title: Endocrine and molecular influences on testicular development in Meishan and White Composite boars.
abstract: The aim of this study was to evaluate developmental changes in thyroid hormone and other key endocrine hormones/molecular markers produced by testicular cells, in relation to breed differences in proliferation and maturation of Sertoli cells and general testicular morphological development in Meishan (MS) and White Composite (WC) boars. Blood samples and testes were collected on days 60, 75, 90 and 105 post coitum (dpc) and days 1, 7, 14 and 25 post partum (dpp). Testes were immunostained for thyroid hormone receptor-beta1 (THRbeta1), GATA4, Müllerian-inhibiting substance (MIS), 17-alpha-hydroxylase (P450(c17)) and inhibin subunits (alpha, betaA, betaB). In addition, protein levels were determined by densitometry. Plasma concentrations of free triiodothyronine (T(3)) were greater in MS (hyperthyroid) compared with WC (hypothyroid) boars (P<0.01) during fetal life, but the reverse was evident postnatally. Elevated levels of free T(3) during fetal life were associated with increased levels of THRbeta1, suggesting increased thyroid responsiveness of the testis during this time, contrasting with observations during early postnatal life. Localization patterns of THRbeta1, MIS, GATA4 and the inhibin subunits were consistent with previous studies. MIS protein levels declined more rapidly (P<0.001) in MS compared with WC Sertoli cells postnatally, consistent with earlier maturation of Sertoli cells as indicated by our previous study. In this study, transient neonatal hyperthyroidism in MS boars during late gestation was associated with a decline in proliferation and early maturation of Sertoli cells, followed by early onset of puberty in this breed. These observations indicate a possible role for thyroid hormone in the modification of Sertoli cell development, thereby influencing growth and differentiation of the testis in pigs.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, US Meat Animal Research Center, Clay Center, Nebraska 68933, USA. sue.mccoard@agreresearch.co.nz
authors.forename: S A
authors.initials: SA
authors.lastname: McCoard
authors.forename: T H
authors.initials: TH
authors.lastname: Wise
authors.forename: J J
authors.initials: JJ
authors.lastname: Ford
mesh_terms: D000818:Animals; D054304:Anti-Mullerian Hormone; D002455:Cell Division / Q000502:physiology; D004268:DNA-Binding Proteins / Q000032:analysis; D050991:GATA4 Transcription Factor; D006023:Glycoproteins / Q000032:analysis; D007150:Immunohistochemistry / Q000379:methods; D028322:Inhibin-beta Subunits / Q000032:analysis; D007265:Inhibins / Q000032:analysis; D008297:Male; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism; D013045:Species Specificity; D013254:Steroid 17-alpha-Hydroxylase / Q000032:analysis; D013552:Swine / Q000196:embryology* / Q000254:growth & development; D013735:Testicular Hormones / Q000032:analysis; D013737:Testis / Q000737:chemistry / Q000196:embryology* / Q000254:growth & development; D037042:Thyroid Hormone Receptors beta / Q000032:analysis; D013963:Thyroid Hormones / Q000097:blood*; D014157:Transcription Factors / Q000032:analysis; D014284:Triiodothyronine / Q000097:blood
chemical_list: D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; D006023:Glycoproteins; D013735:Testicular Hormones; D037042:Thyroid Hormone Receptors beta; D013963:Thyroid Hormones; D014157:Transcription Factors; C103008:inhibin beta A subunit; C094377:inhibin-alpha subunit; D014284:Triiodothyronine; D007265:Inhibins; D054304:Anti-Mullerian Hormone; D028322:Inhibin-beta Subunits; D013254:Steroid 17-alpha-Hydroxylase