Painful nociceptive informations are well known to be transferred from nociceptors through spinal dorsal horn not only in different pathways but also in diverse nature depending on the type of noxious stimuli. There have been some controversies about the role of neuropeptide somatostatin in the transmission of the nociceptive information to the dorsal horn cells of the spinal cord. We performed the study in order to elucidate the effects of somatostatin on transmission of noxious stimuli in the spinal dorsal horn, comparing with those of morphine. Using carbon-filamented microelectrode, the single cell activities of wide dynamic range(WDR) neuron were recorded extracellularly at the lumbosacral enlargement of the spinal cord in cats after noxious mechanical(squeeze), thermal(heat lamp), and cold(dry ice) stimulation to the receptive field. The sciatic nerve was stimulated electrically to evoke, A4-fiber and C-fiber each other. Data were compiled into single pass time histograms or postsimulus time histograms. Twenty micro-gram of somatostatin was injected intravenously to study the changes of single cell activities in 20 minutes, which were compared with the effects of morphine(2m/kg). Then naloxone was administrated(0.1mg/kg) to know whether it antagonized the effects of somatostatin and morphine And those finding were also observed in inverted WDR cells. In WDR cell, somatostain decreased the cellular responses to noxious heat stimuli in 6cell(n=9), but increased those to cold stimuli in 4 cells(n=6). And the responses to noxious mechanical stimuli were so diverse that they were slightly increased in 7 cells(164%), decreased in 5 cells, and were not changed in 6 cells(n=18). A-response, the response to peripheral Ad-afferent activation, showed a tendency to be facilitated(n=6/9), while C-response had a slightly depressed tendency(n=4/9). Morphine strongly suppressed the responses of dorsal horn neurons to noxious heat(n=9/13), cold(n=2/2), mechanical stimuli(n=16/19) and electrical A-response(n=7/10), C-response(n=6/7). Following subsequent injection of naloxone, the effects of morphine on noxious stimuli evoked response were fully reversed but those of somatostatin were not antagonized. There was significant difference between the reversal effects of naloxone on morphine and somatostatin(p<0.05). From the above results it is concluded that somatostatin suppresses the transmission of nociceptive heat stimuli, especially via C-fiber, while facilitates that of nociceptive mechanical and cold stimuli via Adelta-fiber in spinal dorsal horn cells. Also the somatostatin appears to have different nociceptive mechanism from morphine.
Animals ; Cats* ; Horns ; Hot Temperature ; Microelectrodes ; Morphine* ; Naloxone ; Neurons ; Neuropeptides ; Nociceptors ; Peripheral Nerves* ; Posterior Horn Cells* ; Sciatic Nerve ; Somatostatin* ; Spinal Cord

BACKGROUND AND PURPOSE: Cavernous angiomas are frequently encountered in patients with intractable partial epilepsies. Cavernous angioma can make highly epileptogenic foci and dual pathology. Although it is generally thought that the epileptogenic activity originated in neuronal populations adjacent to the lesion, little is known as to the exact location of the epilepsies on electophysiologic, clinical and pathologic view. We investigated nine intractable epilepsy patients with cavernous angioma regarding relation of EEG, semiology and pathology to verify where are the epileptogenic foci in cavernous angioma. METHODS: We included 9 intractable epilepsy patients with cavernous angioma who had been were undergone video-EEG monitoring. They were aged from 15 to 49 years(average:36.7+15.7)and had cavernous angioma in temporal, frontal lobe, or multiple areas(temporal:7, frontal:1, multiple:1 patients). Four patients had invasive EEG study including subdural and/or depth electrodes. Six patients had undergone epilepsy surgery. We analyzed seizure history, semiology of their seizures, interictal and ictal EEG. To know dual pathology, MRI including hippocampal volumetry, invasive EEG, and pathology were studied. RESULTS: Four patients had multiple auras. Eight patients had complex partial seizures and one had right foot clonic seizure, which were related with the location of cavernous angioma. In scalp EEG, ictal recording showed definite EEG changes, but 3 patients had no definite EEG change in some seizures. In invasive EEG with subdural and/or depth electrodes , interictal spikes were more frequently detected than scalp EEG and ictal EEG revealed not only 3 different ictal onset zones in 3 patients but also EEG seizures without clinical events in 3 patients. Regarding dual pathology, mesial temporal involvement was detected in 2 patients in MRI. Among 6 surgery patients 4 patients including 3 patients with normal hippocampus in MRI had hippocampal or dentate gyral change in pathology. Among 4 patients with invasive ictal EEG, 3 patients including 1 patient with normal hippocampus in MRI and pathology had mesial temporal involvement in ictal onset zones. CONCLUSION: Cavernous angiomas can make multiple epileptogenic foci around themselves and often dual pathology of hippocampus, which can be easily detected by invasive ictal EEG but not by imaging and even by pathology. And the foci can have frequent EEG seizures, which do not make clinical events. Precise localization of epileptogenic foci in cavernous angioma were needed to have good medical and surgical treatments.
Electrodes ; Electroencephalography ; Epilepsies, Partial ; Epilepsy ; Foot ; Frontal Lobe ; Hemangioma, Cavernous* ; Hippocampus ; Humans ; Magnetic Resonance Imaging ; Neurons ; Pathology ; Scalp ; Seizures