Chronic intrahypothalamic infusions of insulin or insulin antibodies alter body weight and food intake in the rat.
In Experiment 1, one-week infusion of insulin (0.15, 1.5, or 15.0 microU/hr) into the ventromedial hypothalamus (VMH) of rats reduced body weight (BW) and nighttime food intake (FI). While 0.15 microU/h decreased daytime FI, 1.5 microU/h increased daytime FI and 15.0 microU/h left daytime FI unchanged. Total daily FI was decreased by the two highest doses. In Experiment 2, intra-VMH infusion of specific insulin antibodies (1.5 microUeq/h) increased BW and FI, while C-peptide antibodies were ineffective. In Experiment 3a, intracerebroventricular infusions of insulin failed to decrease FI and BW comparably to similar intrahypothalamic infusions. In Experiment 3b, intra-VMH insulin was infused via cannulae that bypassed the cerebral ventricles. The decrease in FI and BW was comparable to that observed when insulin was infused via cannulae that penetrated a ventricle. Histology from animals used in Experiments 1-3 indicates that optimum sites for insulin-induced changes in BW and FI in the hypothalamus lie in an area that includes portions of the paraventricular, arcuate, dorsomedial, and ventromedial nuclei.
McGowan
M K
MK
Committee on Biopsychology, University of Chicago, IL 60643.
Andrews
K M
KM
Grossman
S P
SP
D000818:Animals; D001835:Body Weight / Q000502:physiology*; D001931:Brain Mapping; D004326:Drinking / Q000502:physiology; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D007328:Insulin / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000502:physiology; D011956:Receptors, Cell Surface / Q000502:physiology; D014697:Ventromedial Hypothalamic Nucleus / Q000502:physiology*
D007328:Insulin; D011956:Receptors, Cell Surface; C027786:glucose receptor; D011972:Receptor, Insulin