Morin Improves Experimental Autoimmune Thyroiditis in Rats via NLRP3/Caspase-1 Pathway

  Objective  To investigate the effects of morin-regulated NLRP3/Caspase-1 pathway on experimental autoimmune thyroiditis in rats.

  Methods   The rats were randomly assigned to 6 groups: control group, experimental autoimmune thyroiditis group (EAT), low-, medium- and high-dose morin groups (post-modeling gavage of 50, 100 and 200 mg/kg morin hydrate per day for 6 weeks) and tripterygium wilfordii polyglycosides group (LGT group, post-modeling gavage of 6.25 mg/kg tripterygium wilfordii polyglycosidesper day for 6 weeks). Except for the control group, the rat model of experimental autoimmune thyroiditis was established by subcutaneous injection of 0.1 mL incomplete Freund’s adjuvant containing porcine thyroglobulin. The levels of serum thyroglobulin (TgAb), thyroid peroxidase antibody (TPOAb), triiodothyronine (T3) and tetraiodothyronine (T4) in serum were detected by radioimmunoassay. The mRNA levels of interleukin-17 (IL-17), interleukin-4 (IL-4) and interferon γ (INF-γ) were detected by reverse transcription-polymerase chain reaction. The levels of serum protein carbonyl content, 8-hydroxydeoxyguanosine (8-OHdG), and malondialdehyde (MDA) activity were checked with test kits. Expressions of NLRP3, apoptosis-related speck-like protein (ASC), and Caspase-1 were detected by Western blot.

  Results   Compared with the EAT group, serum levels of TPOAb, TgAb, T3, and T4 in low-, medium- and high-dose Morin groups and LGT group were reduced (P<0.01) and the mRNA levels of IL-17, INF-γ and IL-4 were increased (P<0.01), the protein hydroxyl content, MDA activity, and 8-OHdG levels were reduced (P<0.01). The levels of NLRP3, ASC and Caspase-1 were reduced (P<0.01), the levels of 8-OHdG were significantly reduced (P<0.01), and the levels of NLRP3, ASC and Caspase-1 were significantly reduced (P<0.01). There were statistically significant differences between the data from the low-dose and the medium-dose Morin groups and the data of the LGT group (P<0.05), while data from the high-dose Morin group showed no significant difference compared with the data of the LGT group. Data from low-, medium- and high-dose Morin groups showed no statistically significant differences (P<0.05).

  Conclusion   The findings suggest that Morin improved experimental autoimmune thyroiditis in rats through regulating NLRP3/Caspase-1 pathway.