a type of drug that works by enhancing the action of the neurotransmitter gaba
gamma-Aminobutyric acid In general, GABA does not cross the blood–brain barrier,[50] although certain areas of the brain that have no effective blood–brain barrier, such as the periventricular nucleus, can be reached by drugs such as systemically injected GABA.[57] At least one study suggests that orally administered GABA increases the amount of human growth hormone (HGH).[58] GABA directly injected to the brain has been reported to have both stimulatory and inhibitory effects on the production of growth hormone, depending on the physiology of the individual.[57] Certain pro-drugs of GABA (ex. picamilon) have been developed to permeate the blood–brain barrier, then separate into GABA and the carrier molecule once inside the brain. This allows for a direct increase of GABA levels throughout all areas of the brain, in a manner following the distribution pattern of the pro-drug prior to metabolism.[citation needed]
Serotonin Serotonin (/ˌsɛrəˈtoʊnɪn, ˌsɪərə-/[6][7][8]) or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Biochemically the indoleamine molecule is derived from the amino acid tryptophan.[9] Serotonin is primarily found in the enteric nervous system located in the gastrointestinal tract (GI tract). However, it is also produced in the central nervous system (CNS), specifically in the Raphe nuclei located in the brainstem. Additionally, serotonin is stored in blood platelets and is released during agitation and vasoconstriction, where it then acts as an agonist to other platelets.[10] Serotonin is popularly thought to be a contributor to feelings of well-being and happiness.[11]