Presence of oestrogen receptor type beta in human retina

Background/aims-Recent studies have demonstrated the existence of two oestr ogen receptor subtypes alpha (OR alpha) and beta (OR beta) with significant differences of expression among organs. Since important pathologies of hum an eye could be linked to hormonal status, the expression of OR beta in ocu lar posterior segment was sought. Methods-Immunohistochemical localisation of OR beta and OR alpha protein an d detection of OR mRNAs by reverse transcription-polymerase chain reaction (RT-PCR) were performed in macular and extramacular regions of the retina a nd in the choroid on male and female donors eyes. Results-OR beta protein was localised in the ganglion cell layer and in the choroid. At the transcriptional level, mRNA for OR beta and for OR alpha w ere both present. Local differences in the expression level were observed, however, suggesting the possibility of variation in the ratio of OR alpha v OR beta. Conclusions-The coexistence of two oestrogen receptor subtypes in the human ocular posterior segment raises acute questions about their potential phys iological role, but offers a perspective for preferential targeting of a sp ecific receptor subtype.