Fig. 4

Orofacial operant assessment of oxaliplatin-induced orofacial cold allodynia/hyperalgesia. a Images show the postures commonly seen during orofacial operant tests at 17°C for control rats (left) and rats after oxaliplatin injections (right). The control rat rested its face on the cooling module while drinking milk. The oxaliplatin-injected (18 days after the injections) rat did no contact the cooling thermal module but tried to bite it off. b Recordings of contact numbers and duration of each contact in orofacial operant tests at 17°C for the control rat (top) and the oxaliplatin-injected rat (bottom). The duration of each orofacial operant test session was 10 min. c Change of total contact time over days after the injections of oxaliplatin (n = 5–8). d Left total contact time at 17°C for the rats 18 day after injection of saline (open bar) or oxaliplatin (oxa, closed bar). Right similar to left panel except the orofacial operant tests were conducted at 12°C. Data represent Mean ± SEM, *P < 0.05, **P < 0.01, ***P < 0.001.