ABSTRACT
This study was designed to investigate the possible participation of morphine in pulmonary oedema induced by alpha-naphthylthiourea (ANTU), which is a well-known noxious chemical agent in the lung. Injection of ANTU (15 mg/kg i.p.) produced pulmonary oedema as indicated by an increase in lung weight/body weight ratio and pleural effusion reaching a maximum within 4 h in rat. Administration of morphine prior to ANTU significantly inhibited to pulmonary oedema with a dose-dependent manner. The protective effect of morphine is prevented by peripheral opioid receptor antagonist, naloxone methiodide. ANTU-treated rats were shown positive by inducible nitric oxide synthase immunohistochemical staining. There was no staining in the control group. On the other hand, the degree of staining was markedly reduced in tissue sections by morphine. These results suggest that previous administration of subcutaneous morphine has preventive effect on ANTU-induced pulmonary inflammatory reaction and its effect mediated via peripheral opioid receptors. Application of naloxone with ANTU has no effect on the lung parameters indicating that endogenous opioids do not modulate ANTU-induced damage.
Subject(s)
Morphine/pharmacology , Naloxone/analogs & derivatives , Nitric Oxide Synthase/metabolism , Pulmonary Edema/prevention & control , Thiourea/analogs & derivatives , Animals , Dose-Response Relationship, Drug , Female , Immunohistochemistry , Lung/blood supply , Lung/drug effects , Lung/pathology , Male , Naloxone/pharmacology , Nitric Oxide Synthase Type II , Pulmonary Edema/chemically induced , Pulmonary Edema/enzymology , Quaternary Ammonium Compounds , Rats , Thiourea/toxicityABSTRACT
Oxidation of the low-density lipoprotein (LDL) results in the production of modified LDLs. Oxidation of LDL cholesterol plays a role on the pathogenesis of endothelial dysfunction. This study was designed to investigate the possible participation of the oxidative modification of low density lipoprotein in the lung edema induced by alpha-naphthylthiourea (ANTU), which is a well-known noxious chemical agent on the lung endothelium. When ANTU injected intraperitoneally into rats (15 mg kg(-1)), it produced lung edema as indicated by an increase in lung weight/body weight (LW/BW) ratio and pleural effusion (PE) reaching a maximum within 4 h. A significant lung edema was observed 4 h after intraperitoneally injection of alpha-naphthylthiourea when compared with olive oil-injected control rats. On microscopic examination of alpha-naphthylthiourea-treated rats were shown to have severe lung injury, while no change was observed in olive oil-treated control rats. While there were no staining in control lungs, positive oxidized low-density lipoproteins immune-fluorescent staining were observed in lung edema group. Our study showed that oxidized low-density lipoprotein (oxLDL) accumulated in ANTU-induced lung damage. This is the first study in which accumulation of oxLDL molecules in the intact lung tissue were shown by fluorescent immune-staining method in experimental lung edema. The potential role of oxLDL in this pathology are still under investigation.
