I'll just chime in and mention the 2 substances I've found most helpful for a anti-anxiety effect, that I'm pretty sure don't cause withdrawals but they might even be beneficial after you stop using them:
Cerebrolysin (I've literally used 1000ml+ over the years, this stuff has some lasting effects on several parameters of my cognition, and some mild immediate relaxing effect)
Selank
both of these IME interestingly potentiate the effects of my low dose prescription stims (I tend not to combine specifically cere with the scripts due to this)
while at the same time Selank is promoted as an anti-anxiety medication, and I think for sure Cere has some (lesser) anti-anxiety effects. so they are basically both stimulating and sedating (to use incorrect terminology to get a point across)
I have no idea what effects you are looking for tho, or why you are mentioning interneurons, but I think these two above will have potential for many things, if for no other reason the neurotrophic effects. In general I think cerebrolysin is the more powerful substance in terms of improving cognition and having rather obvious lasting effect (e.g. when I had protracted benzodiazepine withdrawal way back, problems speaking, general lack of coherent brain function).
Noopept I have tried (underwhelming), bacopa monnieri I have tried and it's ok for short-term anti-anxiety but that's about all I can say about that one (not very pleasant, it's sort of sedating with an "off" feeling IMO).
One of Cerebrolysins main effects is similar to CNTF as far as I recall.