Neurochemical and pharmacological properties of tianeptine, a novel antidepressant.
Tianeptine is a tricyclic antidepressant with an unusual chemical structure (a long lateral chain grafted on to a substituted dibenzothiazepin nucleus), and with biochemical and animal-behavioural properties which are strikingly different from those of classical tricyclics. Unlike the latter, which decrease serotonin (5-HT) uptake, acute and chronic tianeptine treatment enhances 5-HT uptake in rat brain and in rat and human platelets ex vivo. In vivo, tianeptine potentiates the depletion of rat brain 5-HT by 4-methyl-alpha-ethyl metatyramine and increases rat hippocampal 5-HIAA; 5-HT uptake inhibitors (e.g. fluoxetine) have opposite effects. On iontophoretic injection into CA1 pyramidal cells, tianeptine shortens the period of neuronal hypoactivity caused by GABA or 5-HT, whereas other tricyclics prolong it, and it enhances attention, learning, and memory in laboratory animals, while classical tricyclics have opposite effects. However, the relationships between these effects of tianeptine in animal experiments and their relevance to clinical findings remain to be determined.