ANALYSIS OF THE EXPRESSION AND THE FIRST EXON OF AROMATASE MESSENGER-RNA IN MONKEY BRAIN

To elucidate the mechanism of the region-specific expression of the ar omatase in the primate brain, we investigated the distribution and lev el 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 aro matase gene, in male Japanese monkeys. Total RNAs extracted from the h ypothalamus-preoptic area (HPOA), amygdala (AMY), cerebellum, hippocam pus, brainstem, five regions of cerebral cortex and four peripheral ti ssues: liver, kidney, adipose tissue and testis were subjected to a se mi-quantitative reverse transcription-polymerase chain reaction-Southe rn 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 th e 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 undet ectable level of the messenger in the other peripheral tissues. Furthe rmore, 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 mRN A mainly regulated the level of aromatase protein and aromatase activi ty 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 mRN A with the exon 1-f to the total aromatase mRNA varied in the brain re gions. It was implied that the aromatase mRNA using the other first ex ons was also expressed in the brain and was involved in the region-spe cific expression of the brain aromatase.