A growing body of evidence points to the role of glutamate, a widely distributed excitatory neurotransmitter, in mediating response to stress and the formation of traumatic memories. Ketamine is an ionotropic glutamatergic N-methyl-d-aspartate (NMDA) receptor antagonist. Its antidepressant and anti-anxiety effects are presumed to occur through activating synaptic plasticity by increasing brain-derived neutrophic factor translation and secretion and also by inhibiting glycogen synthase kinase-3 and activating mammalian target of rapamycin signaling.
Brain-derived neutrophic factor plays a role in behavioral responses to classical antidepressants, but the impact on synaptic plasticity may take several weeks to manifest. In contrast, ketamine-mediated synaptic plasticity changes appear to occur within a matter of hours after ketamine administration.
“The current thinking is that eventually, 6 to 12 weeks after initiating treatment with traditional antidepressants, dendritic growth and increased synaptic connections occur but with ketamine, these can occur within 24 hours of the infusion,” Dr Masand said.