Mass Spectrometry Imaging for Dissecting Steroid Intracrinology within Target Tissues

Abstract

Steroid concentrations within tissues are modulated by intracellular enzymes. Such 'steroid intracrinology' influences hormone-dependent cancers and obesity, and provides targets for pharmacological inhibition. However, no high resolution methods exist to quantify steroids within target tissues. We developed mass spectrometry imaging (MSI), combining matrix assisted laser desorption ionization with on-tissue derivatization with Girard T and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, to quantify substrate and product (11-dehydrocorticosterone and corticosterone) of the glucocorticoid-amplifying enzyme 11β-HSD1. Regional steroid distribution was imaged at 150-200μm resolution in rat adrenal gland and mouse brain sections, and confirmed with collision induced dissociation/liquid extraction surface analysis. In brains of mice with 11β-HSD1 deficiency or inhibition, MSI quantified changes in sub-regional corticosterone/11-dehydrocorticosterone ratio, distribution of inhibitor, and accumulation of the alternative 11β-HSD1 substrate, 7-ketocholesterol. MSI data correlated well with LC-MS/MS in whole brain homogenates. MSI with derivatization is a powerful new tool to investigate steroid biology within tissues.

Long-term intermittent feeding restores impaired GR signaling in the hippocampus of aged rat

“…Our results are in agreement with the data showing that hippocampal 11b-HSD1 expression increases with aging, which is in correlation with spatial memory deficits [47]. Even though glucocorticoids induce 11b-HSD1 gene expression [48], the contribution of 11-HSD1 to the intracellular pool of corticosterone appears to be relatively modest [49].…”

Elevated hepatic 11β-hydroxysteroid dehydrogenase type 1 induces insulin resistance in uremia

“…However, 11βHSD2 is not expressed in the liver and its renal expression is confined to the distal nephron which alone is unlikely to account for the substantial metabolic impacts observed. Importantly, a crucial, specific role for 11βHSD1 is underlined by the protective metabolic phenotype observed in the uremic 11βHSD1 −/− mice and the fact that a specific 11βHSD1 inhibitor (UE2316) (32), which has no activity against 11βHSD2, also improved glucose tolerance and insulin sensitivity in uremic rats.…”

Pyrylium Salts as Reactive Matrices for MALDI-MS Imaging of Biologically Active Primary Amines

“…The overall sensitivity of MALDI-MSI can be enhanced to some extent by optimizing the type of matrix used, the matrix solvent composition [20], the method of matrix application [21], and the tissue clean up protocol [22], or by chemical derivatization [23][24][25][26][27].…”