Targeting HINT1 to improve synaptic plasticity: toward loganin as a new antidepressant strategy.

Histidine triad nucleotide-binding protein 1 (HINT1) is related to depression. However, the underlying mechanisms and whether HINT1 is a therapeutic target for depression remain unclear. In this study, we report that loganin, an antidepressant candidate from our previous research, directly targets HINT1 to alleviate depressive-like behaviors. Overexpression of HINT1 in the hippocampus induces depressive-like behaviors. Mechanistically, HINT1 hinders sigma-1 receptor (Sigma-1R) binding to N-methyl-D-aspartate receptor (NMDAR), promotes  postsynaptic density protein (PSD95) binding to NMDAR, inhibits  brain derived neurotrophic factor (BDNF) signaling, and impairs synaptic plasticity. The interaction between HINT1 and NMDAR is disturbed by loganin. The antidepressant-like effects of loganin are reversed by HINT1 overexpression, Sigma-1R inhibitor and tropomyosin kinase receptor B (TrkB) inhibitor. These results not only indicate that HINT1 induces depression via impairing synaptic plasticity but also provide a candidate targeting HINT1 for depression therapy. Zhang et al. reported that a natural compound, loganin, improves synaptic plasticity and reduces depressive-like behaviors via its direct target HINT1. Mechanistically, overexpressed HINT1 hinders NMDAR/Sigma-1R interactions and increases NMDAR/PSD95 interactions, and HINT1/NMDAR interactions are disrupted by loganin treatment.