人胎儿脊髓神经肽Y样神经元及其纤维的发育和分布的免疫细胞化学研究

人工流产胎儿标本２３例，孕龄１０～４１周，用免疫组织化学ＡＢＣ法，研究人胎儿脊髓神经肽Ｙ样神经元的发育和分布。结果在胎龄第１０周，发现脊髓后角浅层（ＲｅｘｔｄⅠ、Ⅱ层）已有神经肽Ｙ样免疫阳性神经元胞体存在，且阳性神经元总数随胎龄的增加而递增，并向后角深层（ＲｅｘｅｄⅢ～Ⅳ层）扩展神经肽Ｙ样阳性纤维，在胎龄第１０周，不仅出现于脊髓的灰质和白质，而且见于脊髓的被膜。随胎龄的增长，免疫阳性反应纤维相对集中于脊髓的植物性神经中枢的所在部位，揭示在妊娠早期，神经肽Ｙ可能与脊髓植物神经元的发育及其功能的调节有关。     

Sensitization of nociceptive cutaneous nerve fibers from the rat's tail by noxious mechanical stimulation

Summary This single fiber study on rat tail nerve afferents attempts to establish a peripheral neural correlate for the hyperalgesia to mechanical stimulation which follows injury to the skin. Mechano-heat sensitive C fibers (MH-C or polymodal nociceptors) and high-threshold mechanoreceptive A delta fibers (HTM-A delta) were examined with a series of constant noxious pressure stimulations (4-6-8-4 N on 25 mm², 120 s each, 5 min intervals). These injurious stimuli were either directed to the most sensitive spot of the receptive fields (central stimulation) or closely outside their borders (1–5 mm). With this protocol no clear sensitization was seen in MH-C fibers apart from a stronger dynamic response to central stimulation in some of them. In contrast, most HTM-A delta units, irrespective of the site of noxious stimulation, developed spontaneous activity, lowering of their von Frey thresholds and expansion of their receptive fields. All HTM-A delta units responded to outside stimulation: upon the first stimulus (4 N) there was a delayed discharge of continuously increasing frequency (recruited response), but the onset of the last stimulation (4 N repeated) evoked vigorous dynamic responses in many fibers. The recruitment of HTM-A delta nociceptor activity may contribute to post-injury hyperalgesia to mechanical stimulation and it may counteract adaptation of the single afferent fiber during prolonged noxious influence.On leave from the Laboratoire de Physiologie, Faculté de Médecine Lyon-Sud, Chemin du Petit Revoyet, F-69600 Ouillins, France     

Forelimb reflexes modulated by tonic neck positions in cats

The modulation of monosynaptic forelimb reflexes by tonic neck positions was investigated in cats with the head fixed.Lateral flexion of the body in a horizontal plane markedly facilitates reflexes of the deep radial nerve (DR) in the ipsilateral forelimb, while the antagonistic ulnar nerve (ULN) reflexes are strongly inhibited. Opposite effects are seen after contralateral body movement.Dorsiflexion of the body clearly increases DR-reflexes and exerts a reciprocal although more pronounced inhibition on ULN reflexes. Opposite effects appear after ventriflexion.The reflex modulation starts with head-body displacements of approximately 5° and increases with increasing angles. Furthermore reflex modulation does not depend on the intact cerebrum and cerebellum. The comparison of forelimb and hindlimb reflexes shows a decrease of the neck influences along the spinal cord.Supported by Sonderforschungsbereich Hirnforschung und Sinnes-physiology (SFB 70) der Deutschen Forschungsgemeinschaft (DFG).Essential parts of this paper will be submitted by A. F. as a thesis to the Faculty of Medicine, Freiburg/Breisgau, Germany.     

Differential distribution of spinal cord field potentials

Summary Electrical stimulation of the sural, superficial peroneal and plantar nerves in anesthetized cats produces a sequence of potentials in the spinal cord lumbosacral enlargement. The distributions of the spinal cord dorsum negative intermediary potential (N1 wave) and of the associated field potential recorded in depth from the spinal gray matter were mapped. The N1 wave produced by the sural nerve was largest at the junction of the S1 and L7 segments, whereas that evoked by the other two nerves was maximum in L6 and L7. The field potentials recorded in depth also showed a differential distribution. The maximum negativity during phase 2, corresponding to the N1 cord dorsum potential, was found to lie laterally in the dorsal horn when the sural nerve was stimulated, but medially when the plantar nerve was activated. The superficial peroneal nerve produced its largest negative field potential in the central region of the dorsal horn. The negative field potentials from the sural and superficial peroneal nerves were not as well separated spatially from each other as they were from the potential evoked by the plantar nerve.     

Laser induced thermal injury of rabbit cornea and treatment with anti-inflammatory agents

A moderately severe thermal injury of the central cornea of 48 Dutch-belted rabbit eyes was produced with a carbon (CO₂) laser. The lesions were photographed with a slit lamp (SL) camera immediately following the injury and at 1, 2, 4, 7, 14, 21, 30 and 60 days after the exposure. Lesion size, opaqueness, and depth were graded clinically by SL biomicroscopy at the same intervals. No significant differences were found (p 0.05) between groups of eyes treated with flurbiprofen (0.03%), prednisolone acetate (1%), and vehicle control four-times-a-day for three weeks following injury. Additionally, eyes were studied histopathologically at 3 and 60 days following injury by light and transmission electron microscopy, and clinically at 30 and 60 days by endothelial specular microscopy. Important clinical and histopathological findings included coagulative necrosis of the corneal epithelium, epithelial sloughing, fusion of stromal collagen, stromal edema and inflammatory cell infiltration, stromal scar formation, corneal thinning, endothelial hyperplasia and metaplasia, fibrinous anterior chamber reaction with hypopyon, and retrocorneal fibrous membrane formation.     

Pharmacology of spinal adrenergic systems which modulate spinal nociceptive processing

Spinopetal pathways may be activated by a variety of brainstem manipulations including microinjections of morphine which are known to modulate spinal nociceptive processing. Based on the ability of these manipulations to release spinal noradrenalin; the ability to reverse the antinociceptive effects by intrathecal adrenergic antagonists and the fact that intrathecal injections of noradrenalin mimic the antinociceptive effect, it appears that the descending modulation may be mediated by descending noradrenergic systems. Examination of the spinal receptor systems with intrathecally administered agents indicates that spinal alpha, but not beta adrenergic receptor agonists produce a powerful analgesia as measured on a variety of reflex and operant measures in mouse, rat, cat, primate and man. On the basis of agonist and antagonist structure-activity relationships it appears that a significant effect can be produced in the absence of any detectable effect on motor function by the occupation of spinal alpha 2 receptors. Distinguishable alpha 1 receptors also appear "analgetically-coupled," but their effects are uniformly contaminated by signs of cutaneous hyperreflexia at doses required to produce analgesia. The ordering of potency with which intrathecal adrenergic antagonists reverse the effects of intrathecal noradrenalin is indistinguishable from that of the reversal by these intrathecal agents of the antinociceptive effects evoked by brainstem morphine. This suggests that the population of spinal receptors acted upon by exogenously administered adrenergic agonists and endogenously released noradrenaline have indistinguishable characteristics.     

Post-traumatic epidural hematoma in two patients with long-standing “arrested” hydrocephalus

The occurrence of a post-traumatic epidural hematoma in two patients with long-standing arrested hydrocephalus is reported. There was a relatively long interval between the head injury and the onset of symptoms. The large hematoma was accommodated by the decrease in size of the markedly dilated ventricles. This report stresses the possibility of the presence of an epidural hematoma in the management of head injury in patients with long-standing arrested hydrocephalus.     

Glycogen accumulation in synaptic boutons in Clarke's nucleus neuropil after sciatic nerve crush at birth

Summary Glycogen accumulation in the Clarke's nucleus neuropil of young adult rats whose sciatic nerves were crushed in the first postnatal day was investigated with the electron microscope. Glycogen was observed in synaptic boutons and in small myelinated axons. In some terminals, glycogen accumulated in membranebound structures resembling mitochondria and formed large multigranular bodies which were entirely separated from the axoplasm. The multigranular body reached the size of 1.3 m. Glycogen was present as single beta particles of about 25–40 nm in diameter and in aggregations of large alpha clusters. The astrocytic glycogen distribution was almost similar to that of the control specimens. Glycogen was not observed in other glial cells. It is probable that glycogen accumulation in synaptic terminals of partially deafferentiated Clarke's nucleus may result from impaired glycolysis due to deficient resupply of the distal axon with glycolytic enzymes caused by a defect in axoplasmic transport from the hypoplastic sensory neuronal perikarya.     

No disturbance of myelination in the central nervous system by selective3Hβ-irradiation

Summary The effect of a selective irradiation of myelin by³H -particles was studied by light and electron microscopic methods in guinea pig spinal cord. The animals were injected with [³H]leucine shortly after birth when the rate of myelin biosynthesis is high and sacrificed 130 days later. In spinal cord the radioactivity was mainly preserved in myelin because the half life of myelin proteins is much higher than that of most other CNS protein. As a consequence the irradiation dose in the white matter was much higher than in the gray matter. In myelin internally irradiated by³H -particles within 130 days at a dose of 10 Gy no alterations could be detected either by morphological or by morphometric methods.Supported by the Deutsche Forschungsgemeinschaft     

Changes in neurofilament gene expression occur after axotomy of dorsal root ganglion neurons: Anin situ hybridization study

Neurofilaments (NFs) are predominant elements in large myelinated axons, where they are thought to serve the important function of maintaining axonal caliber. Previous studies have shown that changes in NF synthesis and axonal transport occur after axonal injury in rat dorsal root ganglion (DRG) cells. The resulting reduction in the NF supply to DRG axons is thought to be largely responsible for the observed decrease in axonal diameter in the proximal axonal stump after an injury. In the present study, we test the hypothesis that a change in NF gene expression precedes the changes in synthesis and transport of NF proteins. To address this hypothesis, the levels of mRNA encoding the 68-kilodalton (kd) neurofilament protein (NF68) in adult rat DRG neurons were assessed at different times after peripheral axotomy usingin situ hybridization. For these studies we used a³⁵S-labeled cDNA probe to NF68. The levels of NF68 mRNA in sensory neurons located in ipsilateral fourth and fifth lumbar DRG at 1, 7, and 14 days after sciatic nerve crush were compared to those in normal DRG neurons using quantitative autoradiography. In large DRG neurons (> 1000m²), the levels of NF68 mRNA were significantly reduced relative to normal at 1, 7, and 14 days after axotomy. Medium-sized cells (601–1000m²) exhibited a reduction only at 14 days postinjury, and small-sized cells were not significantly affected. These findings indicate that larger DRG neurons which give rise to large myelinated sensory axons exhibit a change in NF gene expression after axonal injury. The observed changes in NF68 mRNA levels temporally precede changes in NF synthesis and transport in injured DRG cells. Thus, a change in NF gene expression may be an important component of an effective regenerative response and a critical step at which axonal caliber is regulated in injured neurons.