Hippocampal memory processes are modulated by insulin and high-fat-induced insulin resistance

Neurobiol Learn Mem. 2010 May;93(4):546-53. doi: 10.1016/j.nlm.2010.02.002. Epub 2010 Feb 20.

Abstract

Insulin regulates glucose uptake and storage in peripheral tissues, and has been shown to act within the hypothalamus to acutely regulate food intake and metabolism. The machinery for transduction of insulin signaling is also present in other brain areas, particularly in the hippocampus, but a physiological role for brain insulin outside the hypothalamus has not been established. Recent studies suggest that insulin may be able to modulate cognitive functions including memory. Here we report that local delivery of insulin to the rat hippocampus enhances spatial memory, in a PI-3-kinase dependent manner, and that intrahippocampal insulin also increases local glycolytic metabolism. Selective blockade of endogenous intrahippocampal insulin signaling impairs memory performance. Further, a rodent model of type 2 diabetes mellitus produced by a high-fat diet impairs basal cognitive function and attenuates both cognitive and metabolic responses to hippocampal insulin administration. Our data demonstrate that insulin is required for optimal hippocampal memory processing. Insulin resistance within the telencephalon may underlie the cognitive deficits commonly reported to accompany type 2 diabetes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Diabetes Mellitus, Experimental / metabolism
  • Diet
  • Dietary Fats / metabolism
  • Disease Models, Animal
  • Hippocampus / drug effects
  • Hippocampus / enzymology
  • Hippocampus / physiology*
  • Insulin / metabolism*
  • Insulin Resistance / physiology*
  • Male
  • Memory / drug effects
  • Memory / physiology*
  • Memory Disorders / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Random Allocation
  • Rats
  • Rats, Sprague-Dawley
  • Space Perception / drug effects
  • Space Perception / physiology

Substances

  • Dietary Fats
  • Insulin
  • Phosphatidylinositol 3-Kinases