To study the effect of chronic unpredictable stresses (CUS) on the neurotransmitter secretion of dorsal raphe nucleus (DRN) which contains 5-hydroxytryptamine (5-HT) neurons in rats, model group rats were exposed to 21-day CUS, and the controls were stress-free.DRN was electrically stimulated, and the following transient 5-HT signal measured in real time using constant potential amperometry with carbon fiber electrode in the prelimbic cortex (PrL) of anesthetized rat was analyzed to describe the release and uptake kinetics.The CUS rats showed significantly decrease in body weight, open-field scores, sucrose water consumption.5-HT release followed by electrical stimulating DRN was significantly increased in PrL cortex.Hyperforin can not only length the half-decay time of release signals,b ut also enhanced the amplitude of them in both group rats.CUS can increase the 5-HTrelease in PrL cortex followed by stimulating DRN.Hyperforin enhances the 5-HT release in PrL cortex followed by stimulating DRN.