Effects of TNF-alpha inhibition on inner ear microcirculation and hearing function after acute loud noise in vivo

Acute noise-induced inner ear hearing loss is characterized by microcirculatory disturbance in the stria vascularis. In addition to the immunomodulatory effect, inhibition of TNF-α activity might prevent vasoconstriction of the spiral modiolar artery by inactivation of Sphingokinase-1 in the S1P/S1P2 signaling system in vascular smooth muscle cells as well as reduce downregulation of NO-mediated vasodilation. Therefore, early treatment with TNF-α-inhibitors might prevent hearing impairment by restoring cochlear blood flow. In order to investigate acute effects of loud noise exposure on cochlear microcirculation and hearing function, we have established a new standardized animal model by using in vivo-fluorescence microscopy and auditory brainstem response. Fluorescent dextran as a blood plasma marker was given intravenously in guinea pigs under narcosis. On one ear, cochlea and stria vascularis were surgically exposed for microscopic analysis. On the contralateral ear, hearing threshold was measured by auditory brainstem response after exposure of both ears to loud noise (106 dB SPL, 30 min). Control animals were not exposed to noise. In contrast to control animals, cochlear blood flow was reduced by 44 % while the hearing threshold increased by 23 dB SPL at the end of the observation period (210 min) after loud noise exposure. After using this model for therapeutic evaluation, early treatment with a single dose of TNF-α-inhibitor – etanercept - was shown to restore cochlear blood flow and maintain hearing threshold. When cochlear blood flow was reduced by 36.0 % in saline-treated control animals, only 2.2 % reduction was observed under TNF-α-inhibition at the end of the observation. Similarly, when the total hearing threshold shift reached + 20 dB SPL in control animals, there was almost no threshold shift subsequent to TNF-α-inhibition therapy. In conclusion, these data clearly show that TNF-α-inhibition is a promising treatment strategy in acute noise-induced hearing loss

Modeling the Measurements of Cochlear Microcirculation and Hearing Function after Loud Noise

Objective: Recent findings support the crucial role of microcirculatory disturbance and ischemia for hearing impairment especially after noise-induced hearing loss (NIHL). The aim of this study was to establish an animal model for in vivo analysis of cochlear microcirculation and hearing function after a loud noise to allow precise measurements of both parameters in vivo. Study Design: Randomized controlled trial. Setting: Animal study. Subjects and Methods: After assessment of normacusis (0 minutes) using evoked auditory brainstem responses (ABRs), noise (106-dB sound pressure level [SPL]) was applied to both ears in 6 guinea pigs for 30 minutes while unexposed animals served as controls. In vivo fluorescence microscopy of the stria vascularis capillaries was performed after surgical exposure of 1 cochlea. ABR measurements were derived from the contralateral ear. Results: After noise exposure, red blood cell velocity was reduced significantly by 24.3% (120 minutes) and further decreased to 44.5% at the end of the observation (210 minutes) in contrast to stable control measurements. Vessel diameters were not affected in both groups. A gradual decrease of segmental blood flow became significant (38.1%) after 150 minutes compared with controls. Hearing thresholds shifted significantly from 20.0 ± 5.5 dB SPL (0 minutes) to 32.5 ± 4.2dB SPL (60 minutes) only in animals exposed to loud noise. Conclusion: With regard to novel treatments targeting the stria vascularis in NIHL, this standardized model allows us to analyze in detail cochlear microcirculation and hearing function in vivo

Gastroprotective Activities of Ethanol Extract of Black Rice Bran (Oryza sativa L.) in Rats

Black rice is a type of rice in the Oryza sativa L. species. There are numerous reports regarding the pharmacological actions of black rice bran, but scientific evidence on its gastroprotection is limited. This study aimed to evaluate the gastroprotective activities of black rice bran ethanol extract (BRB) from the Thai black rice variety Hom Nil (O. sativa L. indica) as well as its mechanisms of action, acute oral toxicity in rats, and phytochemical screening. Rat models of gastric ulcers induced by acidified ethanol, indomethacin, and restraint water immersion stress were used. After pretreatment with 200, 400, and 800 mg/kg of BRB in test groups, BRB at 800 mg/kg significantly inhibited the formation of gastric ulcers in all gastric ulcer models, and this inhibition seemed to be dose dependent in an indomethacin-induced gastric ulcer model. BRB could not normalize the amount of gastric wall mucus, reduce gastric volume and total acidity, or increase gastric pH. Although BRB could not increase NO levels in gastric tissue, the tissue MDA levels could be normalized with DPPH radical scavenging activity. These results confirm the gastroprotective activities of BRB with a possible mechanism of action via antioxidant activity. The major phytochemical components of BRB comprise carotenoid derivatives with the presence of phenolic compounds. These components may be responsible for the gastroprotective activities of BRB. The 2000 mg/kg dose of oral BRB showed no acute toxicity in rats and confirmed, in part, the safe uses of BRB

Safety of the Oral Triphala Recipe from Acute and Chronic Toxicity Tests in Sprague-Dawley Rats

Background: The Indian Ayurvedic herbal formula Triphala (TPL) is known for its pharmacological properties for immunomodulation, anti-inflammation, antioxidant, and anti-cancer. This study aimed to investigate the acute and chronic toxicities of the Triphala recipe in a rat model. Methods: To assess the acute toxicities, 5000 mg/kg of TPL was orally administered to Sprague-Dawley rats. For chronic toxicities, different dose levels of TPL at 600, 1200, and 2400 mg/kg/day were given daily for 270 days. General health and behaviors and the body and organ weights of the rats were monitored. At the end of the experiment, blood samples were evaluated for hematology and biochemistry profiles. The evaluation of the internal organs’ appurtenance and necropsy was performed to confirm the tissue histopathology. Results: The results showed that there was no sign of acute toxicity in the TPL group with a decrease in sex organ weights. No significant differences in the rats’ behaviors, physical health, body, or organ weights were found between the controls and the rats receiving the 270/day of oral Triphala at 600, 1200, and 2400 mg/kg/day. However, some alterations in blood chemistries and hematology, including glucose, BUN, red blood cells, Hb, HCT, and MCV, were observed without abnormalities in histopathology. Conclusions: It has been demonstrated that the long-term use of TPL in rat models is safe. No toxic effects were found, suggesting possible safety for long-term use in humans

Absence of glutathione peroxidase 4 affects tumor angiogenesis through increased 12/15-lipoxygenase activity.

The selenoenzyme glutathione peroxidase 4 (GPx4) has been described to control specific cyclooxygenases (COXs) and lipoxygenases (LOXs) that exert substantiated functions in tumor growth and angiogenesis. Therefore, we hypothesized a putative regulatory role of GPx4 during tumor progression and created transformed murine embryonic fibroblasts with inducible disruption of GPx4. GPx4 inactivation caused rapid cell death in vitro, which could be prevented either by lipophilic antioxidants or by 12/15-LOX-specific inhibitors, but not by inhibitors targeting other LOX isoforms or COX. Surprisingly, transformed GPx4(+/-) cells did not die when grown in Matrigel but gave rise to tumor spheroids. Subcutaneous implantation of tumor cells into mice resulted in knockout tumors that were indistinguishable in volume and mass in comparison to wild-type tumors. However, further analysis revealed a strong vascular phenotype. We observed an increase in microvessel density as well as a reduction in the number of large diameter vessels covered by smooth muscle cells. This phenotype could be linked to increased 12/15-LOX activity that was accompanied by an up-regulation of basic fibroblast growth factor and down-regulation of vascular endothelial growth factor A protein expression. Indeed, pharmacological inhibition of 12/15-LOX successfully reversed the tumor phenotype and led to "normalized" vessel morphology. Thus, we conclude that GPx4, through controlling 12/15-LOX activity, is an important regulator of tumor angiogenesis as well as vessel maturation