Melatonin rhythms and pineal structure in a tropical bat, Anoura geoffroyi, that does not use photoperiod to regulate seasonal reproduction

A light-exploiting insectivorous bat shows no melatonin disruption under lights with different spectra

Natural light-dark cycles synchronize an animal's internal clock with environmental conditions. The introduction of artificial light into the night-time environment masks natural light cues and has the potential to disrupt this well-established biological rhythm. Nocturnal animal species, such as bats, are adapted to low light conditions and are therefore among the most vulnerable to the impacts of artificial light at night (ALAN). The behaviour and activity of insectivorous bats is disrupted by short-wavelength artificial light at night, while long-wavelength light is less disruptive. However, the physiological consequences of this lighting have not been investigated. Here, we examine the effect of LEDs with different spectra on urinary melatonin in an insectivorous bat. We collected voluntarily voided urine samples from Gould's wattled bats (Chalinolobus gouldii) and measured melatonin-sulfate under ambient night-time conditions (baseline) and under red (λP 630 nm), amber (λP 601 nm), filtered warm white (λP 586 nm) and cool white (λP 457 nm) LEDs. We found no effect of light treatment on melatonin-sulfate irrespective of spectra. Our findings suggest that short-term exposure to LEDs at night do not disrupt circadian physiology in the light-exploiting Gould's wattled bat.

Infections, Pandemics, and Sleep Disorders

Studies of the neurological symptoms and signs associated with the acute and late phases of infectious diseases are important in pandemic conditions. The novel coronavirus infection (COVID-19) pandemic has increased the number of patients with sleeplessness, this being an adverse prognostic factor for infections. This review addresses the factors and mechanisms of sleep impairments and their relationship with inflammation and immune system dysfunction in infectious diseases. In particular, impairments to the functioning of the melatoninergic system are discussed as the cause of sleeplessness during pandemics. The relevance of developing measures for rehabilitating patients, particularly use of Sonnovan to restore normal sleep, which plays a fundamental role in supporting people's mental and physical health, is emphasized.

Potential and Possible Therapeutic Effects of Melatonin on SARS-CoV-2 Infection

The absence of effective drugs for COVID-19 prevention and treatment requires the search for new candidates among approved medicines. Fundamental studies and clinical observations allow us to approach an understanding of the mechanisms of damage and protection from exposure to SARS-CoV-2, to identify possible points of application for pharmacological interventions. In this review we presented studies on the anti-inflammatory, antioxidant, and immunotropic properties of melatonin. We have attempted to present scientifically proven mechanisms of action for the potential therapeutic use of melatonin during SARS-CoV-2 infection. A wide range of pharmacological properties allows its inclusion as an effective addition to the methods of prevention and treatment of COVID-19.

Melatonin effects on sleep quality and outcomes of COVID-19 patients: An open-label, randomized, controlled trial

This trial aims to evaluate the effectiveness of adding melatonin to the treatment protocol of hospitalized coronavirus disease 2019 (COVID-19) patients. This was an open-label, randomized controlled clinical trial in hospitalized COVID-19 patients. Patients were randomized into a treatment arm receiving melatonin plus standard care or a control arm receiving standard care alone. The trial's primary endpoint was sleep quality examined by the Leeds Sleep Evaluation Questionnaire (LSEQ). The trial's secondary endpoints were symptoms alleviation by Day 7, intensive care unit admission, 10-day mortality, white blood cell count, lymphocyte count, C-reactive protein status, and peripheral capillary oxygen saturation. Ninety-six patients were recruited and allocated to either the melatonin arm (n = 48) or control arm (n = 48). Baseline characteristics were similar across treatment arms. There was no significant difference in symptoms on Day 7. The mean of the LSEQ scores was significantly higher in the melatonin group (p < 0.001). There was no significant difference in laboratory data, except for blood oxygen saturation, which has improved significantly in the melatonin group compared with the control group (95.81% vs. 93.65% respectively, p = 0.003). This clinical trial study showed that the combination of oral melatonin tablets and standard treatment could substantially improve sleep quality and blood oxygen saturation in hospitalized COVID-19 patients.

[Infections, pandemics and sleep disorders]

The study of neurological symptoms and signs connected with acute and long-term periods of infectious diseases is relevant during pandemics. The COVID-19 pandemic has increased the number of patients suffering from insomnia. Sleep disturbance is an unfavorable prognostic factor for infections. Risk factors and mechanisms of sleep disturbance, their relationship with inflammation and dysfunction of the immune system in infectious diseases are presented. In particular, dysfunction of the melatonergic system as the cause of insomnia during pandemics is considered. The authors highlight the relevance of measures aimed at the rehabilitation of patients, in particular, the use of sonnovan to restore normal sleep, which is important for a person's mental and physical health.

Possible Prophylactic Approach for SARS-CoV-2 Infection by Combination of Melatonin, Vitamin C and Zinc in Animals

SARS-CoV-2, an epidemic, causes severe stress in both human and animals and may induce oxidative stress (OS) and increases susceptibility to infection. Domestic animals are found infected by their COVID-2 suffering owners. Chronic immobilization stress (CIS), a model of psychological and physical stress of confinement, can trigger depression and anxiety in animals. We evaluated the ameliorative effect of the proposed SARS-CoV-2 prophylactic drugs melatonin, vitamin C, and zinc on CIS-induced OS, inflammation, and DNA damage in rats. Forty male Swiss albino rats (200–250 g, 7–9 weeks old) were divided into five groups as controls, CIS, treated with melatonin (20 mg/kg), and vitamin C plus zinc [VitC+Zn (250 + 2.5 mg/kg)] alone or in combination (melatonin+VitC+zinc) subjected to CIS for 3 weeks. CIS was induced by immobilizing the whole body of the rats in wire mesh cages of their size with free movement of head. Exposure to CIS significantly compromised the circulatory activities of superoxide dismutase, catalase, and glutathione with enhanced malondialdehyde, inflammatory markers (IL-6, IL10, and TNFα), and lymphocyte DNA damage in comparison to controls. Treatment with melatonin and VitC+Zn alone or in combination significantly restored the altered biochemical parameters and DNA damage of stressed rats to their respective control values. However, the cumulative action of melatonin with VitC+Zn was more effective in alleviating the CIS-induced OS, inflammation, and DNA damage. The present study indicates that the antioxidant combination can be an effective preventive measure to combat severe psychological and confinement stress-induced biochemical changes in animals due to abnormal conditions such as SARS-CoV-2.

The prophylaxis and treatment potential of supplements for COVID-19

The global impact of the new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), infection that caused COVID-19 has been evident in the last few months from the unprecedented socioeconomic disruption to more than 600,000 deaths. The lack of vaccine and effective therapeutic agents for the disease prompted world-wide effort to test those antiviral therapeutics already in use for other diseases. Another interesting approach has been based on the pathological sequel of the disease that involve severe inflammatory reaction (or the cytokine storm) associated with pneumonia in critically ill patients. This article outlines the prophylaxis therapeutic potential of supplements vitamins and micronutrients in COVID-19. By ameliorating the inflammatory and oxidative stress associated with the disease and some direct antiviral effects, the application of these agents as adjuvants and other alternative approaches are discussed. Available clinical trials including those currently registered on these supplements are scrutinized.

Melatonin potentials against viral infections including COVID-19: Current evidence and new findings

Viral infections are dangerous diseases for human health worldwide, which lead to significant morbidity and mortality each year. Because of their importance and the lack of effective therapeutic approaches, further attempts should be made to discover appropriate alternative or complementary treatments. Melatonin, a multifunctional neurohormone mainly synthesized and secreted by the pineal gland, plays some roles in the treatment of viral infections. Regarding a deadly outbreak of COVID-19 across the world, we decided to discuss melatonin functions against various viral infections including COVID-19. Therefore, in this review, we summarize current evidence on melatonin therapy for viral infections with focus on possible underlying mechanisms of melatonin actions.

Can melatonin reduce the severity of COVID-19 pandemic?

The current COVID-19 pandemic is one of the most devastating events in recent history. The virus causes relatively minor damage to young, healthy populations, imposing life-threatening danger to the elderly and people with diseases of chronic inflammation. Therefore, if we could reduce the risk for vulnerable populations, it would make the COVID-19 pandemic more similar to other typical outbreaks. Children don't suffer from COVID-19 as much as their grandparents and have a much higher melatonin level. Bats are nocturnal animals possessing high levels of melatonin, which may contribute to their high anti-viral resistance. Viruses induce an explosion of inflammatory cytokines and reactive oxygen species, and melatonin is the best natural antioxidant that is lost with age. The programmed cell death coronaviruses cause, which can result in significant lung damage, is also inhibited by melatonin. Coronavirus causes inflammation in the lungs which requires inflammasome activity. Melatonin blocks these inflammasomes. General immunity is impaired by anxiety and sleep deprivation. Melatonin improves sleep habits, reduces anxiety and stimulates immunity. Fibrosis may be the most dangerous complication after COVID-19. Melatonin is known to prevent fibrosis. Mechanical ventilation may be necessary but yet imposes risks due to oxidative stress, which can be reduced by melatonin. Thus, by using the safe over-the-counter drug melatonin, we may be immediately able to prevent the development of severe disease symptoms in coronavirus patients, reduce the severity of their symptoms, and/or reduce the immuno-pathology of coronavirus infection on patients' health after the active phase of the infection is over.

Artificial Light at Night (ALAN): A Potential Anthropogenic Component for the COVID-19 and HCoVs Outbreak

The origin of the coronavirus disease 2019 (COVID-19) pandemic is zoonotic. The circadian day-night is the rhythmic clue to organisms for their synchronized body functions. The "development for mankind" escalated the use of artificial light at night (ALAN). In this article, we tried to focus on the possible influence of this anthropogenic factor in human coronavirus (HCoV) outbreak. The relationship between the occurrences of coronavirus and the ascending curve of the night-light has also been delivered. The ALAN influences the physiology and behavior of bat, a known nocturnal natural reservoir of many Coronaviridae. The "threatened" and "endangered" status of the majority of bat species is mainly because of the destruction of their proper habit and habitat predominantly through artificial illumination. The stress exerted by ALAN leads to the impaired body functions, especially endocrine, immune, genomic integration, and overall rhythm features of different physiological variables and behaviors in nocturnal animals. Night-light disturbs "virus-host" synchronization and may lead to mutation in the genomic part of the virus and excessive virus shedding. We also proposed some future strategies to mitigate the repercussions of ALAN and for the protection of the living system in the earth as well.

Histology and Histometric Anatomy of the Male Reproductive System of Bat (Eidolon helvum)

The male reproductive system of fruit bat (Eidolon helvum) was studied histologically using light microscope. Thirty males (17 adults and 13 juveniles) were captured using net, weighed, aged using relative ossification of the wing bone, and dissected and reproductive tissue was processed for histomorphometry. On the basis of histological sections, the structures of a pair of testis containing the seminiferous tubules of adults were compacted in organization with spermatogenic cells. The epididymis has a thinner muscular region than the vas deferens with longitudinal folds on the mucosal lining. Two portions were observed in the prostate gland, while seminal vesicle has numerous trabeculae and bulbourethral gland was observed to have multiacini. There was increase in thickness of muscular region, epithelial height, and luminal diameter of epididymis and vas deferens between adults and juveniles. This work has documented the histology of the male reproductive system in bats, and ultrastructure and histochemistry are recommended for further insight into the reproductive biology.

Gross and Morphometric Anatomy of the Male Reproductive System of Bats (Eidolon helvum)

The present study aimed at examining the gross and morphometry of the reproductive tract of the male bats (Eidolon helvum). Thirty male bats (adults n = 17 and juveniles n = 13) were captured using net, weighed, aged using relative ossification of the wing bone, and dissected for gross examination. Morphologically, the mean body weight and forearm length in both adults and juveniles were 235.31 ± 6.30 g, 12.14 ± 0.19 cm and 69.54 ± 7.68 g, 7.77 ± 0.29 cm, respectively. The testicles were completely descended in adults with the penis projected cranially. The epididymides were found at the median border of the testis and continues as vas deferens. No significant differences (P > 0.05) were observed between right and left testicular weights in both adults and juveniles and also in lengths of different parts of the reproductive segments in both age groups assessed, respectively. This work has documented the gross anatomy of the male reproductive tract in bats. Ultrastructure and histochemistry are recommended for further insight into the reproductive biology.

Melatonin affects steroidogenesis and delayed ovulation during winter in vespertilionid bat, Scotophilus heathi

The aim of this study was to evaluate the role of melatonin in ovarian activity of Scotophilus heathi particularly in reference to changes in steroidogenesis and steroid receptor expression during the anovulatory period of delayed ovulation. Female S. heathi showed an increased circulating melatonin level during the period of delayed ovulation in winter coinciding with the increased androstenedione (A(4)) levels, body fat and ovarian androgen receptor expression. The circulating melatonin level decreased to a low level after winter during the period of ovulation in March which also coincided with the decreased circulating A(4) levels and body fat. The circulating estrogen (E(2)) showed two peaks corresponding with the two waves of follicular development in November and February. Both the isoforms of progesterone receptor (PR), PR-A and PR-B, remained high throughout the follicular development, but expression of PR-A declined significantly during the ovulation. The treatment with melatonin, both in vitro and in vivo, significantly increased progesterone and A(4), but not the estradiol synthesis by the ovaries of S. heathi. The study further suggested that the increased androgens during winter may be primarily due to the stimulatory effect of melatonin on steroidogenic enzyme 3beta-hydroxysteroid dehydrogenase (3beta-HSD) activity. Therefore the increased circulating melatonin level in S. heathi during winter delay (inhibits) ovulation through increased androgen synthesis, but suppression of estradiol synthesis.

Light microscopic and ultrastructural observations on the vomeronasal organ of Anoura (Chiroptera: Phyllostomidae)

The vomeronasal organ (VNO) is known to be present in bats of the family Phyllostomidae, but in most species this is inferred from the presence of accessory olfactory bulbs. Like primates, bats have profound intergroup variations in the vomeronasal system. Of the family Phyllostomidae (49 genera, 143 species) the VNO of approximately 60 species has been studied. Here, we report light microscopic observations of the VNO of Anoura geoffroyi (fetus and adult), A. caudifer, and A. cultrata, as well as ultrastructural observations of the VNO in adult A. geoffroyi. The organ is crescent-shaped, with a wide lumen encroached by a "mushroom body" that contains a venous sinus. In adults, the vomeronasal cartilage is reduced, being longer in absolute length in fetal A. geoffroyi compared with the adult. In the neuroepithelium, the receptor cell microvilli are dark, distinct, and short, emerging from a vesicular tuft; the supporting cell microvilli are relatively much longer. Large paravomeronasal ganglia are observed. The receptor-free epithelium is undulating and lacks cilia or microvilli. Some characteristics of the VNO in Anoura have not been reported in other chiropterans to date, such as the marked reduction of the vomeronasal cartilage and absence of cilia in the receptor-free epithelium. Moreover, if A. geoffroyi is representative, the genus has an adult neuroepithelial volume similar to other mammals of its body size. Further examination of uninvestigated phyllostomid VNOs may elucidate a phylogenetic history of the family, as well as ecological or social correlates of the VNO in the order Chiroptera.