Search

Aging and obesity pose significant threats to public health and are major contributors to muscle atrophy. The trends in muscle fiber types under these conditions and the transcriptional differences between different muscle fiber types remain unclear. Here, we demonstrate distinct responses of fast/glycolytic fibers and slow/oxidative fibers to aging and obesity. We found that in muscles dominated by oxidative fibers, the proportion of oxidative fibers remains unchanged during aging and obesity. However, in muscles dominated by glycolytic fibers, despite the low content of oxidative fibers, a significant decrease in proportion of oxidative fibers was observed. Consistently, our study uncovered that during aging and obesity, fast/glycolytic fibers specifically increased the expression of genes associated with muscle atrophy and inflammation, including Dkk3, Ccl8, Cxcl10, Cxcl13, Fbxo32, Depp1, and Chac1, while slow/oxidative fibers exhibit elevated expression of antioxidant protein Nqo-1 and downregulation of Tfrc. Additionally, we noted substantial differences in the expression of calcium-related signaling pathways between fast/glycolytic fibers and slow/oxidative fibers in response to aging and obesity. Treatment with a calcium channel inhibitor thapsigargin significantly increased the abundance of oxidative fibers. Our study provides additional evidence to support the transcriptomic differences in muscle fiber types under pathophysiological conditions, thereby establishing a theoretical basis for modulating muscle fiber types in disease treatment., (© 2024. The Author(s).)

Glaucoma is a leading cause of blindness. Primary open-angle glaucoma, the most common form of glaucoma, is known to increase in prevalence with age. One of its major risk factors is an elevated intraocular pressure believed to be related to the trabecular meshwork (TM), a specialized tissue located at the chamber angle of the eye. Myocilin, a gene linked to open-angle glaucomas (OAG), has been found to be expressed in the TM and a broad range of other ocular and non-ocular tissues. The purpose of this study was to examine the distribution of myocilin protein and mRNA in the TM of normal human eyes to determine whether age-related changes exist. Studies with glaucomatous eyes were carried out concurrently. Immunoperoxidase staining experiments demonstrated positive immunoreactivity for myocilin protein in both the cells and beams in all regions of the TM. The staining intensity and the myocilin level as determined by dot blot assays were not correlated with the ages of donors ranging from 8 weeks to 93 years. Neither did myocilin mRNA, detected by in situ hybridization in cells throughout the TM and quantified by relative quantitative RT-PCR, vary with age. Myocilin mRNA and protein expression in diseased tissues was either comparable to that of normal tissues or reduced. This study represents the first in-depth investigation of myocilin expression in relation to age in the TM of human eyes. The results indicate an age independence, argue thus against a direct role of myocilin and reiterate the involvement of additional factors in the pathogenesis of glaucoma.

[Display omitted] • TP can improve the spatial memory by increasing glucose transport and metabolism. • EGCG has a protective effect on cellular energy metabolism monitored by Seahorse. Tea polyphenols (TP) are the main active components of tea. In our study, the effect of TP on the menopause and aging related memory decline and the mechanisms focused on the brain glucose metabolism were clarified. In vivo, ovariectomy (OVX) combined with D-galactose (D-gal) injection were used to establish the memory decline model. TP administration improved the spatial memory by increasing the expressions of GLUT1, 3 and Tau protein O-GlcNAc glycosylation, decreasing Tau hyper-phosphorylation and the Aβ 1-42 level, and improving the morphology of mitochondria in hippocampus. Furthermore, in vitro, PC12 cells were treated with Aβ 1-42 and EGCG treatment regulated the mitochondrial respiratory function and glycolytic functions, improved the activities of the key enzymes in glycolysis and tricarboxylic acid cycle, increased the SOD activity and decreased the MDA levels in cells. Our study suggests that TP improve the memory in aging ovariectomized rats by regulating brain glucose metabolism. [ABSTRACT FROM AUTHOR]