Putative estrogen receptor beta and alpha mRNA expression in male and female rhesus macaques

The profound effects of estrogen on different tissues may involve at least two estrogen receptor (ER) subtypes, ERalpha and the recently discovered ERbeta. Where and how the two ER subtypes differentially or cooperatively mediate estrogen actions, however, are still unknown. In this study, we report the cloning of a specific ERbeta cDNA fragment and the expression of ERalpha and ERbeta mRNAs in various endocrine and non-endocrine tissues of male and female rhesus macaques. Total RNA from monkey tissues was isolated and subjected to reverse transcription-polymerase chain reaction (RT-PCR) using human-specific ERbeta primers. A 126 bp RT-PCR product was identified in ovarian tissue and subsequently transfected into pGEM-T vectors for DNA sequencing. The cloned rhesus monkey ERbeta fragment contained a sequence nearly identical to the corresponding sequence in the human (four mismatched nucleotides out of 126). Because complete monkey ERbeta and ERalpha DNA sequences have not been established, the expression of the ERbeta and ERalpha fragments in monkey tissues by RT-PCR reflects 'putative' ERbeta and ERalpha mRNA expression, respectively. Both ERbeta and ERalpha mRNAs were present in male and female reproductive organs, in several endocrine and non-endocrine tissues, and in various regions of the brain, whereas several tissues, including liver, frontal cortex, caudate nucleus, locus coeruleus and cerebellum, expressed only ERalpha message. In some brain regions, i.e. the putamen, internal capsule, hippocampus and paraventricular hypothalamus, the ERbeta fragment was expressed in the female but not in the male. These data suggest that ERalpha mRNA is widely distributed in both female and male tissues, while ERbeta mRNA is more widely distributed in female than in male brain.