Neuroreport
-
This study examined the effects of pulsed radiofrequency (PRF) on sciatic nerve ligation-induced mechanical pain hypersensitivity in rats. The nociceptive threshold was evaluated using the paw pressure vocalization test. ⋯ One day after PRF, the effect of morphine (2 mg/kg, subcutaneous) increased the nociceptive threshold in the no PRF/CCI group and more extensively in PRF/CCI animals. These results showed that PRF might represent an interesting strategy not only to reduce neuropathic pain but also to enhance the efficacy of morphine in patients with neuropathic pain, well known to be opioid resistant.
-
TRPV1 is a nonselective cation channel in nociceptors. TRPV1 stimulation has been shown to lead to the activation of microglia and astrocytes in the dorsal horn of the spinal cord. However, information on the effect of TRPV1 stimulation on glial activation in the trigeminal nucleus caudalis (TNC) is lacking. ⋯ The ratio of the cross-sectional area immunoreactive for glial fibrillary acidic protein to the entire TNC showed a significant increase in d2 group and the d4 group compared with the c group on the injected side. Behavioral analysis indicated that mechanical allodynia began to develop after 2 days of capsaicin treatment and persisted for at least 6 days after the onset of the repetitive capsaicin injection. These data indicate that TRPV1 stimulation activates the microglia and astrocytes in temporally distinct ways and that the development of mechanical allodynia is independent of such glial activation.