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

Effect of Withania Somnifera on the antioxidant and neurotransmitter status in sleep deprivation induced Wistar rats

Sleep is normally a period of relaxation and repair, important for the maintenance of physiological homeostasis and psychological balance. "Globally, millions of people experiences sleep deprivation daily". Sleep deprivation (SD) impairs cognitive functions, decreases anti-oxidative defense and induces neuronal changes. Withania somnifera (WS), commonly known as an "Indian Ginseng" has broad therapeutic applications, including anti-inflammatory activities, actions on immune system, circulatory system, central nervous system etc., The study is aimed to assess effect of Withania somnifera on antioxidant status and neurotransmitter level in sleep deprivation induced male Wistar albino rats. The study was done in the Department of Physiology, Meenakshi Medical College and Hospital, Enathur, Kanchipuram. 24 male adult Wistar rats weighing 120-150g were used for the study. They were divided into 4 groups with 6 animals in each group. (Group I - cage control, Group II - large platform control, Group III - sleep deprived group and Group IV - WS treated SD group). Animals were deprived sleep for one week using a modified multiple platform method. Oxidative stress parameters and antioxidant enzymes were measured using spectrophotometry. Neurotransmitters such as dopamine and serotonin concentration in the serum were measured by ELISA method. There was a marked (by one-way ANOVA test) decrease observed in the antioxidants enzymes in the cortex of both large platform control and sleep deprivation induced group. The group treated with W. somnifera root extract significantly reduced the free radical production and lipid peroxidation with simultaneous increase in the level of antioxidant enzymes compared to the untreated group. Also in our study the concentration of dopamine and serotonin was found to be significantly reduced (p < 0.05) in sleep deprived (SD) and large platform control group when compared to cage control group. Whereas the group treated with W. somnifera (400mg/kg b.wt) increased the neurotransmitter levels significantly. Withania somnifera proved to be an effective therapeutic agent by maintaining the antioxidant status and neurotransmitter levels.

Cocaine administration increases angiotensin I-converting enzyme (ACE) expression and activity in the rat striatum and frontal cortex

Some central effects of cocaine administration seem to be related to angiotensin II (Ang II) or its metabolites. Nonetheless, it is still an open question whether or not the levels of angiotensin I-converting enzyme (ACE), the main Ang II generating enzyme, are modified by cocaine administration. To evaluate the effect of acute and subchronic cocaine administration on ACE activity and mRNA expression, male rats were randomly assigned to saline or cocaine group. Acute and subchronic cocaine administration induced a significant increase in ACE activity and mRNA expression in the frontal cortex and striatum but not in the hippocampus. These results suggest that some of the Ang II related effects of cocaine upon the central nervous system can be mediated by changes on the expression and activity of ACE in the striatum and frontal cortex.

Mixing pleasures: review of the effects of drugs on sex behavior in humans and animal models

Drugs of abuse act on the brain circuits mediating motivation and reward associated with natural behaviors. There is ample evidence that drugs of abuse impact male and female sexual behavior. First, the current review discusses the effect of drugs of abuse on sexual motivation and performance in male and female humans. In particular, we discuss the effects of commonly abused drugs including psychostimulants, opiates, marijuana/THC, and alcohol. In general, drug use affects sexual motivation, arousal, and performance and is commonly associated with increased sexual risk behaviors. Second, studies on effects of systemic administration of drugs of abuse on sexual behavior in animals are reviewed. These studies analyze the effects on sexual performance and motivation but do not investigate the effects of drugs on risk-taking behavior, creating a disconnect between human and animal studies. For this reason, we discuss two studies that focus on the effects of alcohol and methamphetamine on inhibition of maladaptive sex-seeking behaviors in rodents. Third, this review discusses potential brain areas where drugs of abuse may be exerting their effect on sexual behavior with a focus on the mesolimbic system as the site of action. Finally, we discuss recent studies that have brought to light that sexual experience in turn can affect drug responsiveness, including a sensitized locomotor response to amphetamine in female and male rodents as well as enhanced drug reward in male rats.

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.

Electrophysiological correlates of sleep disturbance induced by acute and chronic administration of D-amphetamine

Sleep disturbance is the strongest predictor of manic relapse and is considered one of the most important objective measures of treatment response in bipolar disorder (BD). However, the neurobiological mechanisms underlying sleep disturbance in BD are poorly understood. The administration of psychostimulants to rodents can trigger a number of manic-like behaviors. Therefore, the present study aims to investigate the effects of single and repeated D-amphetamine (AMPH) administration on sleep patterns in rats. Sleep was continuously monitored during light periods after single and repeated (7 days) injections of AMPH (2 mg/kg, i.p.) or saline in adult Wistar rats using electrocorticogram and electromyographic recordings. Acute injections of AMPH suppressed sleep for the first 2 h, and were followed by a gradual increase in the amount of sleep. Both slow wave sleep (SWS) and paradoxical sleep (PS) were compromised. Repeated exposure to AMPH led to a drastic disruption of the sleep-wake cycle that was mainly characterized by a decrease of PS during all time-points recorded in comparison to the saline group. Furthermore, both acute and chronic AMPH administration induced longer latencies to both SWS and PS. These findings suggest that AMPH produces profound sleep disturbances and decreases PS sleep. Given that some of these abnormalities are observed in individuals with BD, this animal model can provide a means to investigate neurobiological aspects of sleep disturbance in BD, as well as their response to mood stabilizers.

Effects of sleep loss on sleep architecture in Wistar rats: gender-specific rebound sleep

This study was designed to examine the influence of gender on sleep rebound architecture after a 4-day paradoxical sleep deprivation period. After a 5-day baseline sleep recording, both male and female rats in different phases of the estrus cycle were submitted to paradoxical sleep deprivation for 96 h. After this period, the sleep rebound recording was evaluated for 5 days (one estrus cycle). The findings revealed that after paradoxical sleep deprivation, sleep efficiency and paradoxical sleep returned to baseline values on the second day of the light period, for all except the proestrus group. During the dark rebound period, only the female groups presented increased sleep efficiency on the first day. Paradoxical sleep returned to baseline values on the third day, except for males and the cycling females submitted to paradoxical sleep deprivation in the diestrus phase, whose baseline values returned to normal on the second day of rebound period. Thus, the females and males displayed distinct patterns as a result of sleep disruption.

Influence of chronic cocaine treatment and sleep deprivation on sexual behavior and neurogenesis of the male rat

The present study investigated the influence of chronic cocaine treatment on genital reflexes associated with paradoxical sleep deprivation (PSD), and possible alterations in hippocampus neurogenesis of the male rat. At 21 days of age, the rats were distributed into two groups and injected with saline or cocaine (7 mg/kg, three times a week for 12 weeks). At age 90 days, they were submitted to a four-day period of PSD (PSD groups) or maintained in home-cages (control groups), challenged with saline or cocaine administration, and placed in observation cages to assess genital reflexes. Two additional groups were used to quantify neurogenesis. PSD rats treated chronically with cocaine and challenged with saline did not differ from their respective control groups. The association of PSD with cocaine potentiated penile erection (PE) when compared to PSD-saline (saline challenged) rats, and these effects were similar to those observed in long-term cocaine treated rats. The bromodeoxyuridine (BrdU) assay indicated a reduction in BrdU-positive cells in the adult hippocampus after chronic cocaine treatment. These findings show that long-term cocaine treatment from brain development through adulthood had a marked effect on sexual responses and neuronal proliferation.

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.

Different stress modalities result in distinct steroid hormone responses by male rats

Since both paradoxical sleep deprivation (PSD) and stress alter male reproductive function, the purpose of the present study was to examine the influence of PSD and other stressors (restraint, electrical footshock, cold and forced swimming, N = 10 per group) on steroid hormones in adult Wistar male rats. Rats were submitted to chronic stress for four days. The stressors (footshock, cold and forced swimming) were applied twice a day, for periods of 1 h at 9:00 and 16:00 h. Restrained animals were maintained in plastic cylinders for 22 h/day whereas PSD was continuous. Hormone determination was measured by chemiluminescent enzyme immunoassay (testosterone), competitive immunoassay (progesterone) and by radioimmunoassay (corticosterone, estradiol, estrone). The findings indicate that PSD (13.7 ng/dl), footshock (31.7 ng/dl) and cold (35.2 ng/dl) led to lower testosterone levels compared to the swimming (370.4 ng/dl) and control (371.4 ng/dl) groups. However, progesterone levels were elevated in the footshock (4.5 ng/ml) and PSD (5.4 ng/ml) groups compared to control (1.6 ng/ml), swimming (1.1 ng/ml), cold (2.3 ng/ml), and restrained (1.2 ng/ml) animals. Estrone and estradiol levels were reduced in the PSD, footshock and restraint groups compared to the control, swimming and cold groups. A significant increase in corticosterone levels was found only in the PSD (299.8 ng/ml) and footshock (169.6 ng/ml) groups. These changes may be thought to be the full steroidal response to stress of significant intensity. Thus, the data suggest that different stress modalities result in distinct steroid hormone responses, with PSD and footshock being the most similar.

Cholinergic mechanisms in cocaine-induced genital reflexes in paradoxical sleep-deprived male rats

In view of the fact that paradoxical sleep deprivation (PSD) modifies cocaine-induced genital reflexes (penile erection [PE] and ejaculation [EJ]), the aim of this study was to address the interaction of cholinergic agents with the action of cocaine on the genital reflexes of PSD male rats. After a 4-day period of PSD, each group was administered with cholinergic drugs 1 h prior to cocaine and was placed in observation cages. The administration of nicotine (0.12, 0.25, 0.5 and 1 mg/kg sc) reduced the frequency and number of animals displaying PE and increased PE latency. Pretreatment with mecamylamine (1.25, 5, 10 and 20 mg/kg sc) also significantly reduced PE frequency for all doses used. The percentage of rats showing EJ was significantly reduced in the group pretreated with 1 mg/kg of nicotine compared with the saline group. The administration of pilocarpine (1.25, 2.5, 5 and 10 mg/kg sc) and atropine (1.25, 5, 10 and 20 mg/kg sc) led to a reduction in the frequency of PE displayed by the rats. These data show that agonist and antagonist cholinergic drugs inhibit genital reflexes in PSD male rats injected with cocaine. The data also suggest that the stimulating action of cocaine in potentiating the sexual effects in PSD rats does not override the effects of the cholinergic mechanisms of sexual behavior.

Age-related effects on genital reflexes induced by paradoxical sleep deprivation and cocaine in rats

Although sexual function often decreases with age, a recent study demonstrated that paradoxical sleep deprivation (PSD) was effective in inducing penile erection (PE) in 60% of 22-month-old PSD rats after acute cocaine injection, whereas this behavior was absent in non-PSD control rats. The present study sought to compare alterations in genital reflexes (PE and ejaculation-EJ) induced by PSD followed by acute cocaine or saline at different points in the life span of male rats. Rats of different ages (3, 6, 10, 12, 18, 22 and 28 months), were given a single injection of either saline or cocaine (7 mg/kg, i.p.) after a 4-day period of PSD, and then evaluated for genital reflexes. Results indicated that genital reflexes in PSD rats given saline become less frequent with age and disappear after the age of 18 months. However, cocaine potentiated and prolonged these behaviors until the age of 22 months. Although a number of factors are involved in such a complex phenomenon as PE, we suggest that the previously documented dopamine receptor supersensitivity induced by PSD may be an important contributor to the potentiation by cocaine of genital reflexes after sleep deprivation.

Sleep patterns over 21-day period in rats with chronic constriction of sciatic nerve

The main purpose of the present study was to examine sleep patterns over 21-day periods of rats in a peripheral neuropathy model induced by sciatic nerve constriction. Evaluation of the recordings showed that chronic constrictive injury (CCI) induced sleep alterations such as reduced sleep efficiency and increased number of arousals, especially during the light period. Among these alterations, sleep patterns were most affected between day 2 and day 10. The rats took longer to get to sleep from day 2 to 7 days after the CCI in the light period. Additionally, latency to the first paradoxical sleep episode was reduced in the second to fourth day after CCI in both light and dark period recordings. In conclusion, sciatic nerve constriction induced poor sleep quality with disrupted sleep in rats, particularly during the first week of that condition.

Facilitation of ejaculation after methamphetamine administration in paradoxical sleep deprived rats

This study investigated the effects of methamphetamine (MA) on genital reflexes in paradoxical sleep deprived (PSD) rats. Different doses of MA (0, 4, 16 and 64 mg/kg) were acutely given after PSD or the equivalent time to control animals. We observed enhancement of spontaneous ejaculation in PSD rats with larger doses of MA, the highest of which induced ejaculation in 100% of the PSD rats. This was significantly higher than the 30% in the control. Although testosterone exerts motivational effects on male sexual behavior, our data shows that testosterone levels were lower after the PSD period in saline and in the 64 mg/kg MA groups, which present ejaculation at different rates (20% and 100%, respectively). Progesterone levels were significantly higher in PSD-saline in relation to control group and in the 16 and 64 mg/kg of MA groups compared to the other doses. Since PSD induces dopaminergic alterations and dopamine (DA) has a key role in male sexual behavior, plasma DA was also measured. The DA concentration was enhanced in all PSD groups compared with their control group. The mechanism that activates steroid hormones may represent an important physiological effect through which neurotransmitters can affect behavioral events. These data show that MA facilitates ejaculation in PSD rats, however, further studies need to be carried out in order to clarify the hormonal-neurochemical mechanisms involved.

Influence of paradoxical sleep deprivation and cocaine on development of spontaneous penile reflexes in rats of different ages

Recent studies have established that paradoxical sleep deprivation (PSD) and cocaine administration induce genital reflexes (penile erection and ejaculation) in adult and old rats. To determine whether the same effects would induce spontaneous genital reflexes in rats of different ages (30-90 days old), we administered with cocaine (7 mg/kg) or saline to rats after a 4-day period of PSD, or at the equivalent time-point in control animals, and penile erection and ejaculation were then evaluated. In PSD rats administered cocaine, erection was observed from 30 days old to 90 days old, when both genital reflexes reached a peak. Animals submitted to PSD and saline injection showed erection from 60 to 90 days old. None of the control (saline and cocaine) groups of any age displayed these behaviors. The effects of PSD on steroid hormone levels showed that, although testosterone levels increased with age, PSD caused a marked decrease in testosterone at all ages evaluated. Progesterone and corticosterone levels were higher in PSD groups than in the respective control groups. These findings suggest that the interaction of PSD and cocaine probably enhances dopaminergic transmission in the brain and may accelerate the development of genital reflexes in male rats.

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.

Does paradoxical sleep deprivation and cocaine induce penile erection and ejaculation in old rats?

A recent study has established that paradoxical sleep deprivation (PSD) and cocaine administration elicit genital reflexes (penile erection and ejaculation) in young rats. To discover whether the same effects occurred in old animals submitted to PSD, we administered cocaine (15 mg/kg) to young (3-month) and old (22-month) male rats after a 4-day period of PSD or at the equivalent time-point in control animals. We then evaluated erections and ejaculations. Sixty per cent of the old-PSD group displayed erection, although ejaculation was not observed. Genital reflexes were absent in young and old control groups. We found that PSD reduced testosterone and increased progesterone levels in both young and old PSD groups. In conclusion, our results suggest that although genital reflexes usually decrease with age, testosterone levels alone cannot account for these changes. The interaction of PSD and cocaine probably enhances dopamine transmission in the brain and may elicit penile erection in old rats.

Distinct effects of paradoxical sleep deprivation and cocaine administration on sexual behavior in male rats

As there are data showing enhanced sexual activity in paradoxical sleep deprived (PSD) rats, and cocaine (COC) is a drug of abuse known to also increase the sexual drive, the present study aimed to assess sexual behavior in animals submitted to PSD and/or COC administration. The data revealed that PSD followed by COC administration produced the largest percentage of animals having erection and ejaculation (100% and 60%) and differ statistically from the control groups. The PSD group that received saline produced 50% erections and 20% ejaculations whereas COC administration induced 10% erections and 10% ejaculations. Sexual activity was absent in control animals (saline injection). These findings are due probably to PSD causing supersensitivity of dopamine (DA) receptors exacerbating the cocaine actions on dopaminergic pathways inducing penile erection and ejaculation.