Inhibitory effects of a standardized extract of Justicia pectoralis in an experimental rat model of airway hyper‐responsiveness

Objective Justicia pectoralis is a plant useful for the treatment of respiratory diseases. Here, we studied the antiasthmatic properties of a standardized extract of J. pectoralis (Jp). Methods Ovalbumin (OVA)‐sensitized rats were actively challenged with saline or OVA to study airway hyper‐responsiveness after oral treatment with saline or Jp. The ability of Jp to inhibit hyper‐reactivity was evaluated in isolated trachea mounted in isolated organ bath chamber. Key findings Using KCl or carbachol as contractile agents, tracheal rings of OVA‐challenged rats contracted with higher magnitude than trachea of rats challenged with saline. Such hyper‐responsive phenotype of OVA‐challenged tissues decreased with Jp administration. In Ca+‐free medium, Jp or its major constituent coumarin inhibited preferentially the contractions induced by Ca2+ addition in tissues of OVA‐challenged rats stimulated with KCl or acetylcholine. In tissues depleted of their internal Ca+ stores in the presence of thapsigargin, Jp inhibited the contraction induced by capacitative Ca2+ entry. By gavage, Jp abolished the increase caused by challenge with OVA on the levels of IL‐1β and TNF‐α in the bronchoalveolar fluid and also impaired the changes in gene expression of canonical transient receptor proteins. Conclusions Jp has antiasthmatic properties in an experimental model that reproduces tracheal hyper‐reactivity.