GFAP and depressive disorder: Wistar Kyoto (WKY) rats exhibit heightened anxiety/depression, increased stress-induced behavioural responses,8 and hypothalamic–pituitary–adrenal axis activation.46 Rat models of OA pain mimic key histopathological features of human OA,55 and exhibit spinal neuronal hyperexcitability43 and glial cell activation.42,60 Using the WKY strain of rats to model comorbid negative affect and OA pain, we investigated the potential contribution of astrocytes (using glial fibrillary acidic protein [GFAP] immunofluorescence) at spinal and supraspinal sites to altered OA pain responses.