Evaluation of vitamin C protective effect on the cerebrocortical antioxidant defense, histopathological, pro-apoptotic p53 and anti-apoptotic Bcl2 expressions against tramadol neurotoxicity in rats

Nano-TiO2 aggravates bioaccumulation and developmental neurotoxicity of difenoconazole in zebrafish larvae via oxidative stress and apoptosis: Protective role of vitamin C

Titanium dioxide nanoparticles (n-TiO₂) could enhance the bioavailability and toxicity of coexisting organic contaminants in the aquatic environment. This study attempted to investigate the combined effects of n-TiO₂ and difenoconazole (DIF) on the neurodevelopment of zebrafish and the underlying mechanisms. In this study, zebrafish embryos were exposed to n-TiO₂ (100 μg/L), DIF (0, 0.1 and 0.5 mg/L) and their mixtures from 4 to 96 h post fertilization (hpf) and neurotoxicity was evaluated. Our results indicated that n-TiO₂ adsorbed DIF into the brain of zebrafish and significantly enhanced the bioaccumulation of DIF and n-TiO₂ in the 0.5 mg/L co-exposure group. 100 μg/L n-TiO₂ was not developmentally toxic to the zebrafish larvae, but it exacerbated DIF-induced neurobehavioral alterations in the zebrafish larvae. n-TiO₂ also aggravated DIF-induced suppression of central nervous system (CNS) neurogenesis in Tg (HuC:egfp) zebrafish, motor neuron axon length in Tg (hb9:egfp) zebrafish, and downregulation of neurodevelopmental genes (elavl3, ngn1, gap43, gfap and mbp). In addition, DIF elevated oxidative stress by accumulation of reactive oxygen species (ROS) and inhibition of antioxidant enzymes, and triggered apoptosis by upregulation of p53, bax, bcl-2 and caspase-3, which were markedly intensified in the presence of n-TiO₂. Moreover, vitamin C (VC) ameliorated n-TiO₂/DIF-induced abnormal locomotor behaviors and neurotoxicity by inhibiting oxidative stress and apoptosis, indicating that oxidative stress and apoptosis are involved in n-TiO₂/DIF-induced neurotoxicity. Taken together, our data indicated that n-TiO₂ enhanced the accumulation of DIF and heightened oxidative stress and apoptosis, thereby inducing neurotoxicity. This study exemplifies the importance of the toxicity assessment of chemical mixtures and novel insights to mitigate their combined toxicity.

Boldenone Undecylenate-Mediated Hepatorenal Impairment by Oxidative Damage and Dysregulation of Heat Shock Protein 90 and Androgen Receptors Expressions: Vitamin C Preventive Role

Boldenone Undecylenate (BLD) is a synthetic derivative of testosterone and a widely used anabolic androgenic steroid. The health risk of BLD use as a pharmaceutical or dietary supplement is still underestimated and under-reported. Vitamin C (VC) has been recognized as an antioxidant with prominent hepatorenal protective effects. This study investigated the possible preventive activity of VC against BLD-induced hepatorenal damage. Forty adult male Wistar rats were classified into five groups: control, vehicle control, VC (orally given 120 mg/kg b. wt./day), BLD (intramuscularly injected 5 mg/kg b. wt./week), and BLD + VC-treated groups. The experiment continued for eight weeks. Serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured. Serum contents of total protein (TP), albumin (ALB), globulin, total cholesterol (TC), triglycerides (TG), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), and very-low-density lipoprotein-cholesterol (VLDL-C) were also assayed. Urea, creatinine, and uric acid levels were determined together with sodium and potassium electrolytes measuring. Moreover, oxidative stress indicators including reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GSR) as well as malondialdehyde (MDA) levels were measured in both hepatic and renal tissues. Corresponding histological examination of renal and hepatic tissues was conducted. Besides, immunohistochemical evaluations for androgen receptors protein (AR) and heat shock protein 90 (Hsp 90) expressions were performed. BLD caused significant rises in serum ALT, AST, TP, ALB, TC, TG, LDL-C, VLDL-C, urea, creatinine, uric acid, potassium, and MDA levels. Further, BLD-injected rats showed significant declines in the serum levels of HDL-C, sodium, GSH, GPx, GST, and GSR. Besides, distinct histopathological perturbations were detected in renal and hepatic tissues of BLD-injected rats. AR and Hsp 90 immunoexpression were increased in hepatic and renal tissues. In contrast, VC significantly reversed the BLD-induced hepatorenal damage in co-treated rats but not ameliorated AR protein overexpression. VC could be an efficient preventive supplement for mitigating BLD-induced hepatorenal damage, possibly via controlling oxidative stress events.