Intraocular inflammatory disease is first recognized by breakdown of the blood-aqueous barrier with appearance of protein and leukocytes in the anterior chamber. Secondary problems include cataract, cornea! clouding, glaucoma and anterior synechia. Major signs of inflammation are attributed to the release of inflammatory mediators, including the eicosanoids derived from arachidonic acid. The long-term goal of this project is to fully understand the role of eicosanoids and the mechanisms involved in the initiation, sustenance and resolution of ocular inflammation and also to contribute to the development of improved therapy. The action of eicosanoids is mediated through specific receptors located in the cell membrane. Our previous studies have demonstrated that the eye possesses a great diversity of prostanoid receptor subtypes in keeping with the multiple actions of prostanoids in the eye. Our most recent studies have demonstrated that the up and down regulation of prostanoid receptor expression is limited; thus there is a rather stable population of receptors. All our previous work has created an excellent platform or bridge to undertake in vivo studies which can link the receptors to specific physiological events. To take advantage of current molecular technology we will explore receptor function in the mouse eye where we can readily manipulate the expression of receptors in the living animal. We will test the hypothesis that different subtypes of prostaglandin receptors mediate specific inflammatory responses in vivo. First, we will investigate the impact of specific prostaglandin receptor antagonists on the mouse ocular inflammation induced by exogenously applied prostaglandin E2, anterior chamber paracentesis and endotoxin. Then we will confirm specific observations made in these experiments using selective antisense oligonucleotides of prostaglandin receptors. Inflammation will be evaluated by several methods including iris fluorescein angiography and determination of protein and leukocytes in aqueous humor. Receptor function will be monitored by measuring second messenger generation following stimulation by selected prostanoid agonists. Second, we will study inflammatory responses in homozygous and heterozygous PG receptor knockout mice and in transgenic mouse lines over expressing specific PG receptors. These studies will elucidate the link between prostaglandin receptors and ocular inflammatory responses.