >3 months to 5 years) and a mean age of 37.3 years (SD = 9.7 years) were evaluated. One group (20 patients) received an autologous semitendinosus graft, and another group (20 patients) received an autologous fascia lata graft for PMM reconstruction. These patients with fascia lata grafts by Bak 2criterium 60% of the patients presented excellent results, 20% presented good results, 15% presented fair results, and 5% presented poor results. In the hamstring group 65% of the patients presented excellent results, 30% presented good results, and 5% presented fair results. In this comparative study, no difference was observed regarding the functional result, image, and histology between groups.

Anabolic steroids and the evaluation of patients with acute PM tendon rupture using microscopy and MRI.

This study presented a pioneering investigation of the changes in the magnetic resonance imaging images of pectoralis major muscle (PMM) tendon rupture. In all, 26 men were evaluated with acute total PMM rupture (<3 months since injury) with a mean age of 37.3 years (SD = 9.7 years) and 10 control patients with a mean age of 32.6 years (SD = 4.2 years). The evaluation of the tendon PMM injuries was based on the magnetic resonance imaging exam and the histological analysis. The magnetic resonance imaging of the surgically showed two (7.1%) contralateral sides were normal, 16 (57.1%) showed superior tendinopathy, and 10 (35.7%) had total tendinopathy. Inferior tendinopathy was not observed. The tendon histology revealed degenerative changes in 16 (66.7%) fragments, with 12 (50.0%) considered as mild (<25%), and four considered as (16.7%) high (>50.0%) tendinopathy. Total acute rupture of the PMM tendon among weightlifters might be associated with tendinous degeneration prior to injury.

Social jetlag is associated with adverse cardiometabolic latent traits in early adolescence: an observational study.

Introduction: Adolescence is marked by physiological and social changes, such as puberty, increased responsibilities and earlier school start times. This often leads to insufficient sleep on school nights and the need to compensate for lost sleep on weekends, causing a misalignment between biological and social times, which has been termed social jetlag (SJL). SJL triggers stress responses and is associated with several negative health outcomes, including higher cardiometabolic risk in adults. In adolescence, however, SJL has only been consistently related to increases in adiposity but its association with other cardiometabolic indicators are unclear. Method: In a sample of 278 healthy early adolescents (9-15 years of age; 168 girls) we investigated: 1) whether self-reported SJL is associated (using path analyses) with a cardiometabolic status latent factor obtained by testing the best fitting model via confirmatory factor analyses from an initial set of eight indicators [body mass index (BMI), waist/height ratio, triglyceride concentration, diastolic and systolic blood pressure, glycated hemoglobin, total cholesterol/high-density lipoprotein ratio (chol/HDL), and % body fat]; and 2) whether age and/or pubertal status influence the association between SJL and cardiometabolic status. Result: We found that, for girls, higher SJL was associated with more adverse cardiometabolic latent scores (the shared variance of BMI, waist/height ratio, chol/HDL and systolic blood pressure, which had acceptable model fit indices). However, the role of age and pubertal status in this association was unclear for both sexes. Discussion: SJL was associated with adverse cardiometabolic latent traits beyond increases in adiposity in this observational study in early female adolescents. Because disruptions of circadian rhythms are believed to lead to dysregulated energy homeostasis and not vice-versa, our findings highlight the need for sleep interventions in adolescence to help reduce the global burden of cardiometabolic ill health, especially in girls.

Rupture of the bilateral and simultaneous tendon of the pectoralis major muscle. Description of three cases.

Pectoralis major muscle tendon ruptures associated with physical activity or effort are no longer uncommon in the medical literature. Treatment has also evolved significantly in the last 20 years. However, simultaneous bilateral rupture has only been described in a few cases. This article reports three cases with simultaneous bilateral rupture and describes the examinations and treatment performed. Bilateral lesions, although infrequent, also require early diagnosis and treatment in the acute phase. The chronic phase requires tendon grafting for full correction and a slow rehabilitation process.

Electromyography of the Pectoralis Major Muscle after Surgical Reconstruction of Chronic Tendon Rupture.

Objective To evaluate the electrophysiological activity of the injured pectoralis major (PM) muscle of operated patients who perform weightlifting, more specifically bench press exercises, especially the activity of the clavicular and sternocostal portions of the PM. Methods All athletes in study I (10 patients) had unilateral complete ruptures during bench press exercises and a history of use of anabolic steroids, an association that is described in up to 86.7% of PM tendon ruptures. The control group included 10 men without PM tendon injury who did not perform bench press exercises. Description of the cross-sectional design. The p -values were obtained by multiple comparisons with Bonferroni correction. Results In the comparison between the control (C) group and the weightlifters during the postoperative period (POS), we found no evidence of differences in any measurements obtained in the clavicular and sternocostal portions of the PM muscle: clavicular average level ( p = 0.847); clavicular standard deviation (SD) ( p = 0.777); clavicular area ( p = 0.933); clavicular median ( p = 0.972); sternocostal average level ( p = 0.633); sternocostal SD ( p = 0.602); sternocostal area ( p = 0.931); and sternocostal median ( p = 0.633). Conclusion In the present study, the electromyographic activity of the PM muscle in weightlifters (bench press exercise) who underwent surgery was within the normal parameters for the clavicular and sternocostal portions studied.

Modafinil prevents inhibitory avoidance memory deficit induced by sleep deprivation in rats.

STUDY OBJECTIVES: Evaluation of modafinil effects on the inhibitory avoidance task (IA). DESIGN: Rats were trained on a multiple trial IA task after receiving modafinil or vehicle injections. In experiment 1 they were trained with a weak protocol under baseline condition and in experiment 2, with a stronger protocol under sleep-deprivation condition. RESULTS: In experiment 1 modafinil improved rats' acquisition whereas the retention test remained unaffected. In Experiment 2 modafinil did not interfere with training performance, but the lower dose prevented the retention impairment in sleep-deprived animals. CONCLUSIONS: Modafinil is able to improve acquisition in normal rats and reverse the long-term memory impairment induced by sleep-deprivation.

Chronic mild stress induces widespread decreases in thyroid hormone alpha1 receptor mRNA levels in brain--reversal by imipramine.

While considerable clinical evidence implicates thyroid hormones (THs) in depressive illness, the specific nature of this involvement remains unclear. The alpha1 subtype (TR-alpha1) is the most abundant TH receptor in brain. Here we investigated changes in TR-alpha1 mRNA in the chronic mild stress (CMS) model of depression. Rats were exposed to a CMS schedule for 3 weeks, which resulted in a progressive decreases in sucrose preference (an index of anhedonia). They were then treated daily with either imipramine (IMI, 10mg/kg) or vehicle (VEH) for 2 weeks before being sacrificed for quantitative in situ hybridization analyses of TR-alpha1 mRNA throughout the brain. Results indicated that CMS followed by VEH induced widespread decreases in TR-alpha1 mRNA in brain. In contrast, CMS-exposed rats receiving IMI for the last 2 weeks prior to sacrifice showed full recovery of sucrose preference. Furthermore, brain TR-alpha1 mRNA levels in these animals were similar to those of non-stressed controls receiving either SAL or IMI. These results reveal that TR-alpha1 mRNA brain levels are very sensitive to CMS effects. The reversal of both anhedonic and TR-alpha1 effects of CMS by IMI suggests that TR-alpha1 may play a role both in stress-induced depressive symptoms and in their reversal by antidepressant interventions.

Ethanol-induced behavioral sensitization is associated with dopamine receptor changes in the mouse olfactory tubercle.

Accumulating evidence points to the mesolimbic and the nigrostriatal dopamine systems as critical to behavioral sensitization induced by several drugs of abuse. In the present study, we analyzed D1 and D2 binding to brain regions related to these dopaminergic systems during the expression of ethanol-induced behavioral sensitization. The first experiment was performed to demonstrate the effectiveness of the ethanol treatment schedule and challenge used to induce the expression of the behavioral sensitization phenomenon. The second experiment was conducted to study D1 and D2 alterations in several brain regions during the expression of this phenomenon. Mice were ip treated with ethanol or saline for 21 consecutive days and 24 h after the last injection they received an ethanol or a saline challenge injection. Five minutes later, the animals were observed in an open-field for locomotion quantification or were sacrificed and their brains were submitted to autoradiographic binding analyses. No differences among the groups were found for D1 binding levels in all the brain regions analyzed. However, ethanol-sensitized mice showed reduced levels of D2 binding in the olfactory tubercle when compared to the other groups. Our data suggest that D2 receptor changes in the olfactory tubercle seem to play an important role in the expression of ethanol-induced behavioral sensitization.

Corticosterone Assimilation by a Voluntary Oral Administration in Palatable Food to Rats.

Drug delivery in research on nonhuman animals in the laboratory is still challenging because it is usually invasive and stressful. Stress-free voluntary oral drug administration in water lacks precise control of dose and timing of substance ingestion. Voluntary oral consumption of corticosterone has been previously successfully applied in mice using oat flakes, but protocols for oral corticosterone administration in rats remain unavailable. This study assessed the effectiveness of voluntary oral administration to rats of a palatable piece of bread soaked with corticosterone that can be rapidly prepared and is reliably dose- and timing-controllable. After three familiarization days, all rats ate the bread within 120 seconds of presentation, irrespective of the presence or absence of corticosterone or vehicle. Corticosterone plasma levels remained at basal levels with consumption of vehicle-containing bread, and they were significantly increased with corticosterone-containing bread. Hence, the method enabled corticosterone bodily assimilation while avoiding stress, making it a possible alternative for invasive and stressful procedures. This article includes a methodological refinement that lessens unnecessary discomfort to laboratory animals and is potentially suitable for acute and chronic protocol studies.

Association between ACTN3 and acute mountain sickness.

BACKGROUND: During the process of acclimatization, when our organism needs to adjust several metabolic processes in the attempt of establishing a better oxygenation, it is normal that individuals present some symptoms that can lead to the disease of the mountain. However, not everyone presents such symptoms and individuals native of high altitudes regions present genetic differences compared to natives of low altitudes which can generate a better acute adaptation. One of these differences is the higher proportion of type I muscle fibers, which may originate from the R577X polymorphism of the ACTN3 gene. The aim of this study was to compare the response of individuals with different ACTN3 genotypes at simulated 4500 m altitude on the presence of Acute Mountain Sickness (AMS) symptoms. Twenty-three volunteers (RR = 7, RX = 8, XX = 8) spent 4 hours exposed to a simulated altitude of 4500 m inside a normobaric hypoxia chamber. Lactate and glucose concentrations, SpO2, heart rate and the symptoms of AMS were analyzed immediately before entering the chamber and at each hour of exposure. Statistical analysis was performed using IBM SPSS Statistics 21 software. RESULTS: Our results point to an association between AMS symptoms and the presence of R allele from R577X polymorphism. CONCLUSION: We conclude that individuals with at least one R allele of the R577X polymorphism seems to be more susceptible to the effects of hypoxia during the acclimatization process and may develop AMS symptoms.

The GCN2 inhibitor IMPACT contributes to diet-induced obesity and body temperature control.

IMPACT, a highly conserved protein, is an inhibitor of the eIF2α kinase GCN2. In mammals, it is preferentially expressed in neurons. Knock-down of IMPACT expression in neuronal cells increases basal GCN2 activation and eIF2α phosphorylation and decreases translation initiation. In the mouse brain, IMPACT is particularly abundant in the hypothalamus. Here we describe that the lack of IMPACT in mice affects hypothalamic functions. Impact-/- mice (Imp-KO) are viable and have no apparent major phenotypic defect. The hypothalamus in these animals shows increased levels of eIF2α phosphorylation, as expected from the described role of IMPACT in inhibiting GCN2 and from its abundance in this brain region. When fed a normal chow, animals lacking IMPACT weight slightly less than wild-type mice. When fed a high-fat diet, Imp-KO animals gain substantially less weight due to lower food intake when compared to wild-type mice. STAT3 signaling was depressed in Imp-KO animals even though leptin levels were identical to the wild-type mice. This finding supports the observation that Imp-KO mice have defective thermoregulation upon fasting. This phenotype was partially dependent on GCN2, whereas the lean phenotype was independent of GCN2. Taken together, our results indicate that IMPACT contributes to GCN2-dependent and -independent mechanisms involved in the regulation of autonomic functions in response to energy availability.

Heightened aggression after chronic flunitrazepam in male rats: potential links to cortical and caudate-putamen-binding sites.

RATIONALE: Higher doses of benzodiazepines induce sedation. However, in low to moderate doses, benzodiazepines can increase aggressive behavior both after acute and chronic administration. The determinants for increasing aggression after chronic intake of flunitrazepam, a so-called date rape drug, in violence-prone individuals are incompletely understood. OBJECTIVES: The aim of this study is to assess the effects of acute and chronic treatment with flunitrazepam on male aggression in resident rats. We also examined possible changes in binding to benzodiazepine receptors throughout the brain of rats that display aggressive behavior after repeated flunitrazepam treatment using quantitative receptor autoradiography. MATERIALS AND METHODS: The behaviors of the male Wistar resident rats (n = 35) toward a male intruder were recorded for 10 min twice a week. The salient aggressive and non-aggressive elements in the resident rat's behavior were analyzed. Initially, the dose-dependent effects of flunitrazepam (0.01, 0.03, 0.1, 0.18, and 0.3 mg/kg) or vehicle were determined in all rats; subsequently, 0.3 mg/kg per day flunitrazepam was administered for 42 days (n = 15), and a parallel group was treated with vehicle (n = 20). After the chronic treatment, the flunitrazepam (0, 0.01, 0.03, 0.1, 0.18, and 0.3 mg/kg) effects were again assessed. RESULTS: The most significant finding is the escalation of aggression after chronic treatment with flunitrazepam. A previously sedative 0.3 mg/kg dose of flunitrazepam engendered very high levels of attack bites, sideways threats, and aggressive postures (total aggression) after 6 weeks of daily administration. Individual differences emerged, and these were associated with decreased binding to benzodiazepine receptors, mainly in the limbic structures such as the cingulate cortex (cingulate areas 1 and 2) and caudate-putamen (posterior part) of aggressive animals, suggesting that these areas are pivotal in the control of emotional and aggressive behavior. CONCLUSIONS: Chronic flunitrazepam produces changes in receptor binding in discrete areas of the cingulate cortex and caudate-putamen that are proposed to be part of the mechanisms for increased expression of aggressive behavior.

Hemiparkinsonian rats rotate toward the side with the weaker dopaminergic neurotransmission.

Rats with unilateral lesion of the substantia nigra pars compacta (SNpc) have been used as a model of Parkinson's disease. Depending on the lesion protocol and on the drug challenge, these rats rotate in opposite directions. The aim of the present study was to propose a model to explain how critical factors determine the direction of these turns. Unilateral lesion of the SNpc was induced with 6-hydroxydopamine (6-OHDA) or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Separate analysis showed that neither the type of neurotoxin nor the site of lesion along the nigrostriatal pathway was able to predict the direction of the turns these rats made after they were challenged with apomorphine. However, the combination of these two factors determined the magnitude of the lesion estimated by tyrosine-hydroxylase immunohistochemistry and HPLC-ED measurement of striatal dopamine. Very small lesions did not cause turns, medium-size lesions caused ipsiversive turns, and large lesions caused contraversive turns. Large-size SNpc lesions resulted in an increased binding of [(3)H]raclopride to D2 receptors, while medium-size lesions reduced the binding of [(3)H]SCH-23390 D1 receptors in the ipsilateral striatum. These results are coherent with the model proposing that after challenged with a dopamine receptor agonist, unilaterally SNpc-lesioned rats rotate toward the side with the weaker activation of dopamine receptors. This activation is weaker on the lesioned side in animals with small SNpc lesions due to the loss of dopamine, but stronger in animals with large lesions due to dopamine receptor supersensitivity.

Pain hypersensitivity induced by paradoxical sleep deprivation is not due to altered binding to brain mu-opioid receptors.

Previous studies have established a relationship between sleep disruption and pain, and it has been suggested that hyperalgesia induced by paradoxical sleep deprivation (PSD) could be due to a reduction of opioidergic neurotransmission in the brain. In the present study rats deprived of sleep for 96 h as well as rats allowed to recover for 24h after PSD and normal controls received vehicle or morphine (2.5, 5 and 10 mg/kg, i.p.) and were tested on a hot plate 1h later. Quantitative receptor autoradiography was used to map alterations in binding to brain mu-opioid receptors in separate groups. Results demonstrated that PSD induced a significant reduction in thermal pain threshold, as measured by paw withdrawal latencies. This effect did not return to baseline control values after 24h of sleep recovery. The usual analgesic effect of morphine was observed in the control group but not in PSD or rebound groups except at the highest dose (10 mg/kg). Binding of [3H]DAMGO to mu sites did not differ significantly among the three groups in any of the 33 brain regions examined. These results do not exclude the participation of the opioid system in PSD-induced pain hypersensitivity since sleep-deprived rats were clearly resistant to morphine. However, the fact no changes were seen in [3H]DAMGO binding indicates that mechanisms other than altered mu-opioid binding must be sought to explain the phenomenon.

Fear conditioning performance and NMDA receptor subtypes: NR2A differential expression in the striatum.

While considerable evidence implicates NMDA receptors in the hippocampus in contextual fear conditioning, the role of other brain regions is less well understood. To further investigate this issue, rats were subjected to a contextual fear conditioning task and then classified as high or low responders according to performance. Density of NMDA receptors was evaluated using [3H]MK-801 autoradiography in 52 brain areas and expression of NR2A and NR2B subunits was studied with in situ hybridization in the same brains. Results revealed no differences between high- and low-performance rats in NMDA receptor binding in any of the brain areas studied. Similarly, NR2B subunit expression was also not different between groups. However, NR2A expression was significantly higher in the caudate-putamen of low-performance rats. These results suggest that NMDA receptors in the caudate-putamen may also be involved in contextual fear conditioning performance.

Electromyography of the Pectoralis Major Muscle after Surgical Reconstruction of Chronic Tendon Rupture / Eletromiografia do músculo peitoral maior após reconstrução cirúrgica da ruptura crônica do tendão

Abstract Objective To evaluate the electrophysiological activity of the injured pectoralis major (PM) muscle of operated patients who perform weightlifting, more specifically bench press exercises, especially the activity of the clavicular and sternocostal portions of the PM. Methods All athletes in study I (10 patients) had unilateral complete ruptures during bench press exercises and a history of use of anabolic steroids, an association that is described in up to 86.7% of PM tendon ruptures. The control group included 10 men without PM tendon injury who did not perform bench press exercises. Description of the cross-sectional design. The p-values were obtained by multiple comparisons with Bonferroni correction. Results In the comparison between the control (C) group and the weightlifters during the postoperative period (POS), we found no evidence of differences in any measurements obtained in the clavicular and sternocostal portions of the PM muscle: clavicular average level (p = 0.847); clavicular standard deviation (SD) (p = 0.777); clavicular area (p = 0.933); clavicular median (p = 0.972); sternocostal average level (p = 0.633); sternocostal SD (p = 0.602); sternocostal area (p = 0.931); and sternocostal median (p = 0.633). Conclusion In the present study, the electromyographic activity of the PM muscle in weightlifters (bench press exercise) who underwent surgery was within the normal parameters for the clavicular and sternocostal portions studied.

Resumo Objetivo Avaliar a atividade eletrofisiológica do músculo peitoral maior (PM) lesionado de pacientes operados que realizam halterofilismo, mais especificamente exercícios de supino, especialmente a atividade das porções clavicular e esternocostal do PM. Métodos Todos os atletas no estudo I (10 pacientes) tiveram rupturas completas unilaterais durante o exercício de supino, e tinham histórico de uso de esteroides anabolizantes, associação descrita em até 86,7% das rupturas tendinosas do PM. O grupo controle incluiu 10 homens sem lesão no tendão do PM que não realizaram exercícios de supino. Descrição do projeto transversal. Os valores de p foram obtidos por múltiplas comparações com a correção de Bonferroni. Resultados Na comparação entre o grupo controle (C) e os halterofilistas durante o pós-operatório (POS), não foram encontradas diferenças nas medidas obtidas nas porções clavicular e esternocostal do músculo PM: nível médio clavicular (p = 0,847); desvio padrão (DP) clavicular (p = 0,777); área clavicular (p = 0,933); mediana da clavícula (p = 0,972); nível médio esternocostal (p = 0,633); DP esternocostal (p = 0,602); área esternocostal (p = 0,931); e mediana esternocostal (p = 0,633). Conclusão Neste estudo, a atividade eletromiográfica do músculo PM em atletas de halterofilismo (exercício de supino) que foram submetidos a cirurgia esteve dentro dos parâmetros normais para as porções claviculares e esternocostais estudadas.

Opposite effects of sleep rebound on orexin OX1 and OX2 receptor expression in rat brain.

Orexins (hypocretins) have been implicated in the regulation of the normal sleep-wake cycle, in sensorimotor programming, and in other homeostatic and neuroregulatory processes. The present study examined the effects of sleep deprivation (SD) and sleep recovery on the expression of orexin 1 receptors (OX1R) and orexin 2 receptors (OX2R) throughout the brain. Rats were sacrificed either immediately after 96 h of sleep deprivation (SD group) or after SD followed by 24 h of sleep recovery (Rebound group). Prepro-orexin mRNA showed a non-significant increase in the SD group relative to controls, but a pronounced and significant increase in the Rebound group (+88%, P < 0.007). Similarly, sleep deprivation produced no effect on OX1R or OX2R mRNA levels. However, in the Rebound group, OX1R mRNA levels increased significantly, compared to either control or SD groups, in 37 of 92 brain regions analyzed, with particularly strong effects in the amygdala and hypothalamus. Changes in OX2R mRNA levels were also seen only in the sleep Rebound group, but they were fewer in number (10 out of 86 regions), were in the direction of decreased rather than increased expression, and were predominantly confined to cerebral cortical areas. These observations indicate that some factor associated with sleep recovery, possibly the compensatory increase in REM sleep, has strong effects on the orexin system at the mRNA level. They further indicate that,pOX1 and OX2 receptors are affected in opposite way and that the former are more vulnerable to these effects than the latter.

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.

Learning deficits induced by sleep deprivation and recovery are not associated with altered [(3)H]muscimol and [(3)H]flunitrazepam binding.

Several studies have shown that sleep deprivation produces deficits in learning tasks, but mechanisms underlying these effects remain unclear. Other lines of evidence indicate an involvement of brain GABA systems in cognitive processes. Here, we investigated the possibility that alterations in GABA(A) or benzodiazepine (BDZ) receptor binding might underlie avoidance deficits induced by sleep deprivation. Rats were deprived of sleep for 96 h using the platform method and then trained in a step-through inhibitory avoidance task, or allowed to recover sleep for 24 h before training (sleep rebound group). Thirty minutes after training, animals were given a retention test. Both sleep-deprived and sleep-recovered animals showed a significant impairment in avoidance responding compared to cage controls, and the sleep-deprived group performed significant worse than the sleep-recovered group. A separate group of animals was sacrificed either immediately after 96 h of sleep deprivation or after 96 h of sleep deprivation followed by 24 h of sleep recovery. [(3)H]muscimol and [(3)H]flunitrazepam binding were examined by quantitative autoradiography in 42 brain regions, including areas involved in cognitive processes. No significant differences among groups were found in any brain region, except for a reduction in [(3)H]flunitrazepam binding in the frontal cortex of sleep-recovered animals. These results confirm the deleterious effects of sleep loss on inhibitory avoidance learning, but suggest that such deficits cannot be attributed to altered GABA(A) or BDZ binding in brain.