Cerebral actions of dihydroergocristine]

Dihydroergocristine (DEC, CAS 17479-19-5) is a dihydrogenated ergot alkaloid with a potent dopaminergic activity that has been proved both in vitro and in vivo. Apart from its effect on the secretion of pituitary hormones, the following actions have been evidenced. It induces stereotyped behaviour and changes in the sleep-waking cycle, and reduces hypoxia-induced cerebral metabolic changes and emesis. The effect of DHEC on behaviour patterns has been studied in aged male rats in comparison with young animals. The acquisition of the active avoidance response in the shuttle-box test and the retention of the passive avoidance response in a step-through passive avoidance task were facilitated in aged rats by an acute treatment with DHEC. The effect on the acquisition and extinction of the pole-jumping performance after a single injection of DHEC at the beginning of the acquisition session was restricted to the first acquisition trial. A more potent effect on the acquisition of the shuttle-box response and on the retention of passive avoidance reaction was found in animals treated subchronically with DHEC. The latter animals also showed a facilitation of acquisition and an inhibition of extinction of the pole-jumping performance. In other experiments, the repeated administration of DHEC was followed by a decrease in the excessive grooming in aged rats, which is considered a sign of the lack of adaptability of these animals. A facilitation of the compensatory mechanisms in experimental models of vertigo has also been found in animals treated with DHEC.