Protector mechanisms of the association between gastroesophageal reflux disease and asthma: experimental study in rats

Abstract

-Background -It is well known the association between gastroesophageal reflux disease and asthma. The hyperreactivity of the airways is a characteristic of an asthmatic. Many studies associate the increase of the airways reactivity with gastroesophageal reflux disease. Aim -In this study we have evaluated the effect of the intraluminal exposition to gastric juice of trachea on the reactivity to methacholine from rats submitted to a pulmonary allergic inflammation. Methods -Group of rats were sensitized and challenged with ovalbumin. After 24 hours the animals were sacrificed, and their tracheae were removed to be cultured with gastric juice. The gastric juice was obtained from a donor rat. Subsequently the segments were placed into plastic plates with RPMI-1640 for incubation, under suitable atmosphere and time.After the period of incubation the segments were put into chambers for the analysis of the contractile response to methacholine. ResultsWe observed reduction in the contractile response of trachea cultured with gastric juice from allergic rats. This result was confirmed by the pharmacological treatments with compound 48/80 and dissodium cromoglicate (mast cells blockade), L-NAME (nitric oxide inhibitor, NO), capsaicin (neuropeptides depletion) and indomethacin (ciclooxigenase inhibitor). Conclusions -Our results highlight to the existence of a complex interaction between pulmonary allergy and gastric juice in the airways. The involvement of the non-adrenergic non-cholinergic system, NO, prostanoids and mast cells are directly related to this interaction. We suggest that the reduced contractile response observed in vitro may represent a protector mechanism of the airways. Despite its presence in the human body it can not be observed due to the predominant effects of excitatory the non-adrenergic non-cholinergic system.

Relaxing effect of a new ruthenium complex nitric oxide donor on airway smooth muscle of an experimental model of asthma in rats

“…These results show an important therapeutic effect of TERPY in airways from asthmatic rats. However, the main criticism of rodents as asthma models is the tolerance they develop with increasing allergen challenges . Although the development of tolerance is considered a disadvantage, some research considers it to be a good model for understanding allergic disease .…”

“…It is known that rats develop both immediate and late asthmatic responses after an allergen or nonspecific challenge . In addition, rats are easier than mice to sensitize when using OVA and to challenge with Al(OH) 3 …”

“…However, the main criticism of rodents as asthma models is the tolerance they develop with increasing allergen challenges. 28,29 Although the development of tolerance is considered a disadvantage, some research considers it to be a good model for understanding allergic disease. 28,30 OVA, the most commonly-used allergenic compound in immunology, is known to cause occupational asthma in both humans and animals, which can lead to inflammation with cell migration.…”

“…Asthma was induced in the rats following the Kanikadan and coworkers model but with some modifications. 29 In brief, they were sensitized with an intraperitoneal injection of 100 lg of chicken ovalbumin (OVA) mixed with 10 mg of aluminium hydroxide as adjuvant, 1 mL in total (Day 0). After 7 days, the animals were subcutaneously injected with 100 lg of OVA dissolved in saline (0.5 mL).…”