Prasenjit Guchhait

Bio: Prasenjit Guchhait is an academic researcher from Banaras Hindu University. The author has contributed to research in topics: Spotted owlet & Pinealocyte. The author has an hindex of 3, co-authored 3 publications receiving 53 citations.

Relationship between the annual rhythms in melatonin and immune system status in the tropical palm squirrel, Funambulus pennanti.

Abstract: Melatonin (MEL) regulation of seasonal variation in immunity has been studied extensively in temperate mammals. This report is the first on a tropical mammal, the Indian palm squirrel, F. pennanti. In response to the annual environmental cycle, we studied the rhythms of plasma MEL and the immune parameters of total blood leucocytes, absolute blood lymphocytes and blastogenic responses of blood, thymus and spleen lymphocytes. We found that in parallel with MEL all the immune parameters increased during the month of April onward, when natural day length, temperature, humidity and rainfall were increasing. Maximum values occurred during November (reproductively inactive phase) when the values of all the physical factors were comparatively low. Lowest values occurred during January-March (reproductively active phase) when the values of the physical factors were lowest. In order to establish a clear interrelationship between the pineal MEL and the immune system function, we manipulated these squirrels with exogenous MEL (25mg/100 g B wt/day) at 1730 h during their pineal inactive phase (March) while another group was pinealectomized (Px) during November when their pineal was active. The MEL injection significantly increased all the immune parameters, while Px decreased them significantly. Hence, we suggest that MEL is immuno-enhancing for this tropical squirrel, and plays an important role in the maintenance of its immunity in accordance with the seasonal changes in environmental factors and gonadal status.

Pineal gland of a nocturnal bird, Indian spotted owlet, Athene brama: morphological and endocrine observations.

Abstract: It has been reported that owls (Strigiformes) do not have a pineal gland. However, our light microscopy study revealed an intermediate form of tubulofollicular and solid-type large pineal gland in a tropical owlet, Athene brama. The epithelial cells forming follicles (6–8) in the distal region and the solid cluster of parenchymal cells of different diameters in the proximal region anteriorly tapered with a long cylindrical stalk and continued into commissural organs and choroid plexus. The intrapineal localization of perivascular nerve fibers and blood vessels clearly explained the sympathetic innervation as well as vascularization of this neuroendocrine gland. Further, electron microscopy revealed a developed intracellular structure of the pinealocytes with a large number of mitochondria, Golgi bodies, and granular as well as clear vesicles in the process terminals. The evidence of intrapinealocyte lipid droplets and dense bodies and a moderate amount of melatonin in plasma (ranging from 100–365 pg/mL) during different reproductive phases finally proved a defined secretory activity of the gland in this tropical, nocturnal bird. J. Exp. Zool. 287:145–150, 2000. © 2000 Wiley-Liss, Inc.

Seasonal Adreno-Cortical Cycle of a Nocturnal Bird, Indian Spotted Owlet Athene brama: Biochemical and Morphological Observations

Abstract: It is well reported that the environmental factors along with different endocrine stimulus play a crucial role in maintenance of adrenocortical activity in birds. This study is first to report a detailed seasonal activity cycle of adrenal cortex, particu-larly its secretory physiology in a tropical nocturnal bird, Indian spotted owlet Athene brama. The maximum cortical activity having highest glandular mass, glandular free cholesterol, esterified cholesterol profiles, and peak level of corticosterone in plasma coincided with the long day length, highest temperature and increasing amplitude of relative humidity and rainfall of the early summer month, May. Cortical activity declined to minimum level in August when the ecofactors also declined parallely and hence, the birds entered into partial hibernation. The cortical activity progressed slowly throughout the winter (September–March) to reach maximum level in May. Further, the electron microscopic observations of cortical cell morphology strongly supported...

A review of the multiple actions of melatonin on the immune system

Abstract: This review summarizes the numerous observations published in recent years which have shown that one of the most significant of melatonin’s pleiotropic effects is the regulation of the immune system. The overview summarizes the immune effects of pinealectomy and the association between rhythmic melatonin production and adjustments in the immune system as markers of melatonin’s immunomodulatory actions. The effects of both in vivo and in vitro melatonin administration on non-specific, humoral, and cellular immune responses as well as on cellular proliferation and immune mediator production are presented. One of the main features that distinguishes melatonin from the classical hormones is its synthesis by a number of nonendocrine extrapineal organs, including the immune system. Herein, we summarize the presence of immune system-synthesized melatonin, its direct immunomodulatory effects on cytokine production, and its masking effects on exogenous melatonin action. The mechanisms of action of melatonin in the immune system are also discussed, focusing attention on the presence of membrane and nuclear receptors and the characterization of several physiological roles mediated by some receptor analogs in immune cells. The review focuses on melatonin’s actions in several immune pathologies including infection, inflammation, and autoimmunity together with the relation between melatonin, immunity, and cancer.

The modulatory role of melatonin on immune responsiveness.

Abstract: Afterhe successful discovery of the melatonin molecule by Aaron B Lerner et al at Yale University in 1958, melatonin and the pineal gland, a tiny endocrine gland situated at the center of the human brain, have primarily been considered in terms of their effects on the endocrine and reproductive systems. During the last decade, a substantial body of research has defined melatonin as a remarkable molecule with pleiotropic effects on the immune system. Moreover, its synthesis cannot be considered as exclusively endocrine; key immunocompetent cells have the functional enzymatic machinery for melatonin synthesis, paving the wayfo r complex intracrine, autocrine and paracrine regulatory loops. The immunomodulatory role of melatonin, with regard to infection, inflammation and autoimmunity, is outlined here, and the evidence discussed in this review strengthens the notion that the nature of an immune response may be modified, and therefore therapeutically manipulated, by circadian effector signals.

Can melatonin reduce the severity of COVID-19 pandemic?

Abstract: 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.

The lunar cycle: effects on human and animal behavior and physiology.

Abstract: Human and animal physiology are subject to seasonal, lunar, and circadian rhythms Although the seasonal and circadian rhythms have been fairly well described, little is known about the effects of the lunar cycle on the behavior and physiology of humans and animals The lunar cycle has an impact on human reproduction, in particular fertility, menstruation, and birth rate Melatonin levels appear to correlate with the menstrual cycle Admittance to hospitals and emergency units because of various causes (cardiovascular and acute coronary events, variceal hemorrhage, diarrhea, urinary retention) correlated with moon phases In addition, other events associated with human behavior, such as traffic accidents, crimes, and suicides, appeared to be influenced by the lunar cycle However, a number of reports find no correlation between the lunar cycle and human reproduction and admittance to clinics and emergency units Animal studies revealed that the lunar cycle may affect hormonal changes early in phylogenesis (insects) In fish the lunar clock influences reproduction and involves the hypothalamus-pituitary-gonadal axis In birds, the daily variations in melatonin and corticosterone disappear during full-moon days The lunar cycle also exerts effects on laboratory rats with regard to taste sensitivity and the ultrastructure of pineal gland cells Cyclic variations related to the moon's phases in the magnitude of the humoral immune response of mice to polivinylpyrrolidone and sheep erythrocytes were also described It is suggested that melatonin and endogenous steroids may mediate the described cyclic alterations of physiological processes The release of neurohormones may be triggered by the electromagnetic radiation and/or the gravitational pull of the moon Although the exact mechanism of the moon's influence on humans and animals awaits further exploration, knowledge of this kind of biorhythm may be helpful in police surveillance, medical practice, and investigations involving laboratory animals

Bidirectional communication between the pineal gland and the immune system.

Abstract: The pineal gland is a vertebrate neuroendocrine organ converting environmental photoperiodic information into a biochemical message (melatonin) that subsequently regulates the activity of numerous target tissues after its release into the bloodstream. A phylogenetically conserved feature is increased melatonin synthesis during darkness, even though there are differences between mammals and birds in the regulation of rhythmic pinealocyte function. Membrane-bound melatonin receptors are found in many peripheral organs, including lymphoid glands and immune cells, from which melatonin receptor genes have been characterized and cloned. The expression of melatonin receptor genes within the immune system shows species and organ specificity. The pineal gland, via the rhythmical synthesis and release of melatonin, influences the development and function of the immune system, although the postreceptor signal transduction system is poorly understood. Circulating messages produced by activated immune cells are reciprocally perceived by the pineal gland and provide feedback for the regulation of pineal function. The pineal gland and the immune system are, therefore, reciprocally linked by bidirectional communication.