Chronic sleep deprivation prolongs the reduction of sexual behaviour associated with daily sexual encounter in male rats

The involvement of amyloid-β in the central nervous system regulation underlying sleep deprivation-induced rapid ejaculation in rats

BACKGROUND

Although some studies suggest that sleep deprivation may affect ejaculation regulation, related research is limited, and the mechanisms remain unclear.

AIM

This study aimed to explore whether sleep deprivation influences ejaculation regulation through amyloid-beta and to investigate its potential mechanisms.

MATERIALS AND METHODS

Normal ejaculating rats were randomly distributed into three separate groups for the study, and treated with sleep deprivation combined with saline gavage, sleep deprivation combined with sodium butyrate gavage, and control with saline gavage. The levels of amyloid-beta and 5-HT1A receptors were assessed through Western blotting, PCR, and immunohistochemical techniques. The levels of interleukin-4 and serotonin (5-hydroxytryptamine) in the brain were determined by enzyme-linked immunosorbent assay.

RESULTS

The experiment showed that the rats in the sleep deprivation combined with saline gavage group rats had a significantly faster ejaculation compared to the control combined with saline gavage group rats. Meanwhile, sleep deprivation combined with saline gavage group had the highest levels of amyloid-beta oligomers in the brain tissue. Correlation results revealed that the levels of amyloid-beta oligomers in brain tissue were inversely related to ejaculation latency and positively associated with ejaculation frequency. Furthermore, we found that elevated levels of amyloid-beta oligomers in brain tissue led to upregulation of 5-HT1A receptor expression. Additionally, elevated levels of amyloid-beta oligomers in brain tissue were found to increase interleukin-4 levels, thereby reducing 5-hydroxytryptamine levels.

DISCUSSION

Sleep deprivation indeed accelerates ejaculation, and this acceleration is closely related to amyloid-beta. Sleep deprivation can increase amyloid-beta levels in brain tissue, mediating a decrease in 5-hydroxytryptamine levels and overexpression of 5-HT1A receptors, thereby accelerating ejaculation.

CONCLUSION

There is a significant correlation between elevated amyloid-beta levels in brain tissue because of sleep deprivation and accelerated ejaculation. This study's main findings offer insights into the development of acquired premature ejaculation linked to poor sleep and establish a theoretical framework for investigating potential treatments for this condition.

Low dose of propyl-pyrazole-triol, an agonist of estrogen receptor alpha, administration stimulates the Coolidge effect in fadrozole-treated male rats

Estrogen receptor (ER) α is involved in male sexual function. Here, we aim to investigate how ERα activation influences sexual satiety and the Coolidge effect (i.e., when a rat, that has reached sexual satiety, experiences an increased arousal after exposure to a novel sexual partner) in estrogen-deprived male rats. Male rats (8 per group) were treated daily for 29 days with either saline (Control group) or fadrozole dissolved in saline (1 mg/kg/day) 1 h before mating. On Days 13 and 29, rats treated with fadrozole received either no additional treatment (fadrozole group) or a single injection of propyl-pyrazole-triol (ERα-agonist group, dissolved in sesame oil, 1 mg/kg). Rats mated until reaching sexual satiety on Days 13 and 29. In these sessions, the Control group displayed higher frequency of intromission and ejaculation than the other groups. The ERα-agonist group mounted more frequently but reached sexual satiety sooner than the Control group. On Day 29, when exposed to a new sexual partner, the fadrozole-treated rats were less likely to display intromission than the other groups, or ejaculation than the Control group, or mounting than the ERα-agonist group. The Control group showed more ejaculatory behavior and shorter ejaculation latency than the other groups. Body weights, testosterone levels, estradiol levels, and ERα-immunoreactive cell counts in brain regions for sexual behavior were comparable between groups after 29 days of treatments. Our data suggest that estrogen helps regulate sexual satiety and the Coolidge effect in male rats.

TNF signaling pathway-mediated microglial activation in the PFC underlies acute paradoxical sleep deprivation-induced anxiety-like behaviors in mice

Acute sleep deprivation is a common condition in modern life and increases anxiety symptoms in healthy individuals. The neuroinflammatory response induced by microglial activation could be an important contributing factor, but its underlying molecular mechanisms are still unclear. In the present study, we first found that acute paradoxical sleep deprivation (PSD) induced by the modified multiple platform method (MMPM) for 6 h led to anxiety-like behavior in mice, as verified by the open field test, elevated plus maze test, light-dark box test, and marble burying test. In addition, bioinformatic analysis suggested an important relationship between acute sleep deprivation and brain inflammatory signaling pathways. Key genes enriched in the TNF signaling pathway were confirmed to be altered during acute PSD by qPCR and Western blot analyses, including the upregulation of the prostaglandin-endoperoxide synthase 2 (Ptgs2) and suppressor of cytokine signaling 3 protein (Socs3) genes and the downregulation of the cysteine-aspartic acid protease 3 (Casp3) gene. Furthermore, we found that microglial cells in the prefrontal cortex (PFC) were activated with significant branch structure changes and that the cell body area was increased in the PSD model. Finally, we found that minocycline, a tetracycline with anti-inflammatory properties, may ameliorate the anxiogenic effect and microglial activation. Our study reveals significant correlations of anxiety-like behavior, microglial activation, and inflammation during acute PSD.

Understanding the Associations of Prenatal Androgen Exposure on Sleep Physiology, Circadian Proteins, Anthropometric Parameters, Hormonal Factors, Quality of Life, and Sex Among Healthy Young Adults: Protocol for an International, Multicenter Study

Background

The ratio of the second finger length to the fourth finger length (2D:4D ratio) is considered to be negatively correlated with prenatal androgen exposure (PAE) and positively correlated with prenatal estrogen. Coincidentally, various brain regions are sensitive to PAE, and their functions in adults may be influenced by the prenatal actions of sex hormones.

Objective

This study aims to assess the relationship between PAE (indicated by the 2D:4D ratio) and various physiological (sex hormone levels and sleep-wake parameters), psychological (mental health), and sexual parameters in healthy young adults.

Methods

This study consists of two phases. In phase 1, we will conduct a survey-based study and anthropometric assessments (including 2D:4D ratio and BMI) in healthy young adults. Using validated questionnaires, we will collect self-reported data on sleep quality, sexual function, sleep chronotype, anxiety, and depressive symptoms. In phase 2, a subsample of phase 1 will undergo polysomnography and physiological and genetic assessments. Sleep architecture data will be obtained using portable polysomnography. The levels of testosterone, estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, prolactin, melatonin, and circadian regulatory proteins (circadian locomotor output cycles kaput [CLOCK], timeless [TIM], and period [PER]) and the expression levels of some miRNAs will be measured using blood samples. The rest and activity cycle will be monitored using actigraphy for a 7-day period.

Results

In Poland, 720 participants were recruited for phase 1. Among these, 140 completed anthropometric measurements. In addition, 25 participants joined and completed phase 2 data collection. Recruitment from other sites will follow.

Conclusions

Findings from our study may help to better understand the plausible role of PAE in sleep physiology, mental health, and sexual quality of life in young adults.

International Registered Report Identifier (IRRID)

DERR1-10.2196/29199

Comparison effects of chronic sleep deprivation on juvenile and young adult mice

Sleeplessness leads to a spectrum of neuropsychiatric disorders, affecting both juveniles and young adults. Studies have shown different sleep patterns at different stages of development. However, the molecular mechanisms underlying the effects of the same chronic sleep deprivation (CSD) on behaviours of juveniles and young adults remain elusive. Here, we aimed to evaluate the effects of CSD (6 days, 19 h per day) on anxiety-like behaviour, cognitive performance and molecular alterations in juvenile and young adult mice. Change in body weight suggested impaired physical development in CSD animals, specifically juveniles gaining weight at a lower rate and young adults losing weight. Behavioural performance indicated that CSD had little effect on spatial memory, but induced analogous anxiety-like phenotypes in both juveniles and young adults, as evidenced by no significant difference in the Y-maze experiment (Y-M) or the Morris water maze experiment (MWM), as well as the decreased open-arm distance percentage in the elevated plus maze experiment (EPM). In addition, CSD reduced the N-methyl-D-aspartic receptor subunit 2B (NR2B) and postsynaptic density protein 95 (PSD95) levels in juveniles, but these were increased in young adults. In conclusion, our results suggested that although CSD resulted in analogous anxiety-like behaviours in both juvenile and young adult mice, the underlying mechanisms might be different, which was indicated by the opposite change of synaptic proteins under CSD. These findings may help to better understand the important role of sleep and have constructive significance for human health.

The Rare Phenomenon of Consecutive Ejaculations in Male Rats

Mounting, intromission and ejaculation are commonly reported sexual behaviours in male rats. In a mating session, they can have several copulatory series with post-ejaculatory intervals in between ejaculations before they reach sexual satiety. Here, we describe a phenomenon where male rats displayed consecutive ejaculations (CE) with a short inter-ejaculatory interval (IEI). Male rats were daily mated with a sexually receptive female rat. Two out of 15 rats displayed CE in one of their mating tests. The first rat had CE at 9.9 and 10.1 min (IEI = 16.3 s) after the start of the test. The second rat showed CE at 28.1 and 28.5 min (IEI = 18.7 s) after the test onset. During the IEI, the rats did not show any mounting or intromission.