Glucose uptake in horses with polysaccharide storage myopathy.

The research aims to evaluate if the excessive glycogen storage in the muscles of Quarter Horses with polysaccharide storage myopathy (PSSM) is due to better cellular glucose absorption. The results indicate that these horses show increased glucose uptake, potentially due to heightened insulin sensitivity. Therefore, diets low in soluble carbohydrates can be a practical way to reduce this excessive muscle glycogen accumulation.

Methodology

• This study comprised two groups; one group consisted of six horses diagnosed with polysaccharide storage myopathy (PSSM) while the other group was a control group with ten healthy horses.
• Three different tests were conducted on all horses: Intravenous glucose tolerance tests (IVGTT), oral glucose tolerance tests (OGTT), and modified insulin tolerance tests (MITT).
• These tests were followed by measuring plasma glucose and insulin concentrations in blood samples taken before and up to 8 hours post glucose or insulin administration.

Results

• The peak glucose levels during the IVGTT were similar for both groups.
• However, horses with PSSM showed a 1.5 times faster rate of glucose clearance compared to control horses. These horses also displayed lower circulating insulin concentrations before and after glucose injection.
• In the OGTT, horses with PSSM maintained lower blood glucose levels from minute 90 to minute 300 as compared to the healthy horses.
• The MITT triggered acute drops in blood glucose levels in both groups. However, the horses with PSSM kept low blood glucose levels for over 3 hours post insulin injection, while the control group’s glucose levels returned to baseline within 2 hours.

Conclusions

• The research concluded that Quarter Horses with PSSM show enhanced cellular glucose uptake, possibly due to increased insulin sensitivity.
• Consequently, horses with PSSM display a heightened rate of glucose clearing following insulin release.
• Studies suggest that diets containing low soluble carbohydrates might be effective in reducing glycogen accumulation in the skeletal muscle of these horses.