Localization of EP(1) and FP receptors in human ocular tissues by in situ hybridization

To examine the expression and localization of EP(1) and FP receptor mRNAs in normal human ocular tissues by in situ hybridization.

Digoxigenin-labeled human EP(1) and FP receptor antisense and sense riboprobes were used for in situ hybridization on paraffin sections of normal human eye tissue.

In situ hybridization revealed the presence of high levels of both EP(1) and FP receptor mRNA transcripts in the blood vessels of iris, ciliary body, and choroid. Both the endothelial and smooth muscle cells of blood vessels demonstrated intense hybridization signals corresponding to EP(1) receptor mRNA transcript. EP(1) receptor hybridization signals were present in all the muscle fibers of the ciliary body. In the retina, hybridization signals for EP(1) receptors were observed in photoreceptors and both nuclear layers and in ganglion cells. The hybridization signals corresponding to FP receptor transcript were similar to those of EP(1) receptors in the iris tissues. In the ciliary muscle, FP receptor mRNA transcript was predominantly present in the circular muscle and in the collagenous connective tissues; no hybridization signal for this receptor was observed in the retina.

The wide distribution of EP(1) and FP receptor mRNAs in human ocular tissues appears to be localized in the functional sites of the respective receptor agonists. Selective localization of FP receptor mRNA in the circular muscles and collagenous connective tissues of the ciliary body suggests their involvement in the increased uveoscleral outflow of aqueous humor by PGF(2alpha).