Effect of cAMP and cGMP on Connexin43 Expression in Isolated Human and Bovine Ciliary Epithelium

Abstract

The aim of the study was to assess the distribution of connexin43 (Cx43) and connexin40 (Cx40) in human and bovine ciliary bodies. The effect of the second messengers cAMP and cyclic cGMP on Cx43 protein expression was also investigated. Enucleated human eyes (remnant after corneal transplantation) and bovine eyes were used. Tissue preparations of the anterior segments of the eyes have proceeded for immunohistochemical staining with polyclonal antibodies of Cx43 and Cx40. Isolated ciliary bodies of human and bovine eyes were incubated with cAMP analog 8-Bromo-cAMP or the cGMP analog 8-Bromo-cGMP, the expression of Cx43 protein in the tissues was then assessed by Western blot assay. Both in human and bovine ciliary bodies, strong immunoreactivity of Cx43, but not Cx40, was observed predominantly in the apical cytoplasmic portions of the pigment ciliary epithelial cells and non-pigmented ciliary epithelial cells. In human ciliary body both cAMP and cGMP up-regulated Cx43 expression, while in the bovine ciliary body, cGMP increased Cx43 expression but cAMP decreased it. Cx43 is the major component of human and bovine gap junctions in the ciliary epithelium. The regulation on the Cx43 expression by cAMP and cGMP in human and bovine ciliary bodies suggests the possibly different roles of these signal messengers in the intracellular communication.