[Age-dependent changes in the concentration of active sex steroids, their precursors, metabolites, and regulating agents in male blood].
Blood concentrations of hormone-inactive and active sex-steroid metabolites and their precursors were measured, taking into account changes in protein-peptide hormones that control the reproductive axis (in a total of 14 parameters) in men in the 18- to 72-year-old age interval. A significant decrease in the blood concentration of unutilized precursors of active sex steroids (pregnenolone, progesterone, dehydroepiandrosterone, and its sulfate), unbound testosterone, androstenedione (an inactive metabolite of testosterone), and an active metabolite, 5alpha-dihydrotestosterone was determined after the age of 35. However, the level of total testosterone and of estradiol (another active metabolite of testosterone) remained constant. The systems regulating the production of active sex steroids resisted a higher load, causing the luteinizing and follicle-stimulating hypophyseal hormones and activin of steroidogenic glands to increase and correlate positively with age; these hormones correlated negatively with certain sex steroids that realize negative feedback. A decrease in the level of adrenocorticotropic hypophyseal hormone with age suggests a more substantial role for adrenal glands as compared to that of testicles in reducing the blood concentration of active sex steroids. In general, despite the reduced activity of steroidogenic glands in 60- to 70-year-old men, their testosterone and estradiol concentrations remain unchanged, due to coordinated growth in the concentration of luteinizing and follicle-stimulating hypophyseal hormones, and to the activin of steroidogenic glands, which stimulated sex steroid biosynthesis. At the same time, the androgen effect was inhibited as a result of reduced levels of unbound testosterone and 5alpha-dihydrotestosterone.
Petrov
R V
RV
Kuzina
I N
IN
Kilikovskiĭ
V V
VV
Smirnova
O V
OV
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood*; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged
D012739:Gonadal Steroid Hormones