Effects of leptin on hypothalamic arcuate neurons in Wistar and Zucker rats: an in vitro study.
Leptin, a product of the ob gene, decreases food intake and body weight in both Wistar and Zucker obese rats when administered centrally or peripherally. To examine whether these leptin effects might be mediated through a neuropeptide Y (NPY) signaling pathway in the medial part of the arcuate nucleus of the hypothalamus (vmARC), the effects of leptin on vmARC neurons in Wistar and Zucker obese rats were examined electrophysiologically using brain slice preparations. Bath application of leptin inhibited about 60% of the vmARC neurons recorded in slices from Wistar rats. Similar inhibitory effects of leptin on vmARC neurons were also observed under low-Ca2+, high-Mg2+ Ringer's solution. However, inhibitory effects were almost absent under Ringer's solution containing a protein kinase C inhibitor, chelerythrine chloride. In slices from Zucker obese rats, leptin inhibited only about 25% of the vmARC neurons recorded, and the proportion of neurons inhibited was significantly smaller for these rats than for Wistar rats. These results suggest that reductions in food intake and body weight induced by leptin in both Wistar and Zucker obese rats are partly mediated via inhibition of an NPY signaling pathway in the vmARC.
Nagamori
Katsuhiko
K
Department of Bio-Information Engineering, Faculty of Engineering, Toyama University, Toyama 930-8555, Japan.
Ishibashi
Masaru
M
Shiraishi
Takemasa
T
Oomura
Yutaka
Y
Sasaki
Kazuo
K
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D002118:Calcium / Q000737:chemistry / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D007552:Isotonic Solutions / Q000737:chemistry / Q000494:pharmacology; D020738:Leptin / Q000235:genetics / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009474:Neurons / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011924:Rats, Zucker; D011994:Recombinant Proteins / Q000494:pharmacology; D000077331:Ringer's Solution; D014697:Ventromedial Hypothalamic Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology
D007552:Isotonic Solutions; D020738:Leptin; D011994:Recombinant Proteins; D000077331:Ringer's Solution; D002118:Calcium