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PubMed1994

Differential labeling of converging afferent pathways using biotinylated dextran amine and cholera toxin subunit B.

We report a new technique for 2-tracer anterograde labeling that permits unequivocal identification of the differentially labeled projections in the same section. One pathway is labeled with biotinylated dextran amine and is visualized as a black to dark gray diaminobenzidine (DAB)-cobalt precipitate by an avidin-biotinylated peroxidase reaction. The other pathway is labeled with cholera toxin subunit B and is visualized as a reddish-brown reaction product using DAB without cobalt as the substrate for peroxidase immunohistochemistry. To maintain serial order, sections can be processed mounted on slides without any loss of sensitivity for either tracer.

Afferent Pathways↗
PubMedDate not supplied

[Neurochemical analysis and pharmacological regulation of the corticofugal control of the nociceptive signals in the afferent pathways].

Experimental and clinical data indicate that the cerebral cortex plays an important role in pain perception and endogenous antinociceptive system function. Moreover, the enhancement of descending inhibitory cortical control may be involved in the mechanisms of analgesic effect of some agents. The present study was designed to investigate the effect of cortical electrical stimulation (as a model of descending inhibitory control) on the behavioral and electrophysiological signs of nociceptive response, elucidate the mechanisms involved therein and evaluate the action of central analgesics (both opioid and non-opioid) on descending cortical control. In acute experiments on cats, the inhibitor y cortical influence upon neuronal activity produced by nociceptive stimuli (electrical stimulation of tooth pulp, C-fibers of afferent somatic nerves, afferent cardiac structures) was most marked after stimulation of the first and second sensory and fron-to-orbital areas. In chronic experiments on rats, cortical stimulation reduced behavioral signs of visceral pain (writhing test) and also delayed the development of neuropathic pain syndrome along with lowering its intensity. mu-Opioid receptor agonists (morphine, fentanyl) potentiated the inhibitory cortical effect on the evoked neuronal activity. Pentazocine, which has pronounced kappa-receptor agonist activity, was less effective. Naloxone eliminated the effects of both cortical stimulation and opioid analgesics. Serotonin receptor antagonist methysergide, as well as p-chlorophenylalanine significantly decreased inhibitory cortical control and the effect of opioids. Monoamine re-uptake inhibitors with analgesic properties (imipramine, fluoxetine) potentiated the inhibitory effect of cortical stimulation. Adreno-, dopamine-, acetylcholine-, GABA-receptor agents and antagonists of NMDA receptors had minor or no effect. Among non-narcotic analgesics, the cyclooxygenase inhibitors metamysole and ketorolak increased only moderately the descending cortical control of nociception. Thus, the cerebral cortex is able to control the nociceptive processing in different pain syndromes (somatic, visceral or neuropathic pain). Opioidergic and serotonergic systems play the key role in this control. Action through the cortical descending control is likely to be one of the components of the analgesic effect exerted by opioids and some other central analgesics.

Action Potentials↗
PubMed1982

Unit study in cat claustrum of the effects of iontophoretic neurotransmitters and correlations with the effects of activation of some afferent pathways.

Glutamate (Glut), acetylcholine (ACh) and dopamine (DA) were iontophoretically applied on cat claustral neurons. Glut did not affect all the neurons; ACh had both excitatory and inhibitory effects, while DA was prevalently inhibitory. An analysis was made of the time-course of excitatory and inhibitory responses on the basis of the mean firing rate variations during and after ACh and DA release. Three types of responses are described for each drug: short lasting inhibition, long lasting inhibition and long lasting excitation. The experimental data were statistically elaborated. The effects of ACh and of DA were compared with those of activation obtained by sensorial peripheric and thalamic stimulations. ACh could be supposed to be the transmitter of most of the inhibitory terminals of these sensitive afferences to the claustrum.

Acetylcholine↗
PubMed2001

Jaw-muscle spindle afferent pathways to the trigeminal motor nucleus in the rat.

Neural pathways conveying proprioceptive feedback from the jaw muscles were studied in rats by combining retrograde and intracellular neuronal labeling. Initially, horseradish peroxidase was iontophoresed unilaterally into the trigeminal motor nucleus (Vmo). Two days later, 1-5 jaw-muscle spindle afferent axons located in the mesencephalic trigeminal nucleus were physiologically identified and intracellularly stained with biotinamide. Stained mesencephalic trigeminal jaw-muscle spindle afferent axon collaterals and boutons were predominantly distributed in the supratrigeminal region (Vsup), Vmo, dorsomedial trigeminal principal sensory nucleus (Vpdm), parvicellular reticular formation (PCRt), alpha division of the parvicellular reticular formation (PCRtA), and dorsomedial portions of the spinal trigeminal subnuclei oralis (Vodm), and interpolaris (Vidm). Numerous neurons retrogradely labeled with horseradish peroxidase from the trigeminal motor nucleus were found bilaterally in the PCRt, PCRtA, Vodm, and Vidm. Retrogradely labeled neurons were also present contralaterally in the Vsup, Vpdm, Vmo, peritrigeminal zone, and bilaterally in the dorsal medullary reticular field. Putative contacts between intracellularly stained mesencephalic trigeminal jaw-muscle spindle afferent boutons and trigeminal premotor neurons retrogradely labeled with horseradish peroxidase were found in the ipsilateral Vodm, PCRtA, and PCRt, as well as the contralateral Vsup, Vmo, Vodm, PCRt, and PCRtA. Thus, multiple disynaptic jaw-muscle spindle afferent-motoneuron circuits exist. These pathways are likely to convey long-latency jaw-muscle stretch reflexes and may contribute to stiffness regulation of the masticatory muscles.

Afferent Pathways↗
PubMed1996

[Research of clinic and laboratory of face acupuncture effect and the exploration of their afferent pathways].

This paper shows that face acupuncture point (Liver point through gallbladder point) has significant effect of promoting bile secretion on the patients of cholecystectomy and choledochotomy and drainage. Special different point is that face acupuncture stimulation has very obvious posteffect comparing with other three body acupuncture groups and this posteffect lasts more than fifty minuts. The results also show that the successful rate of face acupuncture anesthesia is better than body acupuncture anesthesia during the ligation of oviduct and subtotal gastrectomy. The above results are all analysed statistically and there is a very significant difference among them. During the research on domestic dog anesthesiaed by face acupuncture, the successful rate is 86.5%, moreover the analgesic effect of face acupuncture can be blocked by blocking bilateral postganglionic fibre of trigeminal ganglion with 2% procaine. The results imply that trigeminal ganglion is the main afferent way of stimulation information of face acupuncture.

Acupuncture Analgesia↗
PubMed2005

Monosynaptic connections between pairs of spiny stellate cells in layer 4 and pyramidal cells in layer 5A indicate that lemniscal and paralemniscal afferent pathways converge in the infragranular somatosensory cortex.

Monosynaptic interlaminar connections between spiny stellate cells in layer 4 (L4), the main cortical recipient layer for thalamic projections, and pyramidal cells in layer 5A (L5A), one of the main cortical output layers, were examined anatomically and functionally by paired recordings in acute brain slices. The somata of pairs forming interlaminar L4-to-L5A connections were located predominantly close to or directly under the barrel-septum wall in layer 4. Superposition of spiny stellate axon arbors and L5A pyramidal cell dendritic arbors suggested an innervation domain underneath an L4 barrel wall. Functionally, the L4-to-L5A connections were of high reliability and relatively low efficacy, with a unitary EPSP amplitude of 0.6 mV, and the connectivity was moderately high (one in seven pairs tested was connected). The EPSP amplitude was weakly depressing (paired-pulse ratio of approximately 0.8) during repetitive presynaptic action potentials at 10 Hz. The existence of monosynaptic L4-to-L5A connections indicates that the specific "lemniscal" thalamic input from the ventro-basal nucleus of the thalamus to the cortex and the more unspecific "paralemniscal" afferent thalamic projections from the posterior medial nucleus of the thalamus merge already at an initial stage of cortical signal processing. These monosynaptic connections establish a monosynaptic coupling of the input to the cortex and its output, thereby effectively bypassing the supragranular layers.

Afferent Pathways↗
PubMed1984

The afferent pathway for carotid body chemoreceptor input to the hypothalamic supraoptic nucleus in the rat.

The pathway for chemoreceptor input to hypothalamic supraoptic nuclei has been examined in anaesthetised lactating and non-lactating rats. In lactating rats, the increase in intramammary pressure following bilateral carotid occlusion, which is probably mainly due to vasopressin, was abolished by lesions in the septum, but not by lesions in more caudal regions of the hypothalamus. In non-lactating rats, electrophysiological experiments demonstrated that the input from carotid body chemoreceptors to phasically-discharging supraoptic neurones is ipsilateral only. The effects of chemoreceptor stimulation on the neurones can be mimicked by electrical stimulation within the medial preoptic area and anterior hypothalamus in a region medial and rostral to the supraoptic nuclei. Lesions within this region abolish the chemoreceptor input to the supraoptic nuclei, but leave the baroreceptor input intact. It is proposed that chemoreceptor afferents to the supraoptic nuclei pass in the lateral hypothalamus to the region of the septum where they turn medially and descent through the medial part of the rostral hypothalamus. The results are discussed in terms of the general role of the chemoreceptor reflex and, more specifically, with respect to the possible significance of vasopressin in the control of arterial blood pressure.

Afferent Pathways↗
PubMed1959

Synaptic components of cerebellar electrocortical activity evoked by various afferent pathways.

Electrical responses evoked in different regions of the cerebellar cortex of cat by stimulating various cerebello-petal pathways have been analyzed for their component postsynaptic potentials (p.s.p.'s). The principal analytical tools of the present work were pharmacological agents; the selective inactivator of depolarizing (excitatory) axodendritic synapses, gamma-aminobutyric acid (GABA, or C(4)); the homologous C(6) and C(8) omega-amino acids, which inactivate selectively the hyperpolarizing (inhibitory) axodendritic synapses; and the general inactivator of inhibitory synapses, strychnine. Some experiments employed the analytical possibilities of activity cycles. The potentials evoked in one cerebellar region by different exciting pathways may differ markedly in their responses to drugs or may show different types of activity cycle. Also, the potentials evoked in various cortical regions by one cerebello-petal pathway are acted upon differently by the testing drugs. These differences are believed to be due to involvement of different proportions of excitatory and inhibitory, axosomatic and axodendritic p.s.p.'s. The analyses of a number of different responses confirm an earlier conclusion, that the cerebellar cortex is relatively lacking in inhibitory axodendritic p.s.p.'s in comparison with the cerebral cortex. Only the cortex of the paramedian lobule appears to be endowed with a considerable proportion of inhibitory p.s.p.'s, a finding which correlates with other data.

Afferent Pathways↗
PubMed1993

Ultrastructural features of the choline acetyltransferase-containing neurons and relationships with nigral dopaminergic and cortical afferent pathways in the rat striatum.

The aim of this study was first to specify the morphology and neuronal environment of the large cholinergic neurons, and second to determine the distribution and mode of termination of the corticostriatal and dopaminergic inputs on these neurons in the rat striatum. Immunocytochemical procedures with a monoclonal antibody against choline acetyltransferase, Golgi staining and standard electron microscopic techniques were used to specify the ultrastructural features of the putatively cholinergic classical large neurons. The large/choline acetyltransferase-positive neurons are characterized by a voluminous, eccentric, and deeply indented nucleus leaving a large cytoplasmic area, and by the presence of an abundant granular endoplasmic reticulum and of many polysomes and free ribosomes. Serial ultrathin sectioning further indicated the presence of nematosomes or nucleolus-like bodies within the nucleus and the cytoplasm of the large neurons. In addition, these neurons were found to be in direct apposition with up to four surrounding neurons showing features typical of medium-sized spiny neurons. These data support the view that the putatively cholinergic neurons may have an intense metabolic activity and may be involved in striatal clusters. When choline acetyltransferase immunostaining was coupled with the identification of degenerating corticostriatal afferents after lesion of the cerebral cortex, degenerating terminals were seen to form synapses of an asymmetrical type on distal labelled dendrites, but these contacts were very rare. On the other hand, nigrostriatal dopaminergic axons, identified by means of either the degeneration method or tyrosine hydroxylase immunostaining, were often found to run directly for long distances around the choline acetyltransferase-positive cell bodies. Occasionally, dopaminergic terminals formed possible symmetrical synapses on choline acetyltransferase-positive cell bodies or proximal dendrites. These data provide evidence that the putatively cholinergic neurons are directly contacted by corticostriatal and dopaminergic nigrostriatal afferents. The respective positions and nature of the two types of contacts further provide morphological support for the hypothesis that postsynaptic interactions may occur between the corticostriatal and dopaminergic nigrostriatal afferents at the level of the cholinergic neurons.

Afferent Pathways↗
PubMed1997

NADPH-diaphorase activity in the vagal afferent pathway of the dogfish, Triakis scyllia.

Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity was examined in the cranial sensory ganglia and brainstem of the banded dogfish, Triakis scyllia. Positive neurons were found in the vagal sensory ganglion projecting to the coelomic organs, but not in those projecting to the gills or the lateral line organs. Nerve terminals in the vagal lobe were also positive. No positive neurons were found in the glossopharyngeal, facial, or trigeminal sensory ganglia. These results suggest that use of nitric oxide in the vagal sensory transmission from the coelomic organs may have been maintained in the evolutionary process from fish to mammals.

Afferent Pathways↗
PubMed1985

Interruption of cholinergic afferent pathways to the amygdala failed to alter electrical kindling.

We investigated the hypothesis that the cholinergic system is involved in the process of amygdala kindling. Electrical kindling of the amygdala was associated with an increase in the concentration of acetylcholine in the kindled amygdala and the ipsilateral hippocampus but was not associated with any alteration of choline acetyltransferase activity. Destruction of cholinergic neurons in the lateral preoptic area significantly decreased the activity of choline acetylase in the ipsilateral amygdala, but had no effect on the duration of time to kindling. We interpret these findings as indicating that the cholinergic system is affected by the kindling process, but does not seem to be crucial to the phenomenon.

Acetylcholine↗
PubMed1980

[Activation of afferent pathways and of control frog olfactory bulb and extracellular field potentials].

It has been recorded the extracellular field potentials of the frog's olfactory bulb produced by electrical stimulation of the commissura anterior and small branches of the olfactory nerve. The activation of the commissural system obtain a positive, long-lasting field potential generated at the soma of the granular cells. The olfactory nerve stimulation produce also a positive surface wave bath at the end of bulbar reply: this effect can be attributed to the activation of the bulbar component of commissural system at the NOA. The recognizable electrical effects of the commissural system allow to make clear the sources of the extracellular field potentials in the bulbar neuronal circuits.

Action Potentials↗
PubMedDate not supplied

[Effect of narcotic analgesics on the cortical control process of impulse transmission in the afferent pathways of the sciatic nerve].

The effect produced by narcotic analgetics with their intravenous administration on the process of cortical control over the transmission of impulses along specific routes of the sciatic nerve was studied. The conditioning stimulation of the cortex was effected by using a monopolar electrode through single electric impulses. The interval between conditioning and test (on sciatic nerve) impulses was of 80-120 ms. Morphine (1-2 mg/kg), promedol (trimeperidin) (1-2 mg/kg) and phentanyl (100 gamma/kg) potentiated the inhibition of evoked potentials in the nucleus gracilis and in VPL, observed upon stimulation of the cortex of optic lobuses. The intensification of inhibitory corticifugal mechanisms occurring under the effect of narcotic analgetics takes place both on the level of the medulla oblongata and of the thalamic one.

Afferent Pathways↗
PubMed1987

Afferent pathways of neural reno-renal reflexes controlling sodium and water excretion in the cat.

We have studied the role of afferent renal nerve fibres in anaesthetized cats in mediating the decrease in sodium and water excretion from the contralateral kidney caused by unilateral renal denervation. Transient denervation of one kidney obtained by cooling of the left renal nerves increases contralateral efferent renal nerve activity and decreased sodium and water excretion from the opposite kidney. The results observed in animals with intact neural pathways were compared with those obtained after the left kidney had been selectively deafferentated by cutting the dorsal roots from T9 to L4. Bilateral section of dorsal roots did not affect the increase in sodium and water excretion from the transiently denervated left kidney, but entirely abolished the decrease in sodium and water excretion from the contralateral kidney. Neither the left nor the right dorsal root section alone, affected the response of the contralateral right kidney. Our data demonstrate that afferent renal nerve fibres project bilaterally to the spinal cord and form the afferent branch of the reno-renal reflex by which one kidney can control the function of the opposite one.

Afferent Pathways↗
PubMed2000

Neurokinin A, calcitonin gene-related peptide, and dynorphin A (1-8) in spinal dorsal horn contribute to descending inhibition evoked by nociceptive afferent pathways: an immunocytochemical study.

Immunocytochemical technique was used to compare the contents of neurokinin A (NKA), calcitonin gene-related peptide (CGRP), and dynorphin A (1-8) (DynA) on two sides of the lumbar dorsal horn of rats in which the unilateral thoracic dorsalateral funiculus (DLF) was transected while formalin (0.2 ml, 0.5%) was injected equally into two hindpaws. The results showed that all the NKA-like, CGRP-like, and DynA (1-8)-like immunoreactivities were significantly lower in the superficial laminae of the dorsal horn on the side ipsilateral to the lesioned DLF than that on the side with intact DLF. This implies that peripheral noxious inputs activate the supraspinal descending inhibitory systems which in turn modulate the transmission of noxious message at the spinal level by changing the release of related neuropeptides.

Afferent Pathways↗
PubMed1977

The seventh cranial nerve of the rat. Visualization of efferent and afferent pathways by cobalt precipitation.

The cobalt sulphide precipitation technique, in conjunction with Timm's intensification procedure, was used to delineate the afferent and efferent intramedullary pathways of the seventh cranial nerve complex in the rat. The branchial motor nucleus with the accompanying first part, genu, and second part of the root are described. The motor branches to the superficial facial musculature do not contain fibres of geniculate ganglion origin or fibres which terminate in the spinal trigeminal nucleus. The motor branches to the deep facial muscles arise from the dorsal part of the branchial motor nucleus and traverse to the midline medial to the genu, then project under the genu into the lateral reticular formation before exiting with the facial nerve. The salivatory and lacrimal nuclei and their intramedullary pathways are described. Sensory fibres from the cutaneous auricular branch enter the spinal trigeminal tract and most of the chorda tympani gustatory fibres enter the fasciculus solitarius. A smaller number of gustatory fibres extend medially to the region of the salivatory nucleus. Fibres of greater superficial petrosal origin also enter the fasciculus solitarius as well as the medial reticular formation. These findings are discussed in relation to previous anatomical, physiological and clinical reports.

Animals↗
PubMed1992

Expression of D2 dopamine receptor mRNA in the arterial chemoreceptor afferent pathway.

Dopamine is a major neurotransmitter in the arterial chemoreceptor pathway. In the present study we wished to determine if messenger RNAs for dopamine D1 and D2 receptor are expressed in carotid body (type I cells), in sensory neurons of the petrosal ganglion which innervate the carotid body and in sympathetic neurons of the superior cervical ganglion. We failed to detect D1 receptor mRNA in any of these tissues. However, we found that D2 receptor mRNA was expressed by dopaminergic carotid body type I cells. D2 receptor mRNA was also found in petrosal ganglion neurons that innervated the carotid sinus and carotid body. In addition, a large number of sympathetic postganglionic neurons in the superior cervical ganglion expressed D2 receptor mRNA.

Afferent Pathways↗
PubMed1995

Anterograde tracing of trigeminal afferent pathways from the murine tooth pulp to cortex using herpes simplex virus type 1.

Due to its predominantly nociceptive innervation, viral tracing from the tooth pulp provides a potential means for tracing central pain pathways. The neural pathways from the tooth pulp to cortex were determined using in situ hybridization to detect the anterograde transneuronal spread of herpes simplex virus type 1 strain H129 following inoculation into the murine mandibular incisor pulp. Virus first appeared in the brain at day 3 in the dorsomedial region of all three subnuclei of the spinal trigeminal nucleus and the principal sensory nucleus. By days 5-6 virus had spread to the contralateral medial nucleus of the medial geniculate complex, posterior thalamus, and ventroposteromedial thalamus. At days 7-8 virus was detected in laminae IV and Va of the primary somatosensory cortex and lamina IV of the secondary somatosensory cortex in regions previously shown to receive input from the lower jaw. Several mice also showed infection of laminae II/III of the ipsilateral dysgranular insular cortex, along with labeling for virus in the ipsilateral external lateral parabrachial nucleus, posterior thalamus, and posterior basolateral amygdala. Our results are highly consistent with previous tracing and electrophysiological studies utilizing the tooth pulp and with studies implicating the infected structures in nociception. Viral spread appeared to define two separate afferent systems with infection of structures which have been implicated in the sensory-discriminative aspects of pain, such as the ventroposteromedial thalamus and somatosensory cortex, as well as in the dysgranular insular cortex and related subcortical nuclei which may have a role in the affective-motivational aspects of pain.

Afferent Pathways↗