Rat Nasal Mucosa Research Articles

Identification of pannexins in rat nasal mucosa.

Pannexins are a second family of gap-junction proteins in vertebrates, classified as pannexin-1, pannexin-2, and pannexin-3. Pannexin-1 is one of the candidates for channel-mediated ATP release into the extracellular space. In airway epithelia, ATP signaling modulates multiple cellular functions such as mucus/ion secretion and mucociliary clearance systems. However, the expression of pannexins in the upper airway has not been investigated. Nasal septal mucosae were collected from adult male Wistar rats aged 20–24 weeks. The expression of pannexin-1, pannexin-2, and pannexin-3 was examined by reverse transcription polymerase chain reaction (RT-PCR) and by whole-mount fluorescence immunohistochemistry. Transcripts for pannexin-1, pannexin-2, and pannexin-3 were detected in nasal septal mucosae of adult rats by RT-PCR. Distinct immunohistochemical fluorescence for pannexin-1 was observed in the epithelial layer, whereas there was no immunoreactivity for pannexin-2 or pannexin-3. This is the first article establishing the existence of pannexins (predominantly pannexin-1) in the upper airway, suggesting their possible participation in the physiological functions of ATP release and signaling in this tissue.

The Effect of Heparin on Antigen-Induced Mucus Hypersecretion in the Nasal Epithelium of Sensitized Rats

Heparin is a potential anti-inflammatory drug for allergic airway inflammation. To elucidate the effects of heparin on allergic inflammation, we examined the in vivo effects of heparin on antigen-induced mucus hypersecretion and infiltration of eosinophils and neutrophils in the nasal epithelium of sensitized rats. We induced hypertrophic and metaplastic changes of goblet cells in the nasal epithelium of ovalbumin (OVA)-sensitized rats by intranasal challenge with OVA. The effects of intranasal instillation with low molecular weight heparin (LMWH; 1-1000IU/0.1ml) on mucus production and eosinophil/neutrophil infiltration were examined. Intranasal instillation with low-dose LMWH (1-10IU/0.1ml) at 30 minutes before OVA instillation stimulated OVA-induced mucus production in the nasal epithelium of sensitized rats, whereas treatment with 100IU/0.1ml LMWH showed no effect. Intranasal instillation with high-dose LMWH (1000IU/0.1ml) significantly inhibited OVA-induced mucus production. Intranasal instillation with LMWH (1-1000IU/0.1ml) dose-dependently inhibited eosinophil and neutrophil infiltration into the rat nasal mucosa. These results indicate that heparin inhibits mucus hypersecretion and infiltration of eosinophils and neutrophils in allergic inflammation, though the inhibitory effect against mucus production is obtained in high-dose heparin. Intranasal instillation with high-dose heparin may provide a new therapeutic strategy for the treatment of nasal allergic inflammation.

Effect of Tong Qiao drops on the expression of eotaxin, IL-13 in the nasal mucosa of rats with allergic rhinitis

BackgroundIn recent years, particularly in China, many Chinese medicines and prescriptions for treating allergic rhinitis have been evaluated for their clinical relevance. Studies have found that numerous herbs and their constituent compounds can significantly alleviate allergic symptoms and are effective treatments for allergic rhinitis. The purpose of this study was to examine the modulatory effect of Tong Qiao nose drops on allergy symptoms and the expression of cytokines in the nasal mucosa of rats with ovalbumin-induced allergic rhinitis. MethodsSixty healthy male Sprague Dawley rats were randomly divided into three groups (n = 20): negative, control, and experimental. Rats in the control or experimental groups were sensitized with ovalbumin to induce allergic rhinitis. The sensitized rats in the experimental group were subsequently exposed to Tong Qiao nose drops, whereas the sensitized control rats were given saline nose drops. Negative control rats were only treated with saline. Allergic symptoms and the pathologic features of the nasal mucosa were observed. The expression of eotaxin in the mucous membrane of rat nasal septums was detected by immunohistochemical staining, and the expression levels of interleukin (IL)-5 and IL-13 were measured by enzyme-linked immunosorbent assay. ResultsThe symptom scores for the experimental group were significantly lower than those of control rats (p < 0.01). Histopathologic examination revealed pathologic changes of nasal mucosa edema in the experimental group was mild and the infiltration of eosinophils was insubstantial. The expression levels of eotaxin, IL-5, and IL-13 in the nasal mucosa from experimental rats were significantly lower than that of control rats (p < 0.01). ConclusionTong Qiao nose drops alleviated the symptoms of allergic rhinitis in a rat model and lowered the expression levels of eotaxin, IL-5, and IL-13.

The Effects of Systemic Use of Nicotine on the Rat Nasal Mucosa: a Histopathologic and Immunohistochemical Study

El objetivo de este estudio fue evaluar los efectos histopatologicos del uso sistemico de nicotina sobre la mucosa nasal de la rata. Se utilizaron como animales de experimentacion 12 ratas Sprague-Dawley adultas, entre 180-220 g, divididas en grupos de nicotina y control. Al grupo de nicotina (n = 6) se le administro sulfato de nicotina 2mg/kg durante 28 dias. Al grupo control (n = 6) se les administro solo 1,5 ml de solucion salina fisiologica por via subcutanea durante 28 dias. Todos los animales fueron sacrificados al final del estudio. Se tomaron muestras del tejido nasal y se examinaron histologicamente. Las secciones fueron tenidas con H-E, acido periodico de Schiff (PAS) y tricromico de Masson, observandose bajo microscopia de luz. Ademas, se evaluo la inmunoreactividad a E-cadherina de las celulas del epitelio pseudoestraficado de la mucosa nasal. Hubo diferencias significativas en la puntuacion histopatologica media entre los grupos tratados y no tratados con nicotina. En el grupo de nicotina, se observaron cambios degenerativos de las celulas epiteliales e hipertrofia de las celulas caliciformes. Se observo una infiltracion significativa de leucocitos en diferentes areas del tejido conectivo. La E-cadherina se redujo significativamente en las celulas epiteliales de la mucosa nasal del grupo nicotina.

Effects of Hyperbaric Oxygen Therapy on Rat Nasal Mucosa

ABSTRACTThe objective of this study was to evaluate the histopathologic effects of hyperbaric oxygen (HBO) therapy on the rat nasal mucosa. Twelve adult Sprague-Dawley rats, each weighing 180–220 g, were used as experimental animals. The rats were divided into HBO (hyperbaric oxygen) and control group. The rats in the HBO group (n = 6) were placed into a 20-liter HBO chamber (2.5 atmospheres absolute [ATA], 25–26°C with 100 % oxygen) for 90 min per day. The rats received hyperbaric oxygen over a period of 7 days. The rats in the control group (n = 6) were not given HBO. All animals were sacrificed at the end of the study, and nasal tissue samples were prepared. The sections were stained with Haematoxylin and Eosin (H-E), Periodic acid-Schiff (PAS) and Trichrome-Masson to observe the under a light microscope. Immunoreactivity of pseudostratified epithelial cells of the nasal mucosa was assessed with E-cadherin expression by immunohistochemical staining. There were significant differences in the average histopathological score between the groups exposed and non-exposed to HBO. In the HBO group, degenerative changes in epithelial cells were observed. The goblet cells showed expansion of their structure. Mononuclear lymphocyte infiltration, dilation of blood vessels, and hemorrhage were observed in considerable areas of connective tissue. In the immunohistochemical evaluation of E-cadherin expression, there were no significant differences between the two groups.

Increased brain radioactivity by intranasal 32P-labeled siRNA dendriplexes within in situ-forming mucoadhesive gels

BackgroundMolecules taken up by olfactory and trigeminal nerve neurons directly access the brain by the nose-to-brain pathway. In situ-forming mucoadhesive gels would increase the residence time of intranasal material, favoring the nose-to-brain delivery. In this first approach, brain radioactivity after intranasal administration of 32P-small interference RNA (siRNA) complexed with poly(amidoamine) G7 dendrimers (siRNA dendriplexes) within in situ-forming mucoadhesive gels, was determined.Materials32P-siRNA dendriplexes were incorporated into in situ-forming mucoadhesive gels prepared by blending thermosensitive poloxamer (23% w/w) with mucoadhesive chitosan (1% w/w, PxChi) or carbopol (0.25% w/w, PxBCP). Rheological properties, radiolabel release profile, and local toxicity in rat nasal mucosa were determined. The best-suited formulation was intranasally administered to rats, and blood absorption and brain distribution of radioactivity were measured.ResultsThe gelation temperature of both formulations was 23°C. The PxChi liquid showed non-Newtonian pseudoplastic behavior of high consistency and difficult manipulation, and the gel retained 100% of radiolabel after 150 minutes. The PxCBP liquid showed a Newtonian behavior of low viscosity and easy manipulation, while in the gel phase showed apparent viscosity similar to that of the mucus but higher than that of aqueous solution. The gel released 35% of radiolabel and the released material showed silencing activity in vitro. Three intranasal doses of dendriplexes in PxCBP gel did not damage the rat nasal mucosa. A combination of 32P-siRNA complexation with dendrimers, incorporation of the dendriplexes into PxCBP gel, and administration of two intranasal doses was necessary to achieve higher brain radioactivity than that achieved by intravenous dendriplexes or intranasal naked siRNA.ConclusionThe increased radioactivity within the olfactory bulb suggested that the combination above mentioned favored the mediation of a direct brain delivery.

Hydrophilic Nasal Gel of Lidocaine Hydrochloride

Intranasal lidocaine hydrochloride (LID, CAS 73-78-9) has been widely and commonly used in the treatment of a series of symptoms such as migraine, cluster headache and trigeminal neuralgia in clinical studies. Nevertheless, rapid nasal mucociliary clearance of intranasal solution presents the predominant obstacle impacting its efficiency. In order to prolong the residence time of LID in the nasal cavity and increase its absorption, a LID nasal gel had been developed previously using hydroxypropyl methyl cellulose (HPMC) as base material. The LID nasal gel formulation has been optimized through central composite design and its in vitro release behavior has been investigated. In the present study, safety studies employing in situ toad palate model and in vivo rat nasal mucosa model showed that compared with LID nasal spray, LID nasal gel was less toxic to mucocilia. The pharmacokinetic parameters, along with olfactory and ventricle delivery of LID from nasal gel were compared with those of LID from nasal spray, intravenous injections and oral solutions in rats using microdialysis, and the drug targeting index (DTI) was used to evaluate their brain delivery. The absolute bioavailability of the optimized LID nasal gel was about 1.5 times of that of LID nasal spray which suggested a better absorption of LID from nasal gel. Moreover, the drug targeting index (DTI) of olfactory/ventricle after nasal gel and spray administration was 2.15/1.51 and 1.66/1.26, respectively. This suggested that a fraction of the LID dose could be transported directly from the nasal cavity into the central nervous system (CNS), and the brain delivery of LID can be enhanced by nasal gel.

Formulation and Evaluation of In Situ Gelling Systems for Intranasal Administration of Gastrodin

Gastrodin is the major bioactive constituent of the traditional Chinese drug "Tianma." It is used in the treatment of some nervous system diseases and can be transported to the brain via intranasal administration. In the current paper, the development of a novel ion-activated in situ gelling system for the nasal delivery of gastrodin is discussed. An in situ perfusion model was used to determine the absorption-rate constant of gastrodin through rat nasal mucosa. The optimal formulation was determined by measuring the critical cation concentration, anti-dilution capacity, gel expansion coefficient, water-holding capacity, and adhesive capacity. The best formulation consisted of 10% gastrodin, 0.5% deacetylated gellan gum as the gelatinizer, and 0.03% ethylparaben as the preservative. The rheological properties of gastrodin nasal in situ gels were also investigated. The viscosity and elasticity sharply increased at temperatures below 25°C. When physiological concentrations of cations were added into the preparation, the mixture gelled into a semi-solid. The results of an accelerated stability test show that gastrodin nasal in situ gels can be stable for more than 2 years. Mucociliary toxicity was evaluated using the in situ toad palate model and the rat nasal mucociliary method; both models demonstrated no measurable ciliotoxicity. Pharmacodynamic studies suggest that similar acesodyne and sedative effects were induced following intranasal administration of 50 mg/kg gastrodin nasal in situ gels or oral administration of 100 mg/kg gastrodin solution. The in situ gel preparation is a safe and effective nasal delivery system for gastrodin.

The Evaluation of Effects of Pseudoephedrine, Xylometazoline, and Budesonide on the Rat Nasal Mucosa

Objective: Systemic decongestants, topical decongestants, and topical corticosteroids have been used in treatment of upper respiratory tract diseases. We proposed to find out histopathological changes caused by these drugs in therapeutic dosages in rat nasal mucosa, so we tried to compare the effects of pseudoephedrine, xylometazoline, and budesonide. Method: The rats in the first group took 80 microL of liquid pseudoephedrine for 15 days twice daily. 10 microL of xylometazoline was administered to rats in the second group for 10 days. 10 microL of budesonide was administered to the third group for 21 days. Results: The whole slides were evaluated histopathologically under 400X microscopic magnification. The evaluation parameters were mucosal edema level, the loss of ciliated epithelium, intraepithelial gland proliferation, vascular changes, and the changes in epithelial thickness. In any group, a significant mucosal edema was detected. In the second group (xylometazoline), ciliated epithelium loss and goblet cell proliferation were detected in posterior nasal slides. In the third group (budesonide), partial fibrosis was detected in some slides. In the first group (pseudoephedrine), statistically significant epithelial thinning was detected. Conclusion: We concluded that xylometazoline causes ciliary epithelium loss and goblet cell proliferation. This change probably is due to preservatives in this medication. The budesonide, the topical corticosteroid, caused no significant side effect, especially ciliated epithelium loss. We could not assess the effect of budesonide in inflammation.

Rapid-onset sildenafil nasal spray carried by microemulsion systems: in vitro evaluation and in vivo pharmacokinetic studies in rabbits

An oleic acid-based microemulsion system with a member of the Tween series or Cremophor EL as the surfactant and a short-chain alcohol as the cosolvent was developed for rapid-onset intranasal delivery of sildenafil.The phase behaviour and solubilization capacity of the microemulsion system were characterized, and nasal absorption of sildenafil from the microemulsion formulations was investigated in rabbits.Sildenafil displayed a high solubility of 124 mg/mL in the microemulsion consisting of 40% oleic acid, 10% H2O, and 50% Tween 80:ethanol (EA) (at a 1:4 weight ratio). Nasal absorption of sildenafil from this microemulsion was found to be fairly rapid. With a 10-mg dose, the onset of action was arrived instantly following intranasal administration and the duration was over 3 h using an in vivo rabbit studies. In addition, nasal ciliotoxicity studies were carried out using in vivo rat nasal mucosa model and showed no ciliotoxicity. Therefore, the prepared systems are no serious nasal ciliotoxicity for intranasal administration.The microemulsion system composed of oleic acid, Tween 80, EA, and water may be a practical approach for the rapid-onset delivery of sildenafil for the treatment of erectile dysfunction.

Drug Transporter Expression and Localization in Rat Nasal Respiratory and Olfactory Mucosa and Olfactory Bulb: Fig. 1.

Uptake of drugs and other xenobiotics from the nasal cavity and into either the brain or systemic circulation can occur through several different mechanisms, including paracellular transport and movement along primary olfactory nerve axons, which extend from the nasal cavity to the olfactory bulb of the brain. The present study was conducted to expand knowledge on a third means of uptake, namely the expression of drug transporters in the rat nasal epithelium. We used branched DNA technology to compare the level of expression of nine transporters [(equilibrative nucleoside transporters (ENT)1 and ENT2; organic cation transporter (OCT)1, 2, and 3; OCTN1; organic anion-transporting polypeptide (OATP)3; and multidrug resistance (MRP)1 and MRP4] in nasal respiratory mucosa, olfactory mucosa, and olfactory bulb to the level of expression of these transporters in the liver and kidney. Transporters with high expression in the nasal respiratory mucosa or olfactory tissues were immunolocalized by immunohistochemistry. ENT1 and ENT2 expression was relatively high in nasal epithelia and olfactory bulb, which may explain the uptake of intranasally administered nucleoside derivatives observed by other investigators. OATP3 immunoreactivity was high in olfactory epithelium and olfactory nerve bundles, which suggests that substrates transported by OATP3 may be candidates for intranasal administration.

Nuclear factor kappa B pathway down-regulates aquaporin 5 in the nasal mucosa of rats with allergic rhinitis

Nuclear factor kappa B (NF-κB) induces gene transcription by binding CREB-binding protein (CBP). The aim of the study was to detect the mechanisms by which NF-κB pathway regulated aquaporin 5 (AQP5) in the nasal mucosa of rats with allergic rhinitis (AR). Rats were divided into control (group C), model (group M), low-dose proline dithiocarbamate (PDTC) (group L) and high-dose PDTC (group H) groups. AR model was established by the sensitization with ovalbumin, then groups L and H were treated with PDTC (50 or 100mg/kg/day) for 5days. AQP5, interleukin-1β, NF-κBp65 and phosphorylated cAMP-response element binding protein (p-CREB) were detected by immunohistochemistry, Western blotting or real-time PCR. AQP5 expression in group M was lower than in group C, but in groups L and H it increased. NF-κBp65 expression in group M was higher than group C, but in groups L and H it reduced. p-CREB expression in group M was lower than group C, but in groups L and H it increased. Interleukin-1β gene level in group M was higher than group C, but in groups L and H it was lower. These data show that the NF-κB pathway could down-regulate AQP5 by interleukin-1β which inhibited CREB phosphorylation or by NF-κBp65 which competitively bound CBP.

Measurement of tumor-associated mutations in the nasal mucosa of rats exposed to varying doses of formaldehyde

This study examined the potential induction of tumor-associated mutations in formaldehyde-exposed rat nasal mucosa using a sensitive method, allele-specific competitive blocker-PCR (ACB-PCR). Levels of p53 codon 271 CGT to CAT and K-Ras codon 12 GGT to GAT mutations were quantified in nasal mucosa of rats exposed to formaldehyde. In addition, nasal mucosa cell proliferation was monitored because regenerative cell proliferation is considered a key event in formaldehyde-induced carcinogenesis. Male F344 rats (6–7weeks old, 5 rats/group) were exposed to 0, 0.7, 2, 6, 10, and 15ppm formaldehyde for 13weeks (6h/day, 5days/week). ACB-PCR was used to determine levels of p53 and K-Ras mutations. Although two of five untreated rats had measureable spontaneous p53 mutant fractions (MFs), most nasal mucosa samples had p53 MFs below 10−5. All K-Ras MF measurements were below 10−5. No dose-related increases in p53 or K-Ras MF were observed, even though significant increases in bromodeoxyuridine incorporation demonstrated induced cell proliferation in the 10 and 15ppm formaldehyde-treatment groups. Therefore, induction of tumor-associated p53 mutation likely occurs after several other key events in formaldehyde-induced carcinogenesis.

Aminated gelatin as a nasal absorption enhancer for peptide drugs: evaluation of absorption enhancing effect and nasal mucosa perturbation in rats.

This study was carried out to evaluate the potential of aminated gelatin as a nasal absorption enhancer for peptide drugs. The absorption-enhancing effect was investigated in rats using insulin and fluorescein isothiocyanate-dextran with a molecular weight of 4.4 kDa (FD-4) as model drugs. The absorption of insulin was estimated by measuring the changes in plasma glucose levels following intranasal administration, and that of FD-4 was determined by measuring its plasma concentration after dosing. The hypoglycaemic effect after intranasal administration of insulin with aminated gelatin significantly increased compared with that after intranasal administration of insulin in phosphate buffered saline, indicating that aminated gelatin effectively enhanced the nasal absorption of insulin. In contrast, neither kind of native gelatin (isoelectric point = 5.0 and 9.0) showed any absorption-enhancing effect. The pH of the formulations and the concentration of aminated gelatin were found to affect the hypoglycaemic effect. In addition, aminated gelatin at a concentration of 0.2% significantly enhanced the absorption and the efflux of FD-4 through the rat nasal mucosa. The possible perturbation of aminated gelatin to nasal mucosa was evaluated by measuring the leaching of lactate dehydrogenase (LDH) using an in-situ perfusion rat model. Aminated gelatin presented a concentration-dependent (0.1-0.4%) but relatively small effect on the LDH leaching from the rat nasal epithelial membrane. These results suggest that positively charged aminated gelatin could be a new absorption enhancer for nasal delivery of peptide drugs.

Effects of cool restrain stress on eosinophils and interleukin 2 and 6 in nasal mucosa of rats with allergic rhinitis.

To study the effects of cool restrain stress on the accumulation of eosinophils and expression of Th cytokines in rat nasal mucosa with allergic rhinitis model. Fifty healthy female rats were randomly divided into 5 groups: control group, allergic rhinitis (AR) group, AR plus stress group, stress plus AR group and simultaneous stress-AR group. Cool restrain stress, AR model and simultaneous stress-AR were made. Nasal mucosa of septum from rats of five groups were stained routinely by haematoxylin eosin (HE) and immunohistochemistry respectively. The density of eosinophils and expression of interleukin (IL)2, IL-6 were observed by using software of image analysis systems under microscope. The density of eosinophiles and IL-6 in the nasal mucosa of stress-AR group were significantly higher than those in AR [(14.1 +/- 3.2) for eosinophiles, and (15.3 +/- 4.8) for IL-6 ] and were also significantly higher than those in control groups [(2.3 +/- 1.4) for eosinophiles, and (4.9 +/- 2.4) for IL-6)], and the differences reached statistical significance. (F were respectively 7.06, 7.14, 8.54, 8.20, P were respectively < 0.05 or < 0.01), but no significant differences of the three groups (AR plus stress, stress plus AR and simultaneous stress-AR groups) were found (F were respectively 2.90 and 3.20, P > 0.05). The expression of IL-2 in nasal mucosa of stress-AR group was significantly reduced compared with AR and control groups (F were respectively 7.27, 7.32, P were respectively < 0.05 or < 0.01). But there were also no significant differences of the three groups (AR plus stress, stress plus AR and simultaneous stress-AR groups, F = 3.12, P > 0.05). The abnormal infiltration and accumulation of eosinophiles and the differences in expression of IL-2 and IL-6 which represented Th1 and Th2 cytokines in rats nasal mucosa varied in different groups. The eosinophiles and IL-6 were rarely expressed in control group and moderately expressed in AR group, but significantly expressed in cool restrain groups. The IL-2 representing Th1 cytokines were reduced in cool restrain stress gruops. All these results indicated that cool restrain stress might play a role in inducing rat allergic rhinitis.

Effect of intranasal glucocorticoid on the pathological change of nasal mucosa in rats with allergic rhinitis.

To investigate the influence of inhaled glucocorticoid on the pathological change of the nasal mucosa in allergic rhinitis. One hundred and eighty Sprague-Dawley (SD) rats were selected. According to the random number table, these animals were randomly divided into two groups: the control Group A and the experimental group. There were 60 rats in Group A and 120 rats in experimental group. First of all, the rats in experimental group were sensitized by intra-peritoneal injection with ovalbumin (OVA), enhanced and local stimulated. Next, the rats in the experimental group were randomly divided into B and C groups. The number of rats in each group was 60. Group B still had the intranasal dropping on each side with OVA in the same volume and concentration twice a week. The rats in Group C also had the intranasal dropping on each side with OVA in the same volume and concentration twice a week. But, at the same time, these animals had fluticasone propionate (FP) nasal spray each side 50 microl/per day. While doing intra-peritoneal injection with physiological saline in the same volume and intranasal dropping on the rats in normal Group A. Ten rats from each group were randomly selected to be killed at the end of first, second, fourth, eighth, twelfth and sixteenth weeks after treatment. One from the ten rats in each group was used for micro-vascular casting of nasal mucosa, and the remaining nine were used for pathological examination. The model of the rats in experimental group was established successfully. After allergen stimulation, the nasal mucosa showed metaplasia of the goblet cells, epithelial denudation, inflammatory cells infiltration especially eosinophils, hyperplasia of the number of gland and density of micro-blood vessels. The capillary became netted. Cilia of epithelial shed to different extent and were uneven, and the layers of reticular formation of basal membrane became thick, and collagen deposition and fabric hyperplasia were seen under the electron microscope. In Group B, due to continuously contact with allergen, the mucosa remodeling enhanced. In Group C, glucocorticoid controlled the symptoms of allergic rhinitis better, but the cilia of epithelial shed, metaplasia of the goblet cells, inflammatory cells infiltration, hyperplasia of gland and micro-blood vessels, collagen deposition and fabric hyperplasia also could be seen in rat nasal mucosa. The pathological change of the nasal mucosa was found in allergic rhinitis. If the allergen was continuously contacted, the pathological change aggravated. Glucocorticoid could control the symptoms of allergic rhinitis better and reverse the mucosa pathological change to some extent, but it could not retro-converse or repair the nasal mucosa while the irreversibile change had occurred.

Kujin Suppresses Histamine Signaling at the Transcriptional Level in Toluene 2,4-Diisocyanate–Sensitized Rats

Kujin, the dried root of Sophorae flavescensis, has been used in Chinese folklore medicine against allergy. Evaluation of its anti-allergic potential as well as its mechanism of action has rarely been established. We investigated the effect of Kujin on toluene-2,4-diisocyanate (TDI)-induced allergic behavior and related histamine signaling including mRNA levels of histamine H1 receptor (H1R) and histidine decarboxylase (HDC), H1R and HDC activities, and histamine content in rat nasal mucosa. We also investigated the effect of Kujin on the mRNA levels of helper T cell type 2 (Th2)-cytokine genes closely related to histamine signaling. TDI provocation caused acute allergic symptoms accompanied with up-regulations of H1R and HDC mRNAs and increases in HDC activity, histamine content, and [3H]mepyramine binding activity in the nasal mucosa, all of which were significantly suppressed by pretreatment with Kujin for 3 weeks. Kujin also suppressed the TDI-induced IL-4 and IL-5 mRNA elevations. These data suggest that oral administration of Kujin showed anti-allergic activity through suppression of histamine signaling by the inhibition of TDI-induced H1R and HDC mRNA elevations followed by decrease in H1R, HDC protein level, and histamine content in the nasal mucosa of TDI-sensitized rats. Suppression of Th2-cytokine signaling by Kujin also suggests that it could affect the histamine-cytokine network.

Effects of formaldehyde inhalation on the junctional proteins of nasal respiratory mucosa of rats

Exposure to formaldehyde, which is an organic compound, disturbs the integrity of nasal mucosa. In this study, we aimed to clarify the protein changes in the junctional complex of nasal mucosa of Wistar rats exposed to formaldehyde inhalation. The study was performed in 20 female Wistar rats. Rats were divided into two groups randomly. Control rats were allowed free access to standard rat chaw and tap water ( n:10). Experimental group was exposed to formaldehyde vapor at 15 ppm, 6 h/day, 5 days/week for 12 weeks ( n:10). Histological evaluation of the experimental model was determined by hematoxylin-eosin (HE) and periodic acid Schiff (PAS) stainings of paraffin-embedded nasal mucosa tissues and by electron microscopy. The effects of formaldehyde inhalation on the distribution of occludin, E-cadherin, and γ-catenin were assessed by immunohistochemistry. The nasal mucosa of the experimental group was correlated with hypertrophy in goblet cell, degeneration in basal lamina, stratification of epithelium, and proliferation. Thickness of basal lamina and also local degenerative regions, vacuole increase in cytoplasmic areas, irregular forms of kinocilium and loss of sharpness in the kinocilium membrane were the findings at the ultrastructural level. The expressions of E-cadherin, occludin, γ-catenin proteins in intercellular junctional complexes of rat nasal mucosa were also decreased in experimental group compared to control group. The findings of the present study indicated that formaldehyde vapor inhalation in the concentrations and duration of exposure used in the present experiment significantly decreased the density of structural proteins of the junctional complex in the nasoepithelium. It was suggested that, the formaldehyde inhalation could cause complete impairment of intercellular junctional complexes and disturb the tissue integrity in nasal mucosa at higher concentrations.

A Comparative Study of Chemically Induced DNA Damage in Isolated Nasal Mucosa Cells of Humans and Rats Assessed by the Alkaline Comet Assay

Single-cell microgel electrophoresis (comet) assay was used to study genotoxic effects in human nasal mucosa cells and rat nasal and ethmoidal mucosa cells in vitro. Human cells were obtained from tissue samples of 10 patients (3 females/7 males), who underwent surgery (conchotomy) for treatment of nasal airway obstruction. Rat nasal mucosa cells were derived from male Sprague-Dawley rats. Cells were exposed for 1 h to either N-nitrosodiethanolamine (NDELA), epichlorohydrin (EPI), 1,2-epoxybutane (EPB), ethylene dibromide (EDB), or 1,2-dibromo-3-chloropropane (DBCP). Dimethyl sulfoxide (DMSO) was used as negative control. Alkaline comet assay was performed according to a standard protocol and DNA damage was quantified as Olive tail moment using image analysis system. All test substances induced an increase in DNA damage in human and rat cells. The absolute amount of DNA damage in rat nasal mucosa cells was usually higher than in ethmoidal mucosa cells. Human nasal mucosa cells were found to be less sensitive than rat mucosa cells to the genotoxic activities of DBCP (lowest effective concentration in human cells [LEChuman]: 1.5, in rat cells [LECrat]: 0.01 mM) and NDELA (LEChuman: 25, LECrat: 12.5 mM), whereas EPB-treated cells were almost equal (LEChuman and LECrat 0.78 mM). NDELA induced a marked concomitant cytotoxicity. For EPI (LEChuman and LECrat: 0.097 mM) and EDB (LEChuman: 0.195, LECrat: 0.048 mM), pronounced interindividual differences were observed in human samples.

Expression of Fos protein in brainstem after application of l-menthol to the rat nasal mucosa

There are two functional pathways for the nasotrigeminal reflex: the spinal nucleus of trigeminal nerve (SPV) to the Kölliker-Fuse (KF) nucleus and the nucleus of solitary tract (NTS) to the lateral parabrachial nucleus (PBl). Although stimulation of the nasal mucosa by cool temperature induces respiratory depression, it is still unknown whether these nuclei are activated. In the present study, we examined the expression of Fos protein in rat brainstem neurons after nasal application of l-menthol, which is known to activate cold-sensitive nasal receptors. Application of l-menthol, but not paraffin oil, decreased the respiratory rate from 99.7+/-15.6 to 78.5+/-7.3 min(-1). Furthermore, a significantly higher density of Fos-immunoreactive cells was observed in the SPV and KF in the l-menthol rats than in the controls. In the SPV, the density of Fos-immunoreactive cells was highest at approximately 0.5mm rostral to the obex in both the l-menthol (48.5+/-11.5 cells/section) and paraffin oil (26.0+/-9.6 cells/section) groups. In the KF, the mean density of Fos-immunoreactive cells was highest at approximately 5.0mm rostral to the obex in both groups (l-menthol: 67.8+/-14.0 cells/section, control: 41.0+/-12.7 cells/section). The present study suggests that the SPV-KF pathway is important for the cold-induced respiratory depression.