Modulation of memory with septal injections of morphine and glucose: Effects on extracellular glucose levels in the hippocampus

Ewan C. McNay, Clinton E. Canal, Robert S. Sherwin, Paul Ernest Gold

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

The concentration of glucose in the extracellular fluid (ECF) of the hippocampus decreases substantially during memory testing on a hippocampus-dependent memory task. Administration of exogenous glucose, which enhances task performance, prevents this decrease, suggesting a relationship between hippocampal glucose availability and memory performance. In the present experiment, spontaneous alternation performance and task-related changes in hippocampal ECF glucose were assessed in rats after intraseptal administration of morphine, which impairs memory on a spontaneous alternation task, and after co-administration of intraseptal glucose, which attenuates that impairment. Consistent with previous findings, spontaneous alternation testing resulted in a decrease in hippocampal ECF glucose levels in control rats. However, rats that received intraseptal morphine prior to testing showed memory impairments and an absence of the task-related decrease in hippocampal ECF glucose levels. Intraseptal co-administration of glucose with morphine attenuated the memory impairment, and ECF glucose levels in the hippocampus decreased in a manner comparable to that seen in control rats. These data suggest that fluctuations in hippocampal ECF glucose levels may be a marker of mnemonic processing and support the view that decreases in extracellular glucose during memory testing reflect increased glucose demand during memory processing.

Original languageEnglish (US)
Pages (from-to)298-303
Number of pages6
JournalPhysiology and Behavior
Volume87
Issue number2
DOIs
StatePublished - Feb 28 2006
Externally publishedYes

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Keywords

  • Glucose
  • Hippocampus
  • Medial septum
  • Memory
  • Morphine
  • Spontaneous alternation

ASJC Scopus subject areas

  • Behavioral Neuroscience
  • Physiology (medical)

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