RESUMO
ObjectiveThere are few animal experiments on ICU acquired weakness (ICU AW), and suitable animal models are the main constraints. The study was to explore the method of ICU AW animal model which satisfies the clinical requirements of ICU and suitable for large-scale animal trials.MethodsThirty six SD rats were randomly divided into Control group(0.9%NS at 2.5 ml/kg intraperitoneal injection once a day for consecutive 3 days), immobilization group(the left hindlimb was immobilizated for 7d, then the immobilization was removed to 14 d), sepsis group(lipopolysaccharide at 2.5 mg/kg intraperitoneal injection once a day for consecutive 3 days) and sepsis-immobilization group(the left hindlimb was immobilizated for 7d, then the immobilization was removed to 14 d and lipopolysaccharide at 2.5 mg/kg intraperitoneal injection once a day for consecutive 3 days).To determine whether the model was successful, the muscle strength of left hindlimb, gastrocnemius/body weight ratio and pathological changes of gastrocnemius were measured at 0 d( immediately after intervention), 3d, 7 d, 10 d, 14 d. To explore the possible pathological mechanism, creatinine/body weight ratio, albumin, lymphocyte, and gastrocnemius pathological scores were measured.Results7 days later, the scores of left hindlimb muscle strength and pathology in sepsis immobilization group were significantly higher than those in the sepsis group and the control group(P<0.05), contary body weight and gastrocnemius weight were lower than those in control group, immobilization group and sepsis group(P<0.05), and gastrocnmiu/body weight ratio(0.528±0.018) was significantly lower than those in control group(0.756±0.315) and sepsis group(0.813±0.040)(P<0.05). Creatinine / body weight in sepsis immobilization group(0.283±0.0268) was significantly higher than those of blank group (0.185±0.022), immobilization group (0.207±0.027) and sepsis group (0.246±0.043)(P<0.05). The lymphocyte count [(5.193±1.493) ×109/L] was significantly lower than that in the blank group[(7.005±0.702) ×109/L] and the immobilization group[(7.208±0.832) ×109/L)](P< 0.05). 14 days later, the scores of left hindlimb muscle strength, body and gastrocnemius weight in sepsis immobilization group were significantly lower than those in control group, immobilization group and sepsis group(P<0.05). Gastrocnmiu/body weight ratio in sepsis immobilization group(0.519± 1.493) was significantly lower than those in control group(0.798±0.015), immobilization group (0.570±0.022)and sepsis group(0.693±0.022)(P<0.05).ConclusionThe qualified animal model of ICU AW can be established by repeated intraperitoneal injection in low dose of lipopolysaccharide combined with limb immobilization. Immunosuppression and Hypercatabolism in ICU AW rats is an important reason that ICU AW can not to be mitigated. Thus, we supposed that it may be the mechanisms for the development of ICU AW,which needs further experimental verification.