title: Growth hormone (GH) and GH-releasing hormone (GHRH): Co-localization and action in the chicken testis.
abstract: Growth hormone (GH) gene expression is not confined to the pituitary gland and occurs in many extrapituitary tissues, including the chicken testis. The regulation and function of GH in extrapituitary tissues is, however, largely unknown. The possibility that chicken testicular GH might be regulated by GH-releasing hormone (GHRH), as in the avian pituitary gland, was investigated in the present study. GHRH co-localized with GH in the germinal epithelium and in interstitial zones within the chicken testes, particularly in the spermatogonia and spermatocytes. In testicular cell cultures, exogenous human GHRH1-44 induced (at 1, 10 and 100nM) a dose-related increase in GH release. Western blot analysis showed a heterogeneous pattern in the GH moieties released during GHRH stimulation. 26kDa monomer GH was the most abundant moiety under basal conditions, but 15 and 17kDa isoforms were more abundant after GHRH stimulation. GHRH treatment also increased the abundance of PCNA (proliferating cell nuclear antigen) immunoreactivity in the testes. This may have been GH-mediated, since exogenous GH similarly increased the incorporation of ((3)H)-thymidine into cultured testicular cells and increased their metabolic activity, as determined by increased MTT reduction. Furthermore, GH and GHRH immunoneutralization blocked GHRH-stimulated proliferative activity. In summary, these results indicate that GHRH stimulates testicular GH secretion in an autocrine or paracrine manner. Data also demonstrate proliferative actions of GHRH on testicular cell number and suggest that this action is mediated by local GH production.
authors: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico; Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors: Carlos G
authors: CG
authors: Martínez-Moreno
authors: Departamento de Nanotecnología, Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico.
authors: Luz M
authors: LM
authors: López-Marín
authors: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico.
authors: Martha
authors: M
authors: Carranza
authors: Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors: Daniel
authors: D
authors: Giterman
authors: Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors: Steve
authors: S
authors: Harvey
authors: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico.
authors: Carlos
authors: C
authors: Arámburo
authors: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico. Electronic address: lunam@unam.mx.
authors: Maricela
authors: M
authors: Luna
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D002645:Chickens / Q000378:metabolism*; D003470:Culture Media; D004797:Enzyme-Linked Immunosorbent Assay; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D008297:Male; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport; D013090:Spermatocytes / Q000166:cytology / Q000378:metabolism; D013737:Testis / Q000166:cytology / Q000378:metabolism*
chemical_list: D003470:Culture Media; D018809:Proliferating Cell Nuclear Antigen; D020033:Protein Isoforms; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone
keywords: Chicken growth hormone (cGH); GH isoforms; Growth hormone releasing hormone (GHRH); Proliferation; Secretion; Testes