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Antagonism of acetaminophen-induced hepatocellular destruction by trifluoperazine in mice
1Department of Environmental Medicine, University of Tsukuba, Ibaraki, Japan.
Abstract:
The effect of trifluoperazine, a specific calmodulin inhibitor, on hepatocellular destruction induced by acetaminophen was investigated in mice. Trifluoperazine 30 mg/kg administered intraperitoneally 30 min. or 0 min. before acetaminophen blocked hepatocellular destruction induced by the hepatotoxin, as evidenced by the determination of plasma GPT activity. Trifluoperazine also completely inhibited an increase of calcium contents in liver induced by acetaminophen administration. Furthermore, the increase of hepatic phosphorylase a activity induced by acetaminophen administration was completely abolished by pretreatment with trifluoperazine. However, hepatic glutathione depletion induced by acetaminophen was not prevented by pretreatment with trifluoperazine. Trifluoperazine administration caused a marked decrease in the body temperature of acetaminophen-treated animals. However, when the trifluoperazine-treated acetaminophen-poisoned animals were kept normothermic, the preventive effects were abolished. These findings suggest that this protective effect may be mediated by the trifluoperazine blockade of the deleterious effects of calcium accumulation in liver or the trifluoperazine decreasing effects on body temperature.
Insights
Trifluoperazine, a calmodulin inhibitor, protected mouse livers from acetaminophen damage by blocking calcium buildup. However, this protective effect was lost when body temperature was maintained, suggesting temperature regulation is key.
Area of Science:
- Hepatology
- Toxicology
- Pharmacology
Background:
- Acetaminophen overdose is a leading cause of acute liver failure.
- Hepatocellular damage involves calcium dysregulation and altered enzyme activity.
- Calmodulin's role in acetaminophen-induced liver injury is not fully understood.
Purpose of the Study:
- To investigate the protective effects of trifluoperazine, a calmodulin inhibitor, against acetaminophen-induced liver injury in mice.
- To elucidate the mechanisms underlying trifluoperazine's potential hepatoprotective effects.
Main Methods:
- Mice were treated with trifluoperazine before acetaminophen administration.
- Hepatocellular damage was assessed by plasma GPT activity.
- Liver calcium content, hepatic phosphorylase a, and hepatic glutathione levels were measured.
- Body temperature was monitored and controlled in some groups.
Main Results:
- Trifluoperazine administration significantly reduced acetaminophen-induced hepatocellular destruction.
- Trifluoperazine inhibited acetaminophen-induced increases in liver calcium content and hepatic phosphorylase a activity.
- Trifluoperazine did not prevent hepatic glutathione depletion.
- The protective effect of trifluoperazine was abolished when acetaminophen-treated mice were maintained at normothermic temperatures.
Conclusions:
- Trifluoperazine exhibits hepatoprotective effects against acetaminophen toxicity in mice.
- The protective mechanism may involve the inhibition of calcium accumulation in the liver or a reduction in body temperature.
- Maintaining normothermia negates the protective effects of trifluoperazine, highlighting the role of temperature in acetaminophen-induced liver injury.