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Microbodies in experimentally altered cells. IX. The fate of microbodies
Abstract:
Male rats were given 0.25% CPIB (ethyl chlorophenoxyisobutyrate) for 4 weeks at which time their liver cells showed the typical increase in number of microbodies (peroxisomes). During the first week after withdrawal of CPIB and simultaneous injection of allylisopropylacetamide (AIA), an inhibitor of catalase synthesis, the microbody matrix, in peroxidase preparations, showed marked decrease in electron opacity. In liver cells of rats from which CPIB was withdrawn but which were not given AIA, there were interruption in the limiting membrane and almost total loss of microbody matrix within 3 days. Simultaneous with the loss of matrix content, the hepatic catalase activity decreased from an average 80 units/mg protein to less than 10 units/mg protein. In liver cells of Mastomys natalensis, a multimammate rodent, withdrawal of CPIB was associated with the frequent occurrence of bare microbody nucleoids situated free in the hyaloplasm. The ultrastructural observations and the associated decrease in catalase activity suggest that one means of disposal of microbodies is by rather rapid dissolution or leakage of their matrix enzymes into the surrounding hyaloplasm.
Insights
Withdrawal of CPIB in rats led to microbody (peroxisome) matrix loss and decreased hepatic catalase activity. This suggests microbodies are rapidly dissolved or leak enzymes into the cytoplasm for disposal.
Area of Science:
- Cell Biology
- Biochemistry
- Toxicology
Background:
- Ethyl chlorophenoxyisobutyrate (CPIB) administration increases liver microbody (peroxisome) proliferation in rats.
- Microbodies are involved in various metabolic processes, including fatty acid metabolism and detoxification.
Purpose of the Study:
- To investigate the fate of microbodies after withdrawal of CPIB.
- To understand the relationship between microbody matrix content and hepatic catalase activity.
Main Methods:
- Rats were treated with CPIB, followed by withdrawal and/or administration of allylisopropylacetamide (AIA).
- Ultrastructural analysis of liver cells using peroxidase preparations.
- Measurement of hepatic catalase activity.
Main Results:
- CPIB withdrawal caused a decrease in microbody matrix electron opacity and integrity.
- Simultaneous AIA administration exacerbated microbody matrix loss.
- Hepatic catalase activity significantly decreased following CPIB withdrawal.
- Ultrastructural changes included bare microbody nucleoids in Mastomys natalensis.
Conclusions:
- Microbody (peroxisome) disposal may occur through rapid dissolution or leakage of matrix enzymes into the hyaloplasm.
- This process is linked to a decrease in hepatic catalase activity.
- The findings provide insights into the dynamic nature and turnover of microbodies.