Diabetes mellitus affects activity of calcium/calmodulin-dependent protein kinase II alpha in rat trigeminal ganglia

The activity of calcium/calmodulin-dependent protein kinase II alpha (CaMKIIα) may play a critical role in the modulation of nociceptor activity and plasticity of primary sensory trigeminal neurons. The aim of this study was to investigate the immunoreactivity of phosphorylated CaMKIIα (pCaMKIIα) in subpopulations of trigeminal ganglion (TG) neurons in rat models of early diabetes type 1 (dm1) and 2 (dm2). DM1 model was induced with intraperitoneally (i.p.) injected streptozotocin (STZ) (55 mg/kg). DM2 rats were fed with the high fat diet (HFD) for 2 weeks and then received 35 mg/kg of STZ i.p. Two weeks and 2 months after the STZ-diabetes induction, rats were sacrificed and immunohistochemical analysis for detection of pCaMKIIα immunoreactivity and double immunofluorescence labelling with isolectin (IB4) was performed. Increased intensity of pCaMKIIα immunofluorescence, restricted to IB4-negative small-diameter neurons, was seen in TG neurons two months after STZ-DM1 induction. DM1 model, as well as the obesity (control dm2 groups) resulted in neuronal impaired growth while dm2 model led to neuron hypertrophy in TG. Observed changes may play a critical role in the modulation of nociceptor activity and plasticity of primary sensory trigeminal neurons. In future, innovative strategies for modulation of CaMKIIα activity in specific subpopulations of neurons could be a novel approach in therapy of diabetic trigeminal neuropathy.