Prompt detection of endogenous hypochlorite (ClO-) in murine macrophages and zebrafish embryos facilitated by a distinctive chemodosimetric mode.

An innovative fluorescein appended naphthalene diimide based probe (FANDI) has been prepared and characterized to selectively recognize hypochlorite or ClO- ions in the presence of other reactive oxygen species (ROS) and biorelevant ions, using a unique chemodosimetric method. Hypochlorite induced oxidation can efficiently alter the initial photophysical properties of FANDI and shows an easily detectable "turn on" green fluorescence. The chemodosimeter FANDI can efficiently detect exogenous as well as endogenous ClO- ions in RAW 264.7 cells (macrophages) and zebrafish embryos (Danio rerio) which further ensures the high potential, easy cell permeability and photostability of FANDI and makes it worth exploring in the future.

Bisphenol A-induced oxidative stress, hepatotoxicity and altered estrogen receptor expression in Labeo bata: impact on metabolic homeostasis and inflammatory response.

Bisphenol A (BPA), a weak estrogenic endocrine disruptor and a well-known plasticizer, has the potential to perturb diverse physiological functions; however, its impact on immune and metabolic function in aquatic vertebrates is relatively less understood. The present study aims to investigate the impact of BPA on hepatotoxicity, metabolic and immune parameters vis-à-vis estrogen receptor expression modulation in a freshwater teleost, Labeo bata (Cyprinidae, Cypriniformes). The 96-h median lethal concentration of BPA in L. bata has been determined as 4.79 mg/L. Our data demonstrate that congruent with induction of plasma vitellogenin (VTG), chronic exposure to sub-lethal BPA (2 and 4 µM/L) attenuates erythrocyte count, hemoglobin concentration, packed cell volume, mean corpuscular hemoglobin, but not leukocyte number. Further, a significant increase in MDA, concomitant with diminished catalase and heightened GST activity corroborates well with hepatic dystrophic changes, appearance of fatty liver (macrovesicular steatosis) and elevated serum lipids (triglyceride, cholesterol, LDL, VLDL) in BPA-treated groups. Interestingly, a differential regulation of estrogen receptor (ER) subtypes at transcript and protein level signifies negative influence of BPA on hepatic ERα/ERß homeostasis in this species. While at a lower dose it promotes Akt phosphorylation (activation), BPA at the higher dose attenuates ERK1/2 phosphorylation (activation), suggesting potential alteration in insulin sensitivity. Importantly, dose-dependent decrease in hepatic TNF-α, IL-1ß, iNOS (NOS2) expression and nitric oxide (NO) level corresponds well with progressive decline in p-NF-κB, p-p38 MAPK, albeit with differential sensitivity, in BPA-exposed groups. Collectively, BPA exposure has wide-spread negative influence on hematological, biochemical and hepatic events in this species.

Chronic exposure to nonylphenol induces oxidative stress and liver damage in male zebrafish (Danio rerio): Mechanistic insight into cellular energy sensors, lipid accumulation and immune modulation.

Nonylphenol (NP), an environmentally persistent and toxic endocrine-disrupting chemical with estrogenic properties, has severe implications on humans and wildlife. Accumulating evidence demonstrates the toxic response of NP on the developmental process, nervous system, and reproductive parameters. Although NP exposure has been implicated in chronic liver injury, the underlying events associated with hepatic pathophysiology remain less investigated. Using male zebrafish (Danio rerio) as the model, the present study investigates the impact of environmentally relevant concentrations of NP (50 and 100 µg/L, 21 days) on hepatic redox homeostasis vis-à-vis cellular energy sensors, inflammatory response, and cell death involving a mechanistic insight into estrogen receptor (ER) modulation. Our results demonstrate that congruent with significant alteration in transcript abundance of antioxidant enzymes (SOD1, SOD2, Catalase, GPx1a, GSTα1), chronic exposure to NP promotes ROS synthesis, more specifically superoxide anions and H2O2 levels, and lipid peroxidation potentially through elevated NOX4 expression. Importantly, NP perturbation of markers associated with fatty acid biosynthesis (srebf1/fasn) and cellular energy-sensing network (sirt1/ampkα/pgc1α) indicates dysregulated energy homeostasis, metabolic disruption, and macrovesicular steatosis, albeit with differential sensitivity at the dose level tested. Besides, elevated p38-MAPK phosphorylation (activation) together with loss of ER homeostasis at both mRNA (esr1, esr2a, esr2b) and protein (ERα, ERß) levels suggest that NP modulation of ER abundance may have a significant influence on hepatic events. Elevated expression of inflammatory markers (TLR4, p-NF-κB, TNF-α, IL-6, IL-1ß, and NOS2) and pro-apoptotic and necrotic regulators, e.g., Bax, caspase- 8, -9 and cleaved PARP1 (50 kDa), indicate chronic inflammation and hepatotoxicity in NP-exposed males. Collectively, elevated oxidative stress, metabolic dysregulation and immune modulation may lead to chronic liver injury in organisms exposed to metabolic disrupting chemicals.

Bisphenol A impairs reproductive fitness in zebrafish ovary: Potential involvement of oxidative/nitrosative stress, inflammatory and apoptotic mediators.

Bisphenol A (BPA) is a highly pervasive chemical in consumer products with its ascribed endocrine-disrupting properties. Several studies have shown the cytotoxic, genotoxic, and carcinogenic property of BPA over a multitude of tissues. Although BPA exposure has earlier been implicated in female infertility, the underlying molecular mechanisms explaining the toxicity of BPA in the ovary remains less understood. In the present study, a plausible correlation between redox balance or inflammatory signaling and reproductive fitness upon BPA exposure has been examined in zebrafish (Danio rerio) ovary. Congruent with significant alteration of major antioxidant enzymes (SOD1, SOD2, catalase, GPx1α, GSTα1) at the transcript level, 30 d BPA exposure at environmentally relevant concentrations (1, 10 and 100 µg L-1) promotes ovarian ROS/RNS synthesis, lipid peroxidation but attenuates catalase activity indicating elevated stress response. BPA promotes a sharp increase in ovarian p38 MAPK, NF-κB phosphorylation (activation), inducible nitric oxide synthase (Nos2a), and pro-inflammatory cytokines (TNF-α and IL-1ß) expression, the reliable markers for inflammatory response. Congruent to an increased number of atretic follicles, BPA-exposed zebrafish ovary reveals elevated Bax/Bcl2 ratio, activation of caspase-8, -3 and DNA breakdown suggesting heightened cell death. Importantly, significant alteration in nuclear estrogen receptor (ER) transcripts (esr1, esr2a, and esr2b) and proteins (ERα, ERß), gonadotropin receptors, and markers associated with steroidogenesis and growth factor gene expression in BPA-exposed ovary correlates well with impaired ovarian functions and maturational response. Collectively, elevated oxidative/nitrosative stress-mediated inflammatory response and altered ER expression can influence ovarian health and reproductive fitness in organisms exposed to BPA environment.

Expression of nitric oxide synthase (NOS) in Anabas testudineus ovary and participation of nitric oxide-cyclic GMP cascade in maintenance of meiotic arrest.

Participation of cyclic nucleotide-mediated signaling in nitric oxide/soluble guanylate cyclase (NO/sGC) regulation of oocyte maturation (OM) in perch (Anabas testudineus) follicle-enclosed oocytes has been investigated. Congruent with sharp decline in follicular cyclic GMP (cGMP) level, nitric oxide synthase (NOS)-inhibitor (L-NAME) attenuates protein kinase A (PKA) phosphorylation but promotes p-ERK1/2 and p-p34Cdc2 (Thr-161) in maturing oocytes. Conversely, NO donor (SNP) prevents OM, potentially through elevated cGMP synthesis. Expression and localization of Nos2 and Nos3 immunoreactivity in perch ovary varied considerably at progressively higher stages of folliculogenesis. While sGC inhibitor (ODQ) alone could induce OM, 8-bromo-cGMP attenuates 17,20ß-P-induced OM indicating functional significance of NO/sGC/cGMP in perch ovary. Interestingly, high NO/cGMP inhibition of OM shows positive relation with elevated cAMP level. MIS induced OM is more susceptible to the oocyte-specific phosphodiesterase (PDE) 3 than PDE4 inhibition. Collectively, high NO/cGMP attenuation of OM potentially involves PDE3 inhibition, cAMP accumulation and PKA activation.