Ligustrazine Inhibits Lung Phosphodiesterase Activity in a Rat Model of Allergic Asthma

Abstract

Objectives. This study sought to examine whether ligustrazine was capable of inhibiting phosphodiesterase (PDE) activity and improving lung function in a rat model of asthma. Methods. Rats were initially sensitized using ovalbumin (OVA) and then were challenged daily with aerosolized OVA beginning 14 days later (30 min/day) to generate a rat model of asthma. Changes in airway function following methacholine (MCh) injection were evaluated by monitoring lung resistance ( $R_{\text{L}}$ ) and dynamic lung compliance ( $C_{\text{dyn}}$ ) values using an AniRes2005 analytic system. In addition, serum IgE was measured via ELISA, while PDE expression was evaluated via qPCR and western blotting. Key Findings. Ligustrazine significantly impaired allergen-induced lung hyperresponsivity and inflammation in this asthma model system. Ligustrazine treatment was also associated with reduced expression of PDEs including PDE4 in the lungs of these rats. Conclusions. Ligustrazine suppresses airway inflammation and bronchial hyperresponsivity in this rat model system, and these changes are associated with decreased PDE expression at the protein and mRNA levels.