| Development of codominant follicles in cattle is associated with a follicle-stimulating hormone-dependent insulin-like growth factor binding protein-4 protease. | |
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MedLine Citation:
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PMID: 11420230 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Low molecular weight insulin-like growth factor binding proteins (IGFBPs), particularly IGFBP-4, are believed to inhibit the actions of insulin-like growth factors (IGFs). We showed previously that ovarian follicular dominance in cattle is associated with the presence of a protease that degrades IGFBP-4. To test the hypothesis that specific IGFBP-4 proteolysis is associated with selection of the dominant follicle, we induced codominant follicles (co-DFs) during the first follicular wave of the estrous cycle. The ovaries of Holstein heifers were examined twice daily by ultrasonography; when the largest follicle reached 6 mm in diameter, saline (control, n = 5) or 2 mg of recombinant bovine (rb) FSH (FSH, n = 5) was injected i.m. every 12 h for 48 h. Follicular fluid was collected by aspiration from the two largest follicles/heifer 12 h after the last injection. IGFBPs in follicular fluid were quantified by Western ligand blotting/phosphorimaging. IGFBP-4 protease activity was measured by incubating follicular fluid with recombinant human (rh) IGFBP-4 substrate, followed by ligand blotting/phosphorimaging to quantify the percent of substrate loss and Western immunoblotting to detect specific proteolytic fragments. Co-DFs of FSH heifers did not differ (P > 0.05) from the single dominant follicle of controls in size, or in concentration of progesterone or level of IGFBP-4 in follicular fluid. In contrast, the largest subordinate follicle of control heifers was smaller, with lower progesterone and higher IGFBP-4 in the follicular fluid (P < 0.05). Concentrations of estradiol in follicular fluid were high in dominant follicles, intermediate in co-DFs, and low in subordinate follicles (P < 0.05). IGFBP-4 protease activity in co-DFs was similar (P > 0.05) to that of dominant follicles, but fourfold higher (P < 0.05) than that of subordinate follicles. The results strongly suggest that an FSH-dependent IGFBP-4 protease is associated with selection of the dominant follicle in cattle. |
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Authors:
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G M Rivera; J E Fortune |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Biology of reproduction Volume: 65 ISSN: 0006-3363 ISO Abbreviation: Biol. Reprod. Publication Date: 2001 Jul |
Date Detail:
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Created Date: 2001-06-22 Completed Date: 2001-10-04 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0207224 Medline TA: Biol Reprod Country: United States |
Other Details:
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Languages: eng Pagination: 112-8 Citation Subset: IM |
Affiliation:
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Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Autoradiography Blotting, Western Cattle Female Follicle Stimulating Hormone / physiology* Immunoblotting Metalloendopeptidases / metabolism* Ovarian Follicle / physiology* Pregnancy-Associated Plasma Protein-A Radioimmunoassay Recombinant Proteins / metabolism Steroids / metabolism |
| Grant Support | |
ID/Acronym/Agency:
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HD38276/HD/NICHD NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Recombinant Proteins; 0/Steroids; 9002-68-0/Follicle Stimulating Hormone; EC 3.4.24.-/Metalloendopeptidases; EC 3.4.24.-/Pregnancy-Associated Plasma Protein-A |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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