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

Abstract

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.

Keywords: biological evaluation of natural products; tissue and cellular pharmacology.