Putative estrogen receptor β and α 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, ER alpha and the recently discovered ER beta. 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 ER beta cDNA fragment and the expression of ER alpha and ER beta 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 ER beta 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 ER beta fragment contained a sequence nearly identical to the corresponding sequence in the human (four mismatched nucleotides out of 126). Because complete monkey ER beta and ER alpha DNA sequences have not been established, the expression of the ER beta and ER alpha fragments in monkey tissues by RT-PCR reflects 'putative' ER beta and ER alpha mRNA expression, respectively. Both ER beta and ER alpha 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 ER alpha message. In some brain regions, i.e. the putamen, internal capsule, hippocampus and paraventricular hypothalamus, the ER beta fragment was expressed in the female but not in the male. These data suggest that ER alpha mRNA is widely distributed in both female and male tissues, while ER beta mRNA is more widely distributed in female than in male brain. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.