MMP9 and Low back pain: Melatonin is known to have multiple effects, including antioxidant, anti-inflammatory, and antiapoptotic impacts, in different systems.28,29 A recent study showed that melatonin downregulates the gene expression of cyclin D1, PCNA, matrix metallopeptidase (MMP)-3, and MMP-9 and upregulates the gene expression of collagen type II alpha 1 chain and aggrecan in NP cells.47 Our results were consistent with previous data and showed that the application of melatonin in an IVDD model alleviated the progression of IVDD and LBP.