ABSTRACT
Melatonin, the main secretory product of the pineal gland, is a free radical scavenger and antioxidant which protects against oxidative damage due to a variety of toxicants. However, there is little information regarding melatonin's antioxidative capacity in tissues of primates. In this study we examined the protective effects of melatonin in monkey liver homogenates against lipid damage that occurred as a result of autoxidation or that induced by exogenous addition of H202 and ferrous iron (Fe2+). Additionally, we tested melatonin's protective effect against oxidative damage to DNA induced by chromium(III) (CrIII) plus H202. The levels of malondialdehyde and 4-hydroxyalkenals were assayed as an index of lipid peroxidation, and the concentrations of 8-hydroxydeoxyguanosine (8-OHdG) as an endpoint of oxidative DNA damage. The increases in malondialdehyde+4-hydroxyalkenals concentrations as a consequence of autoxidation or after the addition of H202 plus Fe2+ to the homogenates were time-dependent. The accumulation of these damaged products due to either auto-oxidative processes or induced by H202 and Fe2+ were significantly reduced by melatonin in a concentration-dependent-manner. The levels of 8-OHdG were elevated in purified monkey liver DNA incubated with a combination of CrCl3 plus H2O2. This rise in oxidatively damaged DNA was prevented by 10 microM concentration of melatonin. Also, melatonin reduced the damage to DNA that was caused by auto-oxidative processes. These findings in monkey liver tissue document the ability of melatonin to protect against oxidative damage to both lipid and DNA in primate tissue, as observed previously in rodent tissue. The findings provide support for the use of melatonin as suitable agent to reduce damage inflicted by free radical species in primates.
Subject(s)
Antioxidants/pharmacology , DNA/drug effects , Deoxyguanosine/analogs & derivatives , Lipid Peroxidation/drug effects , Liver/drug effects , Melatonin/pharmacology , 8-Hydroxy-2'-Deoxyguanosine , Animals , Chlorides/toxicity , Chromium Compounds/toxicity , DNA/genetics , DNA/metabolism , DNA Damage , Deoxyguanosine/metabolism , Dose-Response Relationship, Drug , Drug Interactions , Ferrous Compounds/toxicity , Free Radical Scavengers/pharmacology , Haplorhini , Hydrogen Peroxide/toxicity , Iron/toxicity , Liver/metabolism , Male , Malondialdehyde/metabolism , Oxidative Stress/drug effectsABSTRACT
Only a few cases of severe acute water intoxication (AWI) due to intranasal desmopressin have been reported, none of which occurred in patients with primary polydipsia. We describe a case of AWI with semicoma and convulsions, due to intranasal desmopressin, in a 32-year-old patient with dipsogenic diabetes insipidus. Previous reported cases of AWI due to desmopressin are discussed. The importance of ruling out primary polydipsia when this drug is used, not only for central diabetes insipidus but also for other current indications such as classic hemophilia, is stressed.
Subject(s)
Deamino Arginine Vasopressin/adverse effects , Water Intoxication/etiology , Administration, Intranasal , Adult , Deamino Arginine Vasopressin/administration & dosage , Deamino Arginine Vasopressin/therapeutic use , Drinking/drug effects , Female , Humans , Polyuria/complications , Polyuria/drug therapyABSTRACT
A 25-year-old woman with persistent nephrogenic diabetes insipidus (NDI) following parathyroidectomy for primary hyperparathyroidism is described. NDI is a well recognized complication of primary hyperparathyroidism, generally imputed to hypercalcemia, and promptly reversible after correcting it. In our case, the impaired concentrating ability of the renal tubule was irreversible after the removal of the parathyroid adenoma and the correction of the hypercalcemia, presumptively due to the morphological irreversible changes in the kidney. In addition, hypercalciuria persisted and was the cause of a compensatory hyperparathyroidism. Treatment with thiazide diuretic was effective to decrease relative hypercalciuria, thus reversing the compensatory hyperparathyroidism.