I'm not the first person to have the idea:Tianeptine's action on serotonin receptors is almost identical to sulbutiamine's action on dopamine receptors, look it up, it doesn't increase the release of serotonin at all, the mechanism is receptor regulated.
Neuropsychopharmacol Hung. 2009 Jun;11(2):83-7.
Antidepressant action of tianeptine is connected with acceleration of serotonin turnover in the synapse: a hypothesis.
Uzbekov MG.
Department of Brain Pathology, Research Institute of Psychiatry, Moscow. uzbekovmg@mtu-net.ru
Abstract
Based on the results of our investigation of patients with anxious depression under the treatment with serotonergic antidepressants with different mechanism of action on serotonin reuptake we, the first time in the literature, propose the hypothesis about neurochemical mechanism of tianeptine action. According to this hypothesis tianeptine not only activates serotonin reuptake into the synaptic ending but also activates its release from the ending into the synaptic cleft thus accelerating serotonin turnover rate in the synapse. Proposed mechanism mainly refers the first, acute phase of its action directed to the normalization of serotonergic neurotransmission.
You may be right about agomelatine keeping the 5HT-2C receptors from upregulating substantially in response to the tianeptine's reverse-agonism but since agomelatine has such a gradual and benign effect, and 5HT-2C receptors respond more readily to reverse-agonism I can see it simply being made ineffective.
tianeptine is not an inverse agonist of 5-HT2C receptors, I'm not sure why you keep characterizing it this way.
What I'm saying is that agomelatine is a long term and gradual antidepressant, while tianeptine has primarily short term effects on serotonin, but is extremely potent in comparison. It only has long term effects on D1 + D2 auto-receptors, which are irrelevant to the MOA of agomelatine.
I consider most antidepressants to be gradual and long-term including tianeptine, and indeed it does not reach full effects for 4-6 weeks, underlining the fact that its acute effects, despite the fact that they may be mood-lifting, are not "THE antidepressant effect", which lately researchers seem to think is actually related to glutamate modulation:
Mol Psychiatry. 2010 Mar;15(3):237-49. Epub 2009 Aug 25.
The neurobiological properties of tianeptine (Stablon): from monoamine hypothesis to glutamatergic modulation.
McEwen BS, Chattarji S, Diamond DM, Jay TM, Reagan LP, Svenningsson P, Fuchs E.
Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY, USA. mcewen@mail.rockefeller.edu
Abstract
Tianeptine is a clinically used antidepressant that has drawn much attention, because this compound challenges traditional monoaminergic hypotheses of depression. It is now acknowledged that the antidepressant actions of tianeptine, together with its remarkable clinical tolerance, can be attributed to its particular neurobiological properties. The involvement of glutamate in the mechanism of action of the antidepressant tianeptine is consistent with a well-developed preclinical literature demonstrating the key function of glutamate in the mechanism of altered neuroplasticity that underlies the symptoms of depression. This article reviews the latest evidence on tianeptine's mechanism of action with a focus on the glutamatergic system, which could provide a key pathway for its antidepressant action. Converging lines of evidences demonstrate actions of tianeptine on the glutamatergic system, and therefore offer new insights into how tianeptine may be useful in the treatment of depressive disorders.
PMID: 19704408