Protective effect of metformin on pulmonary fibrosis caused by paraquat through activating AMP-activated protein kinase pathway / 中华危重病急救医学

OBJECTIVE@#To observe whether metformin (MET) inhibits transforming growth factor-β1 (TGF-β1)/Smad3 signaling pathway by activating adenosine activated protein kinase (AMPK), so as to alleviate the pulmonary fibrosis caused by paraquat (PQ) poisoning in mice.@*METHODS@#Male C57BL/6J mice were randomly divided into the Control group, PQ poisoning model group (PQ group), MET intervention group (PQ+MET group), AMPK agonist group (PQ+AICAR group), and AMPK inhibitor group (PQ+MET+CC group), according to a random number table method. A mouse model of PQ poisoning was established by one-time peritoneal injection of 1 mL PQ solution (20 mg/kg). The Control group was injected with the same volume of normal saline. After 2 hours of modeling, the PQ+MET group was given 2 mL of 200 mg/kg MET solution by gavage, the PQ+AICAR group was given 2 mL of 200 mg/kg AICAR solution by intraperitoneal injection, the PQ+MET+CC group was given 2 mL of 200 mg/kg MET solution by gavage and then 1 mL complex C (CC) solution (20 mg/kg) was intraperitoneally injected, the Control group and PQ group were given 2 mL of normal saline by gavage. The intervention was given once a day for 21 consecutive days. The 21-day survival rate of ten mice in each group was calculated, and the lung tissues of remaining mice were collected at 21 days after modeling. The pathological changes of lung tissues were observed under light microscope after hematoxylin-eosin (HE) staining and Masson staining, and the degree of pulmonary fibrosis was evaluated by Ashcroft score. The content of hydroxyproline in lung tissue and oxidative stress indicators such as malondialdehyde (MDA) and superoxide dismutase (SOD) were detected. The protein expressions of E-cadherin, α-smooth muscle actin (α-SMA), phosphorylated AMPK (p-AMPK), TGF-β1 and phosphorylated Smad3 (p-Smad3) in lung tissue were detected by Western blotting.@*RESULTS@#Compared with the Control group, the 21 days survival rate was significantly reduced, lung fibrosis and Ashcroft score were significantly increased in PQ group. In addition, the content of hydroxyproline, MDA and the protein expressions of α-SMA, TGF-β1 and p-Smad3 in lung tissue were significantly increased, while the activity of SOD and the protein expressions of E-cadherin and p-AMPK were significantly decreased in PQ group. Compared with the PQ group, the 21 days survival rates of mice were significantly improved in the PQ+MET group and PQ+AICAR group (70%, 60% vs. 20%, both P < 0.05). The degree of pulmonary fibrosis and the Ashcroft score were significantly reduced (1.50±0.55, 2.00±0.63 vs. 6.67±0.52, both P < 0.05). The content of hydroxyproline and MDA in lung tissue, as well as α-SMA, TGF-β1 and p-Smad3 protein expressions were significantly reduced [hydroxyproline (mg/L): 2.03±0.11, 3.00±0.85 vs. 4.92±0.65, MDA (kU/g): 2.06±1.48, 2.10±1.80 vs. 4.06±1.33, α-SMA/GAPDH: 0.23±0.06, 0.16±0.06 vs. 1.00±0.09, TGF-β1/GAPDH: 0.28±0.03, 0.53±0.05 vs. 0.92±0.06 p-Smad3/GAPDH: 0.52±0.04, 0.69±0.06 vs. 1.11±0.10, all P < 0.05], SOD activity and the protein expressions of E-cadherin and p-AMPK were significantly increased [SOD (μmol/g): 39.76±1.35, 33.03±1.28 vs. 20.08±1.79, E-cadherin/GAPDH: 0.91±0.08, 0.72±0.08 vs. 0.26±0.04, p-AMPK/GAPDH: 0.62±0.04, 0.60±0.01 vs. 0.20±0.04, all P < 0.05]. However, these protective effects of MET were inhibited by the addition of AMPK inhibitor CC solution.@*CONCLUSIONS@#MET can effectively alleviate the degree of pulmonary fibrosis in mice poisoned with PQ, and its mechanism may be related to the activation of AMPK and inhibition of TGF-β1/Smad3 signaling pathway, which can be inhibited by AMPK inhibitor CC.

Research progress on the relationship between diquat poisoning and nuclear factor E2-related factor 2 signaling pathway / 中华危重病急救医学

Since the production and use of paraquat was banned in China in 2016, the use of diquat (DQ) has been increasing and the clinical cases of DQ poisoning have also shown an increasing trend every year. The treatment of DQ poisoning is a worldwide medical problem, and there is no specific antidote. Studies have found that oxidative stress, lipid peroxidation, neurotoxicity, reproductive and developmental toxicity play an important role in DQ poisoning. Nuclear factor E2-related factor 2 (Nrf2) can inhibit oxidative stress, lipid peroxidation and inflammation by regulating the protein expression of upstream and downstream signaling molecules. Therefore, the role of Nrf2 signaling pathway in the poisoning and treatment of DQ has become a hot spot of attention for emergency critical care researchers in recent years. This paper reviews the relationship between Nrf2 signal pathway and DQ poisoning, in order to provide a theoretical basis for improving the treatment strategy for DQ poisoning.

Regularity of agonal respiration after untreated cardiac arrest in a swine model / 中华危重病急救医学

Objective To explore the regularity of incidence of agonal respiration (AR) and agonal respiration frequency rate (ARFR) during untreated cardiac arrest (CA) after ventricular fibrillation (VF) in a swine model.Methods Ten healthy male domestic pigs weighing (25.0± 3.0) kg were employed in this experiment.VF was induced by intraventricular shock with alternating current without treatment for 8 minutes.The incidence of AR and ARFR per minute were recorded for 8 minutes.Statistical analysis was performed using SPSS 19.0 system software.Results AR occurred in all animals after VF induced CA within 8 minutes.There was 1 animal showed AR at the first minute with ARFR (0.2±0.1) times/min,4 animals showed AR at the second minute with ARFR (1.2 ± 1.0) times/min,7 animals showed AR at the third minute with ARFR (2.7 ± 1.4) times/min,all animals showed AR at the fourth to fifth minute with ARFR (3.7 ± 1.6) times/min and (3.2 ± 1.9) times/min,7 animals showed AR at the sixth minute with ARFR (1.3 ± 1.0) times/min,no animal showed AR at the seventh minute,and 1 animal showed AR at the eighth minute with ARFR (0.2±0.1) times/min.The first and the last AR were observed at (2.02±0.84) minutes and (5.21 ± 1.12) minutes respectively.Occurrence of AR reached its peak at the fourth to fifth minute,and it was absent at the seventh minute.ARFR after CA showed a crescendo-decrescendo pattern,which increased from (0.2±0.1) times/min to (3.7±1.6) times/min followed by a fall to (0.2±0.1) times/min.Conclusions AR is one of the symbolic signs after CA.AR occurred in all animals during untreated VF,and it reaches its peak at the fomrth to fifth minute,with a crescendo-decrescendo pattern of ARFR.Effective identification and treatment in victim with AR timely can help to improve the success rate of cardiopulmonary resuscitation and survival rate.

Effects of spontaneous agonal respiration on coronary perfusion pressure during untreated cardiac arrest in swine model / 中华急诊医学杂志

Objective To investigate the effects of spontaneous agonal respiration on coronary perfusion pressure (CPP) during untreated cardiac arrest (ventricular fibrillation) in swine model.Methods Ten male healthy domestic swines (25.0 ± 1.5) kg were anaesthetised,intubated and mechanically ventilated.The catheterizations were separately inserted into the right atrium and thoracic aorta to monitor aortic pressure (AOP) and right atrial pressure (RAP).A pacing electrode was inserted into the right ventricle to induce ventricular fibrillation (VF).VF was induced by intra-ventricular stimulation withalternating electric current and untreated for 8 minutes.AOP and RAP were recorded until respiratory activity ceased.The CPP before and after agonal respiration was calculated and analyzed by paired-sample T test.Results All animals presented with agonal respiration from 1 to 6 minutes after VF during the first attempt.The CPP was (7.18 ±4.22) mmHg at 1 sec before agonal respiration,(11.78 ±5.16) mmHg at 0 sec after agonal respiration,(8.75 t:4.38) mmHg at 5 sec after agonal respiration and (8.23 ± 4.55)mmHg at 6 sec after agonal respiration.The CPP at 0 sec after agonal respiration was higher than that before agonal respiration (t =-3.140,P =0.012).The CPP at 5 sec after agonal respiration was higher than that at 1 sec before agonal respiration (t =-2.828,P =0.020).There was no difference in CPP between at 6 sec after agonal respiration and at 1 sec before agonal respiration (t =-1.778,P =0.109).Conclusions Agonal respiration accompanies ventricular fibrillation.After agonal respiration,the coronary perfusion pressure is increased for 5 seconds being in favor of cardiaopulmonary resuscitation.