Chandana Haldar

Bio: Chandana Haldar is an academic researcher from Banaras Hindu University. The author has contributed to research in topics: Melatonin & Pineal gland. The author has an hindex of 25, co-authored 161 publications receiving 1964 citations. Previous affiliations of Chandana Haldar include Semmelweis University.

Melatonin, Gestation and Fetal Development

Abstract: The pineal gland, the transducer of several environmental cues through its hormone, melatonin, is known to play a critical role in the reproduction of several seasonally breeding mammals. The role of pineal gland in the control of male reproduction is already established beyond doubt. The logical hypothesis that the pineal gland would be involved in the aspects of female reproduction, particularly gestation, embryonic development and fetal growth, has been tested in a few seasonally breeding mammals and this paper reviews the outcome as of now. Evidence for establishment of an inverse relationship before pregnancy followed by moderately high activity with a positive correlation during pregnancy and a sudden increase in pineal activity during parturition has been produced, which suggests that high melatonin level has something to do with parturition or early abortion. The pineal gland perhaps maintains the normal physiology during gestation and post-parturition periods. This is further reflected in the prolactin levels of fetal sheep which is modulated by the photoperiod experienced by the mother during gestation. Maternal photoperiodic exposures during gestation and lactation periods alter the neonatal growth and sexual maturation of the Indian palm squirrel via the maternal transfer of photoperiodic information through the pineal gland, as aspect known as "pineal programming". The primary source of melatonin for the fetus is the maternal pineal gland, which is transferred across the placenta during conception and, later after parturition, through the milk, which suggests that a maternally generated melatonin rhythm would be expressed in fetal cerebrospinal fluid as well as in the circulation. Further, maternal melatonin is necessary for normal somatic growth and postnatal development of reproductive organs of the offspring. Melatonin ultimately affects reproductive activity by modulating hypothalamic neuroendocrine circuits whose activity is necessary for gonadal function. The influence of melatonin on reproductive development begins during the prenatal period and extends into the postnatal life. Photoperiodic information, mediated via the pineal gland may be important for maintaining gestational physiology as well as postpartum recovery in female rodents. Further, melatonin has been shown to play adaptive role in the maintenance of delayed embryonic development in bats. Correlation between a developmental decline in melatonin levels and the timing of puberty in humans led to the speculation that melatonin regulates the timing of puberty in the human. These studies on the influence of melatonin on gestation indicate two major inferences viz., melatonin could be one of the major hormones establishing homeostasis during gestation since any disturbance in the level of melatonin causes abortion, and melatonin is one of the hormones of great adaptive significance for embryonic diapause.

Melatonin Pre-treatment Alleviates UVA Radiation Induced Oxidative Stress andApoptosis in the Skin of a Diurnal Tropical Rodent Funambulus pennanti

Abstract: UV radiation has been established as a pro-oxidant that mediates tissue injury by triggering the generation of free radicals. However UVA induced oxidative injury has never been investigated before in the skin of a tropical diurnal rodent which spends longer time directly under the sun for foraging. The present study aimed to note the level of oxidative stress induced by 6.36 Jcm-2 UVA radiations on the skin and its possible prevention by melatonin. The oxidative load was assessed by the activities of key antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT)) and generation of thiobarbituric acid reactive substances (TBARS). Cutaneous apoptosis if any was checked by the expression of Bcl-2, p53 and Heme oxygenase-I (HO-I). Melatonin membrane receptor expression (MT1) and AANAT activity was also investigated to elucidate the protective effect of melatonin. UVA radiation increased the lipid peroxidation, suppressed the enzymatic antioxidant defense system and increased the HO-I expression. Melatonin restored redox balance and up regulated Bcl-2 and down regulated p53 levels. The restoration of AANAT activity also proved beneficial. In summary melatonin can be a part of topical applications or oral supplements that might help to reduce the UVA radiation mediated cutaneous oxidative damages.

Eco-Immunology: Role of Melatonin in Avian Immune Defense

Abstract: Avian immunology is a fascinating and growing field. Ecologists are now taking an interest in measuring immune-competence and determining its importance as a heritable trait for the survival of the wild species. Seasonally breeding animals encounter different environmental challenges throughout the year. In order to survive in specific environments these animals have developed various strategies that help them to find food, protect themselves from the tough environments, and also reproduce accordingly. Indeed, wild birds are continually challenged with different natural stressors such as shortage of food (during winter and rainy season), lack of water during summer, predator pressure in social system, sudden change in weather, season-bound diseases, infection (like avian influenza), etc. Only a few ecological studies have analyzed the stress and general immunity in wild birds that might have a link with the anti-stress hormone melatonin. Therefore, approaches improving our understanding of the stress-induced immune depression and their interrelationship in birds are most desirable. Unfortunately, our knowledge of the immune system has advanced at a much faster pace for mammals while immunology of wild birds received less attention. The purpose of this review is to bring together the current knowledge on the biological effects of melatonin on avian immune defense with special emphasis on new immerging area of neuro-immuno-endocrinology i.e., eco-immunology.

Controlled drug delivery vehicles for cancer treatment and their performance.

Abstract: Although conventional chemotherapy has been successful to some extent, the main drawbacks of chemotherapy are its poor bioavailability, high-dose requirements, adverse side effects, low therapeutic indices, development of multiple drug resistance, and non-specific targeting. The main aim in the development of drug delivery vehicles is to successfully address these delivery-related problems and carry drugs to the desired sites of therapeutic action while reducing adverse side effects. In this review, we will discuss the different types of materials used as delivery vehicles for chemotherapeutic agents and their structural characteristics that improve the therapeutic efficacy of their drugs and will describe recent scientific advances in the area of chemotherapy, emphasizing challenges in cancer treatments.

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

Abstract: Melatonin, the major hormone produced by the pineal gland, displays characteristic daily and seasonal patterns of secretion. These robust and predictable rhythms in circulating melatonin are strong synchronizers for the expression of numerous physiological processes in photoperiodic species. In mammals, the nighttime production of melatonin is mainly driven by the circadian clock, situated in the suprachiasmatic nucleus of the hypothalamus, which controls the release of norepinephrine from the dense pineal sympathetic afferents. The pivotal role of norepinephrine in the nocturnal stimulation of melatonin synthesis has been extensively dissected at the cellular and molecular levels. Besides the noradrenergic input, the presence of numerous other transmitters originating from various sources has been reported in the pineal gland. Many of these are neuropeptides and appear to contribute to the regulation of melatonin synthesis by modulating the effects of norepinephrine on pineal biochemistry. The aim of this review is firstly to update our knowledge of the cellular and molecular events underlying the noradrenergic control of melatonin synthesis; and secondly to gather together early and recent data on the effects of the nonadrenergic transmitters on modulation of melatonin synthesis. This information reveals the variety of inputs that can be integrated by the pineal gland; what elements are crucial to deliver the very precise timing information to the organism. This also clarifies the role of these various inputs in the seasonal variation of melatonin synthesis and their subsequent physiological function.