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Hepatic mixed-function oxidase system and microsomal lipid peroxidation in rats treated with a synthetic
Abstract:
Effects of synthetic muramyl dipeptide (MDP) on activity of liver microsomal mixed-function oxidase system and on the susceptibility of liver microsomes to lipid peroxidation, were tested in rats at intervals of 1 or 24 hours after single i.p. injection of MDP (1 mg per animal). No significant changes were found in levels of cytochrome P-450 and b5, microsomal heme, or in activities of aniline hydroxylase, ethylmorphine demethylase, glucuronide transferase or cytosol glutathione-S-transferase. However, significantly less (about 45%) TBA-reactive material accumulated in microsomal samples at the 1 h-interval after the MDP administration. The same inhibitory effect of MDP on lipid peroxidation was shown in vitro (in 1 mM concentration) after incubation of microsomes with the NADPH/ADP/Fe system.
Insights
Synthetic muramyl dipeptide (MDP) did not alter liver enzyme activity but significantly inhibited lipid peroxidation in rat liver microsomes. This protective effect against oxidative damage was observed both in vivo and in vitro.
Area of Science:
- Biochemistry
- Pharmacology
- Toxicology
Background:
- Liver microsomes play a crucial role in xenobiotic metabolism via the mixed-function oxidase (MFO) system.
- Lipid peroxidation is a key indicator of oxidative stress and cellular damage.
- Muramyl dipeptide (MDP) is a component of bacterial cell walls with known immunomodulatory effects.
Purpose of the Study:
- To investigate the effects of synthetic muramyl dipeptide (MDP) on rat liver microsomal MFO system activity.
- To determine MDP's influence on the susceptibility of liver microsomes to lipid peroxidation.
Main Methods:
- Rats received a single intraperitoneal injection of MDP (1 mg/animal).
- Liver microsomes were analyzed at 1 and 24 hours post-injection for MFO enzyme activities and lipid peroxidation.
- In vitro experiments assessed MDP's effect on lipid peroxidation using microsomes incubated with NADPH/ADP/Fe.
Main Results:
- No significant changes were observed in cytochrome P-450 and b5 levels, microsomal heme, or the activities of aniline hydroxylase, ethylmorphine demethylase, glucuronide transferase, and glutathione-S-transferase.
- A significant reduction (approximately 45%) in TBA-reactive material, an indicator of lipid peroxidation, was found in microsomes at the 1-hour interval post-MDP administration.
- MDP demonstrated an inhibitory effect on lipid peroxidation in vitro.
Conclusions:
- Single-dose MDP administration does not significantly impact the activity of key rat liver microsomal MFO enzymes.
- MDP exhibits a protective effect against lipid peroxidation in rat liver microsomes, suggesting antioxidant properties.
- The findings indicate that MDP may modulate oxidative stress responses in the liver.