GABAvsTianeptine

GABA binds to GABA-A receptors (ligand-gated Cl- channels with alpha1-6, beta1-3, gamma1-3 subunits) and GABA-B receptors (G-protein coupled, Gi/o mediated), reducing neuronal excitability through hyperpolarization. However, supplemental GABA has limited blood-brain barrier penetration due to absence of a dedicated transporter and rapid metabolism by GABA-transaminase and succinate semialdehyde dehydrogenase in periphery. The calming effects may be mediated through: (1) GABA-A and GABA-B receptors in the enteric nervous system (gut-brain axis) — vagal afferents project to the nucleus tractus solitarius and influence limbic regions; (2) small amounts crossing the BBB via paracellular leakage or in individuals with compromised barrier integrity; (3) peripheral effects reducing systemic stress markers (cortisol, heart rate variability). PharmaGABA (Lactobacillus fermentation product) may have better absorption via peptide-like transport or different pharmacokinetics.

Tianeptine is a full agonist at mu-opioid (MOR) and delta-opioid (DOR) receptors, mediating both its antidepressant/anxiolytic effects and abuse potential at high doses. Paradoxically, it enhances serotonin reuptake via SERT—opposite to SSRIs—yet still produces antidepressant effects, possibly through opioid-mediated mood regulation. Tianeptine modulates glutamatergic signaling by reversing stress-induced downregulation of AMPA receptor subunits (GluA1/GluA2) and restoring synaptic plasticity. In the hippocampus and amygdala, it prevents stress-induced dendritic atrophy, spine loss, and CA3 pyramidal cell damage—likely through opioid receptor activation and downstream HPA axis effects. It increases BDNF levels and promotes neurogenesis. The combination of opioid agonism, glutamate normalization, and neuroplasticity enhancement underlies its unique profile.