Browsing by Author "Chandra Mohini Chaturvedi"

Now showing 1 - 20 of 55

2.45 GHz low level CW microwave radiation affects embryo implantation sites and single strand DNA damage in brain cells of mice, mus musculus
(IEEE Computer Society, 2009) Vineet Prakash Singh; Priyanka Singh; Chandra Mohini Chaturvedi; Ritesh K. Shukla; Alok Dhawan; Ravi Kumar Gangwar; Surya Pal Singh
To study the effect of microwave radiation on the early stages of pregnancy (implantation) and DNA damage in brain cells, female mice were exposed to 2.45 GHz electromagnetic field (EMF) for 2 hours/ day at power density of 0.1250 mW/cm2 for the period of 30 days (pre-mating period, 22 days; mating period, 5 days; post mating period, 3 days). The results indicate asymmetrical implantation in the two horns of the uterus in addition to alteration in embryo positioning and altered embryo spacing in exposed mice as compared to control. The microwave radiation also induced significant DNA break in brain cells. Our findings point towards microwave radiation induced adverse effects on early embryonic development (implantation) as well as increased DNA damage in brain cells, although further studies are required to understand the extent and the mechanism of these effects. In view of the increased use of microwaves in the modern society and MW induced pathogenesis reported earlier as well as in the present study, it is necessary to define the safer use and threshold limit of the non-ionizing radiation in terms of its biological effects.
2.45 GHz microwave irradiation-induced oxidative stress affects implantation or pregnancy in mice, mus musculus
(2013) Saba Shahin; Vineet Prakash Singh; Ritesh K. Shukla; Alok Dhawan; Ravi Kumar Gangwar; Surya Pal Singh; Chandra Mohini Chaturvedi
The present experiment was designed to study the 2.45 GHz low-level microwave (MW) irradiation-induced stress response and its effect on implantation or pregnancy in female mice. Twelve-week-old mice were exposed to MW radiation (continuous wave for 2 h/day for 45 days, frequency 2.45 GHz, power density=0.033549 mW/cm2, and specific absorption rate=0.023023 W/kg). At the end of a total of 45 days of exposure, mice were sacrificed, implantation sites were monitored, blood was processed to study stress parameters (hemoglobin, RBC and WBC count, and neutrophil/lymphocyte (N/L) ratio), the brain was processed for comet assay, and plasma was used for nitric oxide (NO), progesterone and estradiol estimation. Reactive oxygen species (ROS) and the activities of ROS-scavenging enzymes- superoxide dismutase, catalase, and glutathione peroxidase-were determined in the liver, kidney and ovary. We observed that implantation sites were affected significantly in MW-irradiated mice as compared to control. Further, in addition to a significant increase in ROS, hemoglobin (p<0.001), RBC and WBC counts (p<0.001), N/L ratio (p<0.01), DNA damage (p<0.001) in brain cells, and plasma estradiol concentration (p<0.05), a significant decrease was observed in NO level (p<0.05) and antioxidant enzyme activities of MW-exposed mice. Our findings led us to conclude that a low level of MW irradiation-induced oxidative stress not only suppresses implantation, but it may also lead to deformity of the embryo in case pregnancy continues. We also suggest that MW radiation-induced oxidative stress by increasing ROS production in the body may lead to DNA strand breakage in the brain cells and implantation failure/resorption or abnormal pregnancy in mice. © Springer Science+Business Media New York 2013.
2.45 GHz microwave radiation impairs learning and spatial memory via oxidative/nitrosative stress induced p53-dependent/independent hippocampal apoptosis: Molecular basis and underlying mechanism
(Oxford University Press, 2015) Saba Shahin; Somanshu Banerjee; Surya Pal Singh; Chandra Mohini Chaturvedi
A close association between microwave (MW) radiation exposure and neurobehavioral disorders has been postulated but the direct effects of MW radiation on central nervous system still remains contradictory. This study was performed to understand the effect of short (15 days) and long-term (30 and 60 days) low-level MW radiation exposure on hippocampus with special reference to spatial learning and memory and its underlying mechanism in Swiss strain male mice, Mus musculus. Twelve-weeks old mice were exposed to 2.45 GHz MW radiation (continuous-wave [CW] with overall average power density of 0.0248 mW/cm2 and overall average whole body specific absorption rate value of 0.0146 W/Kg) for 2 h/day over a period of 15, 30, and 60 days). Spatial learning and memory was monitored by Morris Water Maze. We have checked the alterations in hippocampal oxidative/nitrosative stress, neuronal morphology, and expression of pro-apoptotic proteins (p53 and Bax), inactive executioner Caspase- (pro-Caspase-3), and uncleaved Poly (ADP-ribose) polymerase-1 in the hippocampal subfield neuronal and nonneuronal cells (DG, CA1, CA2, and CA3). We observed that, short-term as well as long-term 2.45 GHz MW radiation exposure increases the oxidative/nitrosative stress leading to enhanced apoptosis in hippocampal subfield neuronal and nonneuronal cells. Present findings also suggest that learning and spatial memory deficit which increases with the increased duration of MW exposure (15 < 30 < 60 days) is correlated with a decrease in hippocampal subfield neuronal arborization and dendritic spines. These findings led us to conclude that exposure to CW MW radiation leads to oxidative/nitrosative stress induced p53-dependent/independent activation of hippocampal neuronal and nonneuronal apoptosis associated with spatial memory loss. © The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved..
2.45 GHz microwave radiation induced oxidative and nitrosative stress mediated testicular apoptosis: Involvement of a p53 dependent bax-caspase-3 mediated pathway
(John Wiley and Sons Inc., 2018) Saba Shahin; Surya Pal Singh; Chandra Mohini Chaturvedi
Deleterious effects of MW radiation on the male reproduction are well studied. Previous reports although suggest that 2.45 GHz MW irradiation induced oxidative and nitrosative stress adversely affects the male reproductive function but the detailed molecular mechanism occurring behind it has yet to be elucidated. The aim of present study was to investigate the underlying detailed pathway of the testicular apoptosis induced by free radical load and redox imbalance due to 2.45 GHz MW radiation exposure and the degree of severity along with the increased exposure duration. Twelve-week old male mice were exposed to 2.45 GHz MW radiation [continuous-wave (CW) with overall average Power density of 0.0248 mW/cm2 and overall average whole body SAR value of 0.0146 W/kg] for 2 hr/day over a period of 15, 30, and 60 days. Testicular histology, serum testosterone, ROS, NO, MDA level, activity of antioxidant enzymes, expression of pro-apoptotic proteins (p53 and Bax), anti-apoptotic proteins (Bcl-2 and Bcl-xL), cytochrome-c, inactive/active caspase-3, and uncleaved PARP-1 were evaluated. Findings suggest that 2.45 GHz MW radiation exposure induced testicular redox imbalance not only leads to enhanced testicular apoptosis via p53 dependent Bax-caspase-3 mediated pathway, but also increases the degree of apoptotic severity in a duration dependent manner. © 2018 Wiley Periodicals, Inc.
2.45-GHz microwave radiation impairs hippocampal learning and spatial memory: Involvement of local stress mechanism-induced suppression of iGluR/ERK/CREB signaling
(Oxford University Press, 2018) Saba Shahin; Somanshu Banerjee; Vivek Swarup; Surya Pal Singh; Chandra Mohini Chaturvedi
Microwave (MW) radiation induced oxidative stress reduces dendritic arborization, spine density and number of hippocampal pyramidal neurons and hence, impair learning and spatial memory through p53-dependent/independent apoptosis of hippocampal neuronal and nonneuronal cells. However, the mechanisms responsible for MWradiation induced impairment in memory formation remains still unknown. This study elucidates the effect of short (15 days) and long-term(30 and 60 days) low level 2.45 GHz MWradiation-induced local stress on the hippocampal spatial memory formation pathway in adult male mice. Twelve-weeks old mice were exposed to 2.45 GHzMWradiation (continuous-wave with overall average Power density of 0.0248 mW/cm2 and overall average whole body SAR value of 0.0146 W/Kg) @ 2 h/d for 15, 30, and 60 days. Learning and spatial memory was assessed by 8-arm radial maze. We have investigated the alterations in serum corticosterone level and the expression of glucocorticoid receptor, corticotropin-releasing hormone (CRH), inducible nitric oxide synthase (i-NOS), iGluRs, PSD-95-neuronal NOS (n-NOS) system, protein kinase A, protein kinase Cε- ERK1/2-pERK1/2 in all the hippocampal subregions, viz. CA1, CA2, CA3, and DG through immunohistochemistry/immunofluorescence and alterations in the expression of hippocampal glucocorticoid receptor, CRH-receptor 1 (CRH-R1), cAMP-response element-binding (CREB), and phosphorylated-CREB (p-CREB) through western blot analysis. We observed that 2.45 GHz MWirradiated mice showed slow learning and significantly increased number of working and reference memory errors in radial maze task. Further, 2.45 GHzMW radiation exposure increases serum corticosterone level and the expression of CRH, CRH-R1, and i-NOS, while the expression of iGluRs, n-NOS, PSD-95, protein kinase Ce, protein kinase A, ERK-p-ERK, CREB, and p-CREB decreases in above mentioned hippocampal subregions in a duration dependent manner. Our findings led us to conclude that 2.45 GHzMWradiation exposure induced local stress suppresses signaling mechanism(s) of hippocampal memory formation. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved.
2.45GHz (CW) Microwave irradiation alters circadian organization, spatial memory, DNA structure in the brain cells and blood cell counts of male mice, mus musculus
(Electromagnetics Academy, 2011) Chandra Mohini Chaturvedi; V.P. Singh; P. Singh; P. Basu; M. Singaravel; R.K. Shukla; A. Dhawan; A.K. Pati; R.K. Gangwar; S.P. Singh
Present study examines biological effects of 2.45 GHz microwave radiation in Parkes strain mice. Forty-day-old mice were exposed to CW (continuous wave) microwave radiation (2 h/day for 30 days). Locomotor activity was recorded on running wheel for 12 days prior to microwave exposure (pre-exposure), 7 days during the first week of exposure (short-term exposure) and another 7-day spell during the last week of the 30-day exposure period (long-term exposure). Morris water maze test was performed from 17th to 22nd day of exposure. At the termination of the exposure, blood was processed for hematological parameters, brain for comet assay, epididymis for sperm count and motility and serum for SGOT (serum glutamate oxaloacetate transaminase) and SGPT (serum glutamate pyruvate transaminase). The results show that long-term radiation-exposed group exhibited a positive ψ (phase angle difference) for the onset of activity with reference to lights-off timing and most of the activity occurred within the light fraction of the LD (light: dark) cycle. Microwave radiation caused an increase in erythrocyte and leukocyte counts, a significant DNA strand break in brain cells and the loss of spatial memory in mice. This report for the first time provides experimental evidence that continuous exposure to low intensity microwave radiation may have an adverse effect on the brain function by altering circadian system and rate of DNA damage.
A sexual dimorphism in hypothalamic arginine vasotocin (AVT) gene expression and avt plasma levels in the Japanese quail (Coturnix coturnix japonica) in response to water deprivation
(Academic Press Inc., 2000) Chandra Mohini Chaturvedi; Adity Chowdhary; P. Timothy Wall; Thomas I. Koike; Lawrence E. Cornett
To examine a possible sexual dimorphism in the osmotic control of arginine vasotocin (AVT) release in birds, age-matched male and female Japanese quail were subjected to water deprivation. The observed increased plasma osmolalities were accompanied by increased plasma AVT levels. Plasma mesotocin levels did not change with water deprivation. The sensitivity of the osmotic control of AVT release as determined by the slope of the relationship between plasma AVT levels and plasma osmolalities was significantly (P < 0.05) higher in males than in females. By Northern blot analysis, levels of hypothalamic AVT gene transcripts were increased 2.3 ± 0.14- and 3.5 ± 0.13-fold in water-deprived male and female Japanese quail, respectively, compared to normally hydrated birds. Our data suggest gender- related differences in the osmotic control of AVT release and in hypothalamic AVT gene expression in the Japanese quail.
Age and sex dependent variations in the arginine vasotocin gene in response to dehydration in the chicken and Japanese quail
(2004) Rohit Seth; Chandra Mohini Chaturvedi
The present study was conducted to investigate and compare age- and sex-dependent central and peripheral effects of osmotic stress (4 d of water deprivation) in 2 poultry species: the chicken (Gallus gallus domesticus) and Japanese quail (Coturnix coturnix japonica). Following dehydration in sexually immature (young) and mature (adult) birds of both sexes, Northern blot analysis was performed, and changes in body weight and plasma osmolality were estimated. Following 4 d of water deprvation, young and adult quail of both sexes exhibited significant losses of body weight and increases in plasma osmolality compared to their hydrated controls. Northern blot analysis revealed 1.24- and 1.95-fold increases in AVT transcripts in water-deprived adult male and female and 1.45- and 1.42-fold increases in young male and female quail, respectively; whereas 1.27- and 1.6- and 1.44- and 1.65-fold increases compared to the controls in water-deprived adult and young, male and female chickens, respectively, were found. We concluded that osmotic stress induced by water deprivation is a potent stimulator for hypothalamic gene expression in the chicken and Japanese quail, and that the response of the AVT system varies with the reproductive age and sex of the birds. In view of the remarkable difference in the amount of hypothalamic AVT transcripts and the peripheral responses of young and adult birds to osmotic stress, the present study suggests a modulatory role of sex steroids in water homeostasis.
Age dependent variations in the deep brain photoreceptors (DBPs), GnRH-GnIH system and testicular steroidogenesis in Japanese quail, Coturnix coturnix japonica
(Elsevier Inc., 2018) Somanshu Banerjee; Saba Shahin; Chandra Mohini Chaturvedi
The complex physiology of aging involves a number of molecular and biochemical events, manifested as signs of senescence. Japanese quail is a very unique and advantageous model to study the signs and symptoms of senescence in the central and peripheral modules of HPG axis. In the present study, we have investigated the age dependent variations in hypothalamic deep brain photoreceptors (DBPs), central GnRH-I/II-GnIH-Mel 1c R system, testicular GnRH-GnIH system, testicular steroidogenic genes and proteins, androgen receptor (AR) and serum testosterone level in quail of different age groups [3-wk (sexually immature), 6-wk (sexually mature and crossed the puberty), 16-wk (adult, sexually active and showing full breeding phase) and 144-wk (aged)]. Findings of our present study showed the differential expression of these genes/proteins in quail of different age groups. The low levels of the DBPs, GnRH-I, GnIH, Mel 1c R in hypothalamus and GnRH-II in midbrain, significantly decreased testicular GnRH/GnRH-R-GnIH, steroidogenic genes/proteins and serum testosterone were observed in immature quail. The significantly increased expression of opsins in the DBPs, GnRH-I, GnIH, Mel 1c R in hypothalamus and GnRH-II in midbrain influences the testicular GnRH-GnIH and stimulate the testicular steroidogenesis in mature and adult quail. In aged quail, the significantly decreased levels of hypothalamic DBPs, GnRH-I, GnIH, Mel 1c R and midbrain GnRH-II modulates the testicular GnRH-GnIH and further suppresses the genes/proteins involved in steroidogenesis and results in reduced serum testosterone. Hence, it can be concluded from our findings that the testicular steroidogenesis and its neuroendocrine regulation varies with age, in Japanese quail. © 2018 Elsevier Inc.
Age, photoperiod and estrogen dependent variations in the shell gland and the expression of AVT in the ovary of Japanese quail
(Elsevier Inc., 2012) Rashmi Srivastava; Chandra Mohini Chaturvedi
Present work was undertaken to describe (i) age dependent (prepuberal-3, 4, 5 and 6 weeks old, puberal and actively laying 8 and 12 weeks old and aged 78 weeks old) (ii) photoperiodic response dependent (photosensitive and photorefractory) and sex steroid dependent (estradiol benzoate and its antagonist tamoxifen treated) variation in the ovary and shell gland activity of Japanese quail (Coturnix coturnix japonica). Further, in view of the role of neurohypophysial peptide arginine vasotocin (AVT) in many physiological processes including age/reproduction related oviposition, expression of ir-AVT was also monitored in the ovary of quail. All the parameters associated with histodifferentiation increased rapidly during the developing stages followed by a decrease in old age, which also increased in reproductively quiescent photorefractory birds following estradiol treatment and decreased in reproductively active photosensitive quail following tamoxifen treatment. Using AVT-specific antibody, expression of immunoreactive AVT (ir-AVT) observed in the ovary of photosensitive quail was not detected in the photorefractory quail. However, administration of estrogen in the photorefractory quail stimulated the growth and activity of ovary and shell gland also resulted in the expression of ovarian ir-AVT. On the other hand, tamoxifen eliminated the localization of ir-AVT in the ovary of photosensitive quail in addition to a decrease in the shell gland protein and alkaline phosphatase activity. It is concluded that estrogen not only affects the growth and differentiation of ovary and oviduct including shell gland but also regulates the expression of ovarian AVT. It is also suggested that in addition to reported paracrine effect of AVT in the shell gland of Japanese quail for oviposition, ovarian AVT may also affect ovarian function (ovulation), and in part, this regulation is estrogen dependent. © 2012 Elsevier Inc. All rights reserved.
Age-dependent expression of AVT and its oxytocic-like receptor VT3 in the shell gland of Japanese quail, Coturnix coturnix japonica
(Academic Press Inc., 2010) Rashmi Srivastava; Lawrence E. Cornett; Chandra Mohini Chaturvedi
The avian neurohypophyseal hormone AVT is an important regulatory hormone involved in many physiological processes including oviposition; an age-related phenomenon, through its action on the shell gland. In this study, immunohistochemistry and in situ hybridization was performed to study the expression of immunoreactive (ir) AVT and its oxytocic-like receptor VT3 transcript in the ovary/shell gland of Japanese quail representing sexually immature, mature and old condition. Our results indicate that ir-AVT is present in the ovary of sexually active adult only, but in the shell gland it is observed in both sexually active adult and sexually quiescent old quail. Further, VT3 gene transcript although not detected in the shell gland of sexually immature birds, has been found abundantly in the myometrium of shell gland of sexually active adult quail with a slight decrease in old birds. It is concluded that in addition to the ovarian function and shell gland activity, the expression of AVT and VT3 receptor in the shell gland also varies with the age dependent reproductive/egg laying performance of the Japanese quail. Our findings also suggest that (i) local synthesis of AVT and the expression of its oxytocic-like VT3 receptors is estrogen dependent and (ii) shell gland AVT upregulates its VT3 receptor (paracrine role) in advance to facilitate the role of neurohypophyseal AVT during oviposition. © 2009 Elsevier Inc.
Age-dependent variation in the RFRP-3 neurons is inversely correlated with gonadal activity of mice
(Academic Press Inc., 2010) Sumit Sethi; Kazuyoshi Tsutsui; Chandra Mohini Chaturvedi
The present study analyzed changes in the expression of RFamide-related peptide-3 (RFRP-3; a mammalian ortholog of avian gonadotropin-inhibitory hormone), in the brain and correlated it with testicular activity of mice of different age groups (day-old, 1-, 3-, 5-, 7-, 9-, 11-, 13-week and 1.5-year-old). Testicular activity after a progressive increase up to 13-week of age declined in the old mice. On the other hand, while immunoreactive (ir) RFRP-3 neurons were not seen in the day-old mice, few appeared in 1-week-old mice, their number and size increased drastically at 3-week of age. This condition remained unaltered until 7-week of age followed by a progressive decline up to the age of 13-week and thereafter increased again in the old age. The present findings indicate that hyperactivity of the ir-RFRP-3 neurons of dorsomedial nucleus of hypothalamus (DMH) observed in prepubertal mice declines in reproductively active mice and increases again in the old mice having declined reproductive performance. It is concluded that aging mice exhibits inverse correlation of RFRP-3 neurons and gonadal activity suggesting that function of RFRP-3 is not initiated until 1-week of age and thereafter it could participate in the regulation of gonadal development. © 2010 Elsevier Inc.
Apoptosis-mediated testicular alteration in Japanese quail (Coturnix coturnix japonica) in response to temporal phase relation of serotonergic and dopaminergic oscillations
(Company of Biologists Ltd, 2016) Somanshu Banerjee; Kazuyoshi Tsutsui; Chandra Mohini Chaturvedi
Reproductive performance of many avian species, including Japanese quail, is reported to be modulated by specific temporal phase relation of serotonergic and dopaminergic oscillations. Accordingly, it has been shown that the serotonin precursor 5-HTP and the dopamine precursor L-DOPA given 8 h apart induce gonadal suppression and given 12 h apart lead to gonadal stimulation, while other temporal relationships were found to be ineffective. In the present study, we investigated the effects of 8- and 12-h phase relation of neural oscillations on testicular responses including expression of GnRH-I, GnIH, pro-apoptotic proteins (p53 and Bax), inactive and active executioner caspase-3, and the uncleaved DNA repair enzyme PARP-1. Testicular volume and mass decreased significantly in 8-h quail and increased in 12-h quail compared with controls. Expression of ir-GnIH, p53, Bax and active-caspase-3 increased and that of GnRH-I, pro-caspase-3 and uncleaved PARP-1 decreased in 8-h quail compared with controls. A TUNEL assay also confirmed testicular regression in these quail. Testes of 12-h quail exhibited significantly increased expression of GnRH-I, pro-caspase- 3 and uncleaved PARP-1 compared with the control group. Our findings suggest that differential response of avian testes to 8- and 12-h phase relation of serotonergic and dopaminergic neural oscillations may be attributed to autocrine/paracrine action of GnIH expression, which is upregulated in regressed testes, leading to apoptotic changes, and downregulated in developed testes, causing apoptotic inhibition. It is concluded that specific phase relation of neural oscillations may modulate the local testicular GnRH-GnIH system and alter the apoptotic mechanism in quail testes. Moreover, these findings highlight the physiological effects of time-dependent drug delivery, including the specific time intervals between two drugs. © 2016. Published by The Company of Biologists Ltd.
Apoptotic mechanism behind the testicular atrophy in photorefractory and scotosensitive quail: Involvement of GnIH induced p-53 dependent Bax-Caspase-3 mediated pathway
(Elsevier B.V., 2017) Somanshu Banerjee; Chandra Mohini Chaturvedi
In most of the avian species, daylength or photoperiod is the main environmental factor regulating reproduction. During their annual gonadal cycle, birds once sensitive to short or long day effect develop refractoriness to the same daylength and gonad develop or regress accordingly. The present study investigated the effects of photoperiodic alterations on apoptosis mediated testicular responses of photosensitive/photorefractory and scotosensitive/scotorefractory quail, Coturnix coturnix japonica. Testicular apoptosis in the quail of different photoperiodic conditions was assessed by monitoring the alterations in the local testicular expression of GnRH-I, GnIH, pro-apoptotic proteins (p53 and Bax), inactive caspase (pro-Caspase-3), executioner active-Caspase-3 and inactive/uncleaved PARP-1 (DNA repair enzyme) and TUNEL analysis. Alterations in these parameters indicate that testicular quiescence/regression in scotosensitive and photorefractory quail is mediated by apoptosis of testicular cells and hence apoptosis appears to be the key mechanism of testicular regression in Japanese quail. Present findings demonstrated the underlying molecular mechanism of how avian testes respond differentially to same photoperiodic conditions and exhibit scoto-/photo-sensitivity and refractoriness. It is concluded that photoperiod induced testicular stimulation in photosensitive/scotorefractory quail may be due to apoptotic inhibition and testicular regression in scotosensitive/photorefractory quail is guided by apoptosis, an effect invariably regulated by local action of GnRH and GnIH. © 2017 Elsevier B.V.
Changes in vasotocin immunoreactivity of paraventricular nuclei and adrenal function of Japanese quail in relation to different phases of sexual development
(2008) Sajla Singh; Chandra Mohini Chaturvedi
In relevance to osmoregulatory and reproductive functions, activity of hypothalamic neurosecretory neurons may also vary seasonally. The current study was performed to determine annual changes in ir-AVT neurons of hypothalamus and adrenal gland function. We examined changes in ir-AVT neuron by immunohistochemical method and plasma testosterone was measured by enzyme immunoassay. The steroidogenic interrenal activity was studied by histological and biochemical methods. Birds were sampled in February (quiescent), April (recrudescent), June (breeding) and November (regressive). A significant and gradual increase in the number of ir-AVT neurons was observed from quiescent to breeding phase which decreased during regressive phase of annual gonadal cycle. The gradual increase in ir-AVT neurons along with annual gonadal activity of quail were accompanied by increase in plasma levels of testosterone. These results indicate a functional interaction between sex steroid and AVT synthesizing neurons. Adrenal activity (as judged by weight, ascorbic acid content, cortical cord width and cortico-medullary ratio) was also maximum during breeding phase. It is thus postulated that domesticated quail when exposed to natural day length (NDL), exhibits seasonal/annual cyclicity in vastocinergic activity and adrenal function which may be due to difference in sex steroid hormone. © 2007 Elsevier Inc. All rights reserved.
Correlation of nitric oxide (NO) activity and gonadal function in Japanese quail, Coturnix coturnix japonica following temporal phase relation of serotonergic and dopaminergic oscillations
(2008) Pankaj Kumar; Chandra Mohini Chaturvedi
Nitric oxide (NO), a highly reactive and short-lived radical, is considered to be an important trigger molecule for several physiological mechanisms including gonadotrophin releasing hormone (GnRH) secretion in mammals, although there is no such information in avian literature. On the other hand, specific temporal phase relation of circadian neural (serotonergic and dopaminergic) oscillations is reported to modulate reproductive activity in many avian species including Japanese quail. The present study was undertaken to investigate the correlation of NO activity and gonadal function of Japanese quail. In experiment I, the effect of serotonin and dopamine precursors, (5-hydroxytryptophan (5-HTP) and l-dihydroxyphenyalanine (l-DOPA) respectively; 5 mg per 100 g body weight) administered at intervals of 8 or 12 h over a period of 13 days, was studied on reproductive responses and NO activity. Measurements of body weight, cloacal gland size, testosterone concentration, spermatogenesis, nitrite-nitrate concentration in plasma, hypothalamus and testes, and NADPH-diaphorase (NADPH-d) activity in testes were made on the 2nd, 3rd, 6th and 11th days of treatment and 2nd and 30th day post-treatment. In experiment II, quail were divided into five groups including the control. One experimental group received 13 daily injections of 5-HTP and l-DOPA at intervals of 8 h along with 0.1 ml of normal saline administered orally (8-hr + Veh), while another group of 8-hr quail received NO donor (sodium nitroprusside (SNP), 5 mg per 100 g body weight) orally (8-hr + SNP). The third experimental group received 5-HTP and l-DOPA at intervals of 12 h along with normal saline (12-hr + Veh), while the fourth group of quail along with 5-HTP and l-DOPA at intervals of 12 h also received the NOS inhibitor (N-nitro-l-arginine methyl ester, l-NAME, 25 μg per 100 g body weight) intraperitoneally (12-hr + l-NAME) for 13 days. This experiment was terminated after 21 days of the treatment. Results indicate that 5-HTP and l-DOPA administered 8 h apart (8-hr) suppressed but if given 12 h apart (12-hr) stimulated the reproductive system and NO activity compared to the control. These effects were apparent on the 6th day of injections and were maintained 30 days following the termination of the treatment. A significant decrease in nitrite and nitrate concentration and NADPH-d activity in reproductively inhibited 8-hr group and an increase in reproductively stimulated 12-hr quail was also evident. In contrast, these activities were stimulated in 8-hr + SNP quail and were suppressed in 12-hr + l-NAME group quail. It is concluded that activity of the reproductive system and NO activity waxes and wanes simultaneously in Japanese quail. Moreover, experimental modulation of gonadal activity (following changes in the phase relation of serotonergic and dopaminergic activity) or NO activity (following the administration of NO modulator or inhibitor) affects each other maintaining a parallel relation between the two systems. Further, it is interesting to note that the gonado-stimulatory effect of SNP overpowers the gonado-inhibitory effects of the 8-hr time interval and inhibitory effects of l-NAME mask the stimulatory effects of 12-hr temporal relation of 5-HTP and l-DOPA administration. These findings strongly suggest that reproductive effects may be induced via changes in NO activity, however the exact mechanism by which NO drives gonadal axis needs to be ascertained. © 2007 Elsevier B.V. All rights reserved.
Corticosterone- or metapyrone-induced alterations in adrenal function and expression of the arginine vasotocin receptor VT2 in the pituitary gland of domestic fowl, Gallus gallus
(Academic Press Inc., 2009) Dharmendra Sharma; Lawrence E. Cornett; Chandra Mohini Chaturvedi
The avian neurohypophyseal hormone arginine vasotocin (AVT) is known to be involved in the regulation of adrenocorticotropin (ACTH) release by interacting with the VT2 receptor (VT2R), which is homologous to the mammalian vasopressin V1b receptor (V1bR). To study the role of glucocorticoid in the expression and regulation of the VT2R, corticosterone (1 or 5 mg/bird/day) or metapyrone (10 or 50 mg/kg body weight/day) were administered daily for 8 days to white leghorn chickens. While low doses were ineffective, a high dose of corticosterone upregulated, while metapyrone downregulated, pituitary VT2R mRNA expression and ir-VT2 in the cephalic lobe of the anterior pituitary. Further, although no change was observed in the expression of POMC mRNA, adrenal activity (as judged by the changes in total cholesterol, 3β HSD, cortical cord width and cortico-medullary ratio) exhibited suppression or stimulation following treatment with corticosterone or metapyrone, respectively. In view of the classical negative feedback effect of glucocorticoids at the level of hypothalamic CRH neurons and pituitary corticotrophs, high corticosterone level-induced suppression of the CRH-ACTH axis may have been masked by VT2R-mediated stimulation of corticotrophs, and hence the POMC mRNA level did not change. The same argument could be used for metapyrone. It is concluded that expression of the VT2 receptor is regulated by glucocorticoids in chicken. These findings confirm a role for AVT, mediated by the VT2 receptor, in regulating ACTH secretion during stress and suggest that corticotroph VT2 receptor levels may be dynamically regulated depending on the HPA axis activity. © 2009 Elsevier Inc. All rights reserved.
Effect of estrogen and its antagonist on the expression of arginine vasotocin (AVT) and its oxytocic-like receptor VT3 in the shell gland of Japanese quail, Coturnix coturnix japonica
(Elsevier Inc., 2008) Rashmi Srivastava; Lawrence E. Cornett; Chandra Mohini Chaturvedi
Avian neurohypophysial hormone arginine vasotocin (AVT) is known to regulate shell gland contractility during oviposition. While studying the role of estrogen in the expression and regulation of AVT and its oxytocic-like receptor VT3, using in situ hybridization and immunohistochemistry, it was observed that the expression of AVT and its receptor was not detected in the shell gland of sexually immature Japanese quail. However, administration of estrogen to these birds not only stimulates the growth and activity (as assessed by increased mucosal fold length, total protein content and alkaline phosphatase level) of the shell gland but also upregulates the expression of AVT and VT3. Further, administration of estrogen antagonist tamoxifen to sexually mature bird shows opposite results. On the other hand, localization of ir-AVT, observed in the ovary of sexually mature bird, was not detected in the estrogen treated sexually immature quail. It is concluded that estrogen not only affects the growth and differentiation of avian oviduct, but also regulates the expression of shell gland AVT and its receptor VT3. Present findings suggest that the locally synthesized AVT acts in a paracrine way to upregulate VT3 receptor and thus facilitates the endocrine function of neurohypophysial AVT during oviposition. © 2008 Elsevier Inc. All rights reserved.
Effect of estrogen and tamoxifen on the shell gland AVT and VT3R of scotosensitive and scotorefractory Japanese quail
(Academic Press Inc., 2010) Rashmi Srivastava; Chandra Mohini Chaturvedi
The neurohypophyseal hormone arginine vasotocin (AVT) found in most vertebrate species is known to modulate different aspects of reproduction in quail. AVT system is sensitive to gonadal steroids. Previous studies have shown that estradiol benzoate stimulates the proliferation of shell gland and increases the AVT and the vasotocin 3 receptor (VT3R) in long day length. This study was undertaken to investigate the effect of estrogen and tamoxifen on AVT as well as its receptor VT3 under the short day condition (6L:18D). Estradiol benzoate (EB) was administered daily in sexually quiescent (scotosensitive) condition for 15. days. After the initial period of sexual quiescence, the quail of control group exhibited sexual development (scotorefractory condition). Thereafter, scotorefractory quail were administered with anti-estrogen tamoxifen, which eliminated the reoccurrence of scotosensitivity. Immunohistochemical and in-situ hybridization studies indicate the expression of AVT and VT3R transcripts in both scotosensitive as well as scotorefractory conditions. Administration of EB to scotosensitive female quail produced an increase in AVT and VT3 while tamoxifen suppressed them in scotorefractory quail. The results indicate that in quail myometrium the expression of VT3R is upregulated by estrogen when kept under short day condition. © 2010 Elsevier Inc.
Effect of gonadotrophin and sex steroid on the scoto-responses of day old chicks of Japanese quail, coturnix coturnix japonica
(1997) Doris Phillips; A.B. Singh; U.S. Das; Chandra Mohini Chaturvedi
Luteinizing hormone (LH) and testosterone propionate (TP) were tested for their effects on the development of scotorefractoriness in Japanese quail. Day old chicks of both the sexes were divided into four groups and treated with normal saline, LH (1 μg/100 g body weight) and two doses of TP (100 μg/100 g body weight- TP1 and 1 mg/100 gm body weight- TP2) over a periods of 14 weeks. In the male chicks, compared to control LH treatment advanced and low dose of TP suppressed the development of scotorefractoriness, while high dose of TP inhibited it completely and maintained the birds in scotosensitive state. On the other hand, in females, LH treatment increased the rate of sexual development resulting in the onset of egg laying earlier than that of control, but both the doses of steroid hormone suppressed ovarian development. It is suggested that, LH treatment not only induced a higher degree of reproductive development in short day quail but may also advance sexual maturity as under long daylength. Further, both the doses of male hormone had negative feedback effect on neuroendocrine axis and eliminated the attainment of scotorefractoriness i.e., reproductive development under short days.