thiopental and Neuralgia

The concept of deafferentation pain has been developed as an entity distinct from somatic pain which can arise in the course of both cancerous and nonmalignant disease. Its distinctive clinical features and responses to diagnostic and therapeutic manipulations have been reviewed. Evidence is marshalled to show that it results from gradually developing alterations in the central nervous system, which, once established, persist despite removal of the original stimulus. Evidence is presented that the mesencephalic tegmentum may be part of a reticulothalamocortical system undergoing denervation hypersensitivity following deafferentation, whose stimulation by electric impulses, and, presumably, naturally occurring neural inputs, can result in a painful conscious experience reproducing the patient's pain in a manner similar to that whereby stimulation of temporal-parietal association cortex elicits recall of past events.

Topics: Anesthetics, Local; Causalgia; Electric Stimulation; Humans; Neural Pathways; Neuralgia; Neurons, Afferent; Spinal Cord; Stereotaxic Techniques; Thalamus; Thiopental

In this study, we investigated the combined effect of Neurotropin® and pregabalin for L5-spinal nerve ligation (L5-SNL) model in rats and thiopental-induced sleep in mice.. The left fifth lumbar nerve of rats was tightly ligated with silk sutures under pentobarbital anesthesia. The hindpaw withdrawal threshold was measured by application of von Frey filaments. Thiopental sodium was intravenously administered in mice and sleeping time was measured. In L5-SNL rats, an isobolographic analysis was performed to clarify the combined antiallodynic effect of Neurotropin and pregabalin 14 days after ligation in rats. In isobolographic analysis and thiopental-induced sleep test, Neurotropin and pregabalin were orally administered to coincide with the timing of the peak effect of each drug.. Neurotropin (50-200 NU/kg) and pregabalin (2.5-10mg/kg) showed a dose-dependent antiallodynic action in L5-SNL rats. The antiallodynic effect of pregabalin was reversed by intrathecal injection of yohimbine or ondansetron. Isobolographic analysis suggested that the combined antiallodynic effect of Neurotropin and pregabalin in L5-SNL rats may have been more than a mere additive effect. Neurotropin (50-400 NU/kg) had no effect on thiopental-induced sleeping time whereas pregabalin (30-100mg/kg) significantly prolonged it. When the dose of pregabalin was 30 mg/kg, Neurotropin (50-400 NU/kg) did not further exacerbate the prolongation effect of pregabalin on thiopental-induced sleep.. It was suggested that when Neurotropin was administered in combination with pregabalin, it might provide more effective pain relief than that obtained with each agent alone in neuropathic pain without aggravating adverse effects of pregabalin.

Topics: Administration, Oral; Analgesics; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; gamma-Aminobutyric Acid; Hyperalgesia; Ligation; Lumbosacral Region; Male; Neuralgia; Pain Threshold; Polysaccharides; Pregabalin; Rats; Rats, Wistar; Sleep; Spinal Nerves; Thiopental