K-holes for everyone!
via Psychology Today:
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As with everything in the brain, the story isn’t so simple as a single neurotransmitter system like dopamine. Neurotransmitters have complex interactions. Another system using the neurotransmitter glutamate has always been known to be at the heart of depressive disorders. Glutamateis the major excitatory neurotransmitter in the brain, meaning it is the “on” switch. Problem is, if things are put “on” too aggressively or too much, you get what is called “excitotoxicity” leading to neuron damage and even cell death. There’s some evidence that glutamate overload of glutamate receptors like the NMDA receptor may be responsible for the key symptom of depression, anhedonia. Chronic stress seems to damage the nerve synapses.
In a recent paper (news coverage here), researchers described how they used a noncompetitive inhibitor of the NMDA receptor and partial dopamine receptor agonist, ketamine (originally developed as a tranquilizer/anesthetic agent that is now used mostly in veterinary practice and sometimes in children) to rapidly reverse the symptoms of anhedonia in depressed patients.