dihydrotachysterol and Disease-Models--Animal

Although several etiological factors contribute to the complexity of the aging process, the ultimate component of macromolecular damage and consequent cell death involves the altered redox balance inclined towards increased ROS production and/or decreased antioxidant protection. Given that, the chronic dihydrotachysterol (DHT) intoxication in rats induce Hutchinson Gilford progeria like syndrome, the present study provides the evidence for altered redox balance as evidenced by alteration in parameters of oxidative stress in blood plasma and erythrocytes including MDA, GSH, FRAP AOPP PMRS, AGEs, AChE and osmotic fragility which substantiate the suitability of the model for aging studies.

Topics: Acetylcholinesterase; Advanced Oxidation Protein Products; Aging; Animals; Antioxidants; Dihydrotachysterol; Disease Models, Animal; Erythrocytes; Female; Glutathione; GPI-Linked Proteins; Humans; Malondialdehyde; Oxidation-Reduction; Oxidative Stress; Progeria; Rats; Rats, Wistar; Reactive Oxygen Species

Hypercalcemia can cause renal dysfunction such as nephrogenic diabetes insipidus (NDI), but the mechanisms underlying hypercalcemia-induced NDI are not well understood. To elucidate the early molecular changes responsible for this disorder, we employed mass spectrometry-based proteomic analysis of inner medullary collecting ducts (IMCD) isolated from parathyroid hormone-treated rats at onset of hypercalcemia-induced NDI. Forty-one proteins, including the water channel aquaporin-2, exhibited significant changes in abundance, most of which were decreased. Bioinformatic analysis revealed that many of the downregulated proteins were associated with cytoskeletal protein binding, regulation of actin filament polymerization, and cell-cell junctions. Targeted LC-MS/MS and immunoblot studies confirmed the downregulation of 16 proteins identified in the initial proteomic analysis and in additional experiments using a vitamin D treatment model of hypercalcemia-induced NDI. Evaluation of transcript levels and estimated half-life of the downregulated proteins suggested enhanced protein degradation as the possible regulatory mechanism. Electron microscopy showed defective intercellular junctions and autophagy in the IMCD cells from both vitamin D- and parathyroid hormone-treated rats. A significant increase in the number of autophagosomes was confirmed by immunofluorescence labeling of LC3. Colocalization of LC3 and Lamp1 with aquaporin-2 and other downregulated proteins was found in both models. Immunogold electron microscopy revealed aquaporin-2 in autophagosomes in IMCD cells from both hypercalcemia models. Finally, parathyroid hormone withdrawal reversed the NDI phenotype, accompanied by termination of aquaporin-2 autophagic degradation and normalization of both nonphoshorylated and S256-phosphorylated aquaporin-2 levels. Thus, enhanced autophagic degradation of proteins plays an important role in the initial mechanism of hypercalcemic-induced NDI.

Topics: Animals; Aquaporin 2; Autophagy; Chromatography, Liquid; Diabetes Insipidus, Nephrogenic; Dihydrotachysterol; Disease Models, Animal; Down-Regulation; Fluorescent Antibody Technique; Half-Life; Humans; Hypercalcemia; Intercellular Junctions; Kidney Tubules, Collecting; Lysosomal Membrane Proteins; Male; Microscopy, Immunoelectron; Microtubule-Associated Proteins; Parathyroid Hormone; Phosphorylation; Proteolysis; Proteomics; Rats; Rats, Sprague-Dawley; Tandem Mass Spectrometry

This study investigates the proliferative and osteogenic role of marrow stromal/osteoprogenitor cells in the development of the cortical bone deficit in ovariectomized (OVX) female rats. In vitro, clonal growth of marrow stromal cells from OVX rats was significantly impaired (vs. sham-operated controls). Yet in vivo, cells from sham-operated and OVX rats had equal osteogenic potential in several in vivo experimental situations, such as in intraperitoneally implanted millipore diffusion chambers and in intramuscular implants of marrow plus osteoinductive bone matrix (composite grafts). Long-term (6 mo) dihydrotachysterol (DHT) treatment of OVX rats enhanced their in vitro proliferative potential and clonal growth, as well as their osteogenic expression in composite grafts. The observation that the in vivo osteogenic performance of OVX rat marrow stromal cells was normal at extraosseous sites suggests that the mechanisms leading to osteopenia may involve an abnormality in cell-matrix interactions.

Topics: Animals; Bone Diseases; Bone Marrow; Bone Marrow Transplantation; Bone Matrix; Cell Division; Cells, Cultured; Dihydrotachysterol; Disease Models, Animal; Female; Fibroblasts; Minerals; Osteogenesis; Ovariectomy; Rats; Rats, Inbred Strains; Stem Cells

The amount of non-collagenous proteins is increased greatly during the pathological calcification of rat skin experimentally induced by dihydrotachysterol (DHT) and Ovalbumin (topical cutaneous calciphylaxis). This is accompanied by an increase in the total amount and concentrations of protein-bound serine phosphate [Ser(P)], threonine phosphate [Thr(P)] and gamma-carboxyglutamic acid (Gla), almost all of which can be extracted from the tissue and can be dissociated from collagen in 0.5M EDTA. The EDTA-soluble, non-collagenous proteins are rich in aspartic and glutamic acids, similar to the non-collagenous, EDTA-soluble proteins of bone, cementum and calcified cartilage, and quite distinct from those of dentin and enamel.

Topics: 1-Carboxyglutamic Acid; Animals; Calciphylaxis; Dihydrotachysterol; Disease Models, Animal; Female; Glutamates; Ovalbumin; Phosphoserine; Phosphothreonine; Rats; Serine; Skin; Skin Diseases; Threonine

Seven diphosphonate analogs were treated for their effects on myocardial and cardiovascular degeneration and calcification in an experimental model of cardiac calciphylaxis. A single oral dose of dihydrotachysterol (DHT) administered to rats induced myocardial and vascular degeneration, focal myocarditis and vasculitis, and myocardial and vascular mineralization. The results demonstrated a considerable variation among the various diphosphonates in their ability to block the pathological changes observed in this model. Ethane-1-hydroxy-1,1-diphosphonate (EHDP) was the most effective diphosphonate in reducing myocardial and vascular degeneration and calcification, whereas diphosphonates such as ethane-1-amino-1,1-diphosphonate (EADP) and hydroxymethylene diphosphonate (HMDP) had little or no effect compared to saline controls. For those diphosphonates which were effective, e.g., EHDP, the tissue-protective effects were observed whether the rats were treated with drug prior to the administration of DHT, or whether drug treatment commenced after DHT administration. The results are discussed in terms of the known biological properties of the diphosphonate drugs.

Topics: Animals; Calciphylaxis; Cardiomyopathies; Chemical Phenomena; Chemistry; Dihydrotachysterol; Diphosphonates; Disease Models, Animal; Drug Evaluation, Preclinical; Female; Myocardium; Rats

Topics: Animals; Bone Diseases; Calcium; Chemical Phenomena; Chemistry; Cholecalciferol; Dihydrotachysterol; Dihydroxycholecalciferols; Disease Models, Animal; Humans; Hydroxycholecalciferols; Isomerism; Kidney Failure, Chronic; Microradiography; Osteitis Fibrosa Cystica; Osteomalacia; Phosphates; Rats; Renal Dialysis; Uremia; Vitamin D

Focal areas of calcification are frequent in rat myocardium 30 and 60 days after administration of dihydrotachysterol. These areas are PAS-positive, stain deeply with alcian blue and show high affinity for colloidal iron. Calcification is almost completely confined to intracellular structures. Small clusters of needle-shaped crystals are first found in apparently undamaged mitochondria in undamaged myocardial cells. When all the mitochondria are calcified, the cell degenerates, and inorganic crystals are laid down in relationship with its myofilaments. In other myocardial cells, clusters of amorphous or finely granular inorganic substance are found in both mitochondria and myofibrils. Both structures show signs of advanced degeneration. Inorganic substance has only occasionally been found within the structures of the sarcoplasmic reticulum. These structures do not seem to be involved in myocardial calcification under the present experimental conditions. Calcification of myocardial cells gives rise to a cellular reaction. Many macrophagic cells surround the calcified areas, which are rapidly reabsorbed. The present results show that myocardial mitochondria are actively engaged in controlling the intracellular concentration and movement of calcium ions. Their role in the myocardial contraction-relaxation cycle and the possible mechanism of myocardial calcification are discussed.

Topics: Animals; Calcinosis; Cardiomyopathies; Dihydrotachysterol; Disease Models, Animal; Edetic Acid; Female; Hypercalcemia; Microscopy, Electron; Mitochondria, Muscle; Myocardium; Rats

Topics: Androgens; Animals; Dihydrotachysterol; Disease Models, Animal; Female; Gonadotropin-Releasing Hormone; Progeria; Rats; Syndrome; Time Factors

Topics: Animals; Calcinosis; Cornea; Dihydrotachysterol; Disease Models, Animal; Eye Diseases; Histocytochemistry; Rabbits

Topics: Adaptation, Physiological; Aging; Anabolic Agents; Animals; Calcium Metabolism Disorders; Chlorides; Dihydrotachysterol; Disease Models, Animal; Female; Humans; Magnesium; Myocardial Infarction; Necrosis; Potassium Chloride; Progeria; Rats; Sodium; Steroids; Stress, Physiological

Topics: Animals; Calcinosis; Calcium; Dihydrotachysterol; Disease Models, Animal; Female; Glycosaminoglycans; Histocytochemistry; Rats; Scleroderma, Systemic; Skin Diseases

Topics: Animals; Arteriosclerosis; Blood Vessels; Dihydrotachysterol; Disease Models, Animal; Nitriles; Rats