Aminophylline, administered at usual doses for rodents in pharmacological studies, induces hippocampal neuronal cell injury under low tidal volume hypoxic conditions in guinea-pigs

Abstract

Objectives: To establish whether aminophylline, administered at usual doses for rodents in pharmacological studies, induces brain injury in systemic hypoxaemia in guinea-pigs.

Methods: A hypoxaemia (partial oxygen tension of arterial blood (PaO₂) = 40-60 mmHg) model was developed by low tidal volume mechanical ventilation in guinea-pigs.

Key findings: Under hypoxic conditions, aminophylline significantly increased the concentration of brain-specific creatine kinase in the serum in a dose- and time-dependent manner. A reduced number of hippocampal neuronal cells in the CA1 region, an increase in the concentration of neuron-specific enolase (NSE) in cerebrospinal fluid (CSF), an increase in lipid hydroperoxides and a decrease in the ratio of glutathione to glutathione disulfide in the brain tissues were also observed. These effects were not observed when aminophylline at the same doses was administered under normoxic conditions (PaO₂ = 80-100 mmHg). There was no difference in either serum or CSF concentrations of theophylline between normoxic and hypoxic conditions. Another methylxanthine, caffeine, did not increase the concentration of NSE in CSF.

Conclusions: Aminophylline potentially induces brain damage under hypoxic conditions. We suggest that aminophylline treatment has adverse effects in patients with hypoxaemia subsequent to respiratory disorders such as asthma.