Cytokine and microRNA levels during different periods of paradoxical sleep deprivation and sleep recovery in rats.

BACKGROUND: Sleep has a fundamental role in the regulation of homeostasis. The aim of this study was to assess the effect of different periods of paradoxical sleep deprivation (PSD) and recovery on serum levels of cytokines and miRNAs related to inflammatory responses. METHODS: Male Wistar rats were submitted to a PSD of 24, 96, or 192 h, or of 192 h followed by 20 days of recovery (192 h PSD+R). The concentrations of corticosterone, cytokines (IL-6, TNF, IL-10, Adiponectin) and miRNAs (miR-146a, miR-155, miR-223, miR-16, miR-126, miR-21) in serum were evaluated. RESULTS: At PSD 24 h a significant increase of IL-6 and decrease of IL-10 were observed. At PSD 96h adiponectin increased. At 192 h of PSD IL-6 increased significantly again, accompanied by a threefold increase of IL-10 and an increase of serum corticosterone. After 20 days of recovery (192 h PSD+R) corticosterone, IL-6 and TNF levels increased significantly, while IL-10 decreased also significantly. Regarding the miRNAs at 24 h of PSD serum miR-146a, miR-155, miR-223, and miR-16 levels all increased. At 96 h of PSD miR-223 decreased. At 192 h of PSD decreases in miR-16 and miR-126 were observed. After recovery serum miR-21 increased and miR-16 decreased. CONCLUSION: PSD induces a dynamic response likely reflecting the induced cellular stress and manifested as variating hormonal and inflammatory responses. Sleep deprivation disturbed corticosterone, cytokine and miRNA levels in serum related to the duration of sleep deprivation, as short-term PSD produced effects similar to those of an acute inflammatory response and long-term PSD induced long-lasting disturbances of biological mediators.

Inflammation Related MicroRNAs Are Modulated in Total Plasma and in Extracellular Vesicles from Rats with Chronic Ingestion of Sucrose.

Circulating microRNAs (miRNAs) and the functional implications of miRNAs contained in extracellular vesicles (EVs) have gained attention in the last decade. Little is known about the regulation of the abundance of plasma miRNAs in response to chronic ingestion of carbohydrates. Therefore, we explored the circulating levels of miR-21, miR-146a, miR-155, and miR-223 in rats consuming sucrose in drinking water. Weanling Wistar rats were 25 weeks with 30% sucrose in drinking water, and miRNAs expression was determined in total plasma and in microvesicles, by RT-qPCR with TaqMan probe based assays for miR-21, miR-146a, miR-155, and miR-223, using cel-miR-39 (as spike in control and reference). Endotoxemia was also measured. Sucrose-fed animals showed higher body weight and retroperitoneal adipose tissue as well as higher glucose and triglyceride plasma levels than controls. Plasma endotoxin levels were low and not different among groups. Plasma miR-21 and miR-223 were higher in the sucrose group (p < 0.05), whereas miR-155 tended to be lower (p = 0.0661), and miR-146a did not show significant differences. In the plasma EVs the same trend was found except for miR-146a that showed significantly higher levels (p < 0.05). Overall, our results show that high carbohydrate ingestion modulates circulating miRNAs levels related to an inflammatory response.

Effects of different periods of paradoxical sleep deprivation and sleep recovery on lipid and glucose metabolism and appetite hormones in rats.

Sleep has a fundamental role in the regulation of energy balance, and it is an essential and natural process whose precise impacts on health and disease have not yet been fully elucidated. The aim of this study was to assess the consequences of different periods of paradoxical sleep deprivation (PSD) and recovery from PSD on lipid profile, oral glucose tolerance test (OGTT) results, and changes in insulin, corticosterone, ghrelin, and leptin concentrations. Three-month-old male Wistar rats weighing 250-350 g were submitted to 24, 96, or 192 h of PSD or 192 h of PSD with 480 h of recovery. The PSD was induced by the multiple platforms method. Subsequently, the animals were submitted to an OGTT. One day later, the animals were killed and the levels of triglycerides, total cholesterol, lipoproteins (low-density lipoprotein, very-low-density lipoprotein, and high-density lipoprotein), insulin, ghrelin, leptin, and corticosterone in plasma were quantified. There was a progressive decrease in body weight with increasing duration of PSD. The PSD induced basal hypoglycemia over all time periods evaluated. Evaluation of areas under the curve revealed progressive hypoglycemia only after 96 and 192 h of PSD. There was an increase in corticosterone levels after 192 h of PSD. We conclude that PSD induces alterations in metabolism that are reversed after a recovery period of 20 days.

Hormone replacement with 17ß-estradiol plus dihydrotestosterone restores male sexual behavior in rats treated neonatally with clomipramine.

Male sexual behavior (MSB) in rodents, in both its consummatory and motivational components, is regulated by hormones such as testosterone, 17ß-estradiol and 5-α-dihydrotestosterone. In experiments, neonatal treatment with clomipramine (CMI; a serotonin reuptake inhibitor) reproduces some of the signs of depression in adult age, including reduced sexual behavior manifested in a lower percentage of subjects that mount, intromit and ejaculate, although their testosterone levels were not altered. However, the effect of this treatment on estrogen levels and the consequences of hormone substitution using 17ß-estradiol and 5-α-dihydrotestosterone on the expression of male sexual behavior are still unknown. Therefore, the objective of the present study was to analyze the effect of neonatal treatment with CMI on plasma testosterone and 17ß-estradiol levels, and the role of testosterone, 17ß-estradiol and 5-α-dihydrotestosterone in altering the consummatory and motivational components of sexual behavior in male rats. To this end, it analyzed the copulatory parameters and sexual incentive motivation (SIM) of rats treated with CMI under two conditions: basal and post-hormone replacements. Neonatal treatment with CMI did not affect plasma testosterone or 17ß-estradiol concentrations, but did decrease both the consummatory component and sexual motivation according to the results of the SIM test. These aspects were recovered after administering 17ß-estradiol +5-α-dihydrotestosterone, but not testosterone.

Altered expression of 5-HT1A receptors in adult rats induced by neonatal treatment with clomipramine.

Chronic administration of clomipramine (CMI) to neonatal rats produces behaviors that resemble a depressive state in adulthood. Dysfunctions in the activity of the central nervous system's serotonergic function are important in understanding the pathophysiology of depression. The serotonin system is implicated in major depression and suicide and is negatively regulated by somatodendritic 5-HT1A autoreceptors. Desensitization of 5-HT1A autoreceptors is implicated in the long latency of some antidepressant treatments. Alterations in 5-HT1A receptor levels are reported in depression and suicide. In this study, we analyzed the effect of neonatal administration of CMI on the activity of 5-HT1A receptors, both pre- and post-synaptically, by administering an agonist of 5-HT1A receptors, 8-OH-DPAT, and then subjecting the rats to the forced swimming test (FST) a common procedure used to detect signs of depression in rats. Also measured were levels of the mRNA expression of 5-HT1A receptors in the dorsal raphe (DR), the hypothalamus and the hippocampus. Wistar rats were injected twice daily with CMI at doses of 15mgkg(-1) or saline as vehicle (CON) via s.c. from postnatal day 8 for 14days. At 3-4months of age, one set of rats from each group (CON, CMI) was evaluated for the effect of a selective agonist to the 5-HT1A receptor subtype, 8-OH-DPAT, by testing in the FST. Also determined was the participation of the pre- or post-synaptic 5-HT1A receptor in the antidepressant-like action of 8-OH-DPAT. This involved administering an inhibitor of tryptophan hydroxylase, parachlorophenylalanine (PCPA), and pretreatment with 8-OH-DPAT before the FST test and to evaluate the rectal temperature and locomotor activity. The expression of the mRNA of the 5-HT1A receptors was examined in the dorsal raphe nucleus, the hypothalamus and the hippocampus using the semi-quantitative RT-PCR method. The results from this study corroborate that neonatal treatment with clomipramine induces a pronounced immobility in the FST when animals reach adulthood, manifested by a significant decrease in swimming behavior, though counts of climbing behavior were not modified. This effect was similar in magnitude when 8-OH-DPAT was administered to CON group. Furthermore, the administration of 8-OH-DPAT induces a significant and similar increase in rectal temperature and locomotor activity in both the CON as in the CMI group. Neonatal treatment with CMI resulted in a significant decrease in the expression of the mRNA of the 5-HT1A receptors in the DR (% more than vehicle) in adulthood. In the case of the postsynaptic receptors located in the hypothalamus and hippocampus, neonatal treatment with CMI induced a significant increase in the mRNA expression of the 5-HT1A receptors. These data suggest that neonatal treatment with CMI induces a downregulation of the mRNA of the 5-HT1A autoreceptors in the DR, and an increment in the expression of the postsynaptic 5-HT1A receptors. The results after the administration of PCPA and 8-OH-DPAT on FST, rectal temperature and locomotor activity for both groups suggest that the function of postsynaptic receptors remains unchanged. All together these data show that the depressive behavior observed in adulthood in this animal model may be associated with long-term alterations in the expression of the mRNA of the 5-HT1A receptors.

Nicotine and fluoxetine induce arousing effects on sleep-wake cycle in antidepressive doses: a possible mechanism of antidepressant-like effects of nicotine.

A number of studies have reported an association between smoking and depression, and several reports suggest that nicotine (NIC) may act as an antidepressant. The present study was designed to determine whether the effects of NIC on sleep-wake patterns in rats are similar to those of the antidepressant fluoxetine (FLX), a selective serotonin reuptake inhibitor. Male rats were chronically implanted with a standard set of electrodes for sleep recording. We compared the effects of antidepressive doses of NIC, FLX and the combination of both drugs on sleep-wake pattern in rats subjected to one day, one week and two weeks of administration, as well as after the withdrawal of the two-week treatment. The changes observed in our study in an 8-h sleep recording period during one day, one week and two weeks of NIC administration are very similar to those observed in the rats that received FLX, which led to a decrease in both slow wave sleep II and rapid eye movement (REM) sleep as a consequence of an increase in wakefulness. In addition, all treatments also induced a significant lengthening of REM sleep latency onset. These data suggest that the antidepressant-like action of NIC could be caused by its arousing properties.

Antidepressant effects of nicotine and fluoxetine in an animal model of depression induced by neonatal treatment with clomipramine.

The association between smoking and depression has been widely investigated. Most of these reports suggest that nicotine (NIC) may act as an antidepressant. To examine the suggested antidepressant effect of nicotine and its possible interaction with the serotonergic system, we assessed the effect of nicotine and fluoxetine (FLX) in an animal model of depression induced by neonatal treatment with clomipramine (CLI) and submitted to the forced swim test (FST). Results corroborated that CLI-treated rats displayed higher levels of immobility. After the administration of nicotine (0.4 mg/kg sc) acutely (1 day), subchonically (7 days), and chronically (14 days), CLI-treated rats significantly reduced the immobility and increased swimming without affecting climbing. These effects were similar to the effects induced for subchronic and chronic administration of the antidepressant fluoxetine (5 mg/kg sc), a selective serotonin re-uptake inhibitor. However, fluoxetine failed to affect immobility when it was administered acutely. No synergism was observed when both drugs were administered simultaneously. The present results further corroborate the antidepressant action of nicotine and fluoxetine. The increase of swimming during the FST has been linked to an increase of serotonergic activity. Thus, it could be possible that the antidepressant action of nicotine is mediated by the serotonergic system.