Science
August 19, 2010
Nanxin Li, Boyoung Lee, Rongjian Liu et al.
2,875 citations
Ketamine, a drug that blocks NMDA receptors, rapidly activates the mTOR pathway in the prefrontal cortex of rats, increasing synaptic signaling proteins and the number and function of new spine synapses. Blocking mTOR signaling prevented ketamine from inducing synaptogenesis and behavioral antidepressant-like responses in depression models. These effects reverse the synaptic deficits caused by stress and may explain ketamine's fast antidepressant action in treatment-resistant depressed patients, which contrasts with the weeks or months needed for standard medications.
Proceedings of the National Academy of Sciences
December 17, 2018
Kenichi Fukumoto, Manoela V. Fogaça, Rong-Jian Liu et al.
191 citations
A metabolite of ketamine, (2R,6R)-hydroxynorketamine [(2R,6R)-HNK], produces rapid and sustained antidepressant effects in animal models without the side effects of ketamine and without blocking the NMDA receptor. The antidepressant effects require activity-dependent release of BDNF, mediated by stimulation of voltage-dependent Ca2+ channels. Increased BDNF release activates downstream TrkB and mechanistic target of rapamycin complex 1 signaling, which increases synaptic function of pyramidal neurons in the medial prefrontal cortex. Stimulation of BDNF release and increased synaptic function block or reverse the detrimental effects of stress and depression.
American Journal of Psychiatry
January 4, 2019
Satoshi Deyama, Eunyoung Bang, Eric S. Wohleb et al.
100 citations
The antidepressant effects of ketamine require vascular endothelial growth factor (VEGF) signaling through its receptor Flk-1 in excitatory neurons of the medial prefrontal cortex (mPFC). Deleting VEGF or Flk-1 from forebrain excitatory neurons, or blocking VEGF in the mPFC, prevented ketamine's behavioral effects in mice. Infusing VEGF directly into the mPFC produced rapid antidepressant-like actions similar to ketamine, but these were blocked by Flk-1 deletion. Local knockdown of Flk-1 in adult mPFC excitatory neurons also blocked ketamine's effects. Additionally, blocking neuronal VEGF signaling prevented the neurotrophic and synaptogenic actions of ketamine. Neuronal VEGF-Flk-1 signaling in the mPFC is essential for ketamine's rapid antidepressant actions.
Proceedings for Annual Meeting of The Japanese Pharmacological Society
January 1, 2022
Ryota Shinohara, Brendan Hare, Rong-Jian Liu et al.
Ketamine, an NMDA receptor antagonist, rapidly relieves symptoms of depression within hours. While neuroplasticity in the medial prefrontal cortex (mPFC) is known to be critical for these effects, the downstream brain circuits involved were unclear. Using optogenetic and chemogenetic techniques in rodent models, researchers identified two distinct pathways. Activation of mPFC projections to the basolateral amygdala (BLA) and then to the ventral hippocampus mediated ketamine's effects on passive coping behavior, but not on anxiety or reward-seeking. In contrast, mPFC projections to the bed nucleus of stria terminalis (BNST) were necessary and sufficient for effects on anxiety-like and reward-seeking behaviors, but not passive coping. This suggests separate downstream circuits produce different antidepressant-like behavioral responses.
Proceedings for Annual Meeting of The Japanese Pharmacological Society
January 1, 2018
Satoshi Deyama, Eunyoung Baing, T. Kato et al.
Brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) in the medial prefrontal cortex (mPFC) work together to produce antidepressant effects. In cultured cortical neurons, BDNF stimulates VEGF release and VEGF stimulates BDNF release. BDNF increases dendritic complexity, but this effect is blocked by inhibiting the VEGF receptor Flk-1; similarly, VEGF's effect on dendrites is blocked by inhibiting the BDNF receptor TrkB. A single infusion of either BDNF or VEGF into the mPFC of mice produces antidepressant effects lasting at least 5 days in three behavioral tests. These effects are blocked by neutralizing the other factor, indicating that mutual signaling between BDNF and VEGF is required for rapid and sustained antidepressant responses.