FC13-09 - Antidepressant tianeptine (TIA) action is based on the acceleration of serotonin turnover in the synapse: a hypothesis

IntroductionNeurochemical mechanism of TIA action is not clear.AimTo develop possible mechanism of TIA action in patients with anxious depression (Uzbekov et al., 2006, 2009).ResultsIt was found twofold increase of platelet monoamine oxidase (MAO) activity in depressed patients and its significant decrease under TIA action.DiscussionSynapse is considered as a complex biological system (nerve ending + astrocytes). It is supposed that at normal conditions about 75% of serotonin released in synaptic cleft undergoes functional inactivation by its reuptake in presynaptic ending. The remaining serotonin is taken up by astroglia and is undergone its irreversible (chemical) inactivation under MAO action.According to our hypothesis TIA enhancing serotonin reuptake decreases serotonin level in synaptic cleft. Simultaneously in patients-responders we have established the decrease (inhibition) of MAO activity that promotes increase of serotonin concentration in synaptic cleft. It has been shown that TIA activates serotonin release from presynaptic ending (Labrid et al., 1992). Thus TIA enhances not only serotonin reuptake but simultaneously activates its surge from the ending into synaptic cleft. We conclude that under TIA action serotonin turnover rate in the synapse is increased that promotes increase in the unit of time serotonin concentration on postsynaptic receptors; this process is accompanied by decrease of MAO activity.ConclusionThe first time in the literature we propose the hypothesis about neurochemical mechanism of TIA action. Proposed mechanism mainly refers to the first acute phase of TIA action directed on the normalization of serotonergic neurotransmission.

Neurochemical Mechanism of Electroacupuncture: Anti-Injury Effect on Cerebral Function after Focal Cerebral Ischemia in Rats

We explored the neurochemical mechanism of electroacupuncture's (EA) protective effect on brain function in focal cerebral ischemia rats, using cerebral ischemia/reperfusion rats established by the middle cerebral artery occlusion (MCAO) method. Adult male Sprague–Dawley rats were randomly divided into four groups: Sham, Sham+EA, MCAO and MCAO+EA. The rats in Sham+EA and MCAO+EA were accepted EA treatment at ‘GV26’ and ‘GV20’ acupoints for 30 min. Electric stimulation was produced by a G-6805 generator and neurological deficit scores were recorded. Mitochondria respiratory function and the activities of respiratory enzymes were measured by a computer-aided Clark oxygen electrode system. Results showed that EA treatment might reduce the neurological deficit score, and significantly improve respiratory control ratio (RCR), the index of mitochondrial respiratory function, and increase the activities of succinic dehydrogenase, NADH dehydrogenase and cytochrome C oxidase in the MCAO rats. Results suggest that EA might markedly decrease the neurological deficit score, promote the activities of respiratory enzymes and reduce the generation of reactive oxygen species (ROS), resulting in improvement of respiratory chain function and anti-oxidative capability of brain tissues in the infarct penumbra zone. This be a mechanism of EA's anti-injury effect on brain function in MCAO rats.