Analysis of the expression and the first exon of aromatase mRNA in monkey brain

To elucidate the mechanism of the region-specific expression of the aromatase in the primate brain, we investigated the distribution and level of the total aromatase mRNA and the aromatase mRNA with the exon 1-f, which was reported to be the brain-specific exon 1 of the human aromatase gene, in male Japanese monkeys. Total RNAs extracted from the hypothalamus-preoptic area (HPOA), amygdala (AMY), cerebellum, hippocampus, brainstem, five regions of cerebral cortex and four peripheral tissues: liver, kidney, adipose tissue and testis were subjected to a semi-quantitative reverse transcription-polymerase chain reaction-Southern blotting (RT-PCR-SB) assay. The levels of the total aromatase mRNA was high in the HPOA, AMY and testis with a low level of message in the other regions. These results roughly paralleled the distribution of aromatase activity of the monkey brain previously reported. The level of the aromatase mRNA with the exon 1-f was high in the HPOA and AMY, and low in the other regions of the brain and the testis with an undetectable level of the messenger in the other peripheral tissues. Furthermore, the ratio of the aromatase mRNA with the exon 1-f to the total aromatase mRNA was different among various regions of the monkey brain, for example, the ratio in the AMY was distinctly higher than that in the HPOA. These results indicated that the level of the aromatase mRNA mainly regulated the level of aromatase protein and aromatase activity in a region-specific manner, and that the exon 1-f was used in most of the monkey brain regions. Moreover, the ratio of the aromatase mRNA with the exon 1-f to the total aromatase mRNA varied in the brain regions. It was implied that the aromatase mRNA using the other first exons was also expressed in the brain and was involved in the region-specific expression of the brain aromatase.