Ketamine is being used in the treatment of major depressive disorder. Ketamine is a glutamate NMDA receptor antagonist. A ‘modulating ‘effect of ketamine on NMDA receptors has been stated as giving rise an antidepressant effect of ketamine in major depressive disorder.
Glutamate toxicity due to calcium influx through L-, P/Q-, N-type voltage-gated calcium channels and NMDA receptor calcium channels is inhibited by taurine with taurine having a neuroprotective effect. The treatment presented on the Bipolar Depression page, which includes taurine, would address glutamatergic neurotransmission and could be effective for major depressive disorder.
Addressing glutamatergic neurotransmission via taurine is much preferable to addressing glutamatergic neurotransmission via ketamine. Research points to supplemental taurine as reducing homocysteine levels (Ahn, 2009), reducing cholesterol levels in animals (Guo et al., 2017; Chen et al., 2012) having an anti-obesity effect, as being negatively associated with ischemic heart disease, as ameliorating diabetes and points to taurine deficiencies as resulting in premature aging. Research on rats points to the neurotoxic effects of repeated ketamine exposure as being due to changes in purine metabolism and glycerophospholipid metabolism in the prefrontal cortex that persist even after ketamine withdrawal.