Antiasthmatic effects of evening primrose oil in ovalbumin-allergic rats

Asthma is one of the most common long-term conditions worldwide, which places considerable pressure on patients, communities and health systems. The uses of complementary and alternative medicines (CAMs) adjunctively to minimize the need for conventional therapies and hence avoid the profound side-effect profiles.Hence the effects of evening primrose oil (PO) alone or combined with dexamethasone (DEX) have been evaluated on bronchial asthma. we investigated the chronic effect of oval albumin (OVA) in a rat model of allergic asthma. Rats were sensitized to OVA (1 mg/kg; i.p.) for 3 consecutive days, rats were pretreated orally with DEX (1mg/kg), PO alone in three doses(1, 2 and 3 g/kg), PO (1.5 g/kg) combined with DEX (0.5 mg/kg) and saline 1h before exposure to 1% OVA aerosol challenge (1 day/week for 3 weeks) then compared with positive control rats (OVA rats). Lung function tests were assessed after the last challenge and 24 h thereafter, blood films were prepared for assessment of eosinophil count and blood samples were collected for assessment of serum total protein as well as immunoglobulin E (Ig-E) levels. Lungs were isolated for histopathological study and also for determination of tumor necrosis factor-alpha (TNF-α) content in lung tissue . Additionally the effects of test agents were evaluated in acetyl choline (ACh)-induced airway constriction. PO alone and combined with DEX modulate Ig-E, TNF-α, eosinophil recruitment, airway constriction and remodelling. In conclusions, PO alone or combined with a lower dose of DEX possesses antiasthmatic effects.