Increases in PKC gamma expression in trigeminal spinal nucleus is associated with orofacial thermal hyperalgesia in streptozotocin-induced diabetic mice

•STZ-induced type 1 diabetic mice develop orofacial thermal pain.•Increased PKCγ in Sp5C is associated with orofacial thermal pain.•Orofacial thermal pain and the increased PKCγ could be partially attenuated by insulin treatment.

Painful diabetic polyneuropathy (PDN) at the early phrase of diabetes frequently exhibits increased responsiveness to nociception. In diabetic patients and animal models, alterations in the transmission of orofacial sensory information have been demonstrated in trigeminal system. Herein, we examined the changes of protein kinase Cγ subunit (PKCγ) in trigeminal spinal nucleus (Sp5C) and observed the development of orofacial thermal sensitivity in streptozotocin (STZ)-induced type 1 diabetic mice. With hyperglycemia and body weight loss, STZ mice exhibited orofacial thermal hyperalgesia, along with increased PKCγ expression in Sp5C. Insulin treatment at the early stage of diabetes could alleviate the orofacial thermal hyperalgesia and impaired increased PKCγ in Sp5C in diabetic mice. In summary, our results demonstrate that PKCγ might be involved in orofacial thermal hyperalgesia of diabetes, and early insulin treatment might be effective way to treat orofacial PDN.