Pharmacological potential of gardoside in anxiety: Behavioral and molecular evidence

Gardenia jasminoides J. Ellis is a traditional herbal medicine with food-medicine functions. It has the effects of 'draining fire and relieving restlessness, clearing heat, and resolving toxins,' and is widely used in the treatment of anxiety. Gardoside (GS) is an iridoid glycoside compound derived from this plant and is one of its characteristic bioactive components. However, the efficacy and related mechanisms of GS in treating anxiety have not yet been reported.

The aim of this study was to explore the therapeutic potential of GS for anxiety and elucidate its underlying mechanisms.

A mouse anxiety model was established through forced swimming (FS) stress, and behavioral experiments were conducted to evaluate the anti-anxiety effect of GS. The whole-cell patch-clamp technique was employed to record excitatory synaptic transmission in pyramidal neurons of the hippocampal CA1 area. Potential targets and pathways were predicted through network pharmacology and validated using molecular docking and molecular dynamics simulations. Western blotting was used to measure the expression of key proteins in the PI3K/AKT pathway and glutamate receptor-related proteins in hippocampal tissue. The mechanism was verified by intraperitoneal injection of the PI3K/AKT pathway agonist Recilisib (HY-101625).

Behavioral experiments show that GS can improve FS-induced anxiety-like behavior in mice in a dose-dependent manner. The whole-cell patch-clamp recordings showed that GS reversed the FS-induced increases in spontaneous excitatory postsynaptic current (sEPSC) frequency and amplitude, as well as the action potential firing frequency in mouse hippocampal neurons. Additionally, it decreased the phosphorylation levels of the AMPA receptor GluA1 subunit at the S831 and S845 sites, along with the total protein expression level of GluA1. Network pharmacology analysis suggested that the PI3K/AKT signaling pathway is a crucial pathway. Furthermore, molecular docking and molecular dynamics simulations confirmed that GS can stably bind to key targets of the PI3K/AKT signaling pathway, such as EGFR, PIK3R1, and AKT1. Western blotting results demonstrated that GS significantly inhibited the FS-induced increase in p-PI3K and p-AKT levels in hippocampal tissue. More importantly, the PI3K/AKT agonist HY-101625 not only antagonized the anti-anxiety behavioral effects of GS, but also reversed the inhibitory effect of GS on the expression of p-PI3K, p-AKT, p-GluA1-S831, p-GluA1-S845, and p-NR2B-S1303 proteins.

GS can significantly alleviate FS-induced anxiety-like behavior in mice, and its mechanism of action may be related to inhibiting the excessive activation of the PI3K/AKT signaling pathway in the hippocampus, thereby regulating glutamate receptor function and reducing neuronal excitability. Our study provides an important pharmacological basis for the development of GS as a potential anti-anxiety drug.