Determination of Neurosteroids in Rat Brain by Gas Chromatography/Mass Spectrometry
气相色谱/质谱联用测定大鼠脑部的神经甾体

A simplified method has been established to simultaneously characterize different neurosteroids in rat brain by gas chromatography/mass spectrometry (GC-MS). Neurosteroids were isolated separately in a two-step procedure using ethyl acetate in the first step to extract the unconjugated steroids and chloroform/2-butanol(50/50,v/v) in the second step to extract sulfated steroids. All steroid fractions were further purified by solid phase extraction (SPE) and the sulfated steroids were solvolyzed. All steroids were derivatized with heptafluorobutyric acid anhydride and analyzed by GC-MS (electrospray ionization) using selected ion monitoring. In male rat brain, the concentrations of pregnenolone (PREG), progesterone (PROG), allo-pregnanolone (AP) and dihydroepiandrosterone (DHEA) were (8.53 +/- 1.11) ng/g, (7.01 +/- 2.60 )ng/g, (1.17 +/- 0.19 )ng/g, and (0.92 +/- 0.20) ng/g, respectively. The concentrations of pregnenolone sulfate (PREGS) and dihydroepiandrosterone sulfate (DHEAS) were (5.94 +/- 2.03) ng/g and (1.93 +/- 0.92) ng/g, respectively. Good linearity and accuracy were observed for each steroid. The procedure was suitable for measuring the concentrations of endogenous neurosteroids, simultaneously including the sulfates in rat brain.