Trace LC/MS/MS quantitation of 17beta-estradiol as a biomarker for selective estrogen receptor modulator activity in the rat brain.
A sensitive LC/MS/MS method has been developed by derivatization of 17beta-estradiol (E2) with dansyl chloride to quantitate 17beta-E2 in female rat serum. The use of E2-d(5) minimized interferences from endogenous 17beta-E2 in order to achieve a limit of quantitation (LOQ) of 2.5 pg/ml using 150 microl of female rat serum. The recovery of the dansyl derivative was 95% or greater in quality control samples. The intra and interday assay precision was better than 8.2 and 6.2%, respectively, with accuracies ranging from 97 to 101% in the quality control samples. The assay was used for the quantitation of serum E2 as a biomarker for the estrogen receptor (ER) antagonist activity of small molecule SERMs (selective estrogen receptor modulators) in the female rat brain. The study revealed that a statistically significant upregulation of serum 17beta-E2 occurred for rats dosed with SERMs that are known to penetrate the brain and disrupt the hypothalamic-pituitary-ovarian (HPO) axis. Variations in 17beta-E2 in ascending dose studies also correlated with the corresponding trends in CYP17a1 levels, an mRNA biomarker for ovarian hyperstimulation. This biomarker assay has provided a useful screen for medicinal chemistry optimization to produce SERMs that do not interfere with negative feedback of estrogens on the brain and for biological hypothesis testing.
Petucci
Chris
C
Discovery Analytical Chemistry, Pfizer, Collegeville, PA 19426, USA. cmpetucci@verizon.net
Lloyd
Tom
T
Harris
Heather A
HA
Zhang
Xiaochun
X
Chennathukuzhi
Vargheese M
VM
Mekonnen
Belew
B
Cai
Yanxuan
Y
D000818:Animals; D015415:Biomarkers / Q000097:blood*; D001923:Brain Chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D004355:Drug Stability; D004958:Estradiol / Q000097:blood*; D005260:Female; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D020845:Selective Estrogen Receptor Modulators / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013254:Steroid 17-alpha-Hydroxylase / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods*
D015415:Biomarkers; D020845:Selective Estrogen Receptor Modulators; D004958:Estradiol; D013254:Steroid 17-alpha-Hydroxylase