Preventive Effect of an Extract of Terminalia avicennioides on Acetylcholine-Induced Tracheoconstriction in Wistar Strain Rats

Asthma is one of the most common chronic respiratory pathologies worldwide. The cost of its treatment, particularly for populations in developing countries like Senegal, requires an alternative which consists of developing research into new therapeutic approaches with the use of plants from traditional pharmacopoeia. The objective of this study was to determine whether the hydroalcoholic extract of Terminalia avicennioides leaves has a preventive effect on the constriction of tracheal smooth muscle induced by Acetylcholine in Wistar strain rats. Methods: The species used in our experiments were male Wistar rats aged between 12 and 14 weeks. Rings of rat trachea were suspended in isolated organ chambers connected to tension sensors. Two pharmacological agents were used: acetylcholine, for its constrictor effect and adrenaline, for its dilating effect on the pulmonary trachea. Our plant material consisted of a hydroalcoholic extract of Terminalia avicennioides leaves. The experimental protocol was that of the preventive model which consisted of impregnating these rings with the extract at a defined concentration then testing its contractility in the presence of Acetylcholine which was the contractile agonist used in this study. The preventive effect of the extract was studied with an Acetylcholine contraction range on rings pre-incubated with Terminalia avicennioides extract. Results: The results showed that Acetylcholine contracts the trachea and the increase in its contractility was dependent on the dose of Ach added cumulatively (10−5 to 4 × 10−5 mol/l). The administration of the hydroalcoholic extract of Terminalia avicennioides leaves led to a modification of the contractile response to Acetylcholine. Indeed, this extract induced a significant attenuation of the contractile responses of the treated tracheal rings compared to those untreated. Conclusion: Terminalia avicennioides had a relaxing effect on tracheal smooth muscle and this effect could play an important role in the prevention of bronchial hyperreactivity in certain respiratory diseases, particularly asthmatic disease.

Effects of phosphodiesterase 4 inhibitor on cough response in guinea pigs sensitized and challenged with ovalbumin

BACKGROUND: There is currently considerable interest in the potential value of selective inhibitors of cyclic nucleotide phosphodiesterase 4 in the treatment of asthma. However, whether they influence eosinophilic airway inflammation-associated cough remains unclear. The objective of this study was to investigate the effects of selective phosphodiesterase 4 inhibitor SB207499 on cough response and airway inflammation in guinea pigs sensitized and challenged with ovalbumin. METHODS: Forty sensitized guinea pigs were randomly divided into four groups: control (n = 10), challenge (n = 10), SB207499 (n = 10) and aminophylline (n = 10), then challenged with aerosol of 1% ovalbumin or saline. Two hours later, animals were intraperitoneally injected with either saline, 25 mg/kg of SB207499 or aminophylline. At the 24th hour, the injection was repeated with 2.5 mg/kg and 25 mg/kg SB207499 or aminophylline, then cough response to inhaled capsaicin and airway responsiveness to methacholine inducing a 150% of the peak airway pressure to the baseline (PC150) was measured. Finally, total cell number and differentials in bronchoalveolar lavage fluid were analysed. RESULTS: The cough frequency per 3 minutes and PC150 in the challenge group were (22 +/- 4) times/3 minutes and (198 +/- 54) microg/ml, which were significantly different from (6 +/- 2) times/3 minutes and (691 +/- 81) microg/ml in the control group (P