It is well known that trigeminal nerve injury causes hyperexcitability in trigeminal ganglion neurons, which become sensitized. Long after trigeminal nerve damage, trigeminal spinal subnucleus caudalis and upper cervical spinal cord (C1/C2) nociceptive neurons become hyperactive and are sensitized, resulting in persistent orofacial pain. Communication between neurons and non-neuronal cells is believed to be involved in these mechanisms. In this article, the authors highlight several lines of evidence that neuron-glial cell and neuron macrophage communication have essential roles in persistent orofacial pain mechanisms associated with trigeminal nerve injury and/or orofacial inflammation.
Cell Communication ; Cervical Cord ; Facial Pain ; Inflammation ; Macrophages ; Neurons ; Nociceptors ; Trigeminal Ganglion ; Trigeminal Nerve ; Trigeminal Nerve Injuries ; Trigeminal Nucleus, Spinal

The nerves innervating the auricle of the rat were investigated using PRV (pseudorabies virus) as a neural tracer. The neural tracer was injected into rostral part of the right auricle of the rat. The PRV immunoreactive neurons were labeled bilaterally and more densely labeled in the brain than spinal cord. In the brain, PRV immunoreactive neuronal cell bodies and fibers were observed in thalamus, periaqueductal gray matter, reticular formation, spinal trigeminal nucleus, spinal tract of trigeminal nerve and facial nucleus. The more densely labeled PRV immunoreactive neurons were found in thalamus, reticular formation, spinal tract of trigeminal nerve and facial nucleus. In the spinal cord, PRV immunoreactive neurons were extended from T8 to L2 segments. The more densely labeled PRV immunoreactive neurons were found from T11 to L2 segments. Above results, the nerves innervating the auricle of the rat were widely distributed in brain and spinal cord and may have many connections with other nerves. These results may provide a neuroanatomical data on the nerves innervating the auricle of the rat in the central nervous system.
Animals ; Brain* ; Central Nervous System ; Herpesvirus 1, Suid ; Neurons ; Periaqueductal Gray ; Rats* ; Reticular Formation ; Spinal Cord* ; Thalamus ; Trigeminal Nerve ; Trigeminal Nucleus, Spinal

caudal subnucleus of the spinal trigeminal nucleus (medullary dorsal horn ;MDH)receives direct inputs from unmyelinated and thinly myelinated, small diameter primary afferent fibers. Thus, the MDH is implicated in the processing of nociceptive information in the orofacial region. In this study,the types and characteristics of voltage-dependent ion currents were investigated in acutely isolated MDH neurons of postnatal rats by means of the whole cell patch clamp techniques. Coronal slice (400micro meter)of the trigeminal caudal subnucleus region was sequentially treated with pronase 0.2mg/ml and thermolysin 0.2mg/ml, then single neurons were mechanically dissociated.Voltage-dependent sodium currents showed that the half-maximum activation potential was -41.8 +/- 1.8mV and half-maximum inactivation potential was -62.4 +/- 3.0mV.And the currents were blocked totally by application of 100nM tetrodotoxin.In a Ca2+ free solution,low-threshold transient (IA )and high-threshold sustained (IK )currents were recorded.The half-maximum activation and inactivation potential of IK were 2.5 +/- 1.9mV and -37.1 +/- 2.3mV,respectively.IA was activated and inactivated more rapidly than IK. The half-maximum acti-vation and inactivation potential were -21.6 +/- 6.3mV and -84.5 +/- 5.0mV,respectively. When a 4-aminopy-ridine of 5mM was applied, IA was almost totally blocked. These results reveal that MDH neurons express a variety of voltage-dependent ionic currents with distinct physiological and pharmacological properties,and they play an essential role in the transmission and modulation of sensation, especially pain, from trigeminal region.]]>
Animals ; Horns ; Myelin Sheath ; Neurons ; Patch-Clamp Techniques ; Potassium ; Pronase ; Rats ; Sensation ; Sodium ; Thermolysin ; Trigeminal Nucleus, Spinal

The nerves innervating the sublingual gland of the rat was investigated using PRV (pseudorabies virus) as a neural tracer. The neural tracer was injected into left sublingual gland of the rat. In the central nervous system, PRV immunoreactive neurons were labeled bilaterally and tended to be more densely labeled in the left side. PRV immunoreactive neuronal cell bodies and fibers were observed in insular cortex, paraventricular nucleus, deep mesencephalic nucleus, spinal trigeminal tract, lateral paragigantocellular nucleus, parvicellular reticular nucleus, raphe obscurus, gigantocellular reticular nucleus and gigantocellular reticular nucleus, alpha. The more densely labeled PRV immunoreactive neurons were found in the deep mesencephalic nucleus, spinal trigeminal tract and lateral paragigantocellular nucleus. These results may provide a neuroanatomical data on the nerves innervating the sublingual gland in the rat brain.
Animals ; Brain* ; Central Nervous System ; Herpesvirus 1, Suid* ; Neurons ; Paraventricular Hypothalamic Nucleus ; Pseudorabies* ; Raphe Nuclei ; Rats* ; Sublingual Gland* ; Trigeminal Nucleus, Spinal

This experimental studies was to investigate the location of CNS labeled neurons following injection of pseudorabies virus (PRV), Bartha strain, into the rat thymus. After survival times of 96~120 hours following injection of PRV, the rats were perfused, and their spinal cord and brain were frozen sectioned(30micrometer). These sections were stained by PRV immunohistochemical staining method, and observed with light microscope The results were as follows: 1. The PRV labeled spinal cord segments projecting to the rat thymus were founded in cervical and thoracic segments. Densely labeled areas of each spinal cord segment were founded in lamina V, VII, X, intermediolateral nucleus and dorsal nucleus. 2. In the rhombencephalon, PRV labeled neurons projecting to the thymus were founded in the A1 noradrenalin cells/C1 adrenalin cells/caudoventrolateral reticular nucleus, rostroventro-lateral reticular nucleus, medullary reticular nucleus, area postrema, nucleus solitary tract, nucleus raphe obscurus, nucleus raphe pallidus, nucleus raphe magnus, gigantocellular reticular nucleus, lateral paragigantocellular nucleus and spinal trigeminal nucleus. 3. In the mesencephalon, PRV labeled neurons were founded in parabrachial nucleus, Kolliker-Fuse nucleus, central gray matter, substantia nigra, nucleus dorsal raphe, A8 dopamin cells of retrorubral field, Edinger-Westphal nucleus, locus coeruleus, subcoeruleus nucleus and A5 noradrenalin cells. 4. In the prosencephalon, PRV labeled neurons were founded in reuniens thalamic nucleus, paraventricular thalamic nucleus, precommissural nucleus, paraventricular hypothalamic nucleus, anterior hypothalamic nucleus, lateral hypothalamic nucleus, preoptic hypothalamic nucleus, retrochiasmatic area, arcuate nucleus, dorsomedial hypothalamic nucleus and ventromedial hypothalamic nucleus. These results suggest that PRV labeled neurons of the spinal cord projecting to the rat thymus might be the neurons related to the viscero-somatic sensory and sympathetic preganglionic neurons, and PRV labeled neurons of the brain may be the neurons response to the movement of smooth muscle in blood vessels. These PRV labeled neurons may be central autonomic center related to the integration and modulation of reflex control linked to the sensory system monitoring the internal environment. These observations provide evidence for previously unknown projections from spinal cord and brain to the thymus which may be play an important role in the regulation of thymic function.
Animals ; Anterior Hypothalamic Nucleus ; Arcuate Nucleus ; Area Postrema ; Blood Vessels ; Brain ; Dorsomedial Hypothalamic Nucleus ; Herpesvirus 1, Suid* ; Hypothalamic Area, Lateral ; Immunohistochemistry ; Locus Coeruleus ; Mesencephalon ; Midline Thalamic Nuclei ; Muscle, Smooth ; Neurons* ; Paraventricular Hypothalamic Nucleus ; Prosencephalon ; Pseudorabies* ; Rats* ; Reflex ; Rhombencephalon ; Spinal Cord ; Substantia Nigra ; Thymus Gland* ; Trigeminal Nucleus, Spinal ; Ventromedial Hypothalamic Nucleus

In the present study, we performed immunohistochemical studies to investigate the detailed distribution of insulin-like growth factor binding protein 7 (IGFBP7) in the central nervous system of adult rats. Twelve adult (4~6 month old) Sprague-Dawley rats were examined in this study. Immunohistochemistry using specific antibodies against IGFBP7 was performed in accordance with the free-floating method. In the present study, IGFBP7 immunoreactivity was observed in the cerebral cortex, hippocampus, brainstem, cerebellum and spinal cord. In the cerebral cortex, heavily stained neurons were seen in layers II-VI. In the hippocampus, pyramidal cells in CA1-3 region were strongly immunoreactive for IGFBP7. Strong immunoreactive neurons were also found in the supraoptic nucleus, paraventricular nucleus, periaqueductal gray and oculomotor nucleus. In the cerebellum, IGFBP7 immunoreactivity was prominent in the Purkinje cells and cerebellar output neurons. IGFBP7-immunoreactive neurons were prominent in the superior vestibular nucleus, cochlear nucleus, trigeminal motor nucleus, nucleus of the trapezoid, and facial nucleus. IGFBP7-immunoreactive neurons were also observed mainly in the anterior horn of the spinal cord. The first demonstration of IGFBP7 localization in the whole brain may provide useful data for the future investigations on the structural and functional properties of IGFBP7.
Adult ; Animals ; Antibodies ; Brain ; Brain Stem ; Carrier Proteins ; Central Nervous System ; Cerebellum ; Cerebral Cortex ; Cochlear Nucleus ; Hippocampus ; Horns ; Humans ; Immunohistochemistry ; Neurons ; Paraventricular Hypothalamic Nucleus ; Periaqueductal Gray ; Purkinje Cells ; Pyramidal Cells ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; Supraoptic Nucleus ; Trigeminal Nuclei

Discogenic low back pain is the common type of chronic low back pain. However,its mechanism has not been completely clarified. Considerable evidence shows that neurotrophins play an important role in discogenic low back pain. The paper summarizes the mechanism of neurotrophins on discogenic low back pain according to the pain transfer pathway of neurotrophins in intervertebral disc, dorsal horn ganglia and spinal trigeminal nucleus. Changing the pain transmission by regulating neurotrophins and its receptor will provide a new way for the treatment of discogenic low back pain.
Humans ; Intervertebral Disc ; metabolism ; pathology ; Low Back Pain ; metabolism ; pathology ; Nerve Growth Factors ; metabolism ; Posterior Horn Cells ; pathology ; Trigeminal Nucleus, Spinal ; pathology

BACKGROUND AND OBJECTIVES: The transsynaptic transfer of neurotropic viruses is an effective tool for tracing chains of connected neurons, because replication of virus in the recipient neurons after the transfer amplifies the "tracer signal". The aim of this study is to identify the central neural pathways projecting to the facial nerve using the Bartha strain of the Pseudorabies virus (PRV-Ba )as a transsynaptic tracer. MATERIALS AND METHODS: PRV-Ba was injected into the facial nerve in the stylomastoid foramen of a rat, and was localized in the rat brain with light microscopic immunohistochemistry using primary antibodies against the PRV-Ba. Sequential tracing was carried out on the retrogradely labeled neurons were done. RESULTS: The shapes of upper motor neurons of facial nerve were mostly ovoid or polygonal. The positive immunoreactive cells observed in the brainstem nuclei included raphe obscurus nucleus, facial nucleus, parvocellular reticular nucleus, spinal trigeminal nucleus, ventral parabrachial nucleus, central gray, and dorsal raphe nucleus. Other positive cells stained in the diencephalon were found in periventricular hypothalamic nucleus, dorsal hypothalamic area, orbital gyri, and infralimbic cortex in the frontal lobe. CONCLUSIONS: These results show the central neural pathways of facial nerve using PRV-Ba.
Animals ; Antibodies ; Brain ; Brain Stem ; Diencephalon ; Facial Nerve ; Frontal Lobe ; Herpesvirus 1, Suid ; Immunohistochemistry ; Motor Neurons ; Neural Pathways* ; Neurons ; Orbit ; Raphe Nuclei ; Rats ; Trigeminal Nucleus, Spinal

caudal subnucleus of the spinal trigeminal nucleus (medullary dorsal horn : MDH) is implicated in the processing of nociceptive information in the orofacial region. Whole cell patch clamp recordings were carried out on MDH neurons in the brainstem slices of neonatal rats to investigate the roles of metabotropic glutamate receptors on excitatory synaptic transmission. In the presence of strychnine (1 microM) and bicuculline (20 microM), spontaneous inward currents at -70 mV were observed. Spontaneous excitatory postsynaptic currents (sEPSCs) were mediated by non-NMDA and NMDA receptors. The specific AMPA receptor antagonist GYKI 52466 (50 microM) completely blocked the non-NMDA mediated sEPSCs, indicating that they are mediated by an AMPA-preferring receptor. Group I, II metabotropic glutamate receptor (mGluR) agonist ACPD (20 microM) significantly decreased the average sEPSCs frequency. No significant effect on sEPSCs amplitude was observed. Frequency of miniature excitatory postsynaptic currents (mEPSCs) was significantly decreased by 20 microM ACPD, but amplitude of mEPSCs was not changed. The specific mGluR 2, 3 agonist DCG-IV (3 microM) reduced mEPSCs frequency, but did not change mEPSCs amplitude. There were no significant changes in the average sEPSCs frequency and amplitude. The mGluR 1, 5 agonist DHPG (100 microM) decreased sEPSCs and mEPSCs frequency, but had no effects on sEPSCs and mEPSCs amplitude. These data suggest that the activation of metabotropic glutamate receptors, via its presynaptic inhibition, can influence the excitatory synaptic transmission of MDH neurons.]]>
Animals ; Bicuculline ; Brain Stem ; Excitatory Postsynaptic Potentials ; Horns ; Neurons ; Rats ; Receptors, AMPA ; Receptors, Metabotropic Glutamate ; Receptors, N-Methyl-D-Aspartate ; Strychnine ; Synaptic Transmission ; Trigeminal Nucleus, Spinal

Bartha strain of pseudorabies virus[PRV-Ba] was utilized as a tracer to identify the neuronal axis of rat tongue muscles ; intrinsic muscles and extrinsic muscles, styloglossus, genioglossus, and hyoglossus muscle. After injection of 10 microliter of PRV-Ba into tongue muscles and 48-96 hours survivals, rats were perfused with 4% paraformaldehyde lysine periodate and brains were removed. PRV-Ba were localized in neural circuits by immunohistochemistry employing rabbit anti PRV-Ba as a primary antibody and ABC method. Injection of PRV-Ba into the tongue muscles resulted in uptake and retrograde transport of PRV-Ba in the rat brain. The result showed a circuit specific connection of many nerve cell groups along the time sequence : PRV-Ba immunoreactive cells appeared in hypoglossal nucleus and motor trigeminal nucleus ipsilaterally as seen with conventional tracers. Raphe nucleus, prepositus hypoglossal nucleus, spinal trigeminal nucleus, Al, A5 and facial nucleus of rhombencephalon showed immunoreactivity bilaterally. There were positive neurons in parabrachial nucleus, locus ceruleus, mesencephalic trigeminal nucleus, periaqueductal gray and A7 of mesencephalon and paraventricular nucleus, suprachiasmatic nucleus, organum vasculosum of lamina terminalis of diencephalon. Also positive reactions were showed in amygdala, insular cortex, frontal cortex and subfornical organ in telencephalon. Early immunoreactivity was appeared in hypoglossal nucleus and motor trigeminal nucleus, and there were positive neurons in the nuclei of the medulla oblongate, midbrain, pons, hypothalamus, cerebellum and medial preoptic area at middle stage. Subsequently the viral antigens were found in forebrain cell groups, paraventricular nuclei, suprachiasmatic nucleus, lateral hypothalamic area and primary motor cortex in frontal lobe bilaterally at 80-90hrs postinjection. These data demonstrate that the PRV-Ba can across synapses in the central nervous system with projection specific pattern, and this virus defines many elements of the neural network governing tongue. Therefore PRV-Ba are proved as a excellent neurotracer in the tract-tracing researches.
Amygdala ; Animals ; Antigens, Viral ; Axis, Cervical Vertebra ; Brain ; Central Nervous System ; Cerebellum ; Diencephalon ; Frontal Lobe ; Hypothalamic Area, Lateral ; Hypothalamus ; Immunohistochemistry ; Locus Coeruleus ; Lysine ; Mesencephalon ; Motor Cortex ; Muscles ; Neural Pathways* ; Neurons ; Paraventricular Hypothalamic Nucleus ; Periaqueductal Gray ; Pons ; Preoptic Area ; Prosencephalon ; Pseudorabies ; Raphe Nuclei ; Rats* ; Rhombencephalon ; Subfornical Organ ; Suprachiasmatic Nucleus ; Synapses ; Telencephalon ; Tongue* ; Trigeminal Nuclei ; Trigeminal Nucleus, Spinal