A ganglion cell cluster along the glossopharyngeal nerve near the human palatine tonsil.

CONCLUSION: The lingual branches of the glossopharyngeal nerve were most likely to bring not only gustatory nerves to the postsulcal part of the tongue but also autonomic nerves to the small glands and vessels. Tonsillectomy may injure the ganglion or reduce its function due to scar formation after surgery. OBJECTIVES: To determine the topographical anatomy of a suggested ganglion cluster along the lingual branches of the glossopharyngeal nerve and to identify the incidence. METHODS: In the human pharynges of 12 donated cadavers, we studied the ganglia using routine procedures for paraffin-embedded histology and immunohistochemistry. RESULTS: Near the palatine tonsil, the lingual branches of the glossopharyngeal nerve often contained ganglion cells (in 9 of 12 specimens). The ganglion cells, 20-40 µ in diameter, were sparsely distributed along a 0.5-3.0 mm length of the nerve course attached to the posterolateral aspect of the superior pharyngeal constrictor. Most of these cells were positive for neuronal nitric oxide synthase, while some were positive for tyrosine hydroxylase. Thus, the ganglion was composed of a mixed population of sympathetic and parasympathetic neurons.

Presence of neuronal nitric oxide synthase in autonomic and sensory ganglion neurons innervating the lacrimal glands of the cat: an immunofluorescent and retrograde tracer double-labeling study.

It is generally considered that parasympathetic postganglionic nerve fibers innervating the lacrimal gland (LG) arise from the pterygopalatine ganglion (PPG), while sympathetic and sensory innervations arise from the superior cervical ganglion (SCG) and trigeminal ganglion (TG), respectively. Recently, we reported for the first time that the parasympathetic innervation of the cat LG was also provided by the otic ganglion (OG) and ciliary ganglion (CG), and that the sensory innervation was also provided by the superior vagal ganglion (SVG) and superior glossopharyngeal ganglion (SGG). To determine if nitric oxide (NO) is a neurotransmitter of the autonomic and sensory neurons innervating the LG, we injected the cholera toxin B subunit (CTB) as a retrograde tracer into the cat LG, and used double-labeling fluorescent immunohistochemistry for CTB and nitric oxide synthase (NOS). We found that NOS-/CTB-immunofluorescent double-labeled perikarya were localized in the PPG, OG, TG, SVG and SGG, but not in the CG and SCG. The highest numbers of NOS-/CTB-immunofluorescent double-labeled neurons were found in the PPG and TG. In addition, we examined the presence of nitrergic nerve fibers in the LG using NADPH-d histochemistry and found that a large amount of NADPH-d-stained nerve fibers were distributed around the glandular acini and in the walls of glandular ducts and blood vessels. This study provides the first direct evidence showing that NO may act as a neurotransmitter or modulator involved in the parasympathetic and sensory regulation of lacrimal secretion and blood circulation, but may not be implicated in the sympathetic control of LG activities, and that nitrergic nerve fibers in the LG arise mainly from parasympathetic postganglionic neurons in the PPG and sensory neurons in the TG. The present results suggest that NO plays an important role in the regulation of LG activities.

Nitric oxide synthase in the glossopharyngeal and vagal afferent pathway of a teleost, Takifugu niphobles. The branchial vascular innervation.

To examine the presence of nitric oxide synthase (NOS) in the sensory system of the glossopharyngeal and vagus nerves of teleosts, nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) activity and immunoreactivity for NOS were examined in the puffer fish Takifugu niphobles. The nitrergic sensory neurons were located in the ganglia of both the glossopharyngeal and the vagal nerves. In the vagal ganglion, positive neurons were found in the subpopulations for the branchial rami and the coelomic visceral ramus, but not for the posterior ramus or the lateral line ramus. In the medulla, nitrergic afferent terminals were found in the glossopharyngeal lobe, the vagal lobe, and the commissural nucleus. In the gill structure, the nitrergic nerve fibers were seen in the nerve bundles running along the efferent branchial artery of all three gill arches. These fibers appeared to terminate in the proximal portion of the efferent filament arteries of three gill arches. On the other hand, autonomic neurons innervating the gill arches were unstained. These results suggest that nitrergic sensory neurons in the glossopharyngeal and vagal ganglia project their peripheral processes through the branchial rami to a specific portion of the branchial arteries, and they might play a role in baroreception of this fish. A possible role for nitric oxide (NO) in baroreception is also discussed.

Co-localization of mu-opioid receptor-like immunoreactivity with substance P-LI, calcitonin gene-related peptide-LI and nitric oxide synthase-LI in vagal and glossopharyngeal afferent neurons of the rat.

Co-localization of mu-opioid receptor (MOR)-like immunoreactivity (-LI) with substance P (SP)-LI, calcitonin gene-related peptide (CGRP)-LI and nitric oxide synthase (NOS)-LI in the nodose, petrosal and jugular ganglia was examined in the rat by a double immunofluorescence histochemical method. About 0.6%, 41% and 95% of neurons with MOR-LI, respectively, in the nodose, petrosal and jugular ganglia showed SP-LI; about 2%, 51% and 66% of MOR-like immunoreactive neurons displayed CGRP-LI in the nodose, petrosal and jugular ganglia, respectively. In addition, about 59% of MOR-like immunoreactive neurons in the nodose ganglia displayed NOS-LI, whereas no NOS-LI was detected in the petrosal or jugular ganglion. These data provide evidence for co-localization of MOR-LI with SP-LI, CGRP-LI and NOS-LI in the vagal and glossopharyngeal afferent neurons, and suggest that MOR may regulate the release of SP, CGRP and nitric oxide from the visceral primary afferent terminals in the nucleus of the solitary tract of the rat.

Distribution of neurons reactive for NADPH-diaphorase in the branchial nerves of a teleost fish, Gadus morhua.

The NADPH-diaphorase reaction was used to determine the distribution of postganglionic autonomic neurons in the branches of the glossopharyngeal and vagus nerves supplying the gill arches of the cod fish, Gadus morhua. Neurons were common in major nerve trunks in all gill arches, especially in the post-trematic rami of the branchial nerves. From about 55% to more than 85% of the neurons in any branchial nerve were reactive for NADPH-diaphorase. The results suggest that the presence of NADPH-diaphorase, and presumably the ability to synthesise nitric oxide, have been a property of cranial parasympathetic neurons from early in the evolution of the vertebrates.

Organization of the nucleus of the solitary tract in the hamster: acetylcholinesterase, NADH dehydrogenase, and cytochrome oxidase histochemistry.

The distribution of acetylcholinesterase (AChE), NADH dehydrogenase (NADHd), and cytochrome oxidase (CO) was determined in the nucleus of the solitary tract (NST) in the golden hamster. Histochemical staining was compared to cytoarchitectonic subdivisions of the NST (Whitehead: J. Comp. Neurol. 276:547-572, 1988) and to terminal fields of primary afferents of the nerves that innervate the tongue. These three histochemical methods resulted in differential staining patterns within the NST that were related to certain subdivisions. Transganglionic transport of horseradish peroxidase (HRP) was used to determine the central projections of the chorda tympani (CT), the lingual branch of the trigeminal (L-V), and the lingual-tonsilar branch of the glossopharyngeal nerves (L-IX). Alternate or the same brain sections were processed to reveal transported HRP, and NADHd or AChE levels. Increased staining of the neuropil with NADHd and AChE was coincident with the dense part of the afferent terminal fields of all three nerves in the NST and the laterally adjacent dorsomedial part of the spinal trigeminal nucleus. CO showed this pattern only for the most rostral part of the CT field. The densest AChE staining coincided with gustatory afferent terminal fields. The histochemical staining facilitated the interpretation of the organization of the NST. For example, at caudal levels of the gustatory NST, it is suggested that taste processing is localized predominantly in the medial part of the rostral central, and somatosensory processing in the rostral lateral subdivision. AChE or NADHd staining should facilitate studies of connections, topography, and neuroplastic changes of the gustatory NST.

Cytochrome oxidase activity in vagal and glossopharyngeal visceral sensory neurons of the rat: effect of peripheral axotomy.

Cytochrome oxidase (CO) activity, an endogenous metabolic marker, was examined in visceral sensory neurons of the rat nodose and petrosal ganglia by using enzyme histochemistry. In the normal nodose and petrosal ganglia, nerve cells showed various degrees of staining intensity. The population of darkly stained neurons in the nodose ganglion was higher than in the petrosal ganglion. Axotomy of the peripheral axons of these bipolar sensory neurons was used to study potential changes in ganglionic cellular metabolism associated with loss of afferent inputs and/or injury. Peripheral axotomy had a significant effect on CO activity in the nodose ganglion. By 3 days after axotomy, darkly stained neurons decreased in number and lightly stained neurons, which were not observed in the normal ganglion, appeared in the nodose ganglion. At 7 days after axotomy, the average population of these lightly stained neurons increased to 29% in the nodose ganglion. Subsequently, the population decreased so that at 14 days and 21 days, 19% and 7% respectively of neurons were stained lightly. Even at 28 days after axotomy, the lightly stained neurons were still observed. In the petrosal ganglion, no remarkable change was observed at any stage after axotomy. These results suggest that metabolic activity decreases in some nodose neurons after peripheral nerve section.

Developmental regulation of tyrosine hydroxylase expression in primary sensory neurons of the rat.

The regulation of transmitter phenotype in primary sensory neurons remains poorly understood. However, recent studies of catecholaminergic (CA) sensory neurons suggest that expression of this particular phenotype may be related to innervation of specific peripheral tissues. In the glossopharyngeal petrosal ganglion (PG) of adult rats, for example, the vast majority of CA sensory neurons innervate a single target, the carotid body. The present study was undertaken, therefore, to begin investigating factors that underlie CA differentiation in sensory neurons, using the rat PG as a model system. Immunocytochemical, biochemical, and morphometric methods were used to investigate the normal time course of CA development in the PG in vivo, employing tyrosine hydroxylase (TH) as a phenotypic marker. These studies revealed two temporally distinct waves of TH expression during embryogenesis. TH immunoreactivity was initially detectable on Embryonic Day (E) 11.5; the number of stained cells increased markedly by E12.5 and then fell off sharply to near 0 by E15.5. Simultaneous immunostaining for TH and neurofilament proteins revealed a high proportion of double-labeled perikarya on E12.5, indicating that the transiently TH-positive cells are neurons. A second, sustained phase of TH expression began on E16.5, and by Postnatal Day 1 adult numbers of TH-containing ganglion cells were present. Western blot analysis demonstrated that TH levels per cell rose 3.5-fold in the perinatal period, indicating that maturation of this particular catecholaminergic trait in PG sensory neurons is highly regulated around birth. Morphometric techniques were used to define the relationship between neurons that transiently exhibit TH immunoreactivity early in gangliogenesis and those that maintain enzyme expression in the mature PG. These studies revealed separate and distinct growth curves for the early and late TH cells, respectively, demonstrating that the appearance, disappearance, and reappearance of immunoreactive cells reflects the differentiation of two separate populations of PG neurons. Moreover, these data indicate that TH expression in the population of CA cells that persists in the mature PG begins around E16.5. This is after peripheral target innervation has begun, raising the possibility that neuron-target interactions regulate biochemical differentiation of these CA sensory neurons.