Regulatory roles of high-density and low-density lipoproteins in cellular proliferation and secretion of progesterone and insulin-like growth factor I by enriched cultures of bovine small and large luteal cells.
We tested the hypotheses that bovine high-density (HDL) and low-density (LDL) lipoproteins differentially influence cellular proliferation and progesterone and IGF-I production by bovine small and large luteal cells. Unit gravity sedimentation was used to produce enriched cultures of small (> 95% pure) and large (75 to 90% pure) luteal cells from corpora lutea (CL) on d 4 and 10 of the estrous cycle. Addition of LDL, HDL, or both resulted in the maintenance of higher (P < .05) numbers of 3beta-hydroxysteroid dehydrogenase (HSD)-positive small and large cells in culture and produced a marked proliferation of 3beta-HSD-negative small luteal cells compared to control medium. Low-density lipoprotein and HDL each stimulated greater (P < .01) progesterone secretion in enriched large cell cultures on both days of the cycle, and by small luteal cells on d 10, compared to the control. Together, LDL and HDL maximized this response. Lipoproteins markedly stimulated (P < .01) the secretion of IGF-I by bovine large luteal cells, and secretion was greater (P < .05) by cells from d 10 CL compared to d 4 CL. Results suggest that the actions of lipoproteins in bovine luteal cells extend beyond their widely recognized roles in steroidogenesis and include remarkable effects on cellular proliferation and IGF-I secretion. Type of lipoprotein (LDL vs HDL) did not have differential effects on any of the variables measured.
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Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, Beeville 78102, USA.
Thomas
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MG
Williams
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GL
D015096:3-Hydroxysteroid Dehydrogenases / Q000032:analysis; D000818:Animals; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003338:Corpus Luteum / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism*; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000494:pharmacology* / Q000502:physiology; D008077:Lipoproteins, LDL / Q000494:pharmacology* / Q000502:physiology; D007986:Luteinizing Hormone / Q000494:pharmacology; D011374:Progesterone / Q000378:metabolism*; D011863:Radioimmunoassay / Q000662:veterinary; D013997:Time Factors
D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D011374:Progesterone; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone; D015096:3-Hydroxysteroid Dehydrogenases