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

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

Migraine headache is commonly associated with signs of exaggerated intracranial and extracranial mechanical sensitivities. Patients exhibiting signs of intracranial hypersensitivity testify that their headache throbs and that mundane physical activities that increase intracranial pressure (such as bending over or coughing) intensify the pain. Patients exhibiting signs of extracranial hypersensitivity testify that during migraine their facial skin hurts in response to otherwise innocuous activities such as combing, shaving, letting water run over their face in the shower, or wearing glasses or earrings (termed here cephalic cutaneous allodynia). Such patients often testify that during migraine their bodily skin is hypersensitive and that wearing tight cloth, bracelets, rings, necklaces and socks or using a heavy blanket can be uncomfortable and/or painful (termed her extracephalic cutaneous allodynia). This review summarizes the evidence that support the view that activation of the trigeminovascular pathway contribute to the headache phase of a migraine attack, that the development of throbbing in the initial phase of migraine is mediated by sensitization of peripheral trigeminovascular neurons that innervate the meninges, that the development of cephalic allodynia is propelled by sensitization of second-order trigeminovascular neurons in the spinal trigeminal nucleus which receive converging sensory input from the meninges as well as from the scalp and facial skin, and that the development of extracephalic allodynia is mediated by sensitization of third-order trigeminovascular neurons in the posterior thalamic nuclei which receive converging sensory input from the meninges, facial and body skin.
Animals ; Comb and Wattles ; Ear ; Eyeglasses ; Glass ; Headache ; Humans ; Hyperalgesia ; Hypersensitivity ; Intracranial Pressure ; Linear Energy Transfer ; Meninges ; Migraine Disorders ; Motor Activity ; Neurons ; Posterior Thalamic Nuclei ; Scalp ; Skin ; Thalamus ; Trigeminal Nucleus, Spinal ; Tryptamines ; Water

BACKGROUND: The trigeminal nucleus caudalis (Vc) is a primary central site for trigeminal transmitting. Noxious stimulation of the trigeminal nociceptors alters the central synaptic releases and neural expression of some inflammatory and trophic agents. Orexin-A and the orexin 1 receptor (OX1R) are expressed in pain pathways including trigeminal pain transmission. However, the the mechanism(s) underling orexin-A effects on trigeminal pain modulation have not been fully clarified. METHODS: Trigeminal pain was induced by subcutaneous injection of capsaicin in the upper lip in rats. The effect of trigeminal pain on cyclooxygenase-2 (COX-2) and brain-derived neurotrophic factor (BDNF) expression in the Vc of animals was determined by immunofluorescence. Subsequently, OX1R agonist (orexin-A) and antagonist (SB-334867-A) was administrated in the Vc to investigate the possible roles of the Vc OX1R on changes in COX-2 and BDNF levels following pain induction. RESULTS: The data indicated an increase in COX-2 and decrease in BDNF immuno-reactivity in the Vc of capsaicin, and capsaicin- pretreated with SB-334867-A (80 nM), groups of rat. However, the effect of capsaicin on COX-2 and BDNF expressions was reversed by a Vc microinjection of orexin-A (100 pM). CONCLUSIONS: Overall, the present data reveals that orexin-A can attenuate capsaicin-induced trigeminal pain through the modulation of pain effects on COX-2 and BDNF expressions in the Vc of rats.
Animals ; Brain-Derived Neurotrophic Factor ; Capsaicin ; Cyclooxygenase 2 ; Facial Pain ; Fluorescent Antibody Technique ; Injections, Subcutaneous ; Lip ; Microinjections ; Nociceptors ; Orexin Receptor Antagonists ; Orexins ; Pain Measurement ; Pain Perception ; Rats ; Trigeminal Caudal Nucleus ; Trigeminal Neuralgia ; Trigeminal Nuclei

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

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

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

The ultrastructural parameters related to synaptic release of endings which are presynaptic to tooth pulp afferent terminals (p-endings) were analyzed to understand the underlying mechanism for presynaptic modulation of tooth pulp afferents. Tooth pulp afferents were labelled by applying wheat-germ agglutinin conjugated horseradish peroxidase to the rat right lower incisor, whereafter electron microscopic morphometric analysis with serial section and reconstruction of p-endings in the trigeminal oral nucleus was performed. The results obtained from 15 p-endings presynaptic to 11 labeled tooth pulp afferent terminals were as follows. P-endings contained pleomorphic vesicles and made symmetrical synaptic contacts with labeled terminals. The p-endings showed small synaptic release-related ultrastructural parameters: volume, 0.82 ± 0.45 µm³ (mean ± SD); surface area, 4.50 ± 1.76 µm²; mitochondrial volume, 0.15 ± 0.07 µm³; total apposed surface area, 0.69 ± 0.24 µm²; active zone area, 0.10 ± 0.04 µm²; total vesicle number, 1045 ± 668.86; and vesicle density, 1677 ± 684/µm². The volume of the p-endings showed strong positive correlation with the following parameters: surface area (r=0.97, P<0.01), mitochondrial volume (r=0.56, P<0.05), and total vesicle number (r=0.73, P<0.05). However, the volume of p-endings did not positively correlate or was very weakly correlated with the apposed surface area (r=-0.12, P=0.675) and active zone area (r=0.46, P=0.084). These results show that some synaptic release-related ultrastructural parameters of p-endings on the tooth pulp afferent terminals follow the "size principle" of Pierce and Mendell (1993) in the trigeminal nucleus oralis, but other parameters do not. Our findings may demonstrate a characteristic feature of synaptic release associated with p-endings.
Animals ; Horseradish Peroxidase ; Incisor ; Mitochondrial Size ; Rats ; Tooth* ; Trigeminal Nuclei

We used cholera toxin B subunit (CTB) as a neural tracer to localize motor neuronal cell bodies innervating the digastric muscle. After CTB injection into the left anterior belly, CTB-labelled motor neuronal cell bodies were found in caudal half of the left and right trigeminal nucleus, the left and right facial nucleus, the accessory facial nucleus and the accessory trigeminal nucleus in pons. The total number of CTB-labelled motor neuronal cell bodies were 1,179+/-119.5 in the left pons and 246+/-61.8 in the right pons after CTB injections into the left anterior belly of digastric muscle. After CTB injection into left posterior belly, CTB-labelled motor neuronal cell bodies were found only in the left ventral part of accessory facial nucleus in caudal pons and the total number of CTB-labelled motor neuronal cell bodies were 270+/-29.3.
Animals ; Cholera Toxin* ; Cholera* ; Motor Neurons* ; Pons ; Rats* ; Trigeminal Nuclei

The present study was aimed to investigate the ultrastructure of the primary afferent terminals and whether glutamate may be a transmitter in these terminals within the trigeminal nucleus principalis and oralis of the rat. Labeling of primary afferent terminals was performed by the injection of the CTB-HRP into the trigeminal ganglion. Ultrastructural analysis and assessment of the glutamate like immunoreactivity by the immunogold technique was performed with the 66 peroxidased labeled boutons in the nucleus principalis and 62 in the nucleus oralis. Labeled boutons were presynaptic to dendritic shafts of the secondary neurons and postsynaptic to the pleomorphic vesicles containing endings (p-endings). Most of the labeled boutons made synaptic contact with the dendritic shafts. A little labeled boutons in the nucleus oralis but no in the nucleus principalis was observed to make synaptic contact with the soma or proximal dendrite. Most of the labeled boutons made synaptic contact with one to three neurofiles, but labeled boutons showing complex synaptic connections, such as those with five or more neurofiles, were more in principalis than in oralis. The average diameter of p-endings were smaller than that of labeled boutons (p<0.05). The diameter of the postsynaptic dendritic shafts were smaller in nucleus principalis than in nucleus oralis, thus indicated that the labeled boutons made synaptic contact with more distal portion of the postsynaptic dendrite in the nucleus principalis than in the nucleus oralis. The gold particle density over the labeled boutons were significantly higher than that over the p-endings and average tissue particle density. They were ranged from 110 to 430% of the average tissue particle density. These findings indicate that synaptic connection of the primary afferent terminals is organized in different manner in nucleus principalis and oralis, and suggest that glutamate is involved as neuroactive substance in the primary afferent terminals of the trigeminal system.
Animals ; Carisoprodol ; Dendrites ; Glutamic Acid* ; Immunohistochemistry ; Neurons ; Neurotransmitter Agents ; Rats* ; Trigeminal Ganglion ; Trigeminal Nuclei*