Showing papers by "Chandra Mohini Chaturvedi published in 2018"

Targeting DNA repair with PNKP inhibition sensitizes radioresistant prostate cancer cells to high LET radiation

Abstract: High linear energy transfer (LET) radiation or heavy ion such as carbon ion radiation is used as a method for advanced radiotherapy in the treatment of cancer. It has many advantages over the conventional photon based radiotherapy using Co-60 gamma or high energy X-rays from a Linear Accelerator. However, charged particle therapy is very costly. One way to reduce the cost as well as irradiation effects on normal cells is to reduce the dose of radiation by enhancing the radiation sensitivity through the use of a radiomodulator. PNKP (polynucleotide kinase/phosphatase) is an enzyme which plays important role in the non-homologous end joining (NHEJ) DNA repair pathway. It is expected that inhibition of PNKP activity may enhance the efficacy of the charged particle irradiation in the radioresistant prostate cancer cell line PC-3. To test this hypothesis, we investigated cellular radiosensitivity by clonogenic cell survival assay in PC-3 cells.12Carbon ion beam of62 MeVenergy (equivalent 5.16 MeV/nucleon) and with an entrance LET of 287 kev/μm was used for the present study. Apoptotic parameters such as nuclear fragmentation and caspase-3 activity were measured by DAPI staining, nuclear ladder assay and colorimetric caspase-3method. Cell cycle arrest was determined by FACS analysis. Cell death was enhanced when carbon ion irradiation is combined with PNKPi (PNKP inhibitor) to treat cells as compared to that seen for PNKPi untreated cells. A low concentration (10μM) of PNKPi effectively radiosensitized the PC-3 cells in terms of reduction of dose in achieving the same survival fraction. PC-3 cells underwent significant apoptosis and cell cycle arrest too was enhanced at G2/M phase when carbon ion irradiation was combined with PNKPi treatment. Our findings suggest that combined treatment of carbon ion irradiation and PNKP inhibition could enhance cellular radiosensitivity in a radioresistant prostate cancer cell line PC-3. The synergistic effect of PNKPi and carbon ion irradiation could be used as a promising method for carbon-ion therapy in radioresistant cells.

1800 MHz mobile phone irradiation induced oxidative and nitrosative stress leads to p53 dependent Bax mediated testicular apoptosis in mice, Mus musculus.

Abstract: Present study was carried out to investigate the effect of long-term mobile phone radiation exposure in different operative modes (Dialing, Receiving, and Stand-by) on immature male mice. Three-week old male mice were exposed to mobile phone (1800 MHz) radiation for 3 hr/day for 120 days in different operative modes. To check the changes/alteration in testicular histoarchitecture and serum testosterone level, HE staining and ELISA was performed respectively. Further, we have checked the redox status (ROS, NO, MDA level, and antioxidant enzymes: SOD, CAT, and GPx) by biochemical estimation, alteration in the expression of pro-apoptotic proteins (p53 and Bax), active executioner caspase-3, full length/uncleaved PARP-1 (DNA repair enzyme), anti-apoptotic proteins (Bcl-2 and Bcl-xL ) in testes by immunofluorescence and cytosolic cytochrome-c by Western blot. Decreased seminiferous tubule diameter, sperm count, and viability along with increased germ cells apoptosis and decreased serum testosterone level, was observed in the testes of all the mobile phone exposed mice compared with control. We also observed that, mobile phone radiation exposure in all the three different operative modes alters the testicular redox status via increasing ROS, NO, and MDA level, and decreasing antioxidant enzymes levels leading to enhanced apoptosis of testicular cells by increasing the expression of pro-apoptotic and apoptotic proteins along with decreasing the expression of anti-apoptotic protein. On the basis of results, it is conclude that long-term mobile phone radiation exposure induced oxidative stress leads to apoptosis of testicular cells and thus impairs testicular function.

2.45 GHz microwave radiation induced oxidative and nitrosative stress mediated testicular apoptosis: Involvement of a p53 dependent bax-caspase-3 mediated pathway.

Abstract: 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.

Simulated photoperiod influences testicular activity in quail via modulating local GnRHR-GnIHR, GH-R, Cnx-43 and 14-3-3

Abstract: The hypothalamo-hypophyseal-gonadal axis mediated differential photosexual responses in quail kept under different simulated photoperiodic conditions have been studied in details. Local testicular GnRH-GnIH and their receptor system has been hypothesized to be modulated in quail showing different photo-sexual responses and thus influence the testicular activity and steroidogenesis through local (paracrine and autocrine) action. To validate this hypothesis, we studied the expression of gonadotropin releasing hormone receptor (GnRH-R), gonadotropin inhibiting hormone receptor (GnIH-R) mRNA, growth hormone receptor (GH-R), proliferating cell nuclear antigen (PCNA), 14-3-3, Connexin-43 (Cnx-43), steroidogenic factor-1 (SF-1), Steroidogenic Acute Regulatory protein (StAR), steroidogenic enzyme (3β HSD) in testis as well as androgen receptor (AR) in testis and epididymis of photosensitive (PS), scotorefractory (SR), photorefractory (PR) and scotosensitive (SS) quail. Experimental findings clearly indicate the increased expression of GnIH-R mRNA and suppression of GnRH-R, GH-R, PCNA, 14-3-3, Connexin-43, SF-1, StAR, 3β HSD in testis as well as AR in testis and epididymis of PR and SS quail, while PS and SR quail exhibited the opposite results i.e., significantly decreased expression of GnIH-R mRNA and increased expression of GnRH-R, GH-R, PCNA, 14-3-3, Cnx-43, SF-1, StAR, 3β HSD in testis as well as AR in testis and epididymis. The significantly increased intra-testicular testosterone has been observed in the PS and SR quail while, PR and SS quail showed opposite results. Hence, we conclude that PS and SR quail showed significantly increased testicular activity and steroidogenesis while opposite pattern was observed in PR and SS quail.

Neuroendocrine mechanism of food intake and energy regulation in Japanese quail under differential simulated photoperiodic conditions: Involvement of hypothalamic neuropeptides, AMPK, insulin and adiponectin receptors

Abstract: Neuroendocrine coordination between the reproductive and energy regulatory hypothalamic circuitries not only tightly regulates food intake and energy expenditure but also maintains the body weight and reproduction. The effect of different simulated photoperiodic conditions on food intake and neuroendocrine mechanism of energy homeostasis in Japanese quail is not investigated till date. Hence, our present study is designed to elucidate the effect of different simulated photoperiodic conditions on food consumption and neuroendocrine mechanism(s) of energy regulation in this poultry species. The alterations in hypothalamic energy balancing neuropeptides (NPY/AgRP/CART), polypeptide hormone precursor (POMC), protein kinase (AMPK-p-AMPK) as well as receptors of insulin and adiponectin [Insulin Receptor (IR), Adiponectin Receptor 1 & 2] have been investigated in photosensitive (PS), scotorefractory (SR),photorefractory (PR) and scotosensitive (SS) quail. Immunofluorescence and western blotting were used to quantify the expression of these peptides and proteins. Results showed increased food consumption and body weight gain, along with increased expression of NPY, AgRP, IR, adiponectin receptors and p-AMPK, decreased CART and POMC in the hypothalamus of photosensitive and scotorefractory quail. While, opposite findings were observed in photorefractory and scotosensitive quail. Hence, this study may suggest the hypothalamic energy channelization towards reproductive axis in photosensitive and scotorefractory quail to support the full breeding conditions, while hypothalamic energy deprivation in photorefractory and scotosensitive quail leads to reproductive quiescence.

Impact of estrogen and photoperiod on arginine vasotocin and VT3 receptor expression in the shell gland of quail.

Abstract: Role of estrogen and photoperiod is well-established in avian reproduction. In addition, the distribution and the expression of arginine vasotocin (AVT) and its receptor VT3 to ensure reproductive/breeding conditions in Japanese quail influenced by them has been the main focus of this review. To consider this aspect the mRNA expression of VT3 receptor and its ligand AVT in the shell gland has been emphasized. In birds, AVT performs a dual role as an anti-diuretic hormone and the functions accomplished by oxytocin in mammals. The physiological actions of AVT in birds are mediated through its diverse receptor subtypes VT1, VT2, VT3 and VT4. Dynamic alteration of VT3 expression during different reproductive and photo-sexual conditions of quail can be modulated by estrogen. In addition to the endocrine effect of AVT, the shell gland is complemented by its paracrine action via its receptors. Evidences indicate that the expression of shell gland AVT modulated by estrogen appears to play a priming role by modulating the availability of VT3 receptor for the required action of neurohypophysial AVT during oviposition.

Serotonergic and catecholaminergic (dopaminergic) oscillations in the reproductive regulation of Japanese quail

Abstract: Specific temporal phase relation of serotonergic and dopaminergic oscillations alters reproductive responses in many species. Aim of the study was to confirm whether effect of serotonergic drug (5-HTP) and dopaminergic drug (L-DOPA) is due to their conversion into serotonin and dopamine respectively or other products. For this study, PCPA (p-chlorophenylalanine, a long lasting inhibitor of serotonin synthesis), DDC (Diethyldithiocarbamate, which inhibits biosynthesis of nor-adrenaline), α-MT (Methyl-p-tyrosine, an inhibitor for the conversion of tyrosine to DOPA) and DOPS (Dihydroxyphenylserine, a specific precursor for noradrenaline) were used in different groups in addition to 5-HTP and L-DOPA given at specific time interval. Reproductive responses monitored at 10 weeks post treatment indicate that gonadal activity was significantly low in HTP:DOPA (8-hr quail), HTP+PCPA:DOPA and HTP:DOPA+DDC quail compare to control (S:S). However, gonadal activity of HTP:S(HTP control), S:DOPA(DOPA control) and HTP:α-MT+DOPS was not different from S:S control and remained in active condition. These findings indicate that it is not the dose of neurotransmitter precursor drugs (5-HTP and L-DOPA) and the neurotransmitters (serotonin and dopamine itself) that cause the effect, instead it is the function of interval between the drug administration which induces or entrains specific phase relation between serotonergic and dopaminergic oscillations. Further, gonadal suppression observed in HTP:DOPA, HTP+PCPA:DOPA and HTP:DOPA+DDC group three groups is not due to injection of 5-HTP or L-DOPA (alone) but due to conversion of administered 5-HTP into serotonin and conversion of L-DOPA (administered) into dopamine; not due to their further conversion into catecholamines other than dopamine i.e. noradrenaline or adrenaline.