title: Localization of insulin-like growth factor-I (IGF-I) and IGF-I receptor (IGF-IR) in equine testes.
abstract: The insulin-like growth factor-I (IGF-I) is a key regulator of reproductive functions. IGF-I actions are primarily mediated by IGF-IR. The main objective of this research was to evaluate the presence of IGF-I and IGF-I Receptor (IGF-IR) in stallion testicular tissue. The hypotheses of this study were (i) IGF-I and IGF-IR are present in stallion testicular cells including Leydig, Sertoli, and developing germ cells, and (ii) the immunolabelling of IGF-I and IGF-IR varies with age. Testicular tissues from groups of 4 stallions in different developmental ages were used. Rabbit anti-human polyclonal antibodies against IGF-I and IGF-IR were used as primary antibodies for immunohistochemistry and Western blot. At the pre-pubertal and pubertal stages, IGF-I immunolabelling was present in spermatogonia and Leydig cells. At post-pubertal, adult and aged stages, immunolabelling of IGF-I was observed in spermatogenic cells (spermatogonia, spermatocyte, spermatid, and spermatozoa) and Leydig cells. Immunolabelling of IGF-IR was observed in spermatogonia and Leydig cells at the pre-pubertal stage. The immunolabelling becomes stronger as the age of animals advance through the post-pubertal stage. Strong immunolabelling of IGF-IR was observed in spermatogonia and Leydig cells at post-puberty, adult and aged stallions; and faint labelling was seen in spermatocytes at these ages. Immunolabelling of IGF-I and IGF-IR was not observed in Sertoli cells. In conclusion, IGF-I is localized in equine spermatogenic and Leydig cells, and IGF-IR is present in spermatogonia, spermatocytes and Leydig cells, suggesting that the IGF-I may be involved in equine spermatogenesis and Leydig cell function as a paracrine/autocrine factor.
authors.affiliation: Department of Animal Science, University of California, Davis, CA, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Yoon
authors.forename: T
authors.initials: T
authors.lastname: Berger
authors.forename: J F
authors.initials: JF
authors.lastname: Roser
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D015153:Blotting, Western; D005786:Gene Expression Regulation / Q000502:physiology*; D006736:Horses / Q000502:physiology*; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008297:Male; D011817:Rabbits; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism*; D013737:Testis / Q000166:cytology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1