Projections of the gastrointestinal tract organs on afferent ganglions of the vagus nerve in rats

Experiments were carried in 42 mature white male rats. We investigated into the projections of different organs of gastrointestinal tract on afferent neurones of ganglia of the vagus nerve in white rats. Horseradish peroxidase-conjugated lectins were used as a tracer. We investigated into metric parameters (diameter of an equivalent circle) and shape parameters (circular factor of the shape) of marked neurocytes using a method of computer video-analysis. To evaluate reliability of the received data, methods of non-parametric statistics were used. It was determined that the largest neurocytes in afferent ganglions are involved in innervation of the root of the long and ileocecal angle, the smallest ones--in innervation of a cervical department of esophagus and liver. The viscero- and somatosensory neurocytes in caudal ganglion of vagus nerve involved in innervation of different organs in white rat, are characterized by selectivity of the shape and by metric parameters.     

Degeneration of the afferent fibers simulating the effects of motor denervation on skeletal muscle

Degeneration of afferent nerve fibres was induced in rats in order to observe its effects on the properties of the extra-junctional membrane of soleus muscle fibres. In one approach, removal of dorsal root ganglia L4 and L5 was accomplished in preparations with intact or impulse-blocked (with tetrodotoxin containing cuffs around the sciatic nerve) efferent innervation. Spike resistance to tetrodotoxin developed in the inactive deafferented preparations earlier and to a greater extent than in control, that is only impulse-blocked, preparations. In another series of experiments, efferent denervation alone proved to be less effective than the association of efferent and afferent denervation. On the other hand, section of the afferent fibres central to the dorsal root ganglia was without effect. These results are consistent with the interpretation that products of nerve degeneration contribute together with inactivity to the development of the extrajunctional membrane changes observed in skeletal muscle after denervation.     

A Method of Nodose Ganglia Injection in Sprague-Dawley Rat

Afferent signaling via the vagus nerve transmits important general visceral information to the central nervous system from many diverse receptors located in the organs of the abdomen and thorax. The vagus nerve communicates information from stimuli such as heart rate, blood pressure, bronchopulmonary irritation, and gastrointestinal distension to the nucleus of solitary tract of the medulla. The cell bodies of the vagus nerve are located in the nodose and petrosal ganglia, of which the majority are located in the former. The nodose ganglia contain a wealth of receptors for amino acids, monoamines, neuropeptides, and other neurochemicals that can modify afferent vagus nerve activity. Modifying vagal afferents through systemic peripheral drug treatments targeted at the receptors on nodose ganglia has the potential of treating diseases such as sleep apnea, gastroesophageal reflux disease, or chronic cough. The protocol here describes a method of injection neurochemicals directly into the nodose ganglion. Injecting neurochemicals directly into the nodose ganglia allows study of effects solely on cell bodies that modulate afferent nerve activity, and prevents the complication of involving the central nervous system as seen in systemic neurochemical treatment. Using readily available and inexpensive equipment, intranodose ganglia injections are easily done in anesthetized Sprague-Dawley rats.     

Identification of Different Types of Spinal Afferent Nerve Endings That Encode Noxious and Innocuous Stimuli in the Large Intestine Using a Novel Anterograde Tracing Technique

In mammals, sensory stimuli in visceral organs, including those that underlie pain perception, are detected by spinal afferent neurons, whose cell bodies lie in dorsal root ganglia (DRG). One of the major challenges in visceral organs has been how to identify the different types of nerve endings of spinal afferents that transduce sensory stimuli into action potentials. The reason why spinal afferent nerve endings have been so challenging to identify is because no techniques have been available, until now, that can selectively label only spinal afferents, in high resolution. We have utilized an anterograde tracing technique, recently developed in our laboratory, which facilitates selective labeling of only spinal afferent axons and their nerve endings in visceral organs. Mice were anesthetized, lumbosacral DRGs surgically exposed, then injected with dextran-amine. Seven days post-surgery, the large intestine was removed. The characteristics of thirteen types of spinal afferent nerve endings were identified in detail. The greatest proportion of nerve endings was in submucosa (32%), circular muscle (25%) and myenteric ganglia (22%). Two morphologically distinct classes innervated myenteric ganglia. These were most commonly a novel class of intraganglionic varicose endings (IGVEs) and occasionally rectal intraganglionic laminar endings (rIGLEs). Three distinct classes of varicose nerve endings were found to innervate the submucosa and circular muscle, while one class innervated internodal strands, blood vessels, crypts of lieberkuhn, the mucosa and the longitudinal muscle. Distinct populations of sensory endings were CGRP-positive. We present the first complete characterization of the different types of spinal afferent nerve endings in a mammalian visceral organ. The findings reveal an unexpectedly complex array of different types of primary afferent endings that innervate specific layers of the large intestine. Some of the novel classes of nerve endings identified must underlie the transduction of noxious and/or innocuous stimuli from the large intestine.     

淡水蜗牛视觉系统的输入与输出通路(英文)

通过神经生物素在视神经上的逆行性传输对淡水蜗牛(Planorbarius corneus)视网膜及中央神经节的输入、输出神经元进行标记。由于没有发现突触联系,所以至少一部分光感受细胞的轴突可被视为直接参与形成视神经。这些神经元的轴突进入大脑神经节形成密集的细传入神经纤维束-视神经堆。传出神经元则存在于除颊部以外的所有神经节。一些上行轴突在大脑神经节处分叉,通过脑-脑联合,到达对侧眼并在眼杯处形成分枝。部分传出神经元的轴突也投射于不同的外周神经,如:n.n.intestinalis,pallialis dexter,pallialis sinister internus et externus。五羟色胺能纤维和FMRF-酰胺能纤维均存在于视神经上,且这些纤维隶属于只投射在同侧眼的中央神经元。它们形成了位于眼杯处的丰富曲张结构及视网膜核心层,并且可能有助于调节视网膜对光的敏感性。     

Light- and electron-microscopic study of synaptic connections in the paracervical ganglion of the female rat: special reference to calcitonin gene-related peptide-, galanin- and tachykinin (substance P and neurokinin A)-immunoreactive nerve fibers and terminals

Nerve fibers and varicosities in the pelvic paracervical ganglia (PG) are immunoreactive for the neuropeptides calcitonin gene-related peptide, galanin, and the tachykinins substance P and neurokinin A. Many of these fibers and varicosities are capsaicin-sensitive, originate in dorsal root ganglia and, thus, are considered to be primary afferent fibers. Numerous immunoreactive varicosities are pericellular to principal neurons in the PG. The present study examines the ultrastructure of calcitonin gene-related peptide-, galanin-, substance P-, and neurokinin A-immunoreactive nerve fibers and varicosities in the ganglia to determine their relationships to principal neurons and their synaptic connectivity. Paracervical ganglia of female rats were processed for light-microscopic immunohistochemistry using antisera against synapsin I, as a nerve terminal marker, and microtubule-associated protein-2 to define soma and dendrites. The rationale for performing this co-immunohistochemical analysis was to reveal the relationship between nerve endings and principal neurons. Synapsin I endings were predominantly axosomatic with fewer being axodendritic. Other ganglia were processed for electron-microscopic immunohistochemistry using both standard immunogold and peroxidase-anti-peroxidase procedures. Unmyelinated fibers and varicosities immunoreactive for calcitonin gene-related peptide, galanin, and the tachykinins were routinely observed in the interstitium between neuron somas. Numerous immunoreactive axon profiles were present in small groups that were ensheathed by Schwann cells. Immunoreactive fibers and varicosities were also observed within the satellite-cell sheath of the neuron soma and often intimately associated with the membrane of the soma, somal protrusions, or with the proximal part of a dendrite. Membrane specializations, indicative of synaptic contacts, between the fibers and the principal neurons were observed. It is suggested that these peptide-immunoreactive sensory fibers and varicosities are involved in regulation of activity in the PG.     

The distribution and origin of VIP in the spinal cord of six mammalian species

The distribution of VIP-immunoreactivity was studied in the spinal cord and dorsal root ganglia of 6 mammalian species. Immunoreactive fibres and cell bodies were most apparent in the dorsal horn, dorsolateral funiculus, intermediolateral cell columns and the area around the central canal. The distribution of VIP immunoreactivity was similar in all species studied, mouse, rat, guinea pig, cat, horse and the marmoset monkey. There were fewer VIP fibres in the dorsal horn of cervical and thoracic segments than in lumbosacral segments. Using radioimmunoassay this gradient increase was quantitatively most marked in the sacral spinal cord of the cat. In dorsal root ganglia few nerve cell bodies but numerous fibres were present. A dual origin for VIP in the spinal cord is suggested: (A) Extrinsic, from dorsal root afferent fibres since immunoreactivity was decreased in dorsally rhizotomized animals (cats and rats) and in capsaicin pretreated rats (microinjection of dorsal root ganglia). (B) From local cell bodies intrinsic to the spinal cord which became visible after colchicine pretreatment of rats.     

Age-dependent changes of the autonomic neurons expressing vanilloid TRPV1 receptors

Expression of vanilloid receptors in sympathetic and afferent ganglionic neurons was studied in rats of different ages (newborn, 10-day old, 20-day old, 30-day old, 60-, 180-day old) using immunohistochemical methods. The results obtained indicate that the majority of the afferent neurons in the nodose ganglion of vagus nerve (GNVN) and in the spinal ganglia (SG) were TRPV1-positive from birth onwards. The percentage of neurons containing TRPVT receptors in SG slightly increased with age up to 30 days postnatally. In the GNVN, the percentage of TRPV1-positive neurons was higher in comparison with the SG in all age groups. The vast majority of the sympathetic neurons were TRPV1-positive from birth onwards, and the percentage of TRPV1-immunoreactive neurons substantially decreased during further development. In 20-day old and older animals, we observed only few TRPV1-immunoreactive neurons in sympathetic ganglia. Finally, the percentage of neurons containing these types of neurons, become similar to adult animals to the end of the first month of life.     

The proliferation marker pKi-67 becomes masked to MIB-1 staining after expression of its tandem repeats

The P2X(2) subtype of purine receptor was localised by immunohistochemistry to nerve cells of the myenteric ganglia of the stomach, small and large intestines of the guinea-pig, and nerve cells of submucosal ganglia in the intestine. Nerve cells with strong and with weak immunoreactivity could be distinguished. Immunoreactivity in both strongly and weakly immunoreactive neurons was absorbed with P2X(2) receptor peptide. In the myenteric plexus, strong immunoreactivity was in nitric oxide synthase (NOS)- and in calbindin-immunoreactive neurons. In all regions, over 90% of NOS-immunoreactive neurons were strongly P2X(2) receptor immunoreactive. The intensity of reaction varied in calbindin neurons; in the ileum, 90% were immunoreactive for the receptor, about one-third having a strong reaction. In the submucosal ganglia, all vasoactive intestinal peptide-immunoreactive neurons were P2X(2) receptor immunoreactive, but there was no receptor immunoreactivity of calretinin or neuropeptide Y neurons. Varicose nerve fibres with P2X(2) receptor immunoreactivity were found in the gastric myenteric ganglia. These fibres disappeared after vagus nerve section. It is concluded that the P2X(2) receptor is expressed by specific subtypes of enteric neurons, including inhibitory motor neurons, non-cholinergic secretomotor neurons and intrinsic primary afferent neurons, and that the receptor also occurs on the endings of vagal afferent fibres in the stomach.     

Galanin-immunoreactive nerves in the female rat paracervical ganglion and uterine cervix: distribution and reaction to capsaicin

Summary The presence and distribution of galanin-immunoreactivity was examined in the uterine cervix and paracervical autonomic ganglia of the female rat. Some animals were treated with capsaicin to determine if galanin-immunoreactivity was present in small-diameter primary afferent nerves. Other animals were treated with the noradrenergic neurotoxin 6-hydroxydopamine to ascertain if galanin-immunoreactivity was present in sympathetic noradrenergic nerves. Galanin-immunoreactive nerve fibers were sparse in the cervical myometrium and vasculature, but numerous in the paracervical ganglion where they appeared to innervate principal neurons. Immunoreactivity was also present in dorsal root ganglia, dorsal horn of spinal cord, and inferior mesenteric ganglia. Capsaicin treatment resulted in a marked reduction of galanin-immunoreactivity in the spinal cord dorsal horn, but not in the dorsal root ganglia, paracervical ganglia, or cervix (although there was a substantial reduction of substance P-, neurokinin A-, and calcitonin gene-related peptide-immunoreactivity in the dorsal horn, dorsal root ganglia, and uterine cervix). 6-Hydroxydopamine treatment did not cause any appreciable change in the galanin-immunoreactivity in any tissues. We conclude that galanin-like immunoreactivity is expressed in nerve fibers innervating the paracervical ganglia and uterine cervix of the female rat. This immunoreactivity is probably present in afferent nerves and could play a role in neuroendocrine reflexes and in reproductive function.     

Differential effects of airway afferent nerve subtypes on cough and respiration in anesthetized guinea pigs

The hypothesis that respiratory reflexes, such as cough, reflect the net and often opposing effects of activation of multiple afferent nerve subpopulations throughout the airways was evaluated. Laryngeal and tracheal mucosal challenge with either citric acid or mechanical probing reliably evoked coughing in anesthetized guinea pigs. No other stimulus reliably evoked coughing in these animals, regardless of route of administration and despite some profound effects on respiration. Selectively activating vagal C-fibers arising from the nodose ganglia with either adenosine or 2-methyl-5-HT evoked only tachypnea. Selectively activating vagal afferents arising from the jugular ganglia induced respiratory slowing and apnea. Nasal afferent nerve activation by capsaicin, citric acid, hypertonic saline, or histamine evoked only respiratory slowing. Histamine, which activates intrapulmonary rapidly adapting receptors but not airway or lung C-fibers or tracheal bronchial cough receptors induced bronchospasm and tachypnea, but no coughing. The results indicate that the reflexes initiated by stimuli thought to be selective for some afferent nerve subtypes will likely depend on the net and potentially opposing effects of multiple afferent nerve subpopulations throughout the airways. The data also provide further evidence that the afferent nerves regulating cough in anesthetized guinea pigs are distinct from either C-fibers or intrapulmonary rapidly adapting receptors.     

Vagal afferents from the uterus and cervix provide direct connections to the brainstem

Previous anatomical studies demonstrated vagal innervation to the ovary and distal colon and suggested the vagus nerve has uterine inputs. Recent behavioral and physiological evidence indicated that the vagus nerves conduct sensory information from the uterus to the brainstem. The present study was undertaken to identify vagal sensory connections to the uterus. Retrograde tracers, Fluorogold and pseudorabies virus were injected into the uterus and cervix. DiI, an anterograde tracer, was injected into the nodose ganglia. Neurectomies involving the pelvic, hypogastric, ovarian and abdominal vagus nerves were performed, and then uterine whole-mounts examined for sensory nerves containing calcitonin gene-related peptide. Nodose ganglia and caudal brainstem sections were examined for the presence of estrogen receptor-containing neurons in ”vagal locales." Labeling of uterine-related neurons in the nodose ganglia (Fluorogold and pseudorabies virus) and in the brainstem nuclei (pseudorabies virus) was obtained. DiI-labeled nerve fibers occurred near uterine horn and uterine cervical blood vessels, in the myometrium, and in paracervical ganglia. Rats with vagal, pelvic, hypogastric and ovarian neurectomies exhibited a marked decrease in calcitonin gene-related peptide-immunoreactive nerves in the uterus relative to rats with pelvic, hypogastric, and ovarian neurectomies with intact vagus nerves. Neurons in the nodose ganglia and nucleus tractus solitarius were immunoreactive for estrogen receptors. These results demonstrated: (1) the vagus nerves serve as connections between the uterus and CNS, (2) the nodose ganglia contain uterine-related vagal afferent neuron cell bodies, and (3) neurons in vagal locales contain estrogen receptors.     

Vagal innervation of the rat pylorus: an anterograde tracing study using carbocyanine dyes and laser scanning confocal microscopy

In an attempt to identify the distribution and structure of vagal fibers and terminals in the gastroduodenal junction, vagal efferents were labeled in vivo by multiple injections of the fluorescent carbocyanine dye DiA into the dorsal motor nucleus (dmnX), and vagal afferents were anterogradely labeled by injections of DiI into the nodose ganglia of the same or separate rats. Thick frontal cryostat sections were analysed either with conventional or laser scanning confocal microscopy, using appropriate filter combinations and/or different wavelength laser excitation to distinguish the fluorescent tracers. Vagal efferent terminal-like structures were present in small ganglia within the circular sphincter muscle, which, in the absence of a well-developed, true myenteric plexus at this level, represent the myenteric ganglia. Furthermore, vagal efferent terminals were also present in submucosal ganglia, but were absent from mucosa, Brunner's glands and circular muscle fibers. Vagal afferent fibers and terminal-like structures were more abundant than efferents. The most prominent afferent terminals were profusely branching, large net-like aggregates of varicose fibers running within the connective tissue matrix predominantly parallel to the circular sphincter muscle bundles. Profusely arborizing, highly varicose endings were also present in large myenteric ganglia of the antrum and duodenum, in the modified intramuscular ganglia, and in submucosal ganglia. Additionally, afferent fibers and terminals were present throughout the mucosal lining of the gastroduodenal junction. The branching patterns of some vagal afferents suggested that individual axons produced multiple collaterals in different compartments. NADPH-diaphorase positive, possibly nitroxergic neurons were present in myenteric ganglia of the immediately adjacent antrum and duodenum, and fine varicose fibers entered the sphincter muscle from both sides, delineating the potential vagal inhibitory postganglionic innervation. These morphological results support the view of a rich and differentiated extrinsic neural control of this important gut region as suggested by functional studies.     

Neurohistochemical study of autonomic nerve ganglia and lungs in burns

Adreno-cholinergic nerve structures of vegetative nerve ganglia and lungs in 20 departed in different periods of burn disease aged from 19 to 85 have been studied with neurohistological methods. Definite dynamics of mentioned structure changes have been shown. It was stated that in different stages of burn disease adreno-cholinergic nerve structures of vegetative nerve ganglia and lung tissues changed greatly and afferent part suffered more in comparison with efferent one. Adrenergic fluorescence was considerably weaker in elderly and senile patients in comparison with younger ones. Luminescence deterioration was more noticeable in neuron cytoplasm. In young aged such nerve structures were more reactive and remarkable with more compensating abilities.     

Ultrastructure of the sympathetic paravertebral ganglia in rat embryogenesis. II. The development of the neuropil and the interneuronal connections

Electron microscopy was used to study the process of ingrowth of nerve terminals in the primordia of sympathetic ganglia and the formation of specialized contacts. Nerve terminals appeared first in 12 day old embryos. In the forming ganglia of 13 day old embryos there are many preganglionic nerve terminals and processes of principal neuroblasts. The growth cones of nerve endings are usually distended and with transparent cytoplasm. The plasmalemmas of growth cones are lacking often the trilaminar structure. Synapses were observed first in 16 day old fetuses. They are axo-dendritic and axo-somatic ones. The number of synaptic contacts does not increase much during prenatal period. Presumptive afferent nerve terminals were found in the late fetuses.     

Histochemical evidence of chemical sympathectomy by guanethidine in newborn rats

Synopsis Guanethidine is known to cause a loss of catecholamines from sympathetically innervated tissues and sympathetic ganglia in adult animals but its effect on newborn animals has not been examined.Newborn rats were injected daily with guanethidine (20 mg/kg body weight) for 8 days. They were killed when 1 month-old along with untreated litter mate controls. Catecholamines were demonstrated in the iris, in the pineal body and in sympathetic ganglia, using the formaldehyde-induced fluorescence method.In the guanethidine-treated rats there was a complete loss of fluorescent nerve fibres from the pineal body and an almost complete loss of similar fibres from the iris. The sympathetic ganglia were reduced to less than 10% of the control ganglia, and the number of nerve cell bodies per unit area was decreased in the ganglion remnants.It is concluded that guanethidine causes, in newborn rats, an irreversible destruction of most sympathetic neurons, i.e. a chemical sympathectomy closely resembling that obtainable in newborn animals by injections of 6-hydroxydopamine or antiserum to nerve growth factor.     

Renorenal reflexes: interaction between efferent and afferent renal nerve activity.

In rats, stimulation of renal mechanoreceptors by increasing ureteral pressure results in a contralateral inhibitory renorenal reflex response consisting of increases in ipsilateral afferent renal nerve activity, decreases in contralateral efferent renal nerve activity, and increases in contralateral urine flow rate and urinary sodium excretion. Mean arterial pressure is unchanged. To study possible functional central interaction among the afferent renal nerves and the aortic and carotid sinus nerves, the responses to renal mechanoreceptor stimulation were compared in sinoaortic denervated rats and sham-denervated rats before and after vagotomy. In contrast to sham-denervated rats, there was an increase in mean arterial pressure in response to renal mechanoreceptor stimulation in sinoaortic-denervated rats. However, there were no differences in the renorenal reflex responses among the groups. Thus, our data failed to support a functional central interaction among the renal, carotid sinus, and aortic afferent nerves in the renorenal reflex response to renal mechanoreceptor stimulation. Studies to examine peripheral interaction between efferent and afferent renal nerves showed that marked reduction in efferent renal nerve activity produced by spinal cord section at T6, ganglionic blockade, volume expansion, or stretch of the junction of superior vena cava and right atrium abolished the responses in afferent renal nerve activity and contralateral renal function to renal mechanoreceptor stimulation. Conversely, increases in efferent renal nerve activity caused by thermal cutaneous stimulation increased basal afferent renal nerve activity and its responses to renal mechanoreceptor stimulation. These data suggest a facilitatory role of efferent renal nerves on renal sensory receptors.     

Peripheral axotomy of the rat mandibular trigeminal nerve leads to an increase in VIP and decrease of other primary afferent neuropeptides in the spinal trigeminal nucleus

In the vasoactive intestinal polypeptide (VIP)-rich lumbosacral spinal cord, VIP increases at the expense of other neuropeptides after primary sensory nerve axotomy. This study was undertaken to ascertain whether similar changes occur in peripherally axotomised cranial sensory nerves. VIP immunoreactivity increased in the terminal region of the mandibular nerve in the trigeminal nucleus caudalis following unilateral section of the sensory root of the mandibular trigeminal nerve at the foramen orale. Other primary afferent neuropeptides (substance P, cholecystokinin and somatostatin) were depleted and fluoride-resistant acid phosphatase activity was abolished in the same circumscribed areas of the nucleus caudalis. The rise in VIP and depletion of other markers began 4 days postoperatively and was maximal by 10 days, these levels remaining unchanged up to 1 year postoperatively. VIP-immunoreactive cell bodies were absent from trigeminal ganglia from the unoperated side but small and medium cells stained intensely in the ganglia of the operated side after axotomy. These observations indicate that increase of VIP in sensory nerve terminals is a general phenomenon occurring in both cranial and spinal sensory terminal areas. The intense VIP immunoreactivity in axotomised trigeminal ganglia suggests that the increased levels of VIP in the nucleus caudalis are of peripheral origin, indicating a change in expression of neuropeptides within primary afferent neurons following peripheral axotomy.     

Immunohistochemical localisation of cholinergic markers in putative intrinsic primary afferent neurons of the guinea-pig small intestine

Antibodies against choline acetyltransferase (ChAT) and the vesicular acetylcholine transporter (VAChT) were used to determine whether neurons that have previously been identified as intrinsic primary afferent neurons in the guinea-pig small intestine have a cholinergic phenotype. Cell bodies of primary afferent neurons in the myenteric plexus were identified by their calbindin immunoreactivity and those in the submucous plexus by immunoreactivity for substance P. High proportions of both were immunoreactive for ChAT, viz. 98% of myenteric calbindin neurons and 99% of submucosal substance P neurons. ChAT immunoreactivity also occurred in all nerve cell bodies immunoreactive for calretinin and substance P in the myenteric plexus, but in only 16% of nerve cells immunoreactive for nitric oxide synthase. VAChT immunoreactivity was in the majority of calbindin-immunoreactive varicosities in the myenteric ganglia, submucous ganglia and mucosa and also in the majority of the varicosities of neurons that were immunoreactive for calretinin and somatostatin and that had been previously established as being cholinergic. We conclude that the intrinsic primary afferent neurons are cholinergic and that they may release transmitter from their sensory endings in the mucosa.     

Selective stimulation of jugular ganglion afferent neurons in guinea pig airways by hypertonic saline

Pedersen, Karen E., Sonya N. Meeker, Margerita M. Riccio,and Bradley J. Undem. Selective stimulation ofjugular ganglion afferent neurons in guinea pig airways by hypertonicsaline. J. Appl. Physiol. 84(2):499-506, 1998.We evaluated the ability of hyperosmolar stimulito activate afferent nerves in the guinea pig trachea and main bronchiand investigated the neural pathways involved. By usingelectrophysiological techniques, studies in vitro examined the effectof hyperosmolar solutions of sodium chloride (hypertonic saline) onguinea pig airway afferent nerve endings arising from either vagalnodose or jugular ganglia. The data reveal a differential sensitivityof airway afferent neurons to activation with hypertonic saline.Afferent fibers (both A and C fibers) with cell bodies located injugular ganglia were much more sensitive to stimulation with hypertonicsaline, compared with afferent neurons with cell bodies located innodose ganglia. Additional studies in vivo demonstrated that inhalationof aerosols of hypertonic saline induced plasma extravasation in guineapig trachea that was mediated via tachykininNK₁ receptors. Identification of adifferential sensitivity of guinea pig airway afferent nerves tohypertonic saline leads to the speculation that airway responses tohyperosmolar stimuli may result from activation of afferent neuronsoriginating predominantly from the jugular ganglion.