Trh-gly (TRH-glycine) is a precursor of thyrotropin (TSH)-releasing hormone (TRH) that can release thyrotropin and prolactin.In Vitro: In GH3 cells expressing endogenous TRH-R, Trh-gly evokes an immediate rise of intracellular calcium concentration, indicating that Trh-gly reacted directly without converting from Trh-gly to TRH[2].In Vivo: In urethane-anesthetized 2-month-old (250 g) male Sprague-Dawley rats, Trh-gly (intracisternal injection; 1.0 mg) leads to a significant increase in the TRH levels in hypothalamus, medulla and blood.