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Adrenergic modulation of hepatotoxicity
S M Roberts1, R P DeMott, R C James
1Center for Environmental and Human Toxicology, University of Florida, Gainesville 32610, USA. sroberts.vetmed1@mail.health.ufl.edu
Drug Metabolism Reviews
|February 1, 1997
Summary
Adrenergic drugs can dangerously increase liver injury from certain toxins like acetaminophen. However, liver toxicity from other agents, such as cocaine, can be reduced by blocking adrenergic activity.
Area of Science:
- Pharmacology
- Toxicology
- Hepatology
Background:
- Adrenoreceptor activity influences the toxicity of various hepatotoxicants.
- Hepatotoxicants can be categorized based on how adrenergic modulation affects their toxicity.
Purpose of the Study:
- To summarize interactions between adrenoreceptor activity and hepatotoxicant administration.
- To elucidate the mechanisms and receptor subtypes involved in these interactions.
Main Methods:
- Categorization of hepatotoxicants into two groups based on adrenergic potentiation or inhibition of toxicity.
- Analysis of specific adrenoreceptors (alpha(2), alpha(1), beta(2)) and their roles in potentiation.
- Examination of the critical timing of drug administration for interaction effects.
Main Results:
- Group I hepatotoxicants (carbon tetrachloride, acetaminophen, methylphenidate) show potentiated toxicity with adrenergic agonists via different receptor mechanisms and timings.
- Acetaminophen toxicity potentiation involves alpha(1)-adrenoceptor agonists, glutathione depletion, and specific pretreatment timing.
- Carbon tetrachloride toxicity potentiation involves alpha(2)-adrenoceptor stimulation with a different critical time window.
- Methylphenidate potentiation involves beta(2)-adrenoceptor stimulation via a distinct mechanism.
- Group II hepatotoxicants (cocaine, bromobenzene) show diminished toxicity with adrenergic antagonists, as they increase endogenous catecholamines.
Conclusions:
- Adrenergic modulation significantly impacts hepatotoxicant-induced liver injury through diverse mechanisms and receptor pathways.
- The timing of adrenergic stimulation relative to hepatotoxicant exposure is crucial and varies between agents.
- Increased adrenergic activity from common sources (medications, stress) may heighten susceptibility to certain drug-induced liver injuries.
- Adrenergic antagonists can mitigate toxicity for specific hepatotoxicants that elevate endogenous catecholamines.