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Myelotoxicity of methotrexate in animals with pyogenic infection
Abstract:
Rats stimulated into prolonged increased neutrophil production by the induction of a unilateral pyo-hydronephrosis showed consistent profound neutropenia when methotrexate (MTX) was given during the first 2 d of infection. Thereafter greater neutropenia than that observed in non-infected rats was only observed in occasional animals. There was a significant correlation between the degree of neutropenia induced by MTX and the day after MTX upon which this occurred. The main target for myelotoxicity by MTX appears to be the myelocyte. Its precursors seem relatively insensitive.
Insights
Methotrexate (MTX) caused severe neutropenia in rats with pyo-hydronephrosis, especially early in infection. The myelocyte stage appears most sensitive to MTX
Area of Science:
- Hematology
- Pharmacology
- Nephrology
Background:
- Neutrophil production can be altered by infection and inflammatory conditions.
- Methotrexate (MTX) is a chemotherapy agent known for its myelosuppressive effects.
Purpose of the Study:
- To investigate the impact of MTX on neutrophil production in rats with induced pyo-hydronephrosis.
- To determine the specific stage of neutrophil development most affected by MTX-induced myelotoxicity.
Main Methods:
- Rats were induced with unilateral pyo-hydronephrosis to stimulate neutrophil production.
- Methotrexate (MTX) was administered at different time points relative to infection onset.
- Neutrophil counts and the degree of neutropenia were monitored.
Main Results:
- MTX administration during the initial 2 days of infection resulted in profound neutropenia.
- After the initial 2 days, the neutropenic effect of MTX was less pronounced compared to non-infected rats.
- A significant correlation was observed between the severity of neutropenia and the timing of MTX administration.
- Myelocytes were identified as the primary target of MTX-induced myelotoxicity, with precursors showing relative insensitivity.
Conclusions:
- The timing of methotrexate administration is critical in determining its myelosuppressive effects, particularly in the context of infection.
- Pyogenic infections may alter the sensitivity of the bone marrow to MTX, with early infection exacerbating neutropenia.
- Methotrexate primarily targets myelocytes, suggesting a specific mechanism of action within the neutrophil differentiation pathway.