THPO (drug)
THPO, also known as 4,5,6,7-tetrahydroisoxazolopyridin-3-one, is a relatively weak GABA reuptake inhibitor with some glial selectivity. It is a synthetic and conformationally restrained analogue of the GABAA receptor agonist and weak GABA reuptake inhibitor muscimol. Unlike muscimol however, THPO is a selective GABA reuptake inhibitor and lacks GABAA receptor affinity. The drug penetrates into the brain in newborn mice, but shows only [peripherally binding selectivity|selective drug|very limited central penetration] in animals with fully developed brains. Other structurally related selective GABA reuptake inhibitors include guvacine, nipecotic acid, and tiagabine.