Fig. 1

Shank2^−/− mice display hypersensitivity to inflammatory pain and sensory modality-specific allodynia. Behavioural analysis of nociceptive responses in Shank2^−/− and WT mice. a and b Formalin was injected in the hindpaw to measure the licking/flinching response. Shank2^−/− mice show no difference in licking/flinching in the first phase compared to WT (p > 0.05) after the formalin test. However, in the second phase (30–40 min) a significant increase was observed in licking/flinching in the Shank2^−/− mice (p < 0.01) (N = 10 for WT and N = 8 for Shank2^−/−). c and d CFA induced thermal and mechanical hyperalgesia was measured. Thermal hyperalgesia was found in both WT and Shank2^−/− mice the first few days (1–4 days), normalisation of withdrawal time occured in the WT mice from 4 days, but a significant increased sensitivity remained in Shank2^−/− mice until day 6 (p < 0.05). Both WT and Shank2^−/− mice show an increased sensitivity in the first few hours and days of the von Frey filaments. No difference was observed between WT and Shank2^−/− mice in the first days following CFA injection. At day 14 Shank2^−/− mice show a decreased sensitivity compared to WT mice (p < 0.0001) (N = 6 for WT and N = 7 for Shank2^−/−). e–g Latency to escape, preference and distance walked was measured at the thermal preference test (cold plate). Shank2^−/− mice displayed a significant decrease in latency on the cold plate compared to WT mice (p < 0.05), a comparable preference was shown between Shank2^−/− and WT (approx. 5% for both genotypes) and a significant increase of distance walked on the cold side (normalised to the distance walked on RT side) was seen in Shank2^−/− mice compared to WT mice (p < 0.05); (N = 6 for WT and N = 7 for Shank2^−/−). h–j Latency to escape, preference and distance walked was measured in the thermal preference task (hot plate) between WT and Shank2^−/− mice. Shank2^−/− mice displayed no significant difference in latency compared to WT mice (p > 0.05), no difference in preference has been observed (approx. 40% for both genotypes) and no difference in distance walked (approx 40% for both genotypes); (N = 6 for WT and N = 7 for Shank2^−/−). k–m An adhesive tape was stuck to the hindpaw of the mouse to measure tactile allodynia. Shank2^−/− mice showed an increase in removal attempts, latency to notice the adhesive tape and distance walked compared to WT mice (p < 0.01; p < 0.05 and p < 0.05 respectively) (N = 6 for WT and N = 7 for Shank2^−/−). n–p Latency to escape, preference and distance walked has been measured in the texture discrimination task (sandpaper, 60 grit coarse). Shank2^−/− mice showed a significant increase in latency compared to WT mice (p > 0.05) and a comparable preference and distance walked was shown between Shank2^−/− and WT (approx. 50% for both genotypes) (N = 8 for WT and N = 7 for Shank2.^−/−). Data shown as average ± SD. *p < 0.05; **p < 0.01