Biomedical subjects

H S Li

Publications and source records attributed to H S Li.

At least 19 recordsLinked to original sources

PubMed2006

Maturation of dendritic cells by necrotic thyrocytes facilitates induction of experimental autoimmune thyroiditis.

Dendritic cell (DC) maturation is required for efficient presentation of autoantigens leading to autoimmunity. In this report, we have examined whether release of tissue antigens from necrotic thyroid epithelial cells can trigger DC maturation and initiation of a primary anti-self response. DC were cocultured with either viable (VT/DC) or necrotic (NT/DC) thyrocytes, and their phenotypic and functional maturation as well as immunopathogenic potential were assessed. Significant up-regulation of surface MHC class II and costimulatory molecule expression was observed in NT/DC but not in VT/DC. This was correlated with a functional maturation of NT/DC, determined by IL-12 secretion. Challenge of CBA/J mice with NT/DC, but not with VT/DC, elicited thyroglobulin (Tg)-specific IgG as well as Tg-specific CD4(+) T-cell responses and led to development of experimental autoimmune thyroiditis. These results support the view that thyroid epithelial cell necrosis may cause autoimmune thyroiditis via maturation of intrathyroidal DC.

Adoptive Transfer↗

PubMed2004

Effects of mushroom and herb polysaccharides, as alternatives for an antibiotic, on growth performance of broilers.

(1) This in vivo trial was conducted to study the effects of polysaccharide extracts of two mushrooms, Lentinus edodes (LenE) and Tremella fuciformis (TreE), and a herb, Astragalus membranaceus (AstE) on growth performance, and the weights of organs and the gastrointestinal tract (GIT) of broiler chickens. (2) Three extracts (LenE, TreE and AstE) were supplemented at inclusion rates of 0.5, 1, 2, 3 and 4 g/kg from 7 to 14 d of age and compared with an antibiotic treatment group (20 mg/kg, virginiamycin (VRG) as well as a group of non-supplemented birds. (3) Body weight (BW) gain, feed intake and feed conversion ratio (FCR) of the extract-supplemented groups were not significantly different from those of the antibiotic group. Significant effects of type of extract and concentration on growth performance were found from 7 to 28 d of age. Generally, birds fed with LenE showed higher BW gain and lower FCR from 7 to 28 d of age than those fed with TreE and AstE and 2 g/kg LenE was considered the optimal inclusion rate for enhanced broiler growth. However, the extracts had no significant effect on the relative weights of organs and GIT compared with the antibiotic group. (4) The birds fed the extracts showed better growth performance than the non-supplemented birds, but were not significantly different from those fed VRG. Of the three extracts, LenE appeared to be a potential growth promoter. Future studies are needed to investigate whether the extracts can be used as alternatives for antibiotic growth promoters in challenged birds, and to elucidate the mechanisms for potentially enhanced growth performance in poultry.

Animal Nutritional Physiological Phenomena↗

PubMed2004

Effects of mushroom and herb polysaccharides, as alternatives for an antibiotic, on the cecal microbial ecosystem in broiler chickens.

An in vivo experiment was conducted to study the potential prebiotic effects of mushroom and herb polysaccharide extracts, Lentinus edodes extract (LenE), Tremella fuciformis extract, and Astragalus membranaceus Radix extract, on chicken growth and the cecal microbial ecosystem, as compared with the antibiotic Apramycin (APR). This investigation was carried out in terms of a dose-response study. The chickens were naturally infected with avian Mycoplasma gallisepticum prior to the experiment. The BW gain, cecal pH, viscosity, and predominant microbial populations were measured 1 wk after the extract and APR treatments. The extracts and APR significantly stimulated growth of the chickens infected with avian Mycoplasma gallisepticum. The average BW gain of the groups fed with the extracts was significantly lower than that of the antibiotic group. The extracts had no significant effect on cecal pH. However, cecal viscosity and microbial populations were significantly affected by feeding extracts and antibiotic. In contrast to APR, the extracts stimulated the number of the potentially beneficial bacteria (bifidobacteria and lactobacilli), while reducing the number of the potentially harmful bacteria (Bacteroides spp. and Escherichia coli). Of the 3 extracts, LenE was associated with the most cecal bifidobacteria and lactobacilli. With each increase in the LenE dose, birds tended to have higher BW gain and total aerobe and anaerobe counts. Numbers of predominant cecal bacteria, in particular, E. coli, bifidobacteria, and lactobacilli, were significantly increased with increases in the LenE dose. It would seem that these specific mushroom and herb polysaccharide extracts hold some promise as potential modifiers of intestinal microbiota in diseased chickens.

Agaricales↗

PubMed2001

Rat mitochondrial ATP synthase ATP5G3: cloning and upregulation in pancreas after chronic ethanol feeding.

Individuals with chronic excessive alcohol ingestion are put at the risk of acute and chronic pancreatitis. Underlying molecular mechanisms are unknown. Differential gene expression in the pancreas was profiled using mRNA differential display by comparison between control and ethanol-consuming rats. Male Wistar rats were fed with diets containing 6.7% (vol/vol) ethanol for 4 wk. A cDNA tag that was overexpressed in the pancreas of rats fed ethanol was isolated. A 723-bp cDNA was cloned from a rat pancreatic cDNA library, which encodes a novel rat mitochondrial ATP synthase subunit 9, isoform 3 (ATP5G3), which is homologous to a human ATP5G3 gene. Real-time PCR demonstrated that all three nuclear gene isoforms (ATP5G1, ATP5G2, and ATP5G3) were consistently upregulated in the pancreas of alcohol-consuming rats, parallel with mitochondrial injury. The cellular response to mitochondrial damage and metabolic stress may reflect an adaptive process for mitochondrial repair in pancreatic acinar cells during chronic ethanol ingestion.

Amino Acid Sequence↗

PubMed2001

Assessment of the role of the inositol 1,4,5-trisphosphate receptor in the activation of transient receptor potential channels and store-operated Ca2+ entry channels.

The mechanism for coupling between Ca(2+) stores and store-operated channels (SOCs) is an important but unresolved question. Although SOCs have not been molecularly identified, transient receptor potential (TRP) channels share a number of operational parameters with SOCs. The question of whether activation of SOCs and TRP channels is mediated by the inositol 1,4,5-trisphosphate receptor (InsP(3)R) was examined using the permeant InsP(3)R antagonist, 2-aminoethoxydiphenyl borate (2-APB) in both mammalian and invertebrate systems. In HEK293 cells stably transfected with human TRPC3 channels, the actions of 2-APB to block carbachol-induced InsP(3)R-mediated store release and carbachol-induced Sr(2+) entry through TRPC3 channels were both reversed at high agonist levels, suggesting InsP(3)Rs mediate TRPC3 activation. However, electroretinogram recordings of the light-induced current in Drosophila revealed that the TRP channel-mediated responses in wild-type as well as trp and trpl mutant flies were all inhibited by 2-APB. This action of 2-APB is likely InsP(3)R-independent since InsP(3)Rs are dispensable for the light response. We used triple InsP(3)R knockout DT40 chicken B-cells to further assess the role of InsP(3)Rs in SOC activation. (45)Ca(2+) flux analysis revealed that although DT40 wild-type cells retained normal InsP(3)Rs mediating 2-APB-sensitive Ca(2+) release, the DT40InsP(3)R-k/o cells were devoid of functional InsP(3)Rs. Using intact cells, all parameters of Ca(2+) store function and SOC activation were identical in DT40wt and DT40InsP(3)R-k/o cells. Moreover, in both cell lines SOC activation was completely blocked by 2-APB, and the kinetics of action of 2-APB on SOCs (time dependence and IC(50)) were identical. The results indicate that (a) the action of 2-APB on Ca(2+) entry is not mediated by the InsP(3)R and (b) the effects of 2-APB provide evidence for an important similarity in the function of invertebrate TRP channels, mammalian TRP channels, and mammalian store-operated channels.

Adenosine↗

PubMed2001

Chronic ethanol consumption induces gene expression of pancreatic monitor peptide, but not SPINK1/PSTI-56, in rats.

The primary factors that predispose humans to the development of alcoholic pancreatitis are unknown. One of the earliest observations in humans in whom this disease develops is pancreatic hypersecretion caused by unknown mechanisms. Messenger RNA (mRNA) differential display was performed in a rat model to investigate the molecular mechanisms associated with ethanol-induced pancreatic hypersecretion. Male Wistar rats were pair-fed Lieber-DeCarli diets with or without ethanol for 7 days or 4 weeks. Total RNA was extracted from the pancreas and its neurohormonal control sites. Differentially expressed complementary DNA (cDNA) tags were isolated, cloned, and sequenced. One 248-bp cDNA was consistently and strongly induced in the pancreata of rats fed ethanol for 4 weeks. The sequence was highly homologous to both rat pancreatic monitor peptide (MP) and pancreatic secretory trypsin inhibitor (PSTI-56), also known as serine protease inhibitor, Kazal type 1 (SPINK1). Confirmatory reverse-transcription-polymerase chain reaction showed that PSTI-56 expression remained unchanged, whereas MP mRNA levels were elevated more than four times in the pancreata of ethanol-fed rats. These results indicate that long-term ethanol ingestion increases MP mRNA levels in the rat pancreas. Because MP stimulates cholecystokinin release and cholecystokinin is an important stimulant of pancreatic secretion, the enhanced MP gene expression may contribute to pancreatic hypersecretion.

Alcoholism↗

PubMed2000

TRP and the PDZ protein, INAD, form the core complex required for retention of the signalplex in Drosophila photoreceptor cells.

The light response in Drosophila photoreceptor cells is mediated by a series of proteins that assemble into a macromolecular complex referred to as the signalplex. The central player in the signalplex is inactivation no afterpotential D (INAD), a protein consisting of a tandem array of five PDZ domains. At least seven proteins bind INAD, including the transient receptor potential (TRP) channel, which depends on INAD for localization to the phototransducing organelle, the rhabdomere. However, the determinants required for localization of INAD are not known. In this work, we showed that INAD was required for retention rather than targeting of TRP to the rhabdomeres. In addition, we demonstrated that TRP bound to INAD through the COOH terminus, and this interaction was required for localization of INAD. Other proteins that depend on INAD for localization, phospholipase C and protein kinase C, also mislocalized. However, elimination of any other member of the signalplex had no impact on the spatial distribution of INAD. A direct interaction between TRP and INAD did not appear to have a role in the photoresponse independent of localization of multiple signaling components. Rather, the primary function of the TRP/ INAD complex is to form the core unit required for localization of the signalplex to the rhabdomeres.

Age Factors↗

PubMed2000

Up-regulation of prostaglandin EP4 receptor messenger RNA in fetal rabbit skin wound.

BACKGROUND: Scar formation and subglottic stenosis often cause health problems in surgical otolaryngology. However, fetal wounds demonstrate scarless healing. The underlying mechanism remains poorly understood. We isolated differentially expressed genes by comparison between nonwounded with wounded skin of fetal and adult rabbits. METHODS: Skin incisional wounds were made in fetal (21 to 23 days' gestation) and adult rabbits. Nonwounded and wounded skin were harvested 12 hours after surgery. Total RNA was extracted. By means of messenger RNA differential display, differentially expressed complementary DNA fragments were isolated, cloned, and sequenced. The expressed transcripts were verified by reverse RNA dot blot and semiquantitative reverse transcription and polymerase chain reaction. RESULTS: One complementary DNA tag that was induced in fetal skin wounds and repressed in adult skin wounds was isolated. The sequence of this complementary DNA (352 base pairs) encodes the messenger RNA for the E-prostanoid (EP) 4 receptor for prostaglandin E(2) (PGE(2)). The truly differential expression of the transcript was confirmed. In normal skin, the EP4 receptor messenger RNA levels were higher in adults than in fetuses. Twelve hours after wounding, the EP4 receptor transcript was remarkably induced in fetal skin wounds but repressed in adult skin wounds. CONCLUSIONS: Our study demonstrates the differential expression of the EP4 receptor messenger RNA in fetal and adult skin before and 12 hours after wounding. Our results suggest that prostaglandin E(2) is involved in the differential cellular responses and in the regulation of the intracellular signal transduction through its binding to EP4 receptor during fetal wound repair.

Animals↗

PubMed2000

RNA differential display of scarless wound healing in fetal rabbit indicates downregulation of a CCT chaperonin subunit and upregulation of a glycophorin-like gene transcript.

BACKGROUND/PURPOSE: Scars form as wounds heal in adult organisms. In addition to disrupting cosmetic appearance, scar tissue can cause significant morbidity, and even death if it blocks vital organ function. Previous work has established that fetal wounds, especially in early to midgestation, can heal without scarring. Because such inherent physiological mechanisms ultimately are under genetic control, a study was initiated to elucidate the differences in gene expression that produce scarless wound healing in the mammalian fetus but scarring in postnatal wounds. Reverse transcription polymerase chain reaction (RT-PCR) differential display (DD) was used to detect differentially expressed mRNA transcripts in a rabbit model of wound healing. METHODS: Adult and 21-day fetal full-thickness rabbit skin specimens from wounded and unwounded sites were harvested 12 hours postwounding. RNA extracted from the tissue was used as a template in DD reactions using anchoring and random primers to generate tissue-specific gene expression fingerprints. The over 2,000 resulting amplimers (gene transcripts) were screened for differential expression among the 4 types of specimens: fetal control (unwounded), fetal wound, adult control, and adult wound. Selected bands distinctly upregulated or downregulated in fetal wound lanes on the DD gels were excised, and the cDNA was extracted, reamplified, cloned into vectors, and sequenced. DD results were confirmed by limiting-dilution RT-PCR using sequence-specific primers. RESULTS: Differential display (DD) showed 22 amplimers that were significantly upregulated in all fetal wound samples as compared with little or no expression in fetal control, adult control, or adult wound tissues. Conversely, 5 transcripts were downregulated in the fetal wound specimens but highly expressed in the 3 comparison tissues. Reamplification of selected transcripts by PCR, followed by cloning and DNA sequencing, yielded 7 distinct sequences, each representing a gene expressed differently in fetal wound than in the other 3 tissues. A transcript that was downregulated in fetal wound showed very high sequence homology to part of the human gene for the eta subunit of the hetero-oligomeric particle CCT (the chaperonin containing T-complex polypeptide 1 or TCP-1). An upregulated amplimer showed significant DNA sequence homology to glycophorins A and B. One sequence was identified as 28S rRNA. The remaining 4 candidate sequences showed no significant homology to known genes, but 1 had high homology to expressed sequence tags of unknown function. CONCLUSIONS: With careful experimental design and proper controls and verifications, differential display of RNA expression is a potentially powerful method of finding genes that specifically regulate a particular physiological process such as fetal wound healing. No a priori knowledge of what genes might be involved, or why, is necessary. This study indicates that downregulation of a gene that codes for a chaperonin subunit and upregulation of several other genes may be involved in the striking scarless character of wound healing in the mammalian fetus. Results suggest the hypothesis that downregulation of the CCT chaperonin in fetal wound may inhibit the formation of myofibroblasts, a cell type that correlates highly with scarring in postnatal wound healing, by preventing the folding of sufficient alpha-smooth muscle actin to form the stress fibers characteristic of these cells.

Amino Acid Sequence↗

PubMed2000

Embryonic expression and extracellular secretion of Xenopus slit.

The slit genes have recently been found to encode proteins with a conserved chemorepulsive activity for axons in invertebrates and vertebrates. We have determined the expression pattern of a slit gene in Xenopus embryos. In the neural tube, slit is expressed at the ventral and dorsal midlines, and the motor neurons. slit is also expressed in a changing pattern in the retina. The full-length Xenopus Slit protein is secreted extracellularly, whereas its receptor Roundabout can not be secreted. Using a myc-tagged secreted Slit protein, we confirmed the binding of Slit to Roundabout expressed on the cell surface. These results confirm Slit-Roundabout interactions and the biochemical properties of Slit and Roundabout proteins, and further support the idea that Slit may guide axon projections in multiple regions of the embryo.

Animals↗

PubMed1999

Crystal structure of macrophage migration inhibitory factor complexed with (E)-2-fluoro-p-hydroxycinnamate at 1.8 A resolution: implications for enzymatic catalysis and inhibition.

Macrophage migration inhibitory factor (MIF) exhibits dual activities. It acts as an immunoregulatory protein as well as a phenylpyruvate tautomerase. To understand better the relationship between these two activities and to elucidate the structural basis for the enzymatic activity, a crystal structure of a complex between murine MIF and (E)-2-fluoro-p-hydroxycinnamate, a competitive inhibitor of the tautomerase activity, has been determined to 1.8 A resolution. The structure is nearly superimposable on that of the free protein indicating that the presence of the inhibitor does not result in any major structural changes. The inhibitor also confirms the location of the active site in a hydrophobic cavity containing the amino-terminal proline. Within this cavity, the inhibitor interacts with residues from adjacent subunits. At the back of the cavity, the side-chain carbonyl oxygen of Asn-97' interacts with the phenolic hydroxyl group of the inhibitor while at the mouth of the cavity the ammonium group of Lys-32 interacts with a carboxylate oxygen. The other carboxylate oxygen of the inhibitor interacts with Pro-1. The hydroxyl group of Tyr-95' interacts weakly with the fluoro group on the inhibitor. The hydrophobic side chains of five active-site residues (Met-2, Ile-64, Met-101, Val-106, and Phe-113) and the phenyl moiety of Tyr-95' are responsible for the binding of the phenyl group. Further insight into the enzymatic activity of MIF was obtained by carrying out kinetic studies using the enol isomers of phenylpyruvate and (p-hydroxyphenyl)pyruvate. The results demonstrate that MIF processes the enol isomers more efficiently than the keto isomers primarily because of a decrease in Km. On the basis of these results, a mechanism is proposed for the MIF-catalyzed tautomerization reaction.

Animals↗

PubMed1999

Vertebrate slit, a secreted ligand for the transmembrane protein roundabout, is a repellent for olfactory bulb axons.

The olfactory bulb plays a central role in olfactory information processing through its connections with both peripheral and cortical structures. Axons projecting from the olfactory bulb to the telencephalon are guided by a repulsive activity in the septum. The molecular nature of the repellent is not known. We report here the isolation of vertebrate homologs of the Drosophila slit gene and show that Slit protein binds to the transmembrane protein Roundabout (Robo). Slit is expressed in the septum whereas Robo is expressed in the olfactory bulb. Functionally, Slit acts as a chemorepellent for olfactory bulb axons. These results establish a ligand-receptor relationship between two molecules important for neural development, suggest a role for Slit in olfactory bulb axon guidance, and reveal the existence of a new family of axon guidance molecules.

Animals↗

PubMed1999

Activation of a TRPC3-dependent cation current through the neurotrophin BDNF.

Nonvoltage-gated cation currents, which are activated following stimulation of phospholipase C (PLC), appear to be major modes for Ca2+ and Na+ entry in mammalian cells. The TRPC channels may mediate some of these conductances since their expression in vitro leads to PLC-dependent cation influx. We found that the TRPC3 protein was highly enriched in neurons of the central nervous system (CNS). The temporal and spatial distribution of TRPC3 paralleled that of the neurotrophin receptor TrkB. Activation of TrkB by brain-derived nerve growth factor (BDNF) led to production of a PLC-dependent, nonselective cation conductance in pontine neurons. Evidence is provided that TRPC3 contributes to this current in vivo. Thus, activation of TrkB and PLC leads to a TRPC3-dependent cation influx in CNS neurons.

Animals↗

PubMed1999

Termination of phototransduction requires binding of the NINAC myosin III and the PDZ protein INAD.

Many of the proteins that are critical for Drosophila phototransduction assemble into a signaling complex, signalplex, through association with the PDZ-domain protein INAD. Some of these proteins depend on INAD for proper subcellular localization to the phototransducing organelle, the rhabdomere, making it difficult to assess any physiological function of this signaling complex independent of localization. Here we demonstrated that INAD bound directly to the NINAC myosin III, yet the subcellular localization of NINAC was normal in inaD mutants. Nevertheless, the INAD binding site was sufficient to target a heterologous protein to the rhabdomeres. Disruption of the NINAC/INAD interaction delayed termination of the photoreceptor response. Thus one role of this signaling complex is in rapid deactivation of the photoresponse.

Animals↗

PubMed1998

Requirement for the NINAC kinase/myosin for stable termination of the visual cascade.

Activation of the Drosophila photoresponse is a rapid process that results in plasma membrane Ca2+ and Na+ conductances. Ca2+ functions in negative feedback regulation of Drosophila vision including deactivation. Protein kinase C (PKC) binds directly to Ca2+ and is required for deactivation. However, the consequences of disrupting phosphorylation of any individual PKC substrate in the Drosophila retina have not been addressed. In the current work, we show that NINAC p174, which consists of a protein kinase domain joined to the head region of myosin heavy chain, is a phosphoprotein and is phosphorylated in vitro by PKC. Mutation of either of two PKC sites in the p174 tail resulted in an unusual defect in deactivation that had not been detected previously for other ninaC alleles or other loci. After cessation of the light stimulus, there appeared to be a transient reactivation of the visual cascade. This phenotype suggests that a mechanism exists to prevent reactivation of the visual cascade and that p174 participates in this process.

Animals↗

PubMed1998

Retinal targets for calmodulin include proteins implicated in synaptic transmission.

Ca2+ influxes regulate multiple events in photoreceptor cells including phototransduction and synaptic transmission. An important Ca2+ sensor in Drosophila vision appears to be calmodulin since a reduction in levels of retinal calmodulin causes defects in adaptation and termination of the photoresponse. These functions of calmodulin appear to be mediated, at least in part, by four previously identified calmodulin-binding proteins: the TRP and TRPL ion channels, NINAC and INAD. To identify additional calmodulin-binding proteins that may function in phototransduction and/or synaptic transmission, we conducted a screen for retinal calmodulin-binding proteins. We found eight additional calmodulin-binding proteins that were expressed in the Drosophila retina. These included six targets that were related to proteins implicated in synaptic transmission. Among these six were a homolog of the diacylglycerol-binding protein, UNC13, and a protein, CRAG, related to Rab3 GTPase exchange proteins. Two other calmodulin-binding proteins included Pollux, a protein with similarity to a portion of a yeast Rab GTPase activating protein, and Calossin, an enormous protein of unknown function conserved throughout animal phylogeny. Thus, it appears that calmodulin functions as a Ca2+ sensor for a broad diversity of retinal proteins, some of which are implicated in synaptic transmission.

Amino Acid Sequence↗

PubMed1998

Supraspinal inhibition of nociceptive dorsal horn neurones in the anaesthetized rat: tonic or dynamic?

1. Tonic inhibition of sensory spinal neurones is well known to descend from the rostroventral medulla. It is not clear if this inhibition is dynamically activated by peripheral noxious stimuli. 2. Transection of the ipsilateral dorsolateral funiculus (DLF) removed a descending inhibition of multireceptive spinal neurones and disproportionally prolonged the after-discharge component of their response to a noxious cutaneous stimulus. 3. Microinjection of GABA or tetracaine into the medullary nucleus gigantocellularis pars alpha (GiA) similarly prolonged the after-discharge in response to noxious stimuli. 4. Recordings of GiA cells, initially using minimal surgery, revealed that many had low levels of spontaneous activity and responded vigorously to noxious stimuli applied to any part of the body surface. One hour after the surgery necessary to expose the spinal cord, GiA cells had a high firing rate but responded weakly to noxious stimuli. 5. The response of GiA cells to noxious stimuli was abolished by transection of only the DLF contralateral to the stimulus. 6. It is concluded that the inhibition of multireceptive dorsal horn neurones from GiA is dynamically activated by noxious cutaneous stimuli via a projection in the contralateral DLF. Surgical exposure of the spinal cord tonically activates this inhibition and masks the dynamic component.

Anesthesia↗

PubMed1998

Identification of the subunits of the nicotinic cholinergic receptors in the rat cochlea using RT-PCR and in situ hybridization.

There are two tissues in the adult mammalian cochlea that are post-synaptic to cholinergic efferent fibers: The outer hair cells (OHCs) and the dendrites of the afferent fibers of the type I spiral ganglion cells. The unusual nicotinic-like pharmacology of cochlear cholinergic responses and the unique embryonic development of cochlear tissues suggest that the inner-ear nicotinic cholinergic receptor (nAChR) may be different from nAChRs described previously at synapses in the mammalian brain, autonomic ganglia, or skeletal muscle. In this study, we determined the mRNA expression of the alpha2-7, alpha9, and beta2-4 subunits of the nicotinic acetylcholine receptor (nAChR) family in the rat cochlea. In micro-dissected tissue from the organ of Corti, spiral ganglion, and the membranous lateral wall, we found mRNA expression of the alpha7 and alpha9 subunits in the organ of Corti and alpha5-7, and beta2 and beta3 in the spiral ganglion using RT-PCR. Employing in situ hybridization with 35S-riboprobes, we localized alpha9 in hair cells regions and alpha6, alpha7 and beta2 in the type I cells of the spiral ganglion. No evidence of nAChR subunit mRNA expression was found in supporting cells, but beta2 was expressed in type II spiral ganglion cells, which are neither cholinergic nor cholinoceptive.

Animals↗