Dietary Saturated Fatty Acids Modulate Pain Behaviour in Trauma-Induced Osteoarthritis in Rats.

Osteoarthritis (OA) is a degenerative condition of joints, causing pain and swelling, and can be caused or worsened by trauma and obesity. The objectives of this study were to determine whether pain behaviour and progression of OA were increased in rats with trauma-induced OA fed dietary saturated fatty acids (SFA). Male Wistar rats were fed either a corn starch diet (C) or high-carbohydrate high-fat diet (H) with either 20% beef tallow or SFA (lauric (HLA), myristic (HMA), palmitic (HPA) or stearic (HSA) acids) for 16 weeks prior to and 8 weeks after excision of the medial meniscus of right knee joint to initiate OA when pain behaviour, glial activity, progression of knee OA, inflammatory mediators and signs of metabolic syndrome were assessed. Rats fed beef tallow, palmitic or stearic acids showed increased pain symptoms characterised by decreased hind paw/limb withdrawal thresholds and grip strengths and increased spinal astrogliosis and microgliosis compared to rats fed lauric or myristic acids. However, the severity of OA joint damage was unchanged by these dietary manipulations. We conclude that pain symptoms of trauma-induced OA in rats worsen with increased dietary beef tallow or palmitic or stearic acids, but improve with lauric or myristic acids, despite unchanged OA cartilage damage.