[Steroid hormone transformation in the gonads and liver of aged rats].
In order to study some aspects of the steroid hormone balance in old age the following organ functions of young and senescent male and female animals were investigated: 1) The capacity of testicular (45, 68-75 and 900 day-old animals) and ovarian tissue homogenates (29, 45, 66 and 900 day-old animals) to metabolically transform the sex hormone precursor, progesterone. 2) The capacity of liver slices (60-90 and 900 day-old animals) to generate a sex-specific metabolite pattern during incubation with testosterone. 3) The activities of some enzymes of steroid metabolism, which normally show sex differences in liver cell fractions (60-90 and 900 day-old animals). The testicular capacity of senescent animals to synthesize 17 alpha-hydroxyprogesterone, androstenedione and testosterone (main pathway of androgen biosynthesis) is drastically reduced compared to that of young adult rats; the reduction also extends to the production of highly polar C19O3- and C21O3-steroids. In contrast to these deficiencies, conversion of progesterone to 20 alpha-dihydroprogesterone increases in old age, whereas the generation of 5 alpha-hydrogenated compounds from testosterone and androstenedione remains unchanged. If the group of adolescent 45 day-old animals is also taken into consideration, then the biosynthetic sequence from progesterone to testosterone exhibits a biphasic developmental course. Production rates rise from low levels only to fall back to lower rates of synthesis in old age. In no age group can the production of oestrogens in measurable quantities be detected. However, 5 alpha-hydrogenated C19O2-steroid metabolites are detected, albeit only in prepuberal animals. After puberty only progesterone, 20 alpha-dihydroprogesterone and the 5 alpha-pregnane derivatives of these two steroids can be demonstrated. The pattern of the respective metabolites undergoes an age-dependent metabolite-specific development ending (900 day-old animals) with minimal yields of products (less than 21% of progesterone is converted). The production of hydroxylated metabolites (highly polar C21O3-steroid fraction) decreases very early in life (between day 29 and 45) to values indistinguishable from those of old animals. The sexually highly differentiated metabolite pattern of hepatic testosterone metabolism typical of young adult animals (60-90 day-old) is not prominent in old age. Both sexes exhibit a retarded testosterone turnover due to a decrease in the hydroxylating activity (males being more affected than females) and a deficiency of 5 alpha-hydrogenation (females only).(ABSTRACT TRUNCATED AT 400 WORDS)
Schriefers
H
H
Institut für Physiologische Chemie, Universitätsklinikum Essen.
Meyer
S G
SG
Bergheim
E
E
Lax
E R
ER
D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000378:metabolism; D000375:Aging; D000728:Androgens / Q000378:metabolism*; D000818:Animals; D001711:Biotransformation; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism; D008099:Liver / Q000254:growth & development* / Q000378:metabolism; D008297:Male; D009928:Organ Specificity; D010053:Ovary / Q000254:growth & development* / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors; D013737:Testis / Q000254:growth & development* / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism*
D000728:Androgens; D004967:Estrogens; D013739:Testosterone; D011374:Progesterone; D006913:Hydroxysteroid Dehydrogenases; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase
Steroidhormon-Transformation in Gonaden und Leber von Ratten im hohen Alter.