Intracerebroventricular injection of glutathione-related dipeptides induces sedative and hypnotic effects during acute stress in neonatal chicks

To identify the important structural components of glutathione that induce sedative and hypnotic effects, intracerebroventricular (i.c.v.) injection of three glutathione-related dipeptides, i.e., glutamyl-cysteine (Glu-Cys), cysteinyl-glycine (Cys-Gly) and glutamyl-glycine (Glu-Gly) were given during an acute stress condition in neonatal chicks. These peptides attenuated distress vocalizations and spontaneous activity induced by social isolation. The increase in the time for sedation including sleep was also observed following the i.c.v. injection of dipeptides and then the time for active wakefulness decreased. Among the three peptides, Glu-Cys and Glu-Gly had a tendency to attenuate corticosterone release. In conclusion, dipeptides related to glutathione had a sedative and hypnotic effect, and did not vary in their action from each other.