Up-regulation of niacinamide in intervertebral disc aggrecan in vitro

Summary The regulatory effects of niacinamide (Nia) on intervertebral disc (IVD) aggrecan in vitro was investigated. Chiba's 10 ng/mL interleukin-1 (IL-1)-induced rabbit IVD degeneration model in vitro was established. 0. 5, 0. 25 and 0. 05 mg/mL Nia was added to normal and degenerated IVDs for intervention. On the first and second week after intervention, safranin O-fast green staining intensity and glycosaminoglycan (GS) content were measured. The expression of aggrecan core protein was detected by RT-PCR. The results showed: (1) After treatment with 0.5 mg/mL Nia for one week, the GS content in nucleus pulposus (NP) was increased by 44.8%, as compared with control group ( P <0.01); The GS content in IL-1 induction groups was increased with the increase of Nia concentrations: After treatment with 0.5 mg/mL for one week, the GS content in NP was increased by 68.3 % as compared with control group ( P <0.01). After two weeks, GS content in NP and fibrous rings was still higher than in control group at the same period ( P <0.01) and untreated group ( P <0.01). (2) Safranin O-fast green staining revealed that with the increase of Nia concentrations staining density in NP and fibrous rings was increased and histological structure damage to IVDs by IL-1β was alleviated. (3) RT-PCR showed that the expression of core protein gene in IL-1β-induced degenerated IVDS was increased with the increase of Nia concentrations. It was concluded that under conditions in vitro , Nia could up-regulate the expression of aggrecan in IVDs and protect IVDs from IL-1β-induced degeneration at least partially, which offers a potential choice for IVD degeneration clinical therapy.