Studies on neurosteroids XVI. Levels of pregnenolone sulfate in rat brains determined by enzyme-linked immunosorbent assay not requiring solvolysis.
Pregnenolone sulfate (PREGS) is reported to be present in higher concentration in the brain (more than 5 ng/g tissue in the rat) than in blood and is considered to be a neurosteroid. However, there are some doubts on its brain levels, because they were determined by indirect methods (e.g., GC-MS or radioimmunoassay after solvolysis). In the present study, PREGS in rat brains was determined by an enzyme-linked immunosorbent assay, which did not require solvolysis, after pretreatment with an Oasis HLB cartridge. The absolute recovery rate of PREGS through the pretreatment was 60.8%, and the quantitation limit was 33 pg/g tissue for a 200-mg of brain aliquot. Intra- and inter-assay coefficients of variation were less than 15.1 and 9.2%, respectively. The brain PREGS levels in the control rats (n=10) were less than 0.15 ng/g tissue except for one sample (0.42 ng/g tissue) and were lower than the serum levels (n=5, 0.25-0.47 ng/ml). On the contrary, the brain PREGS levels were sufficiently increased after intrapertioneal injection of 2 mg/kg body of PREGS (n=5, 0.37-1.29 ng/g tissue). These results demonstrate that, in rats, the brain PREGS may be derived from peripheral sources, and its actual levels are much lower than those previously measured by indirect methods.
Faculty of Pharmaceutical Sciences, Kanazawa University, Takara-machi, Japan. higashi@p.kanazawa-u.ac.jp
Tatsuya
T
Higashi
Haruko
H
Sugitani
Takako
T
Yagi
Kazutake
K
Shimada
D000818:Animals; D001923:Brain Chemistry; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D008297:Male; D011284:Pregnenolone / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results
D011284:Pregnenolone