Linked Life Data

10999848

Source:http://linkedlifedata.com/resource/pubmed/id/10999848

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
9
pubmed:dateCreated
2000-10-16
pubmed:abstractText
We studied the spatiotemporal distribution of thyroid hormone nuclear receptors (TRs) alpha1 and alpha2 and beta messenger RNA (mRNA) levels in normal human testicular tissue during development and in adulthood. Nonpathological specimens from five aborted fetuses (17 and 23 weeks of gestation, three and two cases, respectively) and from four patients undergoing orchiectomy (18 months old and 38-, 42-, and 52-yr-old, respectively) were analyzed by Northern blot, semiquantitative RT-PCR amplification using DNA sequences or specifically designed primers for the TR isoforms, and in situ hybridization. By using PCR amplification, we found that TRalpha1 and TRalpha2 are both expressed at different levels in fetal and adult testis. At all ages TRalpha2 is found at higher levels. Northern analysis showed hybridization signals corresponding to the expression of TRalpha2 and TRalpha in a ratio that increased from 2.6 at 17 weeks of gestation to 12.0 in adulthood. In fact, the expression of TRalpha1 dramatically decreased throughout development, being faintly detectable in the adult testis. Expression of TRbeta was not detected at any age studied. This finding was further confirmed by PCR, which did not amplify TRbeta either in fetal or in adult testis mRNAs. In situ hybridization studies showed the absence of TRbeta and that TRalpha1 and TRalpha2 colocalized in Sertoli cells of prepubertal testis, whereas germ and interstitial cells appeared devoid of TR mRNA signals. From these results it can be concluded that the human testis exclusively expresses TRalpha, which is localized in Sertoli cells, TRbeta being always undetectable. Fetal and prepubertal ages represent the period of maximal expression of TRalpha1 and TRalpha2. The alpha2/alpha1 ratio rises dramatically after development. These results confirm a critical window for the action of thyroid hormone in human testis, in the period of maximal expression of T3 binding isoform TRalpha1, and may account for the macroorchidism without virilization occurring when hyposecretion of thyroid hormones occurs before puberty.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-972X
pubmed:author
pubmed:issnType
Print
pubmed:volume
85
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3453-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Ontogenetic pattern of thyroid hormone receptor expression in the human testis.
pubmed:affiliation
Department of Experimental Medicine, University of L'Aquila, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't