The author measured the severity of brain damage of 36 rabbits irradiated 2.45 GHz microwave for 10 minutes, 20 minutes and 30 minutes, respectively. Electromicroscopic and light microscopic findings of just after, 1 weeks, 2 weeks and 4 weeks after irradiated brain were compared in each time. Swelling and vacualization of nerve cell and mitochondria were noted. Also these changes tend to increased severity along amount of radiation, but revealed reversible changes with time. Myelinated and unmyelinated nerve fibers were examined as same manner. These nerve fibers also revealed swelling and vascuolization, these findings also tend to increase severity with irradiation power and more prominent at unmyelinated nerve fibers. Reversability of these findings after each time period were more prominent in myelinated nerve fibers than unmyelinated nerve fibers.
Brain ; Cerebrum* ; Microwaves* ; Mitochondria ; Myelin Sheath ; Nerve Fibers ; Nerve Fibers, Myelinated ; Nerve Fibers, Unmyelinated ; Neurons ; Rabbits*

OBJECTIVE: We measured current perception threshold (CPT) with transcutaneous electrical nerve stimulation (TENS) to prove the selective increment of the threshold of C sensory fiber and to determine onset time and duration of effect for application of TENS. METHOD: TENS were applied to fifteen control volunteers for 20 minutes on hand three times per week for 2 weeks duration. The CPT was tested at the distal interphalangeal joint of the second finger with 5 Hz, 250 Hz, and 2,000 Hz in frequency, respectively. The test was repeated immediately and 30 minutes after cessation of TENS. These tests were performed on the first, eighth, and fifteenth day on application of TENS. RESULTS: The baseline CPT of C fiber was 32.7 +/- 6.4 10 2 mA, A gamma fiber 23.2 +/- 9.4 10(-2) mA, and A beta fiber 83.9 +/- 18.1 10(-2) mA. At 30 minutes after cessation of TENS in the fifteenth day, the CPT of C fiber increased markedly and that of A gamma fiber increased a little. The CPT of A beta fiber didn't increase for 2 weeks. CONCLUSION: With application of TENS, the threshold of C and A gamma fibers selectively increased, especially 30 minutes after removal of TENS application. This effect was outstanding after 2 weeks' application.
Fingers ; Hand ; Joints ; Median Nerve* ; Nerve Fibers, Unmyelinated ; Transcutaneous Electric Nerve Stimulation* ; Volunteers

The present study was undertaken to confirm whether melittin, a major constituent of whole bee venom (WBV), had the ability to produce the same nociceptive responses as those induced by WBV. In the behavioral experiment, changes in mechanical threshold, flinching behaviors and paw thickness (edema) were measured after intraplantar (i.pl.) injection of WBV (0.1 mg & 0.3 mg/paw) and melittin (0.05 mg & 0.15 mg/paw), and intrathecal (i.t.) injection of melittin (6microgram). Also studied were the effects of i.p. (2 mg & 4 mg/kg), i.t. (0.2microgram & 0.4microgram) or i.pl. (0.3 mg) administration of morphine on melittin- induced pain responses. I.pl. injection of melittin at half the dosage of WBV strongly reduced mechanical threshold, and increased flinchings and paw thickness to a similar extent as those induced by WBV. Melittin- and WBV-induced flinchings and changes in mechanical threshold were dose- dependent and had a rapid onset. Paw thickness increased maximally about 1 hr after melittin and WBV treatment. Time-courses of nociceptive responses induced by melittin and WBV were very similar. Melittin-induced decreases in mechanical threshold and flinchings were suppressed by i.p., i.t. or i.pl. injection of morphine. I.t. administration of melittin (6microgram) reduced mechanical threshold of peripheral receptive field and induced flinching behaviors, but did not cause any increase in paw thickness. In the electrophysiological study, i.pl. injection of melittin increased discharge rates of dorsal horn neurons only with C fiber inputs from the peripheral receptive field, which were almost completely blocked by topical application of lidocaine to the sciatic nerve. These findings suggest that pain behaviors induced by WBV are mediated by melittin-induced activation of C afferent fiber, that the melittin- induced pain model is a very useful model for the study of pain, and that melittin-induced nociceptive responses are sensitive to the widely used analgesics, morphine.
Analgesics ; Bee Venoms* ; Bees* ; Lidocaine ; Melitten* ; Morphine ; Nerve Fibers, Unmyelinated ; Nociception ; Posterior Horn Cells ; Sciatic Nerve

BACKGROUND: The current perception threshold (CPT) could be quantified by stimulating Abeta and C fibers at 2,000 and 5 Hz, respectively. C fibers play a role in the autonomic nervous system and are involved in temperature and pain sensation. We evaluated the usefulness of CPT for diagnosing distal polyneuropathy (DPN) and cardiovascular autonomic neuropathy (CAN) in diabetic patients. METHODS: The CPT was measured in the index finger (C7 level) and in the third toe (L5 level) in diabetic patients aged 30 to 69 years. We assessed DPN according to the neuropathy total symptom score-6 (NTSS-6) and 10-g monofilament pressure sensation. Subjects with a NTSS-6 >6 or with abnormal 10-g monofilament sensation were defined to have DPN. CAN was evaluated by spectral analysis of heart rate variability and by Ewing's traditional tests. RESULTS: The subjects with DPN had significantly higher CPT at all of the frequencies than the subjects without DPN (P<0.05). Abnormal 10-g monofilament sensation and NTSS-6 >6 could be most precisely predicted by CPT at 2,000 and 5 Hz, respectively. However, only 6.5% and 19.6% of subjects with DPN had an abnormal CPT at 2,000 Hz at the C7 and L5 levels. Although CPT at 5 Hz showed a negative correlation with the power of low and high frequency in the spectral analysis (P<0.05), only 16.7% of subjects with CAN exhibited an abnormal CPT at the same frequency. CONCLUSION: Although the CPT is significantly associated with neuropathic symptoms or signs corresponding to the nerve fiber stimulated, it provides little additional information compared with conventional evaluations.
Autonomic Nervous System ; Diabetes Mellitus* ; Diabetic Neuropathies* ; Fingers ; Heart Rate ; Humans ; Nerve Fibers ; Nerve Fibers, Unmyelinated ; Polyneuropathies ; Sensation ; Toes

Effects of aconitine on the retina and optic nerve were studied in rabbits by means of visual evoked potential(VEP), electroretinogram(ERG), and electron microscopy. Aconitine(0.4mg/kg) was administered intra peritoneally. The effects of aconitine were observed at 1 day, 3 days, 1 week, 2 weeks, 3 weeks, and 3 months after injection, respectively. The amplitude of VEP was decreased significantly at 1 and 2 weeks after injection. However ERG b-wave, c-wave, and the latency of VEP were not significantly changed during the experimental periods. Histopathological changes in the optic nerve and visual streak were characterized by disorganization of the lamellar structures of the myelin sheath, diffuse mitochondrial swelling, and vacuolization in the myelinated nerve fibers, which were increased in degree with time. No perceptible change in the retina including retinal pigment epithelium was observed in the experimental periods. Schwann cells and unmyelinated nerve fibers appeared unaffected, except for mild swelling of mitochondria. Above mentioned electrophysiological and electron microscopic studies indicated that the effect of aconitine on the rabbit eye was toxic myelo-optic neuropathy.
Aconitine* ; Microscopy, Electron ; Mitochondria ; Mitochondrial Swelling ; Myelin Sheath ; Nerve Fibers, Myelinated ; Nerve Fibers, Unmyelinated ; Optic Nerve ; Optic Nerve Diseases* ; Rabbits ; Retina ; Retinal Pigment Epithelium ; Schwann Cells

The purpose of the study was to investigate whether the small fiber-evoked dorsal root reflex (DRR) can be obtained by electrical stimulation of the peripheral nerve in rats. Fifty-one DRRs were recorded from different kinds of fiber filaments in the proximal ends of the cut L(5) dorsal root following electrical stimulation of the sural nerve. According to the kind of afferent fibers in the sural nerve associated with the DRRs from dorsal root, these DRRs were divided into five different types: A(alphabeta) fiber-evoked A(alphabeta).DRR (A(alphabeta)- A(alphabeta).DRR), A(betadelta) - A(delta ).DRR, A(betadelta)-C.DRR, A(alphabetadelta)-C.DRR and C-C.DRR. The results obtained show that the DRR can be obtained from either A-fibers (including A(delta )-fibers) or C-fibers of dorsal root filaments by stimulation of the sural nerve. It is therefore suggested that either A(delta ).DRR or C.DRR can be used as a validity index of presynaptic inhibition of the thin primary afferent terminals for investigation of the modulation mechanisms of peripheral effectors.
Afferent Pathways ; Animals ; Electric Stimulation ; Female ; Male ; Nerve Fibers, Myelinated ; physiology ; Nerve Fibers, Unmyelinated ; physiology ; Rats ; Rats, Sprague-Dawley ; Reflex ; physiology ; Spinal Nerve Roots ; physiology ; Sural Nerve ; physiology

Diabetic neuropathy is a broad term that encompasses many destructive syndromes that various kinds of neuronal population is affected in diabetes mellitus. Diabetic neuropathy has been postulated to occur by diverse pathogenetic mechanisms. Recent studies suggest that the reduction of neurotrophic factors is one of the causes of diabetic neuropathy. This study was performed to identify the effect of nerve growth factor on Schwann cell in the streptozotocin-induced diabetic rats morphologically. Sprague-Dawley rats (weighed about 200 gm) were rendered diabetes by injection of streptozotocin (STZ 65 mg/kg) and nerve growth factor was administered for 4 weeks. The result obtained are as followed: 1. Degenerations in cytoplasmic organelles of Schwann cell of the myelinated nerve fibers in diabetic rats were identified. 2. Degenerations in cytoplasmic organelles of the Schwann cell of the unmyelinated nerve fibers in diabetic rats were identified and abnormal axons were appeared. 3. Nerve growth factor had an effect on the recovery of degeneration and it was more effective in myelinated nerve fibers. These results suggest that early administration of nerve growth factor have the effect of protection of diabetic neuropathy by morphological study.
Animals ; Axons ; Cytoplasm ; Diabetes Mellitus ; Diabetic Neuropathies* ; Nerve Fibers, Myelinated ; Nerve Fibers, Unmyelinated ; Nerve Growth Factor* ; Nerve Growth Factors ; Neurons ; Organelles ; Rats* ; Rats, Sprague-Dawley ; Streptozocin

INTRODUCTION: Mammalian tooth pulp is densely innervated by sensory nerves that are mostly C fibers and A delta fibers. However, there is evidence suggesting that many unmyelinated axons in the pulp are in fact parent meylinated axons. MATERIALS AND METHODS: The pulp was removed from healthy premolars and 3rd molars extracted from juveniles and adults undergoing orthodontic treatment, and immunohistochemical staining were applied with NPF200 antibodies, which specifically dye myelinated axons. The specimens underwent an electron microscopy examination with diaminobenzidine (DAB) immunostaining after observation and analysis by fluorescence and confocal laser scanning microscopy. RESULTS: The NPF200 immuno-positive axons in the radicular pulp areas were observed as bundles of many nerve fibers. Many small bundles were formed with fewer axons when firing to the coronal pulp areas and then reachrd a different direction. CONCLUSION: Myelinated fibers innervated to the dental pulp maintain their myelins in the radicular portion, but these fibers lost myelins in the coronal portion. Afterthe loss of myelin, the size of the axoplasm also decreased.
Adult ; Antibodies ; Axons ; Bicuspid ; Demyelinating Diseases ; Dental Pulp ; Fires ; Fluorescence ; Humans ; Microscopy, Electron ; Molar ; Myelin Sheath ; Nerve Fibers ; Nerve Fibers, Unmyelinated ; Parents ; Tooth

Many researches have focused upon temporal changes of neurotransmitters and/or neuromodulators in the central nervous system after ischemic insult. In sensory neurons, the spatial and temporal alterations of neurotransmitters have been little studied. Calbindin D-28k (CB) and calretinin (CR) have been suggested to play a role in the transmission of neurotransmitters. Therefore, in the present study we investigated the chronological alteration of CB and CR immunoreactivity in the trigeminal ganglion cells of the Mongolian gerbil after ischemic insult. In the sham operated group, CB and CR immunoreactivities were found in small -, medium -and large -sized neurons. One and two days after ischemia-reperfusion, small and large-sized CB immunoreactive neurons increased significantly. Thereafter, number of the CB immunoreactive neurons decreased markedly. Furthermore, five days after ischemia -reperfusion, CB immunoreactivity was detected in a few neurons, and its immunoreactivity was also very weak in the cytoplasm. Number of the large -sized CR immunoreactive neurons increased significantly one day after ischemia -reperfusion. Thereafter, the number of the large -sized CR immunoreactive neurons decreased. Especially, the number of the medium-sized CR immunoreactive neurons increased dramatically 4 days after ischemia-reperfusion. These results suggest that an increase of CB and CR may play an important role in modulating the mechanoception 1 day after ischemia-reperfusion, because the immunoreactivities increased in large -sized neurons which have the myenlinated A fibers. These results also suggest that significant increase of CR expression in medium -sized neurons 4 and 5 days after ischemia-reperfusion may provoke CR in modulating the nociception or thermoception because the medium-sized neurons which have the myenlinated A sigma or C fibers.
Calbindin 2* ; Calbindins* ; Central Nervous System ; Cytoplasm ; Gerbillinae* ; Immunohistochemistry ; Ischemia ; Nerve Fibers, Myelinated ; Nerve Fibers, Unmyelinated ; Neurons ; Neurotransmitter Agents ; Nociception ; Sensory Receptor Cells ; Trigeminal Ganglion*

The vanilloid receptor TRPV1 has been suggested to play an important role in thermal nociception and inflammatory hyperalgesia. In our previous study, we examined the expression of TRPV1 and colocalization of TRPV1 with substance P (SP) and calcitonin gene related peptide (CGRP) through fluorescence immunocytochemistry. Here, we investigated ultrastructural characteristics of TRPV1 immunoreactive fibers in the human tooth pulp through preembedding immunocytochemistry. TRPV1 immunoreactivity was present in the unmyelinated nerve fibers in the tooth pulp. There were two types of TRPV1 IR nerve fibers identified in the human tooth pulp: one containing clear round vesicles and many dense-cored vesicles, the other containing clear round vesicles and few dense-cored vesicles. TRPV1 immunoreactive fibers were constant in diameter without swellings along the length. Boutons en passant and boutons terminaux usually observed in the CNS were not observed in the TRPV1 immunoreactive fibers. Many vesicles were accumulated in the TRPV1 immunoreactive fibers, however synaptic structure was not found. It is known that dense-cored vesicles contain neuropeptides such as SP and CGRP and clear round vesicles contain neurotransmitter such as glutamate. Taken together, our results suggest that TRPV1 immunoreactive fibers showing distinct ultrastructructural features may be involved in inflammatory hyperalgesia and thermal nociception in the tooth pulp.
Calcitonin Gene-Related Peptide ; Fluorescence ; Glutamic Acid ; Humans* ; Hyperalgesia ; Immunohistochemistry ; Nerve Fibers ; Nerve Fibers, Unmyelinated ; Neuropeptides ; Neurotransmitter Agents ; Nociception ; Substance P ; Tooth*