Acute hyperinsulinaemia causes an increase in neuropeptide Y (NPY) concentrations in the hypothalamic arcuate nucleus of the rat

Malabu, U.H., Cotton, S.J., Kruszynska, Y.T., McCarthy, H D., McKibbin, P.E., and Williams, G. (1992) Acute hyperinsulinaemia causes an increase in neuropeptide Y (NPY) concentrations in the hypothalamic arcuate nucleus of the rat. Diabetic Medicine, 9 (S1). A26. 7A-7A.

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Abstract

NPY, a major hypothalamic peptide, stimulates feeding, insulin secretion and weight gain when injected intrahypothalamically. NPY synthesis in the arcuate nucleus (ARC) and levels in NPY-sensitive hypothalamic regions rise in diabetes and starvation, possibly stimulated by insulin deficiency. High pharmacological intracerebroventricular insulin levels inhibit NPY synthesis in the ARC, but the effects of hyperinsulinaemia have not been studied. We therefore measured regional hypothalamic NPY levels in rats during a hyperinsulinaemic, euglycaemic clamps.

Male Wistar rats with implanted jugular cannulae, fasted for 24 hrs, were infused with insulin (128.2 mU1⁻¹ at 780 μl hr⁻¹ (n = 7) together with variable-rate glucose to maintain euglycaemia (3.9± 0.1 mmoll⁻¹), or saline (n=8; glycaemia, 4.0±0.5 mmoll⁻¹), for 2.5 hrs. Insulin levels were 80.2±10.4 mUl⁻¹ in insulin-infused rats and 16.7±11.7 mUl⁻¹ in saline-treated controls (p<0.001). NPY levels were measured by radioimmunoassay in the ARC and 7 other hypothalamic regions. NPY levels in the ARC were significantly higher in hyperinsulinaemic than in control rats (4.80±1.17 vs 2.54±0.58 fmol μg protein⁻¹; p<0.001), but comparable with controls in all other regions.

Acute physiological hyperinsulinaemia therefore increase NPY levels selectively in the ARC. Insulin may cause NPY accumulation in the ARC by blocking its transport to NPY-sensitive areas, consistent with the suggested inhibition by insulin of NPY and the postulated role of insulin as a satiety factor.

Item ID: 29865
Item Type: Article (Abstract)
ISSN: 1464-5491
Date Deposited: 07 Apr 2014 02:54
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1103 Clinical Sciences > 110306 Endocrinology @ 100%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920104 Diabetes @ 100%
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