There's plenty of choline inhibitors - but probably not what you're looking for
https://en.wikipedia.org/wiki/Anticholinergic
But perhaps not much else
https://en.wikipedia.org/wiki/Reuptake_enhancer
Ketamine acts as a NMDA receptor antagonist although it's also a reuptake inhibitor of dopamine, serotonin and norepinephrine. This one is interesting though - Ketamine has had some interest lately as an acute/immediate treatment for serious depression and was also used an CFS/ME instant remission treatment.
Good luck trying to get access to it though.
You're best bet might be N-Acetyl Cysteine
This is a well known glutamate modulator and possibly can raise glutathione - there's enough research to demonstrate its value to act on it's own in treating a range of depressive & pyschiatric disorders - as well as an adjunct to other drugs.
It seems to work by regulating glutamate - thus having a calming effect but without being a sedative. It appears to stop glutamate in areas of the brain where there is too much stimulation - apparently this leads to neurotoxicity and eventually the death of neurons - perhaps this is why people that have been depressed for many years struggle to recover and don't get adequate outcomes from most drugs. Anti-depressants have largely ignored the role of glutamate so far.
A lot of chronic health conditions are supposedly linked to low glutathione too so there may be some secondary benefit there too.
The problem is that a lot of alternative health groups have jumped on NAC so I'm not sure if the science will live up to the hype - so now every snake oil salesman is selling glutathione claiming its a miracle cure for everything.
Some on these boards say NAC helps them sleep. There's heaps on pubmed about this stuff and even more on the web of people claiming it cured all sorts of 'behavioral disorders' like maladaptive daydreaming, obsessive compulsive disorder, anxiety, depression, bi-polar depression, addictions - particularly gambling, reducing cigarette cravings, hair pulling etc....
That leads me to think that the mechanism of action is quite broad but also precise. It seems to alleviate the cravings associated with multiple behavioral disorders and addictions yet it doesn't appear to have any significant negative side-effects. So its mechanism of action is probably quite gentle and may just takes the edge of some of the toxicity caused by excess glutamate.