Localization of receptors for luteinizing hormone/chorionic gonadotropin in neural retina

Although the expression of the luteinizing hormone (LH)/human chorionic gonadotropin (CG) receptor gene has been traditionally thought to be restricted to gonadal tissue, recent studies have shown that LH/CG receptors are present in many regions of the central nervous system (CNS), as well as in peripheral tissues. We now report the characterization of LH/CG receptor gene expression in the neural retina, a component of the CNS. Transcript levels in the retina are approximately equal to levels present in the cerebral cortex, but are at least 100 fold lower than the levels in testis. The density of LH/CG receptor transcripts, receptor protein and 125I-CG binding is the highest in the photoreceptor cells and then decreased throughout the inner retina. Our study is the first to demonstrate the presence of LH/CG receptors in the neural retina. This finding raises the possibility that photoreceptor cells have the potential to mount cellular responses to LH/CG that may impact on visual processing, and poses an intriguing connection to the proposed role of gonadotropins in the progression of proliferative retinopathy.