To investigate the expression and role of NOD-like receptor thermal-protein domain-related protein 3 (NLRP3) inflammasome in the skeletal muscles of the rats with Intensive Care Unit-acquired weakness (ICU-AW).

Forty healthy male Sprague-Dawley rats were randomly divided into a control group (the sham group) and an experimental group (a septic group). The ICU-AW models were established by cecal ligation and puncture, while cecal exposure but no ligation or puncture was carried out in the rats of the control group. The gastrocnemius and diaphragmatic muscle specimens were collected 96 h after modeling. The pathological changes were observed by HE staining and the cross-sectional areas of the muscle fibers were calculated and compared between the two groups. Both gene and protein expressions of atrogin-1, MuRF1, NLRP3, caspase-1, IL-1β and IL-18 in the gastrocnemius and diaphragmatic muscle were detected by qRT-PCR and Western blotting method.

The arrangement of the gastrocnemius and diaphragm muscle fibers was looser 96 h after cecal ligation and puncture compared with that of the controls. And the cross-sectional areas of the muscle fibers from the experimental group were significantly smaller than those of the controls (P<0.05). Both gene and protein expression levels of atrogin-1 and MuRF1 were higher in the muscle samples from the ICU-AW rats than those of the controls (P<0.05). NLRP3 inflammatory body-related molecular studies showed that the expression levels of NLRP3, caspase-1, IL-1β and IL-18 in the gastrocnemius and diaphragmatic muscle of the ICU-AW rats were significantly higher than those of the controls (P<0.05).

Skeletal muscle lysis participates in the occurrence of ICU-AW in the rat models created by cecal ligation and puncture, and NLRP3 inflammasome-related signal pathway participates in the above process.