Hydroxysteroid sulfotransferase (HS-ST) is thought to be a key enzyme in the synthesis of neurosteroid sulfates, which are known to act as potent regulators of neuronal activity within the brain. In rat liver, three isoforms of HS-ST (ST2A1, ST2A2 and ST2A5) have now been identified and to further elucidate the precise contribution of each of these variants in neurosteroid sulfation in rat brain, we analyzed the expression of their transcripts in different brain regions using isoform-specific RT-PCR. The expression of ST2A1 was found exclusively in the olfactory bulb and ST2A2 expression levels were most abundant in the hippocampus, but no ST2A5 expression was detectable in any brain region. We then measured the HS-ST activity in these same regions and detected low but significant activity levels in the olfactory bulb and hippocampus, but less activity in the cortex. These activity levels were found to correlate with the mRNA levels of the HS-ST isoforms. Our findings will further our understanding of the physiological role of HS-ST enzymes within the brain, particularly how they affect neurosteroid metabolism and modulate neuronal activity.
ASJC Scopus subject areas
- Health, Toxicology and Mutagenesis