The influence of phentolamine on the central activity of 5-hydroxytryptamine in rat.

PHENT (20 and 100 mug ivc) affects the central action of 5-HT (0-1, 25 and 250 mug) in rats which shows itself in potentiation of 5-HT-induced inhibition of spontaneous locomotor and exploratory activities and in the prolongation of hexobarbital sleeping time. In case of postamphetamine hyperactivity and body temperature, 5-HT acts antagonistically to a lower PHENT dose and synergistically to a higher dose of this compound. No affect of 5-HT on a slight antistereotypy action of PHENT has been stated. Neither compound affects electrical seizures.