Linked Life Data

6404920

Source:http://linkedlifedata.com/resource/pubmed/id/6404920

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1983-6-23
pubmed:abstractText
To determine the basis for the decline in testosterone production by the aged testis, intratesticular unconjugated steroids, including testosterone, pregnenolone (3 beta-hydroxy-5-pregnen-20-one), 17 alpha-hydroxypregnenolone (3 beta,17 alpha-dihydroxy-5-pregnen-20-one), dehydroepiandrosterone (3 beta-hydroxy-5-androsten-17-one), androstenediol (5-androstene-3 beta,17 beta-diol), progesterone, 17 alpha-hydroxyprogesterone, androstenedione (4-androstene-3,17-dione), and 17 beta-estradiol, were measured by simultaneous RIAs in 32 previously untreated elderly men (aged 61-85 yr) undergoing orchiectomy as therapy for prostatic carcinoma and 20 young men (aged 25-35 yr) with oligospermia and varicocele. In vitro steroidogenesis using labeled pregnenolone as substrate was also investigated. Serum and intratesticular testosterone levels were lower (P less than 0.05) in aged patients [3.3 +/- 1.9 ng/ml and 0.86 +/- 0.53 microgram/g tissue (mean +/- SD)] than in young men (6.4 +/- 1.9 ng/ml and 1.7 +/- 1.1 microgram/g tissue), while circulating LH levels were higher (P less than 0.05) in elderly men (151 +/- 105 ng/ml) than in the young men (79 +/- 33 ng/ml), indicating that a primary pathological process affects the senescent testis, producing a decline in testosterone production. Study of bioconversion of [3H]pregnenolone to delta 4 steroids, 17 alpha-hydroxysteroids, and C19 steroids as well as analysis of the relative amounts of intratesticular steroids, as determined by RIA, revealed no apparent differences in the process of microsomal steroidogenesis in elderly compared to that in young men. The sum of the nine measured intratesticular steroid concentrations per g tissue wt was significantly lower (P less than 0.05) in aged patients (1.94 +/- 0.93 microgram/g tissue), than in young patients (3.68 +/- 1.90 micrograms/g tissue). The sum of the nine intratesticular steroids measured was positively correlated (P less than 0.01) with circulating LH levels in both patient groups, and the slope of this regression line was 14-fold greater for young men than for elderly men. Since the total concentration of the nine measured steroids reflects the pregnenolone supplied by the mitochondria within Leydig cells, it appears that the decline in Leydig cell function in aged men is attributable to a reduced supply of mitochondrial steroid precursors rather than to an impairment in microsomal steroidogenesis.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0021-972X
pubmed:author
pubmed:issnType
Print
pubmed:volume
56
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1178-87
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Studies of the human testis. XVIII. Simultaneous measurement of nine intratesticular steroids: evidence for reduced mitochondrial function in testis of elderly men.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.