Chandra Mohini Chaturvedi

Bio: Chandra Mohini Chaturvedi is an academic researcher from Banaras Hindu University. The author has contributed to research in topics: Quail & Vasotocin. The author has an hindex of 19, co-authored 92 publications receiving 1161 citations. Previous affiliations of Chandra Mohini Chaturvedi include University of Arkansas for Medical Sciences.

Effect of long and short photoperiod on vasotocin neurons of paraventricular nuclei and adrenal function of water deprived Japanese quail.

Abstract: The responses of magnocellular neurons of paraventricular nuclei (PVN) and changes to adrenal activity to water deprivation in Japanese quail maintained under gonado-inhibitory and stimulatory photoperiods were examined. Water deprivation of 4 days resulted in a 12% decrease in body weight of sexually regressed short day (SD, 6L:18D) quail, while the decrease was more (18%) in sexually stimulated long day (LD, 16L:8D) quail. The increase in plasma osmolality following water deprivation was also more (47%) in LD than to SD quail (36%). Under the LD condition, quail had increased numbers, sizes and immunostaining of ir-AVT neurons of PVN compared to SD condition. A significant increase in the number of ir-AVT neurons was observed following 4 days of water deprivation in both SD and LD quail compared to their respective fully hydrated controls. However, the degree of response was more under the LD compared to the SD condition suggesting that gonado-stimulatory long days increase the activity/response of the AVT system. Increased adrenal ascorbic acid content (i.e., activity) was also observed to quail of LD when compared to SD treatment. However, osmotic stress led to adrenal hypertrophy and hyperactivity of quail of both of the photoperiodic regimes. Our findings indicate that not only osmotic stress but also photo-gonadal stimulation upregulates the expression of hypothalamic AVT genes and increases the localization of ir-AVT in many neurons of PVN. The above results support the existence of a parallel adrenal-gonad relationship and increase in adrenal function during osmotic stress, which also leads to simultaneous increase in AVT system. We conclude that photo-sexual conditions alter hypothalamic vasotocinergic and adrenal activity in Japanese quail and the degree of stimulation of the two systems following osmotic stress is higher under gonado-stimulatory LD conditions.

Suppression of annual testicular development in Indian Palm Squirrel, Funambulus pennanti by 8 hr temporal relationship of serotonin and dopamine precursor drugs

Abstract: Daily injections of 5-HTP (5-hydroxytryptophan, serotonin precursor) and L-DOPA (L-Dihydroxyphenylalanine, dopamine precursor) given 8 hour apart inhibited normal testicular growth in seasonally breeding Indian Palm Squirrel,Funambuluspennanti leading to complete gonadal atrophy, which was maintained till the end of the study. HCG administration induced higher degree of gonadal development but, when the two treatments (HCG + 8 hr relationship of 5-HTP and L-DOPA) were given simultaneously no significant difference was observed compared to control.

Seasonal changes in immune function.

Abstract: Winter is energetically demanding Physiological and behavioral adaptations have evolved among nontropical animals to cope with winter because thermoregulatory demands increase when food availability decreases Seasonal breeding is central within the suite of winter adaptations among small animals Presumably, reproductive inhibition during winter conserves energy at a time when the adds of producing viable young are low In addition to the well-studied seasonal cycles of mating and birth, there are also significant seasonal cycles of illness and death among many populations of mammals and birds in the field Challenging winter conditions, such as low ambient temperatures and decreased food availability, can directly induce death via hypothermia, starvation or shock In some cases, survival in demanding winter conditions puts individuals under great physiological stress, defined here as an adaptive process that results in elevated blood levels of glucocorticoids The stress of coping with energetically demanding conditions can also indirectly cause illness and death by compromising immune function Presumably, the increased blood concentrations of adrenocortical steroids in response to winter stressors compromise immune function and accelerate catabolic mechanisms in the field, although the physiological effects of elevated glucocorticoids induced by artificial stressors have been investigated primarily in the laboratory However, recurrent environmental stressors could reduce survival if they evoke persistent glucocorticoid secretion The working hypothesis of this article is that mechanisms have evolved in some animals to combat seasonal stress-induced immunocompromise as a temporal adaptation to promote survival Furthermore, we hypothesize that mechanisms have evolved that allow individuals to anticipate periods of immunologically challenging conditions, and to cope with these seasonal health-threatening conditions The primary environmental cue that permits physiological anticipation of season is the daily photoperiod; however, other environmental factors may interact with photoperiod to affect immune function and disease processes The evidence for seasonal fluctuations in lymphatic organ size, structure, immune function, and disease processes, and their possible interactions with recurrent environmental stressors, is reviewed Seasonal peaks of lymphatic organ size and structure generally occur in late autumn or early winter and seasonal minima are observed prior to the onset of breeding Although many of the field data suggest that immune function and disease processes are also enhanced during the winter, the opposite seasonal pattern is also observed in some studies We propose that compromised immune function may be observed in some populations during particularly harsh winters when stressors override the enhancement of immune function evoked by short day lengths Because so many factors covary in field studies, assessment of our proposal that photoperiod mediates seasonal changes in immune function requires laboratory studies in which only photoperiod is varied A review of the effects of photoperiod on immune function in laboratory studies reveals that exposure to short day lengths enhances immune function in every species examined Short day exposure in small mammals causes reproductive inhibition and concomitant reduction in plasma levels of prolactin and steroid hormones, as well as alterations in the temporal pattern of pineal melatonin secretion These hormones affect immune function, and influence the development of opportunistic diseases, including cancer: however, it appears that either prolactin or melatonin secretion is responsible for mediating the effects of photoperiod on immune function Taken together, day length appears to affect immune function in many species, including animals that typically do not exhibit reproductive responsiveness to day length

Gene regulation in the magnocellular hypothalamo-neurohypophysial system.

Abstract: The hypothalamo-neurohypophysial system (HNS) is the major peptidergic neurosecretory system through which the brain controls peripheral physiology. The hormones vasopressin and oxytocin released from the HNS at the neurohypophysis serve homeostatic functions of water balance and reproduction. From a physiological viewpoint, the core question on the HNS has always been, "How is the rate of hormone production controlled?" Despite a clear description of the physiology, anatomy, cell biology, and biochemistry of the HNS gained over the last 100 years, this question has remained largely unanswered. However, recently, significant progress has been made through studies of gene identity and gene expression in the magnocellular neurons (MCNs) that constitute the HNS. These are keys to mechanisms and events that exist in the HNS. This review is an inventory of what we know about genes expressed in the HNS, about the regulation of their expression in response to physiological stimuli, and about their function. Genes relevant to the central question include receptors and signal transduction components that receive and process the message that the organism is in demand of a neurohypophysial hormone. The key players in gene regulatory events, the transcription factors, deserve special attention. They do not only control rates of hormone production at the level of the gene, but also determine the molecular make-up of the cell essential for appropriate development and physiological functioning. Finally, the HNS neurons are equipped with a machinery to produce and secrete hormones in a regulated manner. With the availability of several gene transfer approaches applicable to the HNS, it is anticipated that new insights will be obtained on how the HNS is able to respond to the physiological demands for its hormones.