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Cholinergic activation produces psychosomatic digitalis toxicity
The Journal of Pharmacology and Experimental Therapeutics
|September 1, 1981
Summary
Psychological stress, specifically Pavlovian fear conditioning, significantly lowers the toxic dose of digitalis in guinea pigs. This stress-induced digitalis toxicity is mediated by a cholinergic mechanism, suggesting a psychosomatic link.
Area of Science:
- Psychoneuroimmunology
- Cardiovascular Pharmacology
- Animal Models of Toxicity
Background:
- Understanding the interplay between psychological stress and physiological responses is crucial for public health.
- Digitalis toxicity poses a significant clinical challenge, and its susceptibility may be influenced by external factors.
- Previous research has not adequately separated physical and psychological stressors in the context of digitalis toxicity.
Purpose of the Study:
- To establish a novel animal model for stress-induced digitalis toxicity, differentiating physical and psychological stress components.
- To investigate the underlying neurobiological mechanisms of this psychosomatic effect on digitalis toxicity.
- To identify potential therapeutic targets for mitigating stress-exacerbated digitalis toxicity.
Main Methods:
- Development of a Pavlovian fear conditioning paradigm in free-ranging guinea pigs using signaled shock.
- Intravenous ouabain infusion in fear-conditioned and control guinea pigs following intraperitoneal administration of saline, atropine sulfate, or atropine methylbromide.
- Assessment of digitalis toxicity thresholds and analysis of the role of cholinergic pathways in arrhythmogenesis.
Main Results:
- Fear-conditioned guinea pigs exhibited digitalis toxicity at significantly lower ouabain doses compared to controls.
- Both atropine sulfate and atropine methylbromide successfully blocked the enhanced digitalis toxicity in fear-conditioned animals.
- Findings suggest a cholinergic mechanism acting on the blood side of the blood-brain barrier contributes to early arrhythmogenesis.
Conclusions:
- Psychological stress, induced by fear conditioning, primes the system for increased susceptibility to digitalis toxicity.
- Cholinergic pathways play a critical role in the observed psychosomatic effect, influencing cardiac arrhythmogenesis.
- This study provides a valuable animal model for exploring stress-related drug toxicity and its neurobiological underpinnings.