Published online Apr 14, 2015. doi: 10.3748/wjg.v21.i14.4195
Peer-review started: October 18, 2014
First decision: December 2, 2014
Revised: December 17, 2014
Accepted: February 12, 2015
Article in press: February 13, 2015
Published online: April 14, 2015
AIM: To investigate the hepatoprotective effects and mechanisms of hydrogen-rich water (HRW) in acetaminophen (APAP)-induced liver injury in mice.
METHODS: Male mice were randomly divided into the following four groups: normal saline (NS) control group, mice received equivalent volumes of NS intraperitoneally (ip); HRW control group, mice were given HRW (same volume as the NS group); APAP + NS group, mice received NS ip for 3 d (5 mL/kg body weight, twice a day at 8 am and 5 pm) after APAP injection; APAP + HRW group, mice received HRW for 3 d (same as NS treatment) after APAP challenge. In the first experiment, mice were injected ip with a lethal dose of 750 mg/kg APAP to determine the 5-d survival rates. In the second experiment, mice were injected ip with a sub-lethal dose of 500 mg/kg. Blood and liver samples were collected at 24, 48, and 72 h after APAP injection to determine the degree of liver injury.
RESULTS: Treatment with HRW resulted in a significant increase in the 5-d survival rate compared with the APAP + NS treatment group (60% vs 26.67%, P < 0.05). HRW could significantly decrease the serum alanine aminotransferase level (24 h: 4442 ± 714.3 U/L vs 6909 ± 304.8 U/L, P < 0.01; 48 h: 3782 ± 557.5 U/L vs 5111 ± 404 U/L, P < 0.01; and 3255 ± 337.4 U/L vs 3814 ± 250.2 U/L, P < 0.05, respectively) and aspartate aminotransferase level (24 h: 4683 ± 443.4 U/L vs 5307 ± 408.4 U/L, P < 0.05; 48 h: 3392 ± 377.6 U/L vs 4458 ± 423.6 U/L, P < 0.01; and 3354 ± 399.4 U/L vs 3778 ± 358 U/L, respectively) compared with the APAP treatment group. The alkaline phosphatase, total bilirubin and lactate dehydrogenase levels had the same result. Seventy-two hours after APAP administration, liver samples were collected for pathological examination and serum was collected to detect the cytokine levels. The liver index (5.16% ± 0.26% vs 5.88% ± 0.073%, P < 0.05) and percentage of liver necrosis area (27.73% ± 0.58% vs 36.87% ± 0.49%, P < 0.01) were significantly lower in the HRW-treated animals. The malonyldialdehyde (MDA) contents were significantly reduced in the HRW pretreatment group, but they were increased in the APAP-treated group (10.44 ± 1.339 nmol/mg protein vs 16.70 ± 1.646 nmol/mg protein, P < 0.05). A decrease in superoxide dismutase (SOD) activity in the APAP treatment group and an increase of SOD in the HRW treatment group were also detected (9.74 ± 0.46 U/mg protein vs 12.1 ± 0.67 U/mg protein, P < 0.05). Furthermore, HRW could significantly increase the glutathione (GSH) contents (878.7 ± 76.73 mg/g protein vs 499.2 ± 48.87 mg/g protein) compared with the APAP treatment group. Meanwhile, HRW could reduce the inflammation level (serum TNF-α: 399.3 ± 45.50 pg/L vs 542.8 ± 22.38 pg/L, P < 0.05; and serum IL-6: 1056 ± 77.01 pg/L vs 1565 ± 42.11 pg/L, P < 0.01, respectively). In addition, HRW could inhibit 4-HNE, nitrotyrosine formation, JNK phosphorylation, connexin 32 and cytochrome P4502E expression. Simultaneously, HRW could facilitate hepatocyte mitosis to promote liver regeneration.
CONCLUSION: HRW has significant therapeutic potential in APAP-induced hepatotoxicity by inhibiting oxidative stress and inflammation and promoting liver regeneration.
Core tip: Acetaminophen (APAP)-induced liver injury is a devastating and fatal disease. Hydrogen is a newly-developed antioxidant that has an obvious effect of selectively reducing the strongest oxidants, such as hydroxyl radicals and peroxynitrite. We launched a research study to evaluate the protective role of hydrogen-rich water on APAP-induced hepatotoxicity in mice. We found that hydrogen-rich water treatment was effective in counteracting APAP-induced hepatic damage, oxidative stress and cellular necrosis. It could also promote hepatocyte proliferation and inhibit the expression of connexin 32, cytochrome P4502E and JNK phosphorylation after APAP administration. These results provide a potential therapy for APAP-induced liver injury.