[β1 receptor blocker decreases the myocardial inflammation in the sepsis adult rats through inhibition of TLR4/NF-ΚB signaling pathway].

Objective: To explore whether β1 receptor blocker could decrease the myocardial inflammation through the Toll-like receptor 4/nuclear factor-ΚB (TLR4/NF-ΚB) signaling pathway in the sepsis adult rats.

Methods: Sixty male Wistar rats (250-300 g) aged 3 months old were allocated to four groups by random number table (n = 15): sham operation group (S group), sepsis model group (CLP group), β1 receptor blocker esmolol intervention group (ES group), and inhibitor of the TLR4 E5564 intervention group (E5564 group). The rat sepsis model was established by cecal ligation and puncture (CLP); S group of rats underwent only an incision. Rats in S group, CLP group and E5564 group were subcutaneous injected with 0.9% sodium chloride (NaCl) 2.0 mL/kg. Besides, the rats in ES group were injected with esmolol (15 mg×kg×h) by micro pump through the caudal vein. The rats in E5564 group were injected with E5564 (0.3 mg×kg×h) by micro pump through the caudal vein 1 hour before the CLP surgery. Samples were collected 6 hours after the modelling in each group. The average arterial pressure (MAP) and cardiac output index (CI) were monitored by PU electrical conduction ECG monitor. The levels of serum cardiac troponin I (cTnI), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were detected by enzyme linked immunosorbent assay (ELISA). The expressions of TLR4, NF-ΚB p65, IL-1β, TNF-α in myocardial tissue was detected by Western Blot.

Results: There was no significant difference in MAP in each group. Compared with the S group, the CI in the CLP group was significantly decreased, the levels of serum cTnI, IL-1β, TNF-α were significantly increased, the protein expressions of myocardial tissue TLR4, NF-ΚB p65, IL-1β and TNF-α were significantly increased. Compared with the CLP group, the CI in the ES group and E5564 group were significantly increased (mL×s×m: 58.6±4.3, 58.9±4.4 vs. 41.2±3.9, both P < 0.01), the levels of serum cTnI, IL-1β and TNF-α were significantly decreased [cTnI (μg/L): 1 113.81±26.64, 1 115.74±25.90 vs. 1 975.96±42.74; IL-1β (ng/L): 39.6±4.3, 38.9±4.4 vs. 61.2±3.9; TNF-α (ng/L): 43.1±2.8, 48.7±2.6 vs. 81.3±4.4, all P < 0.01], the protein expressions of myocardial tissue NF-ΚB p65, IL-1β, TNF-α were significantly decreased (NF-ΚB p65/β-actin: 0.31±0.03, 0.43±0.04 vs. 0.85±0.08; IL-1β/β-actin: 0.28±0.05, 0.32±0.03 vs. 0.71±0.06; TNF-α/β-actin: 0.18±0.04, 0.28±0.03 vs. 0.78±0.07, all P < 0.01), but there was no significant difference in protein expression of TLR4 (TLR4/β-actin: 0.89±0.07, 0.87±0.09 vs. 0.95±0.09, both P > 0.05). There was no significant difference in CI, the levels of serum cTnI, IL-1β, TNF-α, and the protein expressions of myocardial tissue TLR4, NF-ΚB p65, IL-1β, TNF-α between ES group and E5564 group (all P > 0.05).

Conclusions: β1 receptor blocker esmolol may inhibit myocardial inflammatory response in sepsis adult rats through TLR4/NF-ΚB signaling pathway, thereby alleviating sepsis-induced myocardial injury.