Effect of Pycnogenol® on an experimental rat model of allergic conjunctivitis

Background Allergic conjunctivitis (AC) is a frequent and challenging disease in ophthalmology practice. Cell protective effect of Pycnogenol ® (PYC) depends on its antioxidant and anti-inflammatory properties. The aim of the study is to investigate the effect of PYC on an experimental AC model. Methods Ovalbumin and Al(OH) 3 were given seven times intraperitoneally (i.p.) every other day and ovalbumin installed everyday directly on conjunctiva to create an AC rat model. Then, PYC (3 or 10 mg/kg i.p.) was applied in the study groups. Control rats were given adjuvant Al(OH) 3 i.p. and topical saline on conjunctiva. A negative control group in which only PYC (10 mg/kg/7 days) was administered i.p. and an AC positive control group which have been given dexamethasone (1 mg/kg/7 days) was created. Mast cells were counted with a microscope; histological evaluation was performed with H-E and toluidine blue, mast cell tryptase, and TNF-α and TGF-β staining. Results Pycnogenol treatment alone did not show any detrimental effect. Mast cell count (MCC) decreased in both dexamethasone and 10 mg/kg given PYC treatment groups compared to positive control group and these results were statistically significant (MCC 1.85 ± 0.69, p