Damage incurred by traumatic brain injury is believed to be caused in part by mass depolarization leading to excitotoxicity . One way in which progesterone helps to alleviate some of this excitotoxicity is by blocking the voltage-dependent calcium channels that trigger neurotransmitter release.  It does so by manipulating the signaling pathways of transcription factors involved in this release. Another method for reducing the excitotoxicity is by up-regulating the GABA A , a widespread inhibitory neurotransmitter receptor. 
Here's where I had issues... I got red welts from the get go with as little as 3iu's a day (i've used a lot more in the past) when I upped to 6ius the problems persisted and I also felt none of the usual sides. My joints in my wrists are usually painful and my sleep/skin are improved even after a month... I also tend to bloat with anything over 4-5ius (Pharma). I got nothing on 6. Got my bloods done after 6 total weeks on i think, few weeks at 3ius and the rest at 6, tested it 2hrs after pinning in the morning and got a igf-1 lvl of 51.... well within the normal range. (I can supply bloods and I already sent them to Matt). He said I hadn't been on it long enough... which in my opinion is bullshit... I've tested for HGH the same way for a while, only reason I switched was because I couldnt afford pharma anymore... always had results in at least the 200's if not 300's... He also tried to blame the tren im running saying it could impact IGF levels which I thought was ridiculous... if anything it would surely raise IGF? Serum results were 11, so normal range, not that that necessarily matters that much for the purposes of HGH testing. Very poor experience, seem to be some good reviews here but from my experience, the worst HGH i've used to date. Very disappointed.