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Testosterone effect on experimental diabetes mellitus in encephalomyocarditis (EMC) virus infected mice
Abstract:
A diabetes mellitus-like disease occurs in male DBA/2 mice infected with the M variant of the encephalomyocarditis virus. Female mice of this strain sustain systemic infection, but rarely exhibit hyperglycaemia. The diabetogenic effects of the virus were studied in 3 groups of adult DBA/2 males-castrates, castrates treated with testosterone, and sham-operated controls. After infection, pancreatic insulin concentrations decreased precipitously to approximately 10% of control values in intact males and castrates treated with testosterone; hyperglycaemia occurred concomitantly in both groups. In contrast, untreated castrates failed to develop hyperglycaemia and the effect on the insulin content of the pancreas was less striking.
Insights
Encephalomyocarditis virus infection causes diabetes in male mice. Testosterone exacerbates this effect, while castration offers protection against viral diabetes.
Area of Science:
- Virology
- Endocrinology
- Immunology
Background:
- Encephalomyocarditis virus (EMCV) M variant infection in DBA/2 mice can induce a diabetes mellitus-like condition.
- This diabetogenic effect is predominantly observed in male mice, with females rarely exhibiting hyperglycemia.
- The role of sex hormones in modulating the diabetogenic impact of EMCV is not fully understood.
Purpose of the Study:
- To investigate the influence of testosterone on the development of EMCV-induced diabetes in male DBA/2 mice.
- To elucidate the mechanisms underlying sex-based differences in susceptibility to viral diabetes.
Main Methods:
- Adult male DBA/2 mice were divided into three groups: castrates, castrates treated with testosterone, and sham-operated controls.
- All groups were infected with the M variant of EMCV.
- Pancreatic insulin concentrations and blood glucose levels (hyperglycemia) were measured post-infection.
Main Results:
- Infection led to a significant decrease in pancreatic insulin to approximately 10% of control values in intact males and testosterone-treated castrates.
- Hyperglycemia was observed concurrently with reduced insulin levels in intact males and testosterone-treated castrates.
- Untreated castrates showed a less pronounced reduction in pancreatic insulin and did not develop hyperglycemia.
Conclusions:
- Testosterone plays a crucial role in exacerbating the diabetogenic effects of EMCV infection in male mice.
- Castration appears to confer protection against the development of viral diabetes by mitigating the impact on pancreatic insulin.
- These findings highlight the interplay between viral infections, sex hormones, and metabolic dysregulation in diabetes pathogenesis.