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Light and electron microscopic studies of pathologic changes induced in mice by ciguatoxin poisoning
1Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan.
Abstract:
Acute poisoning induced by ciguatoxin or ciguatoxin-4c in male ICR mice was examined by light and electron microscopy. Target organs were the heart, medulla of adrenal glands, autonomic nerves and penis. There were no significant differences between the toxicity of ciguatoxin and ciguatoxin-4c. Either i.p. injection or oral administration (0.7 micrograms/kg) resulted in marked swelling and focal necrosis of cardiac muscle cells and effusion into the interstitial space of the heart. Degeneration of cells in the medulla of the adrenal glands was also observed. Continuous erection of the penis was observed in about 15% of the mice suffering from ciguatoxicosis. Although severe diarrhea was brought about by the administration of these phycotoxins, no morphological alterations were seen in the mucosa and muscle layers of the small intestine except in autonomic nerve fibers and synapses. Atropine suppressed the symptoms of diarrhea but had no effect on the injury to the cardiac muscle. Reserpine aggravated the clinical signs and pathological findings. Guanethidine and 5-hydroxy dopamine as well as those undergoing bilateral adrenalectomy had no significant effects on the ciguatoxicosis.
Insights
Ciguatoxin and ciguatoxin-4c cause acute poisoning in mice, affecting the heart, adrenal glands, and nerves. These toxins lead to cardiac cell damage and adrenal medulla degeneration, with some mice experiencing penile erection.
Area of Science:
- Toxicology
- Pathology
- Marine Biotoxins
Background:
- Ciguatoxins are potent marine phycotoxins responsible for ciguatera fish poisoning.
- Understanding the toxicological mechanisms and target organs of ciguatoxins is crucial for clinical management.
Purpose of the Study:
- To investigate the acute toxic effects and target organs of ciguatoxin and ciguatoxin-4c in a mouse model.
- To examine the pathological alterations induced by these toxins using light and electron microscopy.
Main Methods:
- Male ICR mice were administered ciguatoxin or ciguatoxin-4c via intraperitoneal injection or oral gavage.
- Histopathological examination using light and electron microscopy was performed on various organs, including the heart, adrenal glands, autonomic nerves, and penis.
Main Results:
- No significant difference in toxicity was observed between ciguatoxin and ciguatoxin-4c.
- Cardiac muscle cells showed swelling and focal necrosis, with interstitial effusion.
- Degeneration was noted in the adrenal medulla, and continuous penile erection occurred in approximately 15% of affected mice.
- Autonomic nerve fibers and synapses were affected, but intestinal mucosa and muscle layers remained largely unaltered.
Conclusions:
- Ciguatoxin and ciguatoxin-4c induce acute toxic effects primarily targeting the cardiovascular system, adrenal medulla, and autonomic nervous system.
- Atropine partially mitigated diarrhea, while reserpine exacerbated symptoms, suggesting complex neuroautonomic involvement.
- Further research is needed to elucidate the precise mechanisms of ciguatoxin-induced pathology.