Coenzyme Q10 alleviates tacrolimus-induced mitochondrial dysfunction in kidney.

The major side effect of tacrolimus (Tac) is nephrotoxicity. We studied whether supplementation of coenzyme Q10, (CoQ10) a potent antioxidant, can reduce Tac-induced nephrotoxicity via improving mitochondrial function. In an in vitro study, CoQ10 reduced the production of Tac-induced mitochondrial reactive oxygen species and abolished the loss of mitochondrial membrane potential in proximal tubular cell line. Assessment of mitochondrial function revealed that CoQ10 decreased oxygen consumption and mitochondrial respiration rate increased by Tac, suggesting improvement of mitochondrial function to synthesize ATP with CoQ10 treatment. The effect of the CoQ10in vitro study was observed in an experimental model of chronic Tac-induced nephropathy. CoQ10 attenuated Tac-induced oxidative stress and was accompanied by function and histologic improvement. On electron microscopy, addition of CoQ10 increased not only the number but also the volume of mitochondria compared with Tac treatment only. Our data indicate that CoQ10 improves Tac-induced mitochondrial dysfunction in kidney. Supplementary CoQ10 treatment may be a promising approach to reduce Tac-induced nephrotoxicity.-Yu, J. H., Lim, S. W., Luo, K., Cui, S., Quan, Y., Shin, Y. J., Lee, K. E., Kim, H. L., Ko, E. J., Chung, B. H., Kim, J. H., Chung, S. J., Yang, C. W. Coenzyme Q10 alleviates tacrolimus-induced mitochondrial dysfunction in kidney.

Therapeutic potential of coenzyme Q10 in mitochondrial dysfunction during tacrolimus-induced beta cell injury.

We previously reported that oxidative stress induced by long-term tacrolimus treatment impairs mitochondrial function in pancreatic beta cells. In this study, we aimed to investigate the therapeutic potential of coenzyme Q10, which is known to be a powerful antioxidant, in mitochondrial dysfunction in tacrolimus-induced diabetic rats. In a rat model of tacrolimus-induced diabetes mellitus, coenzyme Q10 treatment improved pancreatic beta cell function. The administration of coenzyme Q10 improved insulin immunoreactivity within islets, which was accompanied by reductions in oxidative stress and apoptosis. Assessment of the mitochondrial ultrastructure by electron microscopy revealed that coenzyme Q10 treatment increased the size, number, and volume of mitochondria, as well as the number of insulin granules compared with that induced by tacrolimus treatment alone. An in vitro study using a pancreatic beta cell line showed that tacrolimus treatment increased apoptosis and the production of mitochondrial reactive oxygen species, while cotreatment with coenzyme Q10 effectively attenuated these alterations. At the subcellular level, tacrolimus-induced impairment of mitochondrial respiration was significantly improved by coenzyme Q10, as evidenced by the increased mitochondrial oxygen consumption and ATP production. Our data indicate that coenzyme Q10 plays an important role in reducing tacrolimus-induced oxidative stress and protects the mitochondria in pancreatic beta cells. These findings suggest that supplementation with coenzyme Q10 has beneficial effects in tacrolimus-induced diabetes mellitus.

Functional survival of rat pituitary gland in hypothermic storage for pituitary transplantation.

PURPOSE: Deteriorated pituitary function can lead to serious complications that might need lifelong hormone replacement therapy. However, long-term hormone administration can have significant adverse effects. Thus, it would be more desirable to restore pituitary function by pituitary transplantation. In this study, we investigated functional preservation of extracted pituitary gland in special preservation solution under hypothermic condition for pituitary transplantation. METHODS: We obtained nineteen pituitary glands from 250-300 g male Sprague-Dawley rats via parapharyngeal approach. These extracted glands were divided into three pieces and stored in histidine-tryptophan-ketoglutarate (HTK) solution at 4 °C and compared to their corresponding glands stored in phosphate buffer saline (PBS). Light and electron microscopic examinations were performed to identify morphological changes of pituitary gland at 0,3, and 7 days after storage. TUNEL assay to confirm cell viability, and adenosine-triphosphate (ATP) concentration were also serially examined. RESULTS: Tissue architecture and cellular viability of specimens preserved in HTK solution for 3 days were considerably maintained and similar to those in normal pituitary gland (0 day specimen). In contrast, specimens stored in PBS were markedly destroyed after 3 days of storage. After 7 days of storage, significant degeneration occurred in tissues stored in both HTK and PBS. However, tissue architecture was preserved more in specimens stored in HTK solution than those stored in PBS. ATP concentration decreased more rapidly in specimens stored in PBS solution, but there was no statistical significance (p= 0.055). CONCLUSIONS: Extracted rat pituitary gland supplemented with special preservation solution could be preserved for 3 days under hypothermic condition.

Progressive accumulation of autofluorescent granules in macrophages in rat striatum after systemic 3-nitropropionic acid: a correlative light- and electron-microscopic study.

A variety of tissue biomolecules and intracellular structures are known to be autofluorescent. However, autofluorescent signals in brain tissues often confound analysis of the fluorescent markers used for immunohistochemistry. While investigating tissue and cellular pathologies induced by 3-nitropropionic acid, a mitochondrial toxin selective for striatal neurons, we encountered many autofluorescent signals confined to the lesion core. These structures were excited by blue (wavelength = 488 nm) and yellow-orange (555 nm), but not by red (639 nm) or violet (405 nm) lasers, indicating that this autofluorescence overlaps with the emission spectra of commonly used fluorophores. Almost all of the autofluorescence was localized in activated microglia/macrophages, while reactive astrocytes emitted no detectable autofluorescence. Amoeboid brain macrophages filled with autofluorescent granules revealed very weak expression of the microglial marker, ionized calcium-binding adaptor molecule 1 (Iba1), while activated microglia with evident processes and intense Iba1 immunoreactivity contained scant autofluorescent granules. In addition, immunolabeling with two lysosomal markers, ED1/CD68 and lysosomal-associated membrane protein 1, showed a pattern complementary with autofluorescent signals in activated microglia/macrophages, implying that the autofluorescent structures reside within cytoplasm free of intact lysosomes. A correlative light- and electron-microscopic approach finally revealed the ultrastructural identity of the fluorescent granules, most of which matched to clusters of lipofuscin-like inclusions with varying morphology. Thus, autofluorescence in the damaged brain may reflect the presence of lipofuscin-laden brain macrophages, which should be taken into account when verifying any fluorescent signals that are likely to be correlated with activated microglia/macrophages after brain insults.

Ultrastructure of a Mobile Threadlike Tissue Floating in a Lymph Vessel.

Observations of the primo vascular system (PVS) floating in lymph ducts were reported by various groups. There have been, however, no studies on the ultrastructure of the entire cross section of a primo vessel (PV) inside a lymph vessel with a transmission electron microscope (TEM). In the current study we took the TEM images of a cross section of the PV inside a lymph vessel. We used the Alcian blue staining method for the finding of the target PV in a lymphatic vessel by injecting the dye into the inguinal lymph nodes. The stained PV was harvested together with the lymph vessel and some parts of the specimens were used for studying with optical microscopes. Some other parts were treated according to a standard protocol for TEM. As the results the TEM study revealed the loosely distributed collagen fibers with plenty of empty spaces and the lumens with the endothelial nuclei. It turned out to be very similar to the ultrastructure of the PVs observed on the surfaces of internal organs. It also showed how compactly the PV is surrounded with lymphocytes. In conclusion, the detailed morphological features like the distribution of fibers in the PV were revealed and shown to be similar to another kind of the PV on the surfaces of internal organs.

Renexin as a rescue regimen for noise-induced hearing loss.

Renexin, a compound of cilostazol and ginkgo biloba extract, has been reported to produce neuroprotective effects through antioxidant, antiplatelet, and vasodilatory mechanisms. This study was designed to investigate the protective effects of renexin on hearing, the organ of Corti (OC), and medial olivocochlear efferents against noise-induced damage. C57BL/6 mice were exposed to 110 dB SPL white noise for 60 min and then randomly divided into three groups: high- and low-dose renexin-treated groups and noise only group. Renexin were administered for 7 days: 90 mg/kg to the low-dose, and 180 mg/kg to the high-dose groups. All mice, including the controls underwent hearing tests on postnoise day 8 and were killed for cochlear harvest. We compared the hearing thresholds and morphology of the OC and cochlear efferents across the groups. The renexin-treated groups recovered from the immediate threshold shifts in a dose-dependent manner, while the noise group showed a permanent hearing loss. The renexin-treated ears demonstrated less degeneration of the OC. The diameters of the efferent terminals labeled with α-synuclein were preserved in the high-dose renexin-treated group. In the western blot assay of the cochlear homogenates, the treated groups displayed stronger expressions of α-synuclein than the noise and control groups, which may indicate that noise-induced enhanced activity of the cochlear efferent system was protected by renexin. Our results suggest that pharmacologic treatment with renexin is hopeful to reduce or prevent noise-induced hearing loss as a rescue regimen after noise exposure.