[Antagonist of cannabinoid receptor 1 improves nerve injury caused by chronic intermittent hypoxia by inhibiting the NLRP3 inflammasome pathway in mice].

Objective: To explore the regulatory mechanism of the targeted blockade of cannabinoid receptor 1 (CB1R) in relation to the neuroinflammatory response mediated by the NOD like receptor pyrin domain-containing 3 (NLRP3) inflammasome under chronic intermittent hypoxia (CIH) conditions. Methods: Forty adult male C57BL/6 mice were randomly divided into five groups: a normoxic control group (NC group), a CIH for 4 weeks group (4wCIH group), a CIH for 6 weeks group (6wCIH group), a CIH+CB1R antagonist AM251 intervention for 4 weeks group (4wCIH+AM251 group), and a CIH+AM251 intervention for 6 weeks group (6wCIH+AM251 group). Hematoxylin and eosin (HE) staining was used to observe the morphological changes of brain tissue. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expression of CB1R mRNA. Western blotting was used to analyze the protein levels of the NLRP3 inflammasome, and the enzyme-linked immunosorbent assay (ELISA) method was used to determine the contents of IL-1β and IL-18. Statistical analysis was performed using GraphPad Prism 9.5.0 software. Results: (1) Compared with the NC group, the CIH group displayed pathological changes characterized by neuronal degeneration and necrosis, nuclear pyknosis, and cytoplasmic hyperchromasia. These lesions were markedly attenuated in the CIH+AM251 group compared with the CIH group. (2) The relative expression levels of CB1R mRNA in the CIH groups were significantly higher than those in the NC group (all P<0.05), with the 6w CIH group showing higher levels than the 4w CIH group (P<0.05). Conversely, the 4w and 6w CIH+AM251 groups exhibited significantly lower relative expression levels compared with the corresponding CIH groups (all P<0.05).(3) Western blot analysis showed that NLRP3 protein expression in the CIH groups was significantly higher than that in the NC group (all P<0.05), and higher in the 6w CIH group than in the 4w CIH group (P<0.05). IL-1β protein expression levels in the 4w and 6w CIH groups were significantly elevated compared with the NC group [4w: (55.45±0.75) pg/ml vs. (49.85±1.41) pg/ml; 6w: (58.03±0.95) pg/ml vs. (49.85±1.41) pg/ml, both P<0.05]. Similarly, IL-18 protein expression levels in the 4w and 6w CIH groups were significantly higher than in the NC group [4w: (55.65±1.00) pg/ml vs. (50.34±1.61) pg/ml; 6w: (58.98±0.37) pg/ml vs. (50.34±1.61) pg/ml, both P<0.05]. Conversely, IL-1β protein expression in the 4w and 6w CIH+AM251 groups was significantly lower than in the corresponding CIH groups [4w: (52.82±0.94) pg/ml vs. (55.45±0.75) pg/ml, 6w: (52.58±0.52) pg/ml vs. (58.03±0.95) pg/ml, both P<0.05], and IL-18 protein expression was also significantly reduced [4w: (53.04±0.33) pg/ml vs. (55.65±1.0) pg/ml, 6w: (55.36±0.40) pg/ml vs. (58.98±0.37) pg/ml, both P<0.05]. Conclusion: Targeted blockade of CB1R effectively attenuates CIH-induced neuroinflammatory injury by regulating the activation pathway of the NLRP3 inflammasome, with protective effects that progressively accumulate over time.