[Role of the adrenergic system in lateral hypothalamic self stimulation behavior: effects induced by intraventricular injection of epinephrine, norepinephrine, isoproterenol and dopamine].

A bipolar electrode was stereotaxically implanted in or near the medial forebrain bundle at the level of the posterior lateral hypothalamus of male albino Wistar-Imamichi rats. The relationship between the adrenergic system and the lateral hypothalamic self-stimulation (SS) behavior was investigated by intraventricular injection (by the use of the modelled hypodermic needle) of catecholamines. l-Epinephrine(Ep), l-norepinephrine (NE) facilitated the SS behavior dose-dependently. On the other hand, l-isoproterenol and dopamine revealed no detectable effects. Phentolamine inhibited the SS behavior, but propranolol had no marked effects. Facilitation by NE for the SS behavior was not induced when the current was cut off at the time of the injection of NE. These results suggest the following: a) the adrenergic or the noradrenergic system in the brain may play a more important role in the positive reinforcement of the lateral hypothalamic SS behavior than does the dopaminergic system. b) The action of Ep or NE may be facilitated through alpha-receptors rather than through beta-receptors. c) Facilitation by NE for the lateral hypothalamic SS behavior may not be due to the non-specific facilitation of lever pressing, but rather may be related to intracranial stimulation.