title: Type 2 iodothyronine deiodinase is highly expressed in germ cells of adult rat testis.
abstract: The testis has been classically described as a thyroid hormone unresponsive tissue, but recent studies indicate that these hormones might play an important role in developing testes. We have previously demonstrated that type 2 iodothyronine deiodinase (D2), a thyroid hormone-activating enzyme, is expressed in adult rodent testis and that its activity is induced by hypothyroidism. Nevertheless, the precise location of D2 in testis is not known. The aim of the present work was to determine the testicular cell types in which D2 is expressed using real-time PCR analysis, in situ hybridization histochemistry, and determination of D2 activity in cell fractions isolated from adult euthyroid and/or hypothyroid rat testis. The D2 mRNA levels in germ cells were higher than those from somatic cells (6.94 +/- 1.49 vs 2.32 +/- 0.79 arbitrary units (au); P = 0.017). Hypothyroidism increased D2 expression in germ cells (6.94 +/- 1.49 vs 8.78 +/- 5.43 au, P = 0.002) but did not change D2 transcripts in somatic cells significantly (2.12 +/- 0.79 vs 2.88 +/- 1.39 au, P = 0.50). In situ hybridization analysis showed that D2 mRNA is specifically present in elongated spermatids undergoing differentiation, whereas other germ cell types and Sertoli cells of seminiferous epithelium and the interstitial cells were virtually negative for this enzyme. The enzyme activity measured in germ and somatic isolated cell fractions (0.23 +/- 0.003 vs 0.02 +/- 0.013 fmol/min per mg protein respectively; P < 0.001) further confirmed the real-time PCR and in situ hybridization results. Hence, our findings demonstrated that D2 is predominantly expressed in elongated spermatids, suggesting that thyroid hormone might have a direct effect on spermatogenesis in the adult rats.
authors.affiliation: Endocrine Division, Thyroid Section, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Simone Magagnin
authors.initials: SM
authors.lastname: Wajner
authors.forename: Márcia
authors.initials: M
authors.lastname: dos Santos Wagner
authors.forename: Rossana C N
authors.initials: RC
authors.lastname: Melo
authors.forename: Gleydes G
authors.initials: GG
authors.lastname: Parreira
authors.forename: Hélio
authors.initials: H
authors.lastname: Chiarini-Garcia
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Bianco
authors.forename: Csaba
authors.initials: C
authors.lastname: Fekete
authors.forename: Edith
authors.initials: E
authors.lastname: Sanchez
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Lechan
authors.forename: Ana Luiza
authors.initials: AL
authors.lastname: Maia
mesh_terms: D000818:Animals; D007037:Hypothyroidism / Q000201:enzymology; D017403:In Situ Hybridization / Q000379:methods; D007453:Iodide Peroxidase / Q000235:genetics*; D008297:Male; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012670:Seminiferous Epithelium; D013087:Spermatids / Q000166:cytology / Q000201:enzymology*; D013091:Spermatogenesis / Q000502:physiology; D013094:Spermatozoa / Q000166:cytology / Q000201:enzymology; D000097564:Iodothyronine Deiodinase Type II
chemical_list: D007453:Iodide Peroxidase; D012333:RNA, Messenger; D000097564:Iodothyronine Deiodinase Type II