Viability of Glioblastoma Cells and Fibroblasts in the Presence of Imidazole-Containing Compounds

Dual Effect of Carnosine on ROS Formation in Rat Cultured Cortical Astrocytes

Carnosine is composed of β-alanine and L-histidine and is considered to be an important neuroprotective agent with antioxidant, metal chelating, and antisenescence properties. However, children with serum carnosinase deficiency present increased circulating carnosine and severe neurological symptoms. We here investigated the in vitro effects of carnosine on redox and mitochondrial parameters in cultured cortical astrocytes from neonatal rats. Carnosine did not alter mitochondrial content or mitochondrial membrane potential. On the other hand, carnosine increased mitochondrial superoxide anion formation, levels of thiobarbituric acid reactive substances and oxidation of 2',7'-dichlorofluorescin diacetate (DCF-DA), indicating that carnosine per se acts as a pro-oxidant agent. Nonetheless, carnosine prevented DCF-DA oxidation induced by H2O2 in cultured cortical astrocytes. Since alterations on mitochondrial membrane potential are not likely to be involved in these effects of carnosine, the involvement of N-Methyl-D-aspartate (NMDA) receptors in the pro-oxidant actions of carnosine was investigated. MK-801, an antagonist of NMDA receptors, prevented DCF-DA oxidation induced by carnosine in cultured cortical astrocytes. Astrocyte reactivity induced by carnosine was also prevented by the coincubation with MK-801. The present study shows for the very first time the pro-oxidant effects of carnosine per se in astrocytes. The data raise awareness on the importance of a better understanding of the biological actions of carnosine, a nutraceutical otherwise widely reported as devoid of side effects.

Effect of muscle fibre types and carnosine levels on the expression of carnosine-related genes in pig skeletal muscle

It is generally accepted that carnosine (β-alanyl-L-histidine) content is higher in glycolytic than in oxidative muscle fibres, but the underlying mechanisms responsible for this difference remain to be elucidated. A first study to better understand potential mechanisms involved was undertaken (1) to determine whether differences in the expression of carnosine-related enzymes (CARNS1, CNDP2) and transporters (SLC6A6, SLC15A3, SLC15A4, SLC36A1) exist between oxidative and glycolytic myofibres and (2) to study the effect of carnosine on myoblast proliferative growth and on carnosine-related gene expression in cultured myoblasts isolated from glycolytic and oxidative muscles. Immunohistochemistry analyses were conducted to determine the cellular localization of carnosine-related proteins. Laser-capture microdissection and qPCR analyses were performed to measure the expression of carnosine-related genes in different myofibres isolated from the longissimus dorsi muscle of ten crossbred pigs. Myogenic cells originating from glycolytic and oxidative muscles were cultured to assess the effect of carnosine (0, 10, 25 and 50 mM) on their proliferative growth and on carnosine-related gene expression. The mRNA abundance of CNDP2 and of the studied carnosine transporters was higher in oxidative than in glycolytic myofibres. Since carnosine synthase (CARNS1) mRNA abundance was not affected by either the fibre type or the addition of carnosine to myoblasts, its transcriptional regulation would not be the main process by which carnosine content differences are determined in oxidative and glycolytic muscles. The addition of carnosine to myoblasts leading to a dose-dependent increase in SLC15A3 transcripts, however, suggests a role for this transporter in carnosine uptake and/or efflux to maintain cellular homeostasis.