Our MEMRI investigation indicates new functional activity of cerebral regions in rats due to the effect of itching or GBP. This information could be used to monitor the therapeutic effects of novel agents or for clinical strategies to treat pathological itch.

To provide clear information on the cerebral regions according to peripheral neuropathy, the functional activation was investigated using manganese-enhanced magnetic resonance imaging (MEMRI). L5-spinal nerve ligation (SNL) was applied to the rats to induce neuropathic pain. Mechanical allodynia and thermal hyperalgesia were measured to confirm neuropathic pain induction following before and after gabapentin (GBP) treatment. The cerebral regions were investigated using a 4.7T MRI system in the sham, SNL, and GBP-treated SNL rats. Neuropathic pain was severely induced by SNL on the postoperative day 14, excepting the sham group. While MEMRI indicated many activation regions in the brain of SNL rats before GBP treatment, the activities were chronologically attenuated after GBP treatment. The brain regions relating SNL-induced neuropathic pain were as follows: the posterior association area of the parietal region, superior colliculus, inferior colliculus, primary somatosensory area, cingulate cortex, and cingulum bundle. SNL induced- neuropathic pain is transmitted to the primary somatosensory area and parietal region through the cingulum bundle and limbic system. These findings would be helpful for the understanding of neuropathic pain-associated process and be an accurate target for a relief of neuropathic pain.

Our MEMRI investigation indicates functionally different activity of cerebral regions due to the effect of PI or NP. These findings provide clear information of the signal transduction in the brain regarding PI or NP that share a similar neuronal pathway.

IV.

Abstract.[Purpose] To analyze the electrophysiological characteristics of diabetic sensorimotor polyneuropathy (DSPN), also known as DPN, and to determine sensitive indicators of the disease using sensory nerve conduction studies (SNCSs).[Methods] SNCSs of the median, ulnar, and sural nerve were performed on 120 patients diagnosed with DSPN and compared with those of 77 healthy controls. We performed analysis to detect abnormal conduction velocities and the distal amplitude of the compound nerve action potential (CNAP). In addition, we determined the optimal cut-off values for the diagnosis of DSPN.[Results] More severe abnormal nerve conduction was found in the lower limbs than in the upper limbs. The severity of the abnormal nerve conduction was more apparent in the distal CNAP amplitude than in the conduction velocity.[Conclusion] Our findings suggest that SNCSs of the lower limb nerve seem to be more sensitive at detecting DSPN than SNCSs of the upper limb. In particular, the sural nerve is the best indicator for the early detection of DSPN.