Amiodarone attenuates apoptosis, but induces phospholipidosis in rat alveolar epithelial cells

J Physiol Pharmacol. 2010 Dec;61(6):671-7.

Abstract

Amiodarone-induced pulmonary toxicity is a serious side-effect, but the underlying molecular mechanisms remain unclear. We examined phospholipidosis and apoptosis in rat alveolar epithelial cells after medium-term oral amiodarone treatment. Amiodarone (30 mg/kg daily, a dosage corresponding to that used clinically) or vehicle was administered by gavage in 33 Wistar rats for two weeks. Apoptosis was assessed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labelling (TUNEL) and the expression of apoptosis- and phospholipidosis-related proteins was measured by immunohistochemistry. Amiodarone decreased phospholipase-C-γ1 and increased phosphatidylinositol-(4,5)-bisphosphate, resulting in phospholipidosis, evidenced by the appearance of intracellular inclusion bodies with a multi-lamellated interior. Amiodarone exerted two opposite effects on apoptosis; compared to controls, the expression of activated-caspase-8 was higher in treated rats, while the expression of apoptosis inhibitors survivin, Bcl-2 and c-Flip was lower. On the other hand, the expression of activated-caspase-3 was lower after treatment. Overall, amiodarone attenuated apoptosis, evidenced by fewer TUNEL-positive cells. Medium-term oral amiodarone administration induced phospholipidosis in rat alveolar epithelial cells. Although such treatment decreased anti-apoptotic proteins, apoptosis was attenuated via a decrease in the caspase-3 pathway. These findings improve current understanding on the mechanisms underlying amiodarone-induced pulmonary toxicity.

MeSH terms

  • Amiodarone / pharmacology*
  • Animals
  • Apoptosis / drug effects*
  • Apoptosis Regulatory Proteins / antagonists & inhibitors
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism
  • Caspase 3 / genetics
  • Caspase 3 / metabolism
  • Caspase 8 / genetics
  • Caspase 8 / metabolism
  • Caspase Inhibitors
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism
  • Female
  • In Situ Nick-End Labeling / methods
  • Lipidoses / chemically induced
  • Lipidoses / metabolism
  • Lung / cytology
  • Lung / drug effects
  • Lung / metabolism
  • Phosphatidylinositol 4,5-Diphosphate / genetics
  • Phosphatidylinositol 4,5-Diphosphate / metabolism
  • Phospholipase C gamma / genetics
  • Phospholipase C gamma / metabolism
  • Phospholipids / biosynthesis*
  • Pulmonary Alveoli / cytology
  • Pulmonary Alveoli / drug effects*
  • Pulmonary Alveoli / metabolism
  • Rats
  • Rats, Wistar

Substances

  • Apoptosis Regulatory Proteins
  • Caspase Inhibitors
  • Phosphatidylinositol 4,5-Diphosphate
  • Phospholipids
  • Phospholipase C gamma
  • Caspase 3
  • Caspase 8
  • Amiodarone