Food intake and lateral hypothalamic self-stimulation covary after medial hypothalamic lesions or ventral midbrain 6-hydroxydopamine injections that cause obesity.
In rats with perifornical lateral hypothalamic (LH) electrodes that induced feeding, self-stimulation through the same electrodes increased immediately after ventromedial hypothalamic (VMH) lesions and did not return to normal until food intake normalized and the rats had become obese. In a second experiment a unilateral far-LH lesion decreased both feeding and contralateral perifornical LH self-stimulation. In Experiment 3, 6-hydroxydopamine (6-OHDA) injected into the midbrain to destroy the ventral noradrenergic bundle (VNAB) caused hyperphagia and increased LH self-stimulation. In summary, VMH or VNAB damage increased feeding and self-stimulation; contralateral far-LH damage decreased both. These results confirm the earlier suggestion that the VMH region is necessary for normal inhibition of feeding and feeding reward as reflected in self-stimulation rate. Although massive 6-OHDA-induced depletion of the dopamine system that passes through the LH can cause starvation and impair self-stimulation, the results suggest that selective catecholamine depletion of ventral midbrain neurons with sparing of the A9 and A10 dopaminergic cells can disinhibit feeding and self-stimulation. In all three experiments LH self-stimulation and food intake covaried, which suggests that they are functionally related.
Hernandez
L
L
Department of Psychology, Princeton University, New Jersey 08544-1010.
Hoebel
B G
BG
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001931:Brain Mapping; D004435:Eating / Q000187:drug effects; D005260:Female; D006892:Hydroxydopamines / Q000494:pharmacology; D007026:Hypothalamic Area, Lateral / Q000502:physiology*; D008636:Mesencephalon / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects; D009434:Neural Pathways / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology*; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D012528:Satiety Response / Q000502:physiology; D012653:Self Stimulation / Q000502:physiology*; D014697:Ventromedial Hypothalamic Nucleus / Q000502:physiology*
D006892:Hydroxydopamines; D016627:Oxidopamine; D009638:Norepinephrine