Manganese-enhanced magnetic resonance imaging (MEMRI) offers a novel neuroimaging method in visualizing the activity patterns of neural circuits. MEMRI is using the divalent manganese ion, which has been used as a cellular contrast agent. The present study was conducted to determine the contrast-enhancing effects of manganese ion administered into the spinal cord of rats. Manganese ion was administered into the spinal cord by lumbar puncture. Ex vivo magnetic resonance images were obtained at 6, 12, 24, and 48 hours after manganese ion injection. Although the highly contrasted images were not observed 6 or 12 hr after manganese injection, the distinctive manganese-enhanced images began to appear at 24 hours after manganese ion injection. These results suggest that the gray matter is the foci of intense paramagnetic signals and MEMRI may provide an effective technique to visualize the activity-dependent patterns in the spinal cord.
Animals ; Magnetic Resonance Imaging ; Magnetic Resonance Spectroscopy ; Magnetics ; Magnets ; Manganese ; Neuroimaging ; Rats ; Spinal Cord ; Spinal Puncture

Peripheral nerve injury often results in abnormal neuropathic pain such as allodynia or hyperalgesia. Acupuncture, a traditional Oriental medicine, has been used to relieve pain and related symptoms. However, the efficiency of acupuncture in relieving neuropathic pain is not clear. The aim of this study was to investigate the anti-allodynic effects of acupuncture through behavioral and electrophysiological examinations. Male Sprague-Dawley rats were subjected to neuropathic surgery consisting of a tight ligation and transection of the left tibial and sural nerves, under pentobarbital anesthesia. The acupuncture experiment consisted of four different groups, one treated at each of three different acupoints (Zusanli (ST36), Yinlingquan (SP9), and a sham-acupoint) and a control group. Behavioral tests for mechanical allodynia and cold allodynia were performed for up to two weeks postoperatively. Extracellular electrophysiological recordings were made from the dorsal roots using platinum wire electrodes. Mechanical and cold allodynia were significantly reduced after acupuncture treatment at the Zusanli and Yinlingquan acupoints, respectively. Electrophysiological neural responses to von Frey and acetone tests were also reduced after acupuncture at the same two acupoints. These results suggest that acupuncture may be beneficial in relieving neuropathic pain.
Spinal Nerve Roots/*physiology ; Rats, Sprague-Dawley ; Rats ; Neuralgia/physiopathology/*therapy ; Male ; Electrophysiology ; Animals ; *Acupuncture Analgesia

Peripheral nerve injury often results in abnormal neuropathic pain such as allodynia or hyperalgesia. Acupuncture, a traditional Oriental medicine, has been used to relieve pain and related symptoms. However, the efficiency of acupuncture in relieving neuropathic pain is not clear. The aim of this study was to investigate the anti-allodynic effects of acupuncture through behavioral and electrophysiological examinations. Male Sprague-Dawley rats were subjected to neuropathic surgery consisting of a tight ligation and transection of the left tibial and sural nerves, under pentobarbital anesthesia. The acupuncture experiment consisted of four different groups, one treated at each of three different acupoints (Zusanli (ST36), Yinlingquan (SP9), and a sham-acupoint) and a control group. Behavioral tests for mechanical allodynia and cold allodynia were performed for up to two weeks postoperatively. Extracellular electrophysiological recordings were made from the dorsal roots using platinum wire electrodes. Mechanical and cold allodynia were significantly reduced after acupuncture treatment at the Zusanli and Yinlingquan acupoints, respectively. Electrophysiological neural responses to von Frey and acetone tests were also reduced after acupuncture at the same two acupoints. These results suggest that acupuncture may be beneficial in relieving neuropathic pain.
Spinal Nerve Roots/*physiology ; Rats, Sprague-Dawley ; Rats ; Neuralgia/physiopathology/*therapy ; Male ; Electrophysiology ; Animals ; *Acupuncture Analgesia