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Intratracheal administration of microcystin-LR, and its distribution
1Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Inohana, Japan.
Abstract:
Microcystin-LR (MCLR) was injected into mice intratracheally, absorption from the lungs was easy and it was confirmed that both the cause of death and lethality dose level were the same as by intraperitoneal injection treatment. An immunostaining method revealed that there was a time lag of about 60 min before accumulation of MCLR, and that it caused bleeding in the liver. Clearance from internal organs took about 2 weeks; during the initial stage (the first 2 days), the small intestine, kidney, cecum and large intestine were already involved. However, even after 2 weeks, small amounts of MCLR were still present in epithelial cells in the gastrointestinal mucosa.
Insights
Intratracheal microcystin-LR (MCLR) exposure in mice proved lethal, mirroring intraperitoneal injection effects. MCLR accumulated in the liver, causing bleeding, and persisted in the gastrointestinal tract for weeks.
Area of Science:
- Toxicology
- Environmental Health
- Pharmacokinetics
Background:
- Microcystin-LR (MCLR) is a potent cyanotoxin with significant public health implications.
- Understanding the toxicokinetics and organ distribution of MCLR following different exposure routes is crucial for risk assessment.
Purpose of the Study:
- To investigate the absorption, distribution, metabolism, and excretion (ADME) of MCLR after intratracheal instillation in a mouse model.
- To compare the toxic effects and lethality of intratracheally administered MCLR with intraperitoneal administration.
Main Methods:
- Mice were administered MCLR via intratracheal instillation.
- Immunostaining techniques were employed to track MCLR accumulation and distribution in various organs.
- Lethality and dose-response relationships were assessed and compared to intraperitoneal injection data.
Main Results:
- Intratracheal instillation of MCLR resulted in rapid lung absorption and systemic toxicity, with lethality comparable to intraperitoneal injection.
- A 60-minute time lag was observed before MCLR accumulation, leading to liver bleeding.
- Organ clearance took approximately 2 weeks, with initial involvement of the small intestine, kidney, cecum, and large intestine.
Conclusions:
- The lungs serve as a significant entry route for MCLR, leading to systemic toxicity and mortality.
- MCLR exhibits prolonged persistence in the gastrointestinal tract, with detectable levels in mucosal epithelial cells even after 2 weeks.
- These findings highlight the importance of considering inhalation exposure to MCLR and its extended gastrointestinal presence in toxicological evaluations.