Structure-activity relationship of the preservation and restoration of glucocorticoid receptors in rat hepatocytes and rat liver homogenates by sulfhydryl, phosphorothioate and disulfide compounds.
The purpose of this work was to examine whether the ability of dithiothreitol to preserve the steroid-binding capacity of glucocorticoid receptors in subcellular preparations is specific or a general property of sulfhydryl compounds and selected phosphorothioate and disulfide derivatives. A further goal was to see if this effect could be demonstrated in intact cells. The ability to preserve the steroid-binding capacity of the glucocorticoid receptor is not a universal property of all sulfhydryl compounds since many of the compounds tested were inactive. The steroid-binding capacity of the glucocorticoid receptor of the 100,000 g supernatant of rat liver homogenate is preserved/restored by sulfhydryl compounds containing a mercaptoethylamine or mercaptopropylamine subunit. However, small changes in the structure of the sulfhydryl compound such as the rearrangement of a methylene group significantly alter its effectiveness. All of the phosphorothioates examined are derivatives of active sulfhydryl compounds and are effective in preserving steroid-binding. The extent of metabolism of the phosphorothioates and their failure to restore steroid-binding capacity after short-time exposure to receptor preparations are consistent with the sulfhydryl form being the active form of the phosphorothioates. S-2-(3-Amino-propylamino)ethylphosphorothioic acid (WR 2721) preserved steroid-binding capacity in isolated intact rat hepatocytes down to 25 microM demonstrating that concentrations obtainable in whole animals are effective with intact cells. Disulfide derivatives of active sulfhydryl compounds are either immediately toxic or ineffective except for 1,18-diamino-6,13-diaza-9,10-dithiaoctadecane (WR 149,024) which is more effective than its corresponding sulfhydryl. The demonstration that some sulfhydryl-forming compounds preserve the steroid-binding capacity of glucocorticoid receptors in intact cells at potentially physiologically obtainable concentrations suggests a potential role for these or similar compounds to bolster the efficacy of conventional glucocorticoid therapy.
Karle
J M
JM
Department of Pharmacology, Walter Reed Army Institute of Research, Washington, DC 20307-5100.
Olmeda
R
R
Ridder
W E
WE
Park
A S
AS
Nielsen
C J
CJ
D000315:Adrenalectomy; D000818:Animals; D004220:Disulfides / Q000494:pharmacology; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D009946:Organothiophosphorus Compounds / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011965:Receptors, Glucocorticoid / Q000187:drug effects* / Q000378:metabolism; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000494:pharmacology*
D004220:Disulfides; D009946:Organothiophosphorus Compounds; D011965:Receptors, Glucocorticoid; D013438:Sulfhydryl Compounds