Biological Psychiatry
January 1, 2018
Chun Yang, Q. Ren, Y. Qu et al.
249 citations
The antidepressant effects of the two enantiomers of ketamine rely on different signaling pathways in mice. (S)-ketamine requires mTOR signaling, as blocking mTOR with rapamycin or AZD8055 eliminated its effects, while (R)-ketamine does not. Instead, (R)-ketamine requires ERK signaling; blocking ERK with SL327 eliminated its effects. (S)-ketamine restored reduced mTOR phosphorylation in the prefrontal cortex of stressed mice, whereas (R)-ketamine restored reduced ERK phosphorylation in the prefrontal cortex and hippocampal dentate gyrus. These findings indicate that mTOR activation is not necessary for (R)-ketamine's antidepressant actions.
Molecular Psychiatry
November 24, 2021
W. Yao, Qianqian Cao, Shilin Luo et al.
208 citations
In a mouse model of depression, (R)-ketamine produces longer-lasting antidepressant effects than (S)-ketamine. The study identifies a molecular pathway in microglia—cells in the brain's medial prefrontal cortex—that mediates these effects. (R)-ketamine activates the ERK-NRBP1-CREB-BDNF signaling cascade in microglia, increasing BDNF transcription. Blocking this pathway with specific inhibitors or depleting microglia prevented (R)-ketamine's antidepressant-like effects and its ability to restore reduced dendritic spine density. These findings suggest that microglial signaling is essential for (R)-ketamine's antidepressant actions.
Military Medical Research
July 23, 2024
Hai-Lou Zhang, Yan Sun, Zhang-Jie Wu et al.
24 citations
The neuropeptide PACAP in the hippocampal dentate gyrus (DG) mediates rapid antidepressant responses. Chronic paroxetine increased hippocampal PACAP, and blocking PACAP in the DG slowed the antidepressant effect. PACAP levels were reduced in two depression models, and knocking down PACAP in the DG caused depression-like behaviors. A single infusion of PACAP into the DG produced a rapid and sustained antidepressant effect in normal and stressed mice. Optogenetic excitation of PACAP-expressing neurons instantly elicited antidepressant responses, while inhibition induced depression-like behaviors. PACAP infusion inhibited CaMKII-eEF2 signaling and activated mTOR-BDNF signaling. Acute ketamine increased PACAP, and blocking PACAP attenuated ketamine's rapid antidepressant effect.
Science advances
July 11, 2025
Lujuan He, Xuenan Wang, Shilin Luo et al.
8 citations
Arketamine, the (R)-enantiomer of ketamine, produces faster and longer-lasting antidepressant-like effects than esketamine in mice subjected to chronic social defeat stress. Activating the proteins CREB and MeCP2 drives the production of brain-derived neurotrophic factor (BDNF) in microglia, the brain's immune cells. This microglia-derived BDNF strengthens excitatory synaptic transmission in the infralimbic region of the medial prefrontal cortex (mPFC). It also activates mPFC neurons that project to the nucleus accumbens (NAc) shell, a brain area involved in reward and mood. These mechanisms together underlie arketamine's antidepressant-like effects, highlighting the essential role of microglial BDNF in modulating this neural pathway.