NAC facilitates energy metabolism transition toward oxidative phosphorylation in hypoxia-inducible goat temporomandibular joint disc cells

Abstract I. Background: The roles of antioxidants on the energy metabolism of disc cells are not clear. In this study, we clarified the roles of antioxidant N-acetylcysteine (NAC) on the energy metabolism of goat temporomandibular joint (TMJ) disc cells exposed to hypoxia. II. Methods and Results: The Isolated and cultured goat TMJ disc cells were divided into control, NAC group, cobalt chloride (CoCl2) group, and CoCl2 with NAC group, exposed to 21% O2 and 2% O2. The glucose consumption, lactate content, intracellular ATP, ROS, HIF-1α, GLUT1, LDHA, PKM2 and PGK1 expressions were detected respectively. Under the hypoxia model, NAC inhibited the mRNA expression of HIF-1α, GLUT1, LDHA, PKM2, and PGK1. And it significantly decreased the lactate content in the culture supernatant and the intracellular ROS. However, NAC increased glucose consumption and simultaneously promoted the production of ATP in goat TMJ disc cells under hypoxia. We speculated that NAC would transfer energy metabolism toward oxidative phosphorylation under hypoxia. And NAC would become a potential therapeutic target for TMJ disc engineering and disease study. III. Conclusions: The antioxidant NAC promoted the proliferation of hypoxia-inducible goat TMJ disc cells, and the CoCl2 group (21% O2) was promoted effectively (P < 0.05). NAC promoted glucose consumption in culture supernatants under hypoxia and significantly reduced lactate production (P < 0.01). NAC effectively eliminated intracellular ROS expression in hypoxia-inducible cells (P < 0.001) and promoted intracellular ATP production (P < 0.05). However, NAC inhibited the relative mRNA level of HIF-1α, GLUT1, LDHA, PKM2, and PGK1 (P < 0.05).