a In the prevention experiment, mice were fed with normal chow or chow containing roxadustat (12.8 mg/100 g food) for 11 days. On day 3, 5, 7, 9 and 11, mice received i.p. injection of normal saline or NTG (10 mg/kg bodyweight). Before NTG injection, mouse was conducted tail-flick and PAM test for determination the threshold of thermal nociceptive (b) and pressure pain (c), respectively. Before NTG injection, mouse was conducted light-aversive behaviour test for determination the motion trajectory (d) and the time (e) of mouse in the light chamber. After treatment, mice were sacrificed, followed by collection of brain tissues. Protein expression of c-Fos and p-ERK1/2 in TNC was determined by Western blot with quantitative analysis of band intensity (f); TNC frozen sections were conducted co-immunofluorescence staining with c-Fos (red, g) or p-ERK1/2 (red, h) and NeuN (neuronal marker, green) antibodies. White arrow indicates expression of c-Fos or p-ERK1/2 in neuron cells of TNC. #P < 0.05; ##P < 0.01; ###P < 0.001 vs. NS group; *P < 0.05; **P < 0.01; ***P < 0.001 vs. NTG group (n = 5); Rox: roxadustat.