title: Testosterone regulates 25-hydroxycholesterol production in testicular macrophages.
abstract: Recently, we found that testicular macrophages produce 25-hydroxycholesterol (25-HC) and express 25-hydroxylase, the enzyme that converts cholesterol to 25-HC. In addition, 25-HC may be an important paracrine factor mediating the known interactions between macrophages and neighboring Leydig cells, because it is efficiently converted to testosterone by Leydig cells. The purpose of the present study was to determine if testosterone can regulate the production of 25-HC in rat testicular macrophages, representing a potential negative-feedback loop from Leydig cells. We found that expression of 25-hydroxylase mRNA and production of 25-HC by cultured testicular macrophages were significantly inhibited by testosterone at 10 micro g/ml. This dose of testosterone did not have an effect on cell viability and did not change the rate of mRNA degradation in the presence of actinomycin D. These studies indicate that production of 25-HC is negatively regulated by testosterone, which may be representative of a paracrine negative-feedback loop.
authors.affiliation: Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA.
authors.forename: Yevgeniya
authors.initials: Y
authors.lastname: Lukyanenko
authors.forename: Jau-Jiin
authors.initials: JJ
authors.lastname: Chen
authors.forename: James C
authors.initials: JC
authors.lastname: Hutson
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D053493:Cholestanetriol 26-Monooxygenase; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D025461:Feedback, Physiological; D006888:Hydroxycholesterols / Q000378:metabolism*; D007985:Leydig Cells / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013250:Steroid Hydroxylases / Q000235:genetics / Q000378:metabolism; D013737:Testis / Q000166:cytology / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D006888:Hydroxycholesterols; D012333:RNA, Messenger; D003609:Dactinomycin; D013739:Testosterone; C007997:25-hydroxycholesterol; D013250:Steroid Hydroxylases; D053493:Cholestanetriol 26-Monooxygenase