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Studies on N, N'-dimethylnitrosourea-induced brain tumors in rats--especially, on microtumors
Abstract:
The incidences, distribution and histopathological findings of N, N'-dimethylnitrosourea (DMNU)-induced brain microtumors in Sprague-Dawley rats were studied. Subcutaneous injections of DMNU in young adult rats one a week resulted in the induction of 122 gliomas in 38 animals with an incidence of 69% after a time lapse of between 157 and 246 days from the first injection. Of these tumors, 66 were classified as microtumors (diameter less than about 1 mm) by detailed light microscopy observation of serial sections. The microtumors were of 3 types: 55 oligodendrogliomas, 8 astrocytomas and 3 mixed gliomas. As the tumors became larger in size, anaplasia appeared, especially in the central part of the tumors. The microtumors developed randomly throughout the brain. It was concluded that, in adult rat brains, the target cells of DMNU were well differentiated glial cells which had already migrated from the matrix layer.
Insights
N, N'-dimethylnitrosourea (DMNU) induced brain microtumors in rats, with 69% incidence. These microtumors were primarily oligodendrogliomas, suggesting differentiated glial cells are DMNU targets.
Area of Science:
- Neuro-oncology
- Toxicology
- Experimental Pathology
Background:
- N, N '-dimethylnitrosourea (DMNU) is a chemical agent known to induce tumors.
- Understanding the early stages of chemically induced brain tumors is crucial for developing preventative and therapeutic strategies.
Purpose of the Study:
- To investigate the incidence, distribution, and histopathological characteristics of DMNU-induced brain microtumors in Sprague-Dawley rats.
- To identify the specific glial cell types targeted by DMNU in the adult rat brain.
Main Methods:
- Young adult Sprague-Dawley rats received weekly subcutaneous injections of DMNU.
- Tumor incidence and latency were recorded.
- Histopathological analysis of serial brain sections was performed using light microscopy to classify and measure induced tumors.
- Tumor types were categorized based on cellular morphology.
Main Results:
- A 69% incidence of gliomas was observed in 38 rats after DMNU administration, with a latency of 157-246 days.
- 66 microtumors (diameter < 1 mm) were identified, predominantly oligodendrogliomas (55), followed by astrocytomas (8) and mixed gliomas (3).
- Anaplasia was noted in larger tumors, particularly in their central regions. Microtumors were distributed randomly throughout the brain.
Conclusions:
- DMNU effectively induces gliomas in adult rat brains.
- The study identified well-differentiated, migrated glial cells as the primary target cells for DMNU.
- The findings contribute to understanding the mechanisms of chemical carcinogenesis in the brain.
