Peptide 19 in the rat vagal and glossopharyngeal sensory ganglia

Peptide 19 (PEP 19) is a 7.6-kDa polypeptide which binds to calmodulin and inhibits calcium-calmodulin signaling. In this study, PEP 19-immunoreactivity (PEP 19-IR) was examined in the rat vagal and glossopharyngeal sensory ganglia. Twenty-nine percent, 59%, and 41% of sensory neurons contained PEP 19-IR in the jugular, petrosal, and nodose ganglia, respectively. These neurons were of various sizes (jugular, mean +/- SD = 635.8 +/- 392.6 microm2, range = 105.9-1695.9 microm2; petrosal, mean +/- SD = 370.9 +/- 228.5 microm2, range = 57.7-1662.7 microm2; nodose, mean +/- SD = 380.5 +/- 157 microm2, range = 87.5-950.4 microm2) and scattered throughout these ganglia. Double immunofluorescence method revealed that PEP 19-IR neurons which had parvalbumin-IR were rare in the ganglia (jugular, 4%; petrosal, 10%; nodose, 8%). PEP 19-IR neurons which contained calbindin D-28k were abundant in the petrosal (20%) and nodose (22%) ganglia but not in the jugular ganglion (8%). Retrograde tracing method indicated that many PEP 19-IR neurons projected to the circumvallate papilla and soft palate. In the soft palate, taste buds were innervated by PEP 19-IR nerve fibers. The present study suggests that PEP 19-IR neurons include chemoreceptors in the vagal and glossopharyngeal sensory ganglia.     

Osteocalcin-immunoreactive neurons in the vagal and glossopharyngeal sensory ganglia of the rat

Immunohistochemistry for osteocalcin (OC) was performed on the rat vagal and glossopharyngeal sensory ganglia. OC-immunoreactive (IR) neurons were detected in the jugular (10%), petrosal (11%) and nodose ganglia (6%). The cell size analysis demonstrated that OC-IR neurons were predominantly small to medium-sized in the jugular ganglion (mean+/-S.D.=356.3+/-192.2 microm(2), range=86.5-831.5 microm(2)). On the other hand, such neurons were medium-sized to large in the petrosal (mean+/-S.D.=725.6+/-280.7 microm(2), range=124.7-1540.4 microm(2)) and nodose ganglia (mean+/-S.D.=857.5+/-330.2 microm(2), range=367.1-1608.0 microm(2)). In the circumvallate papilla, OC-IR nerve fibers were located in the vicinity of taste buds. Some taste bud cells were also immunoreactive for the calcium-binding protein (CaBP). In the carotid body, however, OC-IR nerve fibers could not be detected. Retrograde tracing with fluorogold revealed that OC-IR nerve fibers in the circumvallate papilla mainly originated from the petrosal ganglion. These findings may suggest that OC-IR petrosal neurons have chemoreceptive function in the tongue.     

ASIC3-immunoreactive neurons in the rat vagal and glossopharyngeal sensory ganglia

ASIC3-immunoreactivity (ir) was examined in the rat vagal and glossopharyngeal sensory ganglia. In the jugular, petrosal and nodose ganglia, 24.8%, 30.8% and 20.6% of sensory neurons, respectively, were immunoreactive for ASIC3. These neurons were observed throughout the ganglia. A double immunofluorescence method demonstrated that many ASIC3-immunoreactive (ir) neurons co-expressed calcitonin gene-related peptide (CGRP)- or vanilloid receptor subtype 1 (VRL-1)-ir in the jugular (CGRP, 77.8%; VRL-1, 28.0%) and petrosal ganglia (CGRP, 61.7%; VRL-1, 21.5%). In the nodose ganglion, however, such neurons were relatively rare (CGRP, 6.3%; VRL-1, 0.4%). ASIC3-ir neurons were mostly devoid of tyrosine hydroxylase in these ganglia. However, some ASIC3-ir neurons co-expressed calbindin D-28k in the petrosal (5.5%) and nodose ganglia (3.8%). These findings may suggest that ASIC3-containing neurons have a wide variety of sensory modalities in the vagal and glossopharyngeal sensory ganglia.     

The co-expression of VR1 and VRL-1 in the rat vagal sensory ganglia

Immunohistochemistry for two nociceptive transducers, the vanilloid receptor 1 (VR1) and vanilloid receptor 1-like receptor (VRL-1), was performed on the vagal sensory ganglia. In the jugular ganglion, VR1-immunoreactive (IR) neurons were small to medium-sized (range 49.7–1125.6 μm², mean±S.D. 407.7±219.7 μm²), whereas VRL-1-IR neurons were medium-sized to large (range 223.6–1341.1 μm², mean±S.D. 584.3±253.5 μm²). In the nodose ganglion, VR1- and VRL-1-IR neurons were mostly small to medium-sized (VR1: range 148.5–1464.4 μm², mean±S.D. 554.3±207.4 μm²; VRL-1: range 161.7–1166.2 μm², mean±S.D. 541.9±186.2 μm²). The double immunofluorescence method revealed that co-expression of VR1-immunoreactivity among VRL-1-IR neurons was more abundant in the nodose ganglion (63%) than in the jugular ganglion (4%). The present study suggests that co-expression of VR1 and VRL-1 may be more common in visceral sensory neurons than in somatic sensory neurons.     

The co-expression of VR1 and VRL-1 in the rat vagal sensory ganglia

Immunohistochemistry for two nociceptive transducers, the vanilloid receptor 1 (VR1) and vanilloid receptor 1-like receptor (VRL-1), was performed on the vagal sensory ganglia. In the jugular ganglion, VR1-immunoreactive (IR) neurons were small to medium-sized (range 49.7–1125.6 μm², mean±S.D. 407.7±219.7 μm²), whereas VRL-1-IR neurons were medium-sized to large (range 223.6–1341.1 μm², mean±S.D. 584.3±253.5 μm²). In the nodose ganglion, VR1- and VRL-1-IR neurons were mostly small to medium-sized (VR1: range 148.5–1464.4 μm², mean±S.D. 554.3±207.4 μm²; VRL-1: range 161.7–1166.2 μm², mean±S.D. 541.9±186.2 μm²). The double immunofluorescence method revealed that co-expression of VR1-immunoreactivity among VRL-1-IR neurons was more abundant in the nodose ganglion (63%) than in the jugular ganglion (4%). The present study suggests that co-expression of VR1 and VRL-1 may be more common in visceral sensory neurons than in somatic sensory neurons.     

Coexistence of calbindin D-28k and NADPH-diaphorase in vagal and glossopharyngeal sensory neurons of the rat

The presence and coexistence of calbindin D-28k-immunoreactivity (ir) and nicotinamide adenosine dinucleotide phosphate (NADPH)-diaphorase activity (a marker of neurons that are presumed to convert L-arginine to L-citrulline and nitric oxide) were examined in the glossopharyngeal and vagal sensory ganglia (jugular, petrosal and nodose ganglia) of the rat. Calbindin D-28k-ir nerve cells were found in moderate and large numbers in the petrosal and nodose ganglia, respectively. Some calbindin D-28k-ir nerve cells were also observed in the jugular ganglion. NADPH-diaphorase positive nerve cells were localized to the jugular and nodose ganglia and were rare in the petrosal ganglion. A considerable portion (33–51%) of the NADPH-diaphorase positive neurons in these ganglia colocalized calbindin D-28k-ir. The presence and colocalization of calbindin D-28k-ir and NADPH-diaphorase activity in neurotransmitter-identified subpopulations of visceral sensory neurons were also studied. In all three ganglia, calcitonin gene-related peptide (CGRP)-ir was present in many NADPH-diaphorase positive neurons, a subset of which also contained calbindin D-28k-ir. In the nodose ganglion, many (42%) of tyrosine hydroxylase (TH)-ir neurons also contained NADPH diaphorase activity but did not contain calbindin D-28k-ir. These data are consistent with a potential co-operative role for calbindin D-28k and NADPH-diaphorase in the functions of a subpopulation of vagal and glossopharyngeal sensory neurons.     

Calretinin-immunoreactivity in vagal and glossopharyngeal sensory neurons of the rat: distribution and coexistence with putative transmitter agents.

Immunoreactivity for the calcium binding protein, calretinin (calretinin-ir), was demonstrated in cell bodies of vagal and glossopharyngeal sensory ganglia (jugular, petrosal, and nodose ganglia) and in associated nerve fibers. In the jugular and petrosal ganglia, many calretinin-ir neurons were also immunoreactive for calcitonin gene-related peptide and substance P. In the nodose ganglion, most of the calretinin-ir neurons lacked these peptides. None of the calretinin-ir neurons in these ganglia were also immunoreactive for tyrosine hydroxylase.     

Substance P in the vagal sensory ganglia: Localization in cell bodies and pericellular arborizations

The distribution of Substance P-like immunoreactivity in the jugular and nodose ganglia of rabbits and pigeons has been studied using immunocytochemical staining techniques. Substance P-like immunoreactivity is localized to neuronal cell bodies and processes in the jugular and nodose ganglia, and to pericellular fiber plexi in the nodose ganglia of both species. The numbers and sizes of cells which exhibited Substance P-like immunoreactivity in each ganglion were determined using quantitative morphometric techniques. The distribution of Substance P-like immunoreactivity in the rabbit and pigeon vagal sensory ganglia is characterized by several general features. In most of the ganglia, immunoreactive neurons factor into discrete types which can be distinguished from one another, and from non-immunoreactive neurons, by size. In addition, immunoreactive nodose and jugular ganglion cells, respectively, are distinguishable on the basis of size. Finally, a considerably higher percentage of immunoreactive neurons is found in the jugular ganglion than in the nodose ganglion. Substance P-like immunoreactivity was also seen in pericellular fiber plexi which encircle individual neurons in the nodose ganglion of rabbits and pigeons. These plexi are composed of varicose fibers which appear to terminate as boutons on the surfaces of the cells which they encircle. The distribution of Substance P-like immunoreactivity within the vagal sensory ganglia is discussed with respect to the possible peripheral targets and functions of Substance P-containing vagal afferents. Our findings suggest that Substance P-containing vagal sensory neurons are involved in a variety of visceral and somatic afferent functions.     

The coexistence of TrkA with putative transmitter agents and calcium-binding proteins in the vagal and glossopharyngeal sensory neurons of the adult rat

The presence of the neurotrophin receptor, TrkA, in neurochemically identified vagal and glossopharyngeal sensory neurons of the adult rat was examined. TrkA was colocalized with calcitonin gene-related peptide (CGRP), parvalbumin, or calbindin D-28k in neurons of the nodose, petrosal and/or jugular ganglia. In contrast, no TrkA-immunoreactive (ir) neurons in these ganglia colocalized tyrosine hydroxylase-ir. About one-half of the TrkA-ir neurons in the jugular and petrosal ganglia contained CGRP-ir, whereas only a few of the numerous TrkA-ir neurons in the nodose ganglion contained CGRP-ir. Although 43% of the TrkA-ir neurons in the nodose ganglion contained calbindin D-28k-ir, few or no TrkA-ir neurons in the petrosal or jugular ganglia were also labeled for either calcium-binding protein. These data show distinct colocalizations of TrkA with specific neurochemicals in vagal and glossopharyngeal sensory neurons, and suggest that nerve growth factor (NGF), the neurotrophin ligand for TrkA, plays a role in functions of specific neurochemically defined subpopulations of mature vagal and glossopharyngeal sensory neurons.     

Coexistence of S100β and putative transmitter agents in vagal and glossopharyngeal sensory neurons of the rat

The coexistence of S100β with calcitonin gene-related peptide (CGRP), substance P (SP), somatostatin (SOM), nicotinamide adenosine dinucleotide phosphate-diaphorase (NADPH-d), and tyrosine hydroxylase (TH) was examined in the glossopharyngeal and vagal sensory ganglia. S100β immunoreactive (-ir) neurons in the jugular and petrosal ganglia frequently colocalized CGRP- or SP-ir, whereas S100β-ir neurons in the nodose ganglion infrequently contained CGRP- or SP-ir. No S100β-ir neurons in the jugular and petrosal ganglia showed SOM-ir while the small number of SOM-ir neurons in the nodose ganglion colocalized S100β-ir. Many neurons in the nodose ganglion colocalized S100β-ir and NADPH-d activity, whereas S100β-ir neurons in the jugular and nodose ganglia infrequently contained NADPH-d activity. S100β- and TH-ir were frequently colocalized in nodose ganglion but not in petrosal or jugular ganglion neurons. These findings suggest relationships between S100β and specific putative transmitters in functions of subpopulations of vagal and glossopharyngeal sensory neurons.     

Intramucosal distribution of the glossopharyngeal sensory fibers of cats

In order to determine distribution of the sensory fibers of the glossopharyngeal nerve (IX) in the pharynx of cats, wheat germ agglutinin-horseradish peroxidase was injected into the superior and inferior ganglia of IX. Results were as follows: Labeled peripheral sensory nerve fibers in the pharynx were recognized ipsilaterally. The pharyngeal branch of IX innervated the nasopharyngeal mucosa at the level of the torus tubarius. The tonsillo-lingual branch was divided into four rami. The first ramus innervated the caudal one-third of the tongue and the vallate papillae. The second ramus innervated the palatine tonsil and the caudal half of the soft palate. The third ramus supplied a part of the radix linguae, the vallecula epiglottica and the lingual aspect of the epiglottis. The fourth ramus supplied the hypopharyngeal mucosa rostral to the middle level of the aryepiglottic fold.     

Effect of injury on nerve growth factor uptake by sensory ganglia

The level of the nerve growth factor protein, NGF, in vivo has a profound influence on axonal sprouting by sensory neurons of vertebrate dorsal root ganglia. There is evidence also that NGF may play similar roles in cholinergic central structures in brain. In both instances, retrograde transport of NGF has been demonstrated. Here we examined uptake of NGF by DRG neurons in response to contusion injury of the spinal cord. Under these conditions there was uptake and transport of NGF into large DRG neurons via central processes but no uptake by non-DRG central neurons. Thus, any effects of NGF on spinal neurons or their processes would be secondary to the direct effects of NGF on DRG neurons.     

Co-expression of VRL-1 and calbindin D-28k in the rat sensory ganglia

The co-expression of vanilloid receptor 1-like receptor (VRL-1), a newly cloned capsaicin-receptor homologue, with calbindin D-28k was examined in the rat sensory ganglia. The co-expression was rare in the dorsal root, trigeminal and jugular ganglia and abundant in the petrosal and nodose ganglia. In the dorsal root ganglion, none of VRL-1-immunoreactive (ir) neuron co-expressed calbindin D-28k-immunoreactivity (ir). Of the VRL-1-ir neurons, 9 and 5% showed calbindin D-28k ir in the trigeminal and jugular ganglia, respectively. On the other hand, 35 and 63% of VRL-1-ir neurons in the petrosal and nodose ganglia, respectively, co-expressed these substances. The retrograde tracing method indicated that petrosal neurons which co-expressed VRL-1-and calbindin D-28k-ir innervated taste buds in the circumvallate papilla. The present findings may suggest that VRL-1 is associated with chemosensory functions in visceral sensory neurons.     

Membrane properties of glossopharyngeal sensory neurons in the petrosal ganglion of the cat

The active and passive properties of petrosal ganglion sensory neurons with axons in the glossopharyngeal nerve were examined with intracellular microelectrodes in an in vitro preparation. Glossopharyngeal neurons could be classified into two groups: H-cells showing an inflexion or hump on the falling phase of the spike and F-cells, generating a short action potential without a hump. Most of the neurons found (85%) were H-cells. The axonal conduction velocity of both types of cells fell into the A delta range, although the average value for F-cells (13 m/s) was higher than that found for H-cells (10 m/s). H- and F-cells had similar resting membrane potentials and input resistances, but different action potential characteristics. F-cells showed a smaller action potential with a faster rate of depolarization, followed by a shorter after-hyperpolarization. The response to depolarizing current pulses applied through the microelectrode was also different in both types of cells. About half of the H-cells could not be depolarized to threshold while 85% of F-cells generated spikes. It is concluded that two different populations of petrosal ganglion neurons send axons into the glossopharyngeal nerve.     

Neurotrophins alter the numbers of neurotransmitter-ir mature vagal/glossopharyngeal visceral afferent neurons in vitro

Mature nodose and petrosal ganglia neurons (placodally derived afferent neurons of the vagal and glossopharyngeal nerves) contain TrkA and TrkC, and transport specific neurotrophins [nerve growth factor (NGF), neurotrophin-3 (NT-3), neurotrophin-4 (NT-4)]. This study evaluated neurotrophin influences on the presence of neuropeptides and/or neurotransmitter enzymes in these visceral sensory neurons. NGF, NT-3 and NT-4 (10-100 ng/ml) were applied (5 days) to dissociated, enriched, cultures of mature nodose/petrosal ganglia neurons, and the neurons processed for tyrosine hydroxylase (TH), vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP) and neurofilament (NF-200) immunocytochemistry. Addition of NGF to nodose/petrosal ganglia neuron-enriched cultures significantly increased the number of TH-immunoreactive (ir) neurons, decreased the number of VIP-ir neurons in the cultures, and did not affect the numbers of CGRP-ir neurons. The addition of an NGF neutralizing antibody attenuated the effects of NGF on TH and VIP-ir neurons. NT-3 increased the number of VIP-ir neurons in the nodose/petrosal ganglia cultures and did not alter the numbers of TH-, or CGRP-ir neurons. The addition of an NT-3 neutralizing antibody attenuated the effects of NT-3 on VIP-ir neurons. NT-4 had no significant effects on the numbers of TH, VIP and CGRP-ir neurons. The absence of neurotrophin-induced changes in the numbers of NF-200-ir neurons in culture showed the lack of neurotrophin-mediated changes in survival of mature vagal afferent neurons. These data demonstrate that specific neurotrophins influence the numbers of neurons labeled for specific neurochemicals in nodose/petrosal ganglia cultures. These data, coupled with previous evidence for the presence of TrkA and TrkC mRNA and of the retrograde transport of NGF and NT-3, suggest important roles for NGF and NT-3 in the maintenance of transmitter phenotype of these mature visceral afferent neurons.     

Neurotrophins alter the numbers of neurotransmitter-ir mature vagal/glossopharyngeal visceral afferent neurons in vitro

Mature nodose and petrosal ganglia neurons (placodally derived afferent neurons of the vagal and glossopharyngeal nerves) contain TrkA and TrkC, and transport specific neurotrophins [nerve growth factor (NGF), neurotrophin-3 (NT-3), neurotrophin-4 (NT-4)]. This study evaluated neurotrophin influences on the presence of neuropeptides and/or neurotransmitter enzymes in these visceral sensory neurons. NGF, NT-3 and NT-4 (10–100 ng/ml) were applied (5 days) to dissociated, enriched, cultures of mature nodose/petrosal ganglia neurons, and the neurons processed for tyrosine hydroxylase (TH), vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP) and neurofilament (NF-200) immunocytochemistry. Addition of NGF to nodose/petrosal ganglia neuron-enriched cultures significantly increased the number of TH-immunoreactive (ir) neurons, decreased the number of VIP-ir neurons in the cultures, and did not affect the numbers of CGRP-ir neurons. The addition of an NGF neutralizing antibody attenuated the effects of NGF on TH and VIP-ir neurons. NT-3 increased the number of VIP-ir neurons in the nodose/petrosal ganglia cultures and did not alter the numbers of TH-, or CGRP-ir neurons. The addition of an NT-3 neutralizing antibody attenuated the effects of NT-3 on VIP-ir neurons. NT-4 had no significant effects on the numbers of TH, VIP and CGRP-ir neurons. The absence of neurotrophin-induced changes in the numbers of NF-200-ir neurons in culture showed the lack of neurotrophin-mediated changes in survival of mature vagal afferent neurons. These data demonstrate that specific neurotrophins influence the numbers of neurons labeled for specific neurochemicals in nodose/petrosal ganglia cultures. These data, coupled with previous evidence for the presence of TrkA and TrkC mRNA and of the retrograde transport of NGF and NT-3, suggest important roles for NGF and NT-3 in the maintenance of transmitter phenotype of these mature visceral afferent neurons.