Abstracts

Rationale: Several lines of evidence suggest that antidepressant treatment might be linked with an increase in glutamatergic transmission. Hippocampus is implicated in the pathophysiology and treatment of mood disorders. We evaluated effects of commonly used antidepressants on the glutamatergic transmission in the rat hippocampus. Methods: Following fluoxetine, paroxetine, citalopram, or amitriptyline treatment, we investigated changes in paired-pulse responses, evoked responses and electroencephalography in the rat hippocampus. Vesicular glutamate transporter 1 (VGLUT1) in the hippocampus was also examined by immunohistochemical methods. Results: Except fluoxetine, VGLUT1 immunoreactivity in the hippocampus was increased in all drugs. In addition, the latter three drugs evoked abnormal EEG, and altered paired pulse responses (increased fEPSP slope and decrease paired-pulse inhibition). Differential effects of drugs on power spectrum were also observed (fluoxetine and citalopram increased β frequencies, whilst paroxetine and amitriptyline increased δ frequencies). Conclusions: These findings indicate that anti-depressants have distinct effects on neurotransmission and sleep pattern. Therefore, the differential pharmacological profiles of SSRI may be considerable to apply to the depressive patients with epilepsy or sleep disorders.