Ectopic adrenergic sensitivity in damaged peripheral nerve axons in the rat

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Treatment of bladder pain with transsacral nerve block. - - D.L. Simon, H. Carron and J.C. Rowlingson, Ane,sth. Analg. Curr. Res., 61 (1982) 46-48. In this prospective study patients with bladder spasticity and pain of 3 different etiologies, refractory to all prior non-surgical methods of treatment, were referred to the pain clinic by urologic specialists. Of 10 patients treated with transsacral nerve blocks using 0.25% bupivacaine followed by 67o aqueous phenol at one or more sacral ventral foramina, 7 patients reported long term pain relief lasting upward of 24 months. Of 5 patients treated with bupivacaine only, one obtained long term relief. The associated morbidity was negligible and there was no mortality. The technique is proposed as a successful and economical outpatient treatment.

NEUROLOGY Evidence against a serotonin involvement in the tonic descending inhibition of nociceptor-driven neurons in the cat spinal cord. - - P.J. Soja and J.G. Sinclair, Brain Res., 199 (1980) 225-230. The response of dorsal horn nociceptor driven neurons to a noxious stimulus was examined while a serotonin enhancing drug (fluoxetine) and a serotonin decreasing drug (parachlorophenylalanine) were given. 'Neither the response with the spinal cord intact nor with the enhanced response with the spinal cord cold blocked was altered by these drugs. These results strongly suggest that 5-HT is not involved in the tonic descending inhibition which exists on nociceptor-driven spinal cord neurons.' Development of ongoing activity, mechanosensitivity, and adrenaline sensitivity in severed peripheral nerve axons. - - J.W. Scadding, Exp. Neurol., 73 (1981) 345-364. After neuromata had been induced in the sciatic nerve of mice, spontaneous activity of regular, irregular and intermittent patterns developed. 76% of the fibers with ongoing activity showed an increase in discharge frequency with mechanical stimulation, often followed by a decreased firing rate or even a cessation of firing. Intravenous adrenalin increased the firing rate in 55% of fibers; this might last for 2 rain. 68% of fibers were silent until stimulated mechanically. The spontaneous activity was present in all mice within 24 h of nerve transection. The great majority of these fibers were afferent and the evidence indicated that they belonged to all groups; delta fibers formed a larger group of spontaneously active fibers than would have been expected from their distribution ratio. Wall has found that 10-20 days after sciatic section in the rat, more than half the C fibers were spontaneously active and showed the same mechanical sensitivity. Ectopic aOrenergic sensitivity in damaged peripheral nerve axons in the rat. E.M.D. Korenman and M. Devor, Exp. Neurol., 72 (1981) 63-81. Recordings were made of spontaneously discharging and other small myelinated afferent fibers of neuromata of rats. About 80% of these fibers with ongoing activity responded to adrenaline; but motor fibers were not spontaneously active nor did they respond to adrenaline. Adrenaline caused increased activity, decreased activity,

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or an increase followed by a decrease. Typically the firing of single impulses was replaced by doublets or triplets. Adrenaline also fired some previously silent fibers. Although ischemia also fired off the same fibers, it was shown that the adrenergically induced activity was not due to this factor. Phentolamine blocked the effect of adrenaline but had no effect on the spontaneous discharge nor that induced by ischemia. Acetylcholine had no effect. Various experiments showed that the region of abnormal adrenergic sensitivity was in the region of the nerve end. It was concluded that the region of abnormal sensitivity to adrenaline was at sprouts of the axons or at "the zone of dysmyelination just proximal to the cut end.' Spontaneous rhythmic motor unit potentials in the carpal tunnel syndrome. - - F. Spaans, J. Neurol. Neurosurg. Psychiat., 45 (1982) 19-28. Ongoing spontaneous motor unit activity was found in the lateral thenar muscles in 18 of 164 patients with the carpal tunnel syndrome. In most cases a single motor unit was firing off in doublets or triplets. Ischemia at first increased and later greatly decreased the activity. This activity was also suppressed by strong contraction of the muscles and by supramaximal stimulation of the median nerve. By blocking the median nerve at the elbow, it was shown that the site of generation of the spontaneous motor impulses was distal to the elbow and probably at the compression site at the carpus.

PEPTIDES Review: Endogenous opiates: 1980. - - G.A. Olson, R.A. Olson, A.J. Kastin and D.H. Coy, Peptides, 2 (1981) 349-369. This useful review covers over 300 recent (1980) papers in several areas related to endogenous opioids. Topics receiving attention are: opiate receptors, opioid peptide precursors, opioids in non-mammalian vertebrates and invertebrates, the anatomical distribution of opioid peptides and receptors, new peptides (including Dynorphin) and metabolically stable analogs, behavioral and clinical aspects, hormonal interactions and clinical aspects, hormonal interactions and other related topics. Debate continues over the significance of multiple opiate receptors. New and interesting synthetic analogs have been developed. Our knowledge of the synthesis and catabolism of opioid peptides continues its rapid advance. Substance P analog, DiMe-C7: evidence for stability in rat brain and prolonged central actions. - - A.S. Eison, S.D. lversen, B.E.B. Sandberg, S.P. Watson, M.R. Hanley and L.L. Iversen, Science, 215 (1982) 188-190. The authors show that a substance P analog produces behavioral effects that are prolonged by a duration that reflects its increased metabolic stability. Depletion of substance P axons in substantia gelatinosa of patients with diminished pain sensitivity. - - J. Pearson, L. Brandeis and A.C. Cuello, Nature (Lond.), 295 (1982) 7. Patients with familial dysautonomia have reduced pain and temperature sensitiv-