RESUMEN
Although research on hearing loss, including the identification of causative genes, has become increasingly active, the pathogenic mechanism of hearing loss remains unclear. One of the reasons for this is that the structure of the inner ear of mice, which is commonly used as a genetically modified animal model, is too small and complex, making it difficult to accurately capture abnormalities and dynamic changes in vivo. Especially, Reissner's membrane is a very important structure that separates the perilymph and endolymph of the inner ear. This malformation or damage induces abnormalities in hearing and balance. Until now, imaging analyses, such as magnetic resonance imaging (MRI) and computed tomography, are performed to investigate the inner ear structure in vivo; however, it has been difficult to analyze the small inner ear structure of mice owing to resolution. Therefore, there is an urgent need to develop an image analysis method that can accurately capture the structure of the inner ear of mice including Reissner's membrane, both dynamically and statically. This study aimed to investigate whether it is possible to accurately capture the structure (e.g., Reissner's membrane) and abnormalities of the inner ear of mice using an 11.7 T MRI. By combining two types of MRI methods, in vivo and ex vivo, we succeeded for the first time in capturing the fine structure of the normal mouse inner ear, such as the Reissner's membrane, and inflammatory lesions of otitis media mouse models in detail and accurately. In the future, we believe that understanding the state of Reissner's membrane during living conditions will greatly contribute to the development of research on inner ear issues, such as hearing loss.
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Oído Interno , Imagen por Resonancia Magnética , Animales , Imagen por Resonancia Magnética/métodos , Ratones , Oído Interno/diagnóstico por imagen , Oído Interno/patología , Ratones Endogámicos C57BLRESUMEN
Sexual differentiation is a major developmental process. Sex differences resulting from sexual differentiation have attracted the attention of researchers. Unraveling what contributes to and underlies sex differences will provide valuable insights into the development of neurodevelopmental disorders that exhibit sex biases. Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects an individual's social interaction and communication abilities, and its male preponderance has been consistently reported in clinical studies. The etiology of male preponderance remains unclear, but progress has been made in studying prenatal sex hormone exposure. The present review examined studies that focused on the association between prenatal testosterone exposure and ASD development, as well as sex-specific behaviors in individuals with ASD. This review also included studies on maternal immune activation-induced developmental abnormalities that also showed striking sex differences in offspring and discussed its possible interacting roles in ASD so as to present a potential approach for future studies on sex biases in ASD.
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Trastorno del Espectro Autista , Trastornos del Neurodesarrollo , Efectos Tardíos de la Exposición Prenatal , Embarazo , Humanos , Masculino , Femenino , Trastorno del Espectro Autista/etiología , Testosterona , Causalidad , Trastornos del Neurodesarrollo/complicaciones , Caracteres SexualesRESUMEN
Autism spectrum disorder (ASD) is a neurodevelopmental disorder (NDD) characterized by impairments in social communication, repetitive behaviors, restricted interests, and hyperesthesia/hypesthesia caused by genetic and/or environmental factors. In recent years, inflammation and oxidative stress have been implicated in the pathogenesis of ASD. In this review, we discuss the inflammation and oxidative stress in the pathophysiology of ASD, particularly focusing on maternal immune activation (MIA). MIA is a one of the common environmental risk factors for the onset of ASD during pregnancy. It induces an immune reaction in the pregnant mother's body, resulting in further inflammation and oxidative stress in the placenta and fetal brain. These negative factors cause neurodevelopmental impairments in the developing fetal brain and subsequently cause behavioral symptoms in the offspring. In addition, we also discuss the effects of anti-inflammatory drugs and antioxidants in basic studies on animals and clinical studies of ASD. Our review provides the latest findings and new insights into the involvements of inflammation and oxidative stress in the pathogenesis of ASD.
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Trastorno del Espectro Autista , Efectos Tardíos de la Exposición Prenatal , Humanos , Embarazo , Animales , Femenino , Trastorno del Espectro Autista/patología , Enfermedades Neuroinflamatorias , Inflamación/complicaciones , Estrés OxidativoRESUMEN
As a fundamental and essential property, gastrointestinal (GI) tract pH reflects its condition and changes in several GI diseases such as inflammatory bowel disease (IBD), gastritis, etc. As a result, accurately measuring the GI pH is crucial for treatment, diagnosis, and prevention of GI diseases and contributes to developing GI disease models for basic studies. However, among pH measuring studies with animal models, there is no reliable method that can reflect the value and changing trends of GI pH in actual patients. In the current study, we developed a fast, simple method with pH indicator paper to measure the GI pH changes with GI content in normal mice and mice with colitis or hepatitis. Results demonstrated that normal mice's mean GI pH values were between 6.0 and 8.0, which was consistent with previous reports. Furthermore, the GI pH of colitis and hepatitis model mice showed the same pattern of lower values in the intestine and higher values in the stomach compared with normal mice. Our simple and timesaving method can accurately measure the dramatic changes in the GI pH of mice with GI diseases and is suitable for measuring the pH of sticky liquids with limited volume. Given all the merits listed above, this method is helpful for further research.
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Colitis , Gastritis , Enfermedades Gastrointestinales , Enfermedades Inflamatorias del Intestino , Animales , Enfermedades Gastrointestinales/diagnóstico , Tracto Gastrointestinal , Concentración de Iones de Hidrógeno , RatonesRESUMEN
Specific amino acid substitutions in degenerin mechano-gated channels (DEGs) of C. elegans convert these channels into constitutively active mutants that induce the degeneration of neurons where DEGs are expressed. Acid-sensing ion channel-2a (ASIC2a), a proton-gated cation channel predominantly expressed in central neurons, is a mammalian ortholog of DEGs, and it can remain unclosed to be cytotoxic once the same mutations as the DEG mutants are introduced into its gene. Here we show that heterozygous transgenic (Tg) rats expressing ASIC2a-G430F (ASIC2aG430F), the most active form of the gain-of-function mutants, under the control of the intrinsic ASIC2a promoter exhibited marked cerebellar maldevelopment with mild whole-brain atrophy. The Tg rats were small and developed an early-onset ataxic gait, as evidenced by rotarod and footprint tests. The overall gross-anatomy of the Tg brain was normal just after birth, but a reduction in brain volume, especially cerebellar volume, gradually emerged with age. Histological examination of the adult Tg brain revealed that the cell-densities of cerebellar Purkinje and granule cells were markedly reduced, while the cytoarchitecture of other brain regions was not significantly altered. RT-PCR and immunoblot analyses demonstrated that ASIC2aG430F transcripts and proteins were already present in various regions of the neonatal Tg brain before the deforming cerebellum became apparent. These results suggest that, according to the spatiotemporal pattern of the wild-type (WT) ASIC2a gene expression, the ASIC2aG430F channel induced lethal degeneration in Tg brain neurons expressing both ASIC2aG430F and ASIC2a channels.
Asunto(s)
Canales Iónicos Sensibles al Ácido , Cerebelo , Mutación con Ganancia de Función , Canales Iónicos Sensibles al Ácido/genética , Canales Iónicos Sensibles al Ácido/metabolismo , Animales , Cerebelo/patología , Mutación , RatasRESUMEN
Pain is influenced by various factors, such as fear, anxiety, and memory. We previously reported that pain-like behaviors in mice can be induced by environmental cues in which a pain stimulus was previously presented, and that pain was reduced using fentanyl (an opioid). Although opioid analgesics are currently used to treat persistent pain, their inappropriate use causes a significant number of deaths in the United States. Thus, alternative medicines to opioids are needed. Here, we reported that SR 57227A, a serotonin type-3 receptor agonist, significantly reduced pain-like behaviors. The number of c-Fos positive cells increased by environmental cues in PFC was decreased by SR 57227A. Moreover, SR 57227A reduced pain-like behaviors of the formalin test, and restored reductions in paw withdrawal thresholds by acidic saline intramuscular injection and sciatic nerve ligation. Unlike opioids, SR 57227A induced no preference behaviors as measured by the conditioned place preference test. These data suggested that SR 57227A is an effective alternative pain reliever to opioids that targets chronic pain.
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Agonistas de Receptores de Serotonina , Serotonina , Analgésicos/farmacología , Analgésicos/uso terapéutico , Analgésicos Opioides/farmacología , Analgésicos Opioides/uso terapéutico , Animales , Ratones , Dolor/tratamiento farmacológico , Piperidinas , Ratas , Ratas Sprague-Dawley , Serotonina/farmacologíaRESUMEN
The cochlear efferent feedback system plays important roles in auditory processing, including regulation of the dynamic range of hearing, and provides protection against acoustic trauma. These functions are performed through medial olivocochlear (MOC) neurons. However, the underlying cellular and molecular mechanisms are not fully understood. The serotonin type 3A (5-HT3A) receptor is widely expressed throughout the nervous system, which suggests important roles in various neural functions. However, involvement of the 5-HT3A receptor in the MOC system remains unclear. We used mice in this study and found that the 5-HT3A receptor was expressed in MOC neurons that innervated outer hair cells in the cochlea and was involved in the activation of MOC neurons by noise exposure. 5-HT3A receptor knockout impaired MOC functions, potentiated noise-induced hearing loss, and increased loss of ribbon synapses following noise exposure. Furthermore, 5-HT3 receptor agonist treatment alleviated the noise-induced hearing loss and loss of ribbon synapses, which enhanced cochlear protection provided by the MOC system. Our findings demonstrate that the 5-HT3A receptor plays fundamental roles in the MOC system and critically contributes to protection from noise-induced hearing impairment.
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Cóclea/fisiología , Células Ciliadas Auditivas Externas/patología , Pérdida Auditiva Provocada por Ruido/prevención & control , Ruido/efectos adversos , Receptores de Serotonina 5-HT3/fisiología , Animales , Vías Eferentes , Pérdida Auditiva Provocada por Ruido/etiología , Pérdida Auditiva Provocada por Ruido/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones NoqueadosRESUMEN
INTRODUCTION: The serotonin 3A receptor (5-HT3AR) is involved in vomiting and gastrointestinal motility. However, it is not well understood the expression pattern of 5-HT3AR in the gut immunohistochemically and how much contribution of 5-HT3AR to upper or lower intestinal motility. OBJECTIVES: We investigated the contribution of 5-HT3AR to gastrointestinal motor function by using 5-HT3AR KO mice and sought to identify 5-HT3AR-expressing cells via immunohistochemical staining using 5-HT3AR-GFP reporter mice. METHODS: The expression of 5-HT3AR was measured in each section of the gut through real-time PCR. The motor function of the stomach and colon was assessed via the 13C-octanoic acid breath test and colonic bead expulsion test, respectively, using 5-HT3AR KO mice. 5-HT3AR-expressing cells in the muscle layer of the gut were identified by immunohistochemical staining using 5-HT3AR-GFP reporter mice. RESULTS: 5-HT3AR was expressed throughout the digestive tract, and 5-HT3AR expression in the stomach and lower digestive tract was higher than that in the other sections. Motor function in the stomach and colon was lower in 5-HT3AR KO mice than in WT mice. As a result of immunohistochemical staining using GFP reporter mice, cholinergic neurons and PDGFRα+ cells were shown to express 5-HT3AR. In contrast, 5-HT3AR indicated by GFP fluorescence was rarely detected in ICC and smooth muscle cells. CONCLUSIONS: These results show that 5-HT3AR is highly expressed in the stomach and large intestine and that the activation of 5-HT3AR accelerates gastric emptying and large intestine transit. Additionally, 5-HT3AR is highly expressed in cholinergic neurons and some interstitial cells, such as PDGFRα+ cells.
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Células Intersticiales de Cajal , Serotonina , Animales , Vaciamiento Gástrico , Motilidad Gastrointestinal , Tracto Gastrointestinal , RatonesRESUMEN
Antagonists of the 5-hydroxytryptamine (serotonin) 3 receptor (5-HT3R) have anti-inflammatory and anti-apoptotic activities, but the detailed, underlying mechanisms are not well understood. We focused on anti-apoptotic activities via 5-HT3R signaling to clarify the underlying mechanisms. Mice were administered 5-fluorouracil (5-FU), which induced apoptosis in intestinal epithelial cells. Coadministration with 5-HT3R antagonists or agonists tended to decrease or increase the number of apoptotic cells, respectively. In serotonin 3A receptor (5-HT3AR) null (HTR3A-/-) mice, the number of apoptotic cells induced by 5-FU was decreased compared with that in wild-type (WT) mice. Bone marrow (BM) transplantation was performed to determine if BM-derived immune cells regulated 5-FU-induced apoptosis, but they were found to be unrelated to this process. Data from 5-HT3AR/enhanced green fluorescent protein reporter mice revealed that 50% of enterochromaffin (EC) cells expressed 5-HT3AR, but the number of apoptotic cells induced by 5-FU in the intestinal crypt organoids of HTR3A-/- mice was not altered compared with WT mice. In contrast, plasma 5-HT concentrations in WT mice but not in HTR3A-/- mice administered 5-FU were increased significantly. In conclusion, 5-HT3R signaling may enhance 5-HT release, possibly from EC cells intravascularly, or paracrine, resulting in increases in plasma 5-HT concentration, which in turn, enhances apoptotic activities induced by 5-FU.-Mikawa, S., Kondo, M., Kaji, N., Mihara, T., Yoshitake, R., Nakagawa, T., Takamoto, M., Nishimura, R., Shimada, S., Ozaki, H., Hori, M. Serotonin 3 receptor signaling regulates 5-fluorouracil-mediated apoptosis indirectly via TNF-α production by enhancing serotonin release from enterochromaffin cells.
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Antimetabolitos/farmacología , Apoptosis/efectos de los fármacos , Células Enterocromafines/efectos de los fármacos , Fluorouracilo/farmacología , Serina Endopeptidasas/metabolismo , Serotonina/metabolismo , Transducción de Señal , Factor de Necrosis Tumoral alfa/biosíntesis , Animales , Células de la Médula Ósea/citología , Células Enterocromafines/metabolismo , Proteínas Fluorescentes Verdes/genética , Intestino Delgado/citología , Intestino Delgado/efectos de los fármacos , Intestino Delgado/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Serina Endopeptidasas/genéticaRESUMEN
SAD kinases regulate presynaptic vesicle clustering and neuronal polarization. A previous report demonstrated that Sada-/- and Sadb-/- double-mutant mice showed perinatal lethality with a severe defect in axon/dendrite differentiation, but their single mutants did not. These results indicated that they were functionally redundant. Surprisingly, we show that on a C57BL/6N background, SAD-A is essential for cortical development whereas SAD-B is dispensable. Sada-/- mice died within a few days after birth. Their cortical lamination pattern was disorganized and radial migration of cortical neurons was perturbed. Birth date analyses with BrdU and in utero electroporation using pCAG-EGFP vector showed a delayed migration of cortical neurons to the pial surface in Sada-/- mice. Time-lapse imaging of these mice confirmed slow migration velocity in the cortical plate. While the neurites of hippocampal neurons in Sada-/- mice could ultimately differentiate in culture to form axons and dendrites, the average length of their axons was shorter than that of the wild type. Thus, analysis on a different genetic background than that used initially revealed a nonredundant role for SAD-A in neuronal migration and differentiation.
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Movimiento Celular/fisiología , Corteza Cerebral/embriología , Corteza Cerebral/enzimología , Neuronas/enzimología , Proteínas Serina-Treonina Quinasas/fisiología , Animales , Axones/enzimología , Células Cultivadas , Femenino , Isoenzimas , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Serina-Treonina Quinasas/genéticaRESUMEN
The serotonin (5-hydroxytryptamine) type 3 (5-HT3) receptors are transmembrane ligand-gated ion channels. Although several 5-HT3 receptor agonists have been used as preclinical tools, SR 57227A is the most commonly used 5-HT3 receptor agonist with the ability to cross the blood brain barrier. However, the precise pharmacological profile of SR 57227A remains unclear. Therefore, we examined the pharmacological profile of SR 57227A at the 5-HT3A and 5-HT3AB receptors. We microinjected Xenopus laevis oocytes with human 5-HT3A complementary RNA (cRNA) or a combination of human 5-HT3A and human 5-HT3AB cRNA and performed two electrode voltage clamp recordings of 5-HT3A and 5-HT3AB receptor current in the presence of SR 57227A. Results showed that SR 57227A acts as partial agonist/partial antagonist at the 5-HT3 receptor. Interestingly, SR 57227A specifically reduced subsequent current amplitudes induced by 5-HT or SR 57227A. Based on its 5-HT3 receptor partial agonist/partial antagonist properties, we predict that SR 57227A functions as a serotonin stabilizer.
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Canales Iónicos Activados por Ligandos/metabolismo , Piperidinas/farmacología , Receptores de Serotonina 5-HT3/efectos de los fármacos , Animales , Barrera Hematoencefálica/metabolismo , Humanos , Oocitos , ARN Complementario , Agonistas del Receptor de Serotonina 5-HT3/farmacología , Antagonistas del Receptor de Serotonina 5-HT3/farmacología , Xenopus laevisRESUMEN
The major symptoms of Ménière's disease are episodic vertigo, fluctuating hearing loss, and tinnitus. Direction-changing spontaneous nystagmus is a characteristic vestibular finding in Ménière's disease. In the acute stage, spontaneous nystagmus beating to the affected side (irritative nystagmus) is often observed, while paralytic nystagmus beating to the healthy side is found in the chronic stage. This direction-changing nystagmus can be reproduced in guinea pigs by increasing the potassium ion concentration in the perilymph. The objectives of the present study were to examine the effects of increasing the potassium ion concentration of the rat perilymph on hearing and nystagmus. Under isoflurane anesthesia, 22 rats received intratympanic injection of different concentrations of potassium chloride (KCl) solution or distilled water: groups 1, 2, 3, and 4 received saturated (3.4 M) KCl solution, 2 M KCl, 1 M KCl, and distilled water, respectively. The nystagmus direction and number per 15 s were monitored for 150 min. In the other 8 rats, hearing was monitored 30 min and 20 h after intratympanic injection of 2 M KCl (group 5) or distilled water (group 6) using the auditory brainstem responses. Rats in groups 1 and 2 showed spontaneous irritative nystagmus beating to the affected ear followed by paralytic nystagmus beating to the contralateral side. In group 3, irritative nystagmus occurred but paralytic nystagmus was rarely observed. Rats in group 4 showed no nystagmus. Rats in group 5 showed significant hearing impairment 30 min after KCl injection that recovered 20 h later. Control animals in group 6 showed no significant changes in hearing. The reversible hearing impairment with direction-changing spontaneous nystagmus induced by potassium injection into the tympanic cavity in rats was quite similar to that observed in acute Ménière's attacks. This rat model could be used for basic research investigating the pathophysiological mechanisms underlying Ménière's attacks.
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Modelos Animales de Enfermedad , Audición/fisiología , Enfermedad de Meniere/inducido químicamente , Nistagmo Patológico/inducido químicamente , Cloruro de Potasio , Animales , Inyección Intratimpánica , Masculino , Enfermedad de Meniere/fisiopatología , Nistagmo Patológico/fisiopatología , Ratas , Ratas WistarRESUMEN
ATP in the suburothelial layer is released from the bladder urothelium by mechanical stimuli. ATP directly activates purinergic receptors that are expressed on primary bladder afferent neurons and induces the micturition reflex. Although ATP is also released to the bladder lumen from the bladder urothelium, the role of ATP in the bladder lumen is unknown. Recently, clinical studies have reported that urinary ATP levels are much higher in patients with an overactive bladder than healthy controls. These results suggest that ATP in the bladder lumen is also involved in the micturition reflex. In this study, we performed intravesical ATP instillation in the mouse bladder. We evaluated urinary function with novel reliable methods using improved cystometry and ultrasonography, which we previously established. We found that intravesical ATP instillation induced urinary frequency because of activation of bladder afferent nerves without inflammatory changes in the bladder or an increase in post-void residual urine. These results suggest that not only ATP in the suburothelial layer, but also ATP in the bladder lumen, are involved in enhancement of the micturition reflex.
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Adenosina Trifosfato/farmacología , Inflamación/patología , Neuronas Aferentes/patología , Vejiga Urinaria Hiperactiva/patología , Vejiga Urinaria/inervación , Micción/efectos de los fármacos , Adenosina Trifosfato/administración & dosificación , Administración Intravesical , Animales , Modelos Animales de Enfermedad , Masculino , Ratones Endogámicos C57BL , Neuronas Aferentes/efectos de los fármacos , Tamaño de los Órganos , Proteínas Proto-Oncogénicas c-fos/metabolismo , Médula Espinal/efectos de los fármacos , Médula Espinal/patología , Vejiga Urinaria/efectos de los fármacos , Vejiga Urinaria/patologíaRESUMEN
The study of inner ear specific transcripts has revealed novel information about hereditary hearing loss and a mechanism of normal hearing. In this study, by analyzing a published cDNA library, we focused on Epiphycan (Epyc), a member of the small leucine-rich repeat proteoglycan family, whose transcript is enriched in the inner ear. Epyc mRNA was expressed abundantly and specifically in adult mice cochleae and was localized in supporting cells within the organ of Corti of both neonatal and adult mice. To examine the function of Epyc, we generated Epyc knockout (KO) mice using the CRISPR/Cas9 system. Epyc KO mice cochleae exhibited normal morphology. However, measurement of the auditory brain-stem response in Epyc KO mice revealed an elevated hearing threshold above 16 kHz frequency. This study suggests that Epyc is necessary for normal auditory function.
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Cóclea/citología , Cóclea/metabolismo , Audición/fisiología , Proteoglicanos Pequeños Ricos en Leucina/genética , Animales , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteoglicanos Pequeños Ricos en Leucina/deficiencia , Proteoglicanos Pequeños Ricos en Leucina/metabolismoRESUMEN
AIM: Bladder functional disorders are common health problems; however, their pathologies are poorly understood. Adenosine triphosphate (ATP) released from the urothelium has been suggested to have an essential role in the micturition reflex, and its involvement in bladder functional disorders has been intensively investigated. Here, we review the latest advances in research on urothelial ATP signaling. METHODS: We reviewed research articles on the role of the urothelium and urothelial ATP release in bladder function. RESULTS: Mice lacking purinergic receptors have been reported to exhibit marked bladder hyporeflexia. Based on this observation, it was commonly believed, according to the widely held ATP urothelial signaling theory, that stretch-induced urothelial ATP release mediates the sensation of bladder filling via purinergic receptors. However, recent studies employing novel experimental methods and approaches have demonstrated that there are no significant differences in bladder function between wild-type and purinergic receptor knockout mice under physiological conditions. Nonetheless, under pathological conditions, inhibition of purinergic receptors has been shown to improve bladder hyperactivity. Moreover, enhanced urothelial ATP release has been reported in patients with bladder functional disorders. CONCLUSIONS: Recently, conflicting evidence has led us to question the role of urothelial ATP signaling in normal micturition reflex. In contrast, under pathological conditions, it seems likely that enhanced urothelial ATP signaling mediates bladder hyperactivity. These recent findings suggest that the urothelial ATP signaling pathway is a potential therapeutic target for bladder functional disorders.
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Adenosina Trifosfato/metabolismo , Sensación/fisiología , Enfermedades de la Vejiga Urinaria/fisiopatología , Vejiga Urinaria/fisiología , Micción/fisiología , Urotelio/metabolismo , Humanos , Transducción de Señal , Vejiga Urinaria/metabolismo , Enfermedades de la Vejiga Urinaria/metabolismoRESUMEN
Serotonin [5-hydroxytryptamine (5-HT)] is involved in both motor and sensory functions in hollow organs, especially in the gastrointestinal tract. However, the involvement of 5-HT in visceral sensation of the urinary bladder remains unknown. Because distention-induced ATP release from the urothelium plays an essential role in visceral sensation of the urinary bladder, we investigated the regulation of urothelial ATP release by the 5-HT signaling system. RT-PCR and immunohistochemical analyses of the urothelium revealed specific expression of 5-HT1D and 5-HT4 receptors. The addition of 5-HT did not affect urothelial ATP release without bladder distention, but it significantly reduced distention-induced ATP release by physiological pressure during urine storage (5 cmH2O). The inhibitory effect of 5-HT on distention-elicited ATP release was blocked by preincubation with the 5-HT1B/1D antagonist GR-127935 but not by the 5-HT4 antagonist SB-204070. mRNA encoding tryptophan hydroxylase 1 was detected in the urinary bladder by nested RT-PCR amplification, and l-tryptophan or the selective serotonin reuptake inhibitor citalopram also inhibited ATP release, indicating that 5-HT is endogenously synthesized and released in the urinary bladder. The addition of GR-127935 significantly enhanced the distention-elicited ATP release 40 min after distention, whereas SB-204070 reduced the amount of ATP release 20 min after distention. These data suggest that 5-HT4 facilitates the distention-induced ATP release at an earlier stage, whereas 5-HT1D inhibits ATP release at a later stage. The net inhibitory effect of 5-HT indicates that the action of 5-HT on the urothelium is mediated predominantly by 5-HT1D.
Asunto(s)
Adenosina Trifosfato/metabolismo , Receptor de Serotonina 5-HT1D/metabolismo , Receptores de Serotonina 5-HT4/metabolismo , Serotonina/farmacología , Vejiga Urinaria/metabolismo , Urotelio/metabolismo , Animales , Citalopram/farmacología , Dioxanos/farmacología , Masculino , Ratones , Oxadiazoles/farmacología , Piperazinas/farmacología , Piperidinas/farmacología , Antagonistas de la Serotonina/farmacología , Inhibidores Selectivos de la Recaptación de Serotonina/farmacología , Vejiga Urinaria/efectos de los fármacos , Urotelio/efectos de los fármacosRESUMEN
Transient receptor potential vanilloid (TRPV) 4 is a nonselective cation channel expressed in sensory neurons such as those in the dorsal root and trigeminal ganglia, kidney, and inner ear. TRPV4 is activated by mechanical stress, heat, low osmotic pressure, low pH, and phorbol derivatives such as 4α-phorbol 12,13-didecanoate (4α-PDD). We investigated the expression of TRPV4 in rat vestibular ganglion (VG) neurons. The TRPV4 gene was successfully amplified from VG neuron mRNA using reverse-transcription polymerase chain reaction. Furthermore, immunoblotting showed positive expression of TRPV4 protein in VG neurons. Immunohistochemistry indicated that TRPV4 was localized predominantly on the plasma membrane of VG neurons. Calcium (Ca2+) imaging of VG neurons showed that 4α-PDD and/or hypotonic stimuli caused an increase in intracellular Ca2+ concentration ([Ca2+]i) that was almost completely inhibited by ruthenium red, a selective antagonist of TRPV channels. Interestingly, a [Ca2+]i increase was evoked by both hypotonic stimuli and 4α-PDD in approximately 38% of VG neurons. These data indicate that TRPV4 is functionally expressed in VG neurons as an ion channel and that TRPV4 likely participates in VG neurons for vestibular neurotransmission as an osmoreceptor and/or mechanoreceptor.
Asunto(s)
Ganglios Sensoriales/metabolismo , Neuronas/metabolismo , ARN Mensajero/metabolismo , Canales Catiónicos TRPV/genética , Nervio Vestibular/metabolismo , Animales , Calcio/metabolismo , Ganglios Sensoriales/efectos de los fármacos , Neuronas/efectos de los fármacos , Forboles/farmacología , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Canales Catiónicos TRPV/metabolismo , Nervio Vestibular/efectos de los fármacosRESUMEN
Various animal models have been used in research into bladder dysfunction, and in vivo cystometry is a common method to analyze bladder function in animals. However, it is rather difficult to perform reliably in small animals. Transabdominal bladder ultrasonography combined with cystometry in urethane-anesthetized mice have revealed physical inhibition of bladder wall movement by a bladder catheter conventionally placed in the bladder apex. For reliable evaluation of mouse lower urinary tract function, we established a novel cystometry method in which a catheter was placed in the bladder anterior wall, in combination with bladder ultrasonography. This new method allowed the bladder to be well distended (i.e., larger maximum bladder capacity, lower pressure threshold, higher voided volume, and higher bladder compliance compared with conventional methods), which reflected more spontaneous voiding than conventional cystometry methods. We also demonstrated the usefulness of bladder ultrasonography for analysis of mouse bladder function, especially bladder dynamics, maximum bladder capacity, and post-voiding residual volume. We analyzed bladder functional changes in lipopolysaccharide (LPS)-induced cystitis by combining bladder ultrasonography and this new cystometry method. Bladder ultrasonography revealed a rapid decrease in bladder capacity, and cystometry showed a rapid decrease in voided volume due to intravesical LPS instillation. This new cystometry method also revealed a rapid decrease in bladder compliance caused by LPS instillation, which was not detectable by conventional methods. The combination of ultrasonography and the new cystometry method may become a powerful tool for analysis of mouse bladder function and could contribute to the development of new treatments for bladder dysfunction.
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Cistitis/diagnóstico por imagen , Cistitis/fisiopatología , Endotoxinas , Vejiga Urinaria/diagnóstico por imagen , Vejiga Urinaria/fisiopatología , Cateterismo Urinario/métodos , Animales , Catéteres de Permanencia , Adaptabilidad , Cistitis/inducido químicamente , Modelos Animales de Enfermedad , Masculino , Ratones , Ratones Endogámicos C57BL , Valor Predictivo de las Pruebas , Presión , Factores de Tiempo , Ultrasonografía , Cateterismo Urinario/instrumentación , Catéteres Urinarios , UrodinámicaRESUMEN
The 5-HT3 receptor, the only ionotropic 5-HT receptor, is expressed in limbic regions, including the hippocampus, amygdala, and cortex. However, it is not known whether it has a role in fear memory processes. Analysis of 5-HT3A receptor knockout mice in fear conditioning paradigms revealed that the 5-HT3A receptor is not required for the acquisition or retention of fear memory but is essential for the extinction of contextual and tone-cued fear. Our data suggest that the 5-HT3A receptor could be a key molecule regulating fear memory processes and a potential therapeutic target for fear disorders.
Asunto(s)
Extinción Psicológica/fisiología , Miedo/fisiología , Memoria/fisiología , Receptores de Serotonina 5-HT3/fisiología , Análisis de Varianza , Animales , Encéfalo/metabolismo , Condicionamiento Clásico/fisiología , Electrochoque/efectos adversos , Masculino , Aprendizaje por Laberinto/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores de Serotonina 5-HT3/deficienciaRESUMEN
The progression of small bowel ischemia-reperfusion (IR) injury causes cells in the intestinal tract to undergo necrosis, necessitating surgical resection, which may result in loss of intestinal function. Therefore, developing therapeutic agents that can prevent IR injury at early stages and suppress its progression is imperative. As IR injury may be closely related to oxidative stress, antioxidants can be effective therapeutic agents. Our silicon (Si)-based agent, an antioxidant, generated a large amount of hydrogen in the intestinal tract for a prolonged period after oral administration. As it has been effective for ulcerative colitis, renal failure, and IR injury during skin flap transplantation, it could be effective for small intestinal IR injury. Herein, we investigated the efficacy of an Si-based agent in a mouse model of small intestinal IR injury. The Si-based agent suppressed the apoptosis of small intestinal epithelial cells by reducing the oxidative stress induced by IR injury. In addition, the thickness of the mucosal layer in the small intestine of the Si-based agent-administered group was significantly higher than that in the untreated group, revealing that Si-based agent is effective against small intestinal IR injuries. In the future, Si-based agents may improve the success rate of small intestine transplantation.