t-hca t-hca trans-4-hydroxycrotonic acid (t-hca), also known as γ-hydroxycrotonic acid (ghc), is an agent used in scientific research to study the ghb receptor. it is an analogue of γ-hydroxybutyric acid (ghb), as well as an active metabolite of ghb. similarly to ghb, t-hca has been found to be endogenous to the rat central nervous system, and as a metabolite of ghb, is almost certain to be endogenous to humans as well. t-hca binds to the high-affinity ghb receptor with 4-fold greater affinity than ghb itself, where it acts as an agonist, but does not bind to the low-affinity ghb binding site, the gabab receptor. because of this, t-hca does not produce sedation. t-hca has been shown to cause receptor activation-evoked increases in extracellular glutamate concentrations, notably in the hippocampus. t-hcaclinical dataother namestrans-4-hydroxycrotonic acidatc codenoneidentifiers iupac name (2e)-4-hydroxybut-2-enoic acid cas number24587-49-3 ypubchem cid6155526chemspider4825947 yuniintm454u33fchemblchembl507046 ychemical and physical dataformulac4h6o3molar mass102.089 g·mol−13d model (jsmol)interactive image smiles o=c(o)\c=c\co inchi inchi=1s/c4h6o3/c5-3-1-2-4(6)7/h1-2,5h,3h2,(h,6,7)/b2-1+ ykey:rmqjecwpwqiipw-owojbtedsa-n y ny (what is this?) (verify)