| Research Abstract |
Pregnenolne sulfate (PS) and dehydroepiandrosterone sulfate (DS) are reported to be present in higher concentration in the brain than in blood and are considered to be a neurosteroid, which is synthesized independently in the brain and accumulated in the central nervous system. However, there are some doubts on its brain levels, because they were measured indirect methods such as GC-MS or radioimmunoassay after solvolysis. In this project, anti-PS and -DS antibodies were prepared from new haptens having bridge at 11 α position of PS and DS, respectively, and the new ELISAs using these new antibodies were developed. The ELISAs used bridge-heterologous system employing sequential saturation method. The methods were highly sensitive and did not require solvolysis, after pretreatment with an Oasis HLB cartridge. That is, although the antibodies cross-reacted with the respective non-conjugated steroid (pregnenolone and dehdroepiandtrsterone) in few percent, non-conjugated steroids were clearly separated after treatment with the cartridge.
The developed methods were applied to the rat brain samples and the levels of PS and DS were about less than 1/20 of those reported previously. On the contrary, the brain PS levels were sufficiently increased after intrapertioneal injection of 2 mg/kg body of PS. These results demonstrate that, in rats, the brain PS may be derived from peripheral sources, and its actual levels are much lower than those previously measured by indirect methods. We inferred the same story in case of brain DS.
The further investigation is necessary to clarify the physiological significance of neurosteroid.
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