HMOX1 and neuropathic pain: These results reveal a synergy between HO-1 and H2 systems in inhibiting PIPN, which agrees with the demonstrated positive interplay among them for the inhibition of the allodynia and hyperalgesia caused by nerve injury in rodents [26], and with the participation of the HO-1/CO pathway in the analgesic effects of HRW in animals with nerve-injury-induced neuropathic pain [24,25].