Cholelithiasis induced in the Syrian hamster: evidence for an intramucinous nucleating process and down regulation of cholesterol 7 alpha-hydroxylase (CYP7) gene by medroxyprogesterone. 1997

J Gilloteaux, and S Karkare, and A Q Don, and R C Sexton
Summa Health System Foundation, Akron, Ohio, 44304, USA.

This report reviews previously published studies from our laboratory and shows some recent morphological data obtained with scanning and transmission electron microscopy regarding gallstone formation and alteration of the gallbladder epithelium in the Syrian hamster model. Both male and female hamsters were treated with female sex steroids (estradiol alone, estradiol and medroxyprogesterone, medroxyprogesterone alone) during one month. The results show that the Syrian hamster is a good model to study bile changes, gallbladder structure changes, including gallstone formation, and the regulation of cholesterol metabolism at the molecular level. Arguments in favor of this animal model are presented and, during gallstone formation, epithelial cell changes, anionic mucus secretion, and formation of gallbladder luminal deposits can be demonstrated. Recent molecular biology observations related to the effect of female sex steroids on liver cholesterol 7 alpha-hydroxylase (CYP7) gene suggest that progestin alone or primed by estrogen down regulates CYP7 transcription and activity. In addition, progesterone in cell culture systems has been shown to enhance intracellular accumulation of free cholesterol by increasing its uptake and synthesis and by decreasing its esterification by inhibiting the activity of acylcoenzyme A: cholesterol acyltransferase. Non-esterified cholesterol is free to migrate to the extracellular spaces and may contribute to nucleation within the bile. It is suggested that these effects of progesterone on cholesterol metabolism combined with the CYP7 gene down regulation, physical changes in the mucus and the hypomotility of the gallbladder and biliary ducts result in hypersaturation of cholesterol in the bile which favors gallstone formation.

UI MeSH Term Description Entries
D008055 Lipids A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed) Lipid
D008297 Male Males
D008525 Medroxyprogesterone A synthetic progestational hormone used in veterinary practice as an estrus regulator. (6 alpha)-17-Hydroxy-6-methylpregn-4-ene-3,20-dione,Methylhydroxyprogesterone,Pregn-4-ene-3,20-dione, 17-hydroxy-6-methyl-, (6alpha)-,17 alpha-Hydroxy-6 alpha-Methylprogesterone,Adgyn Medro,17 alpha Hydroxy 6 alpha Methylprogesterone
D008854 Microscopy, Electron Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen. Electron Microscopy
D008855 Microscopy, Electron, Scanning Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY. Scanning Electron Microscopy,Electron Scanning Microscopy,Electron Microscopies, Scanning,Electron Microscopy, Scanning,Electron Scanning Microscopies,Microscopies, Electron Scanning,Microscopies, Scanning Electron,Microscopy, Electron Scanning,Microscopy, Scanning Electron,Scanning Electron Microscopies,Scanning Microscopies, Electron,Scanning Microscopy, Electron
D008861 Microsomes Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed) Microsome
D009077 Mucins High molecular weight mucoproteins that protect the surface of EPITHELIAL CELLS by providing a barrier to particulate matter and microorganisms. Membrane-anchored mucins may have additional roles concerned with protein interactions at the cell surface. Mucin
D009093 Mucus The viscous secretion of mucous membranes. It contains mucin, white blood cells, water, inorganic salts, and exfoliated cells.
D011372 Progestins Compounds that interact with PROGESTERONE RECEPTORS in target tissues to bring about the effects similar to those of PROGESTERONE. Primary actions of progestins, including natural and synthetic steroids, are on the UTERUS and the MAMMARY GLAND in preparation for and in maintenance of PREGNANCY. Gestagenic Agent,Progestagen,Progestagenic Agent,Progestational Agent,Progestational Compound,Progestational Hormone,Progestogen,Progestogens,Gestagen,Gestagen Effect,Gestagen Effects,Gestagenic Agents,Gestagenic Effect,Gestagenic Effects,Gestagens,Progestagenic Agents,Progestagens,Progestational Agents,Progestational Compounds,Progestational Hormones,Progestin,Progestin Effect,Progestin Effects,Progestogen Effect,Progestogen Effects,Agent, Gestagenic,Agent, Progestagenic,Agent, Progestational,Compound, Progestational,Effect, Gestagen,Effect, Gestagenic,Effect, Progestin,Effect, Progestogen,Effects, Gestagen,Effects, Gestagenic,Effects, Progestin,Effects, Progestogen,Hormone, Progestational
D011987 Receptors, Steroid Proteins found usually in the cytoplasm or nucleus that specifically bind steroid hormones and trigger changes influencing the behavior of cells. The steroid receptor-steroid hormone complex regulates the transcription of specific genes. Corticosteroid Receptors,Receptors, Corticosteroid,Steroid Receptors,Corticosteroid Receptor,Receptors, Steroids,Steroid Receptor,Receptor, Corticosteroid,Receptor, Steroid,Steroids Receptors

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