U50, 488 increases ultrasonic vocalizations in 3-, 10-, and 18-day-old rat pups in isolation and the home cage

摘要: Separation-induced calling in the young of many species can be modulated by opioid system. Morphine reduces ultrasonic vocalizations (USVs) produced isolated rat pups, an effect blocked naltrexone. Central administration mu and delta opiate receptor agonists DAMGO DPDPE reduce USV; kappa agonist U50,488 increases them. We now find that peripheral not only boosted rates 3-, 10-, 18-day-old but also induced pups these ages tested home cage with their littermates, where USVs are seldom heard nature. lowered rectal temperature, although temperature loss USV were correlated within drug treatment groups.