Development of shoulder osteoarthritis and bone lesions in female and male rats subjected to a high fat/sucrose diet

Abughazaleh N, Smith H, Seerattan RA, Hart DA, Reimer RA, Herzog W · Scientific Reports

A null at the shoulder, in a diet model that produces osteoarthritis at the knee. Typical, non-typical and total OA scores were the same across chow, high-fat/high-sucrose and fibre-supplemented groups in both sexes, while the diet did what it usually does to the animal — heavier, fatter, higher cholesterol and triglycerides in both sexes. The sex difference the paper reports is not a diet effect: pooling all three diet groups, males scored higher than females for bone lesions in the humerus (p = 0.018) and scapula (p = 0.046), and the discussion records such lesions in both sexes, less severe in females. Fibre likewise left the joint scores unchanged; what it improved, in males only, was body mass, cholesterol and triglycerides, alongside sex-specific shifts in the gut microbiota.

Population

28 male and 35 female Sprague-Dawley rats across chow, high-fat/high-sucrose, and high-fat/high-sucrose plus 10% oligofructose groups, 12 weeks from 12 weeks of age

Intervention

High-fat/high-sucrose diet, with or without prebiotic fibre

Comparator

Chow diet

Limitations

Rats, 12 weeks, histological scoring, and one arm of six at n=6 (fibre-fed males). An earlier study in the same model did find shoulder changes on this diet; these authors attribute the disagreement partly to the new scoring system they use here, which separates typical OA from the bone lesions Sprague-Dawley rats get anyway and is described only in a manuscript listed as submitted. They read the shoulder as protected and offer the missing fat pad and lower load as candidates, while also allowing that twelve weeks may simply be too short for a systemic effect to reach it. No chow-plus-fibre arm, so fibre is never tested outside the obesogenic diet.