611 Immunohistochemical study on the role of substance P in baroreceptor reflex

Abstract Background Abdominal pain is a common complaint in patients with chronic gastrointestinal disorders. Accumulating evidence suggests that gut microbiota is an important determinant of gut function, including visceral sensitivity. Germ-free (GF) mice have been shown to display visceral hypersensitivity, which normalizes after colonization. Sex also appears to play a key role in visceral sensitivity, as women report more abdominal pain than men. Thus, both gut bacteria and sex are important in the regulation of gut nociception, but the underlying mechanisms remain poorly understood. Aims To investigate the role of gut microbiota and sex in abdominal pain. Methods We used primary cultures of sensory neurons from dorsal root ganglia (DRG) of female and male conventionally raised (SPF) or germ-free (GF) mice (7–18 weeks old). To study the visceral afferent activity in vitro, calcium mobilization in DRG sensory neurons was measured by inverted fluorescence microscope using a fluorescent calcium probe Fluo-4 (1mM). Two parameters were considered i) the percentage of responding neurons ii) the intensity of the neuronal response. First, DRG sensory neurons were stimulated by a TRPV1 agonist capsaicin (12.5nM, 125nM and 1.25µM) or by a mixture of G-protein coupled receptors agonist (GPCR: bradykinin, histamine and serotonin; 1µM, 10µM and 100µM). We next measured the neuronal production of substance P and calcitonin gene-related peptide (CGRP), two neuropeptides associated with nociception, in response to capsaicin (1.25µM) or GPCR agonists (100µM) by ELISA and EIA, respectively. Results The percentage of neurons responding to capsaicin and GPCR agonists was similar in male and female SPF and GF mice. However, the intensity of the neuronal response was higher in SPF male compared to SPF female in response to capsaicin (125nM: p=0.0336; 1.25µM: p=0.033) but not to GPCR agonists. Neuronal activation was similar in GF and SPF mice of both sexes after administration of capsaicin or GPCR agonists. Furthermore, substance P and CGRP production by sensory neurons induced by capsaicin or GPCR agonists was similar in SPF and GF mice, regardless of sex. However, while the response to capsaicin was similar, the GPCR agonists-induced production of substance P was higher in SPF male mice compared to SPF females (p=0.003). The GPCR agonists-induced production of CGRP was similar in SPF male and female mice. Conclusions Our data suggest that at the level of DRG neurons, the absence of gut microbiota does not predispose to visceral hypersensitivity. The intensity of DRG neuronal responses to capsaicin and the GPCR agonists-induced production of substance P are higher in male compared to female mice, in contrast to previously published studies in various models of acute and chronic pain. Further studies are thus needed to investigate the role of sex in visceral sensitivity. Funding Agencies CIHR

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CD206+ macrophage is an accelerator of endometriotic-like lesion via promoting angiogenesis in the endometriosis mouse model

Scientific Reports ◽

10.1038/s41598-020-79578-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yosuke Ono ◽

Osamu Yoshino ◽

Takehiro Hiraoka ◽

Erina Sato ◽

Akiko Furue ◽

...

Keyword(s):

Mouse Model ◽

Diphtheria Toxin ◽

Immunohistochemical Study ◽

Mrna Levels ◽

Cytokines And Chemokines ◽

Diphtheria Toxin Receptor ◽

Endothelial Cell Marker ◽

Toxin Receptor ◽

Group A

AbstractIn endometriosis, M2 MΦs are dominant in endometriotic lesions, but the actual role of M2 MΦ is unclear. CD206 positive (+) MΦ is classified in one of M2 type MΦs and are known to produce cytokines and chemokines. In the present study, we used CD206 diphtheria toxin receptor mice, which enable to deplete CD206+ cells with diphtheria toxin (DT) in an endometriosis mouse model. The depletion of CD206+ MΦ decreased the total weight of endometriotic-like lesions significantly (p < 0.05). In the endometriotic-like lesions in the DT group, a lower proliferation of endometriotic cells and the decrease of angiogenesis were observed. In the lesions, the mRNA levels of VEGFA and TGFβ1, angiogenic factors, in the DT group significantly decreased to approximately 50% and 30% of control, respectively. Immunohistochemical study revealed the expressions of VEGFA and an endothelial cell marker CD31 in lesions of the DT group, were dim compared to those in control. Also, the number of TGFβ1 expressing MΦ was significantly reduced compared to control. These data suggest that CD206+ MΦ promotes the formation of endometriotic-like lesions by inducing angiogenesis around the lesions.

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Role of the C Domain of IGFs in Synergistic Promotion, with a Substance P–Derived Peptide, of Rabbit Corneal Epithelial Wound Healing

Investigative Opthalmology & Visual Science ◽

10.1167/iovs.03-0626 ◽

2004 ◽

Vol 45 (4) ◽

pp. 1125 ◽

Cited By ~ 33

Author(s):

Naoyuki Yamada ◽

Ryoji Yanai ◽

Masatsugu Nakamura ◽

Makoto Inui ◽

Teruo Nishida

Keyword(s):

Wound Healing ◽

Substance P ◽

Corneal Epithelial ◽

Epithelial Wound Healing

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Role of substance P in allergic nasal symptoms in rats

European Journal of Pharmacology ◽

10.1016/j.ejphar.2005.12.020 ◽

2006 ◽

Vol 532 (1-2) ◽

pp. 155-161 ◽

Cited By ~ 7

Author(s):

Md. Ashequr Rahman ◽

Toshio Inoue ◽

Chiaki Kamei

Keyword(s):

Substance P ◽

Nasal Symptoms

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Paradoxical effect of salbutamol in a model of acute organophosphates intoxication in guinea pigs: role of substance P release

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00253.2005 ◽

2007 ◽

Vol 292 (4) ◽

pp. L915-L923 ◽

Cited By ~ 10

Author(s):

Jaime Chávez ◽

Patricia Segura ◽

Mario H. Vargas ◽

José Luis Arreola ◽

Edgar Flores-Soto ◽

...

Keyword(s):

Substance P ◽

Guinea Pigs ◽

Smooth Muscle Contraction ◽

In Vivo Experiments ◽

Intracellular Ca ◽

Neurokinin 1 ◽

Substance P Release

Organophosphates induce bronchoobstruction in guinea pigs, and salbutamol only transiently reverses this effect, suggesting that it triggers additional obstructive mechanisms. To further explore this phenomenon, in vivo (barometric plethysmography) and in vitro (organ baths, including ACh and substance P concentration measurement by HPLC and immunoassay, respectively; intracellular Ca2+ measurement in single myocytes) experiments were performed. In in vivo experiments, parathion caused a progressive bronchoobstruction until a plateau was reached. Administration of salbutamol during this plateau decreased bronchoobstruction up to 22% in the first 5 min, but thereafter airway obstruction rose again as to reach the same intensity as before salbutamol. Aminophylline caused a sustained decrement (71%) of the parathion-induced bronchoobstruction. In in vitro studies, paraoxon produced a sustained contraction of tracheal rings, which was fully blocked by atropine but not by TTX, ω-conotoxin (CTX), or epithelium removal. During the paraoxon-induced contraction, salbutamol caused a temporary relaxation of ∼50%, followed by a partial recontraction. This paradoxical recontraction was avoided by the M2- or neurokinin-1 (NK1)-receptor antagonists (methoctramine or AF-DX 116, and L-732138, respectively), accompanied by a long-lasting relaxation. Forskolin caused full relaxation of the paraoxon response. Substance P and, to a lesser extent, ACh released from tracheal rings during 60-min incubation with paraoxon or physostigmine, respectively, were significantly increased when salbutamol was administered in the second half of this period. In myocytes, paraoxon did not produce any change in the intracellular Ca2+ basal levels. Our results suggested that: 1) organophosphates caused smooth muscle contraction by accumulation of ACh released through a TTX- and CTX-resistant mechanism; 2) during such contraction, salbutamol relaxation is functionally antagonized by the stimulation of M2 receptors; and 3) after this transient salbutamol-induced relaxation, a paradoxical contraction ensues due to the subsequent release of substance P.

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