Feeding behavior elicited by electrical stimulation of the lateral hypothalamic area in the rat: role of the adrenergic pathways and receptors.

To study the role played by neurotransmitters and their receptor mechanisms in the control of feeding behavior elicited by electrical stimulation, drugs that affect neurotransmission were injected via cannula electrodes into the lateral hypothalamic area. Pretreatment with noradrenaline (0.5 and 1.0 nmol) significantly increased the effect of hypothalamic stimulation on feeding, whereas injection of 1.0, 2.0 and 4.0 nmol of adrenaline or dopamine was ineffective. Phentolamine (40.0, 80.0 and 100.0 nmol) and propranolol (40.0, 80.0 and 120.0 nmol) induced a decrease in food intake, suggesting the involvement of both alpha and beta receptors in this mechanism. However, isoprenaline (20.0 nmol) also reduced food intake. Reduction of food intake by propranolol was probably related to the action of the local anesthetic. Alphamethyl-p-tyrosine (203.0 nmol), reserpine (32.8 nmol) and 6-hydroxydopamine (200.0 nmol) inhibited the feeding behavior elicited by electrical stimulation of the lateral hypothalamic area. These results suggest that electrical stimulation of the lateral hypothalamic area elicits feeding behavior by releasing noradrenaline. Alpha-adrenergic receptors seem to play a facilitatory role in feeding behavior.