Possible Mechanism of Action
As a couple of people in the original post have noted, the MOA might be linked to a neurosteroid effect, particularly an increase in allopregnanolone is responsible for improving GABA sensetivity, therefore this might be a reson why some effects similar to Phenibut.The following articles might give a hint in regards of the MOA and related compounds.
PubMed: Selective brain steroidogenic stimulants (SBSSs)
- Main clue
SSRIs act as selective brain steroidogenic stimulants (SBSSs) at low doses that are inactive on 5-HT reuptake
Brain principal glutamatergic neurons synthesize AlloP, a neurosteroid that potently, positively, and allosterically modulates GABA action at GABAA receptors. Cerebrospinal fluid (CSF) Allo levels are decreased in patients with posttraumatic stress disorder (PTSD) and major depression. This decrease is corrected by fluoxetine in doses that improve depressive symptoms. Depression-like behavioral dysfunctions (aggression, fear, and anxiety) associated with a decrease of corticolimbic AlloP content can be induced in mice by social isolation. In socially isolated mice, fluoxetine and analogs stereospecifically normalize the decrease of Allo biosynthesis and improve behavioral dysfunctions by a mechanism independent from 5-HT reuptake inhibition. Thus, fluoxetine and related congeners facilitate GABAA receptor neurotransmission and effectively ameliorate emotional and anxiety disorders and depression by acting as selective brain steroidogenic stimulants (SBSSs).
- Another compound
Etifoxine stimulates the biosynthesis of endogenous neurosteroids, for example: allopregnanolone, a nanomolar potentiator of GABA activity.
These neurosteroids exert inhibitory actions on neurotransmission. They act as positive allosteric modulators of the GABAA receptor (especially δ subunit-containing isoforms), and possess, in no particular order, antidepressant, anxiolytic, stress-reducing, rewarding, prosocial, antiaggressive, prosexual, sedative, pro-sleep, cognitive and memory-impairing, analgesic, anesthetic, anticonvulsant, neuroprotective, and neurogenic effects.
Certain antidepressant drugs such as fluoxetine and fluvoxamine, which are generally thought to affect depression by acting as selective serotonin reuptake inhibitors (SSRIs), have also been found to normalize the levels of certain neurosteroids (which are frequently deficient in depressed patients) at doses that are inactive in affecting the reuptake of serotonin. This suggests that other actions involving neurosteroids may also be at play in the effectiveness of these drugs against depression.
PubMed: AlloP increase in DA response
- Might explain alleviating anhedonia
The neurosteroid allopregnanolone increases dopamine release and dopaminergic response to morphine in the rat nucleus accumbens
AlloP dose-dependently increased the release of DA in the nucleus accumbens. Furthermore, this hormone doubled the DA response to morphine. These effects were observed for AlloP doses of 50 and 100 pmol injected intracerebroventricularly. These results suggest that the stimulatory effect of AlloP on DA could mediate some of the behavioural effects of neurosteroids and, in particular, the interaction of these hormones with mood and motivation.