Microinjections of the dopamine D2 receptor antagonist sulpiride into the medial prefrontal cortex attenuate glucocorticoid-induced impairment of long-term memory retrieval in rats

Neurobiol Learn Mem. 2007 Mar;87(3):385-90. doi: 10.1016/j.nlm.2006.10.002. Epub 2006 Nov 22.

Abstract

We recently reported that blockade of dopamine (DA) D2 receptors attenuated deficits in long-term memory retrieval induced by a systemic injection of corticosterone, but the anatomical sites of such interaction were not known. In this study, we investigated whether the DA D2 receptors located in the medial prefrontal cortex (mPFC) may play a role in the impairing effects of glucocorticoids on the memory retrieval process. Young adult male rats were trained in a one trial inhibitory avoidance task (0.5 mA, 3s footshock). On the retention test given 48 h after training, the latency to re-enter the dark compartment and the time spent in light compartment of the apparatus were recorded. Systemically administered corticosterone (1mg/kg) given to rats 30 min before retention testing impaired their memory retrieval. Bilateral microinjections of the DA D2 receptor antagonist sulpiride (10 or 100 ng/0.5 microl per side) into the mPFC 30 min before corticosterone administration attenuated the glucocorticoid-induced impairment of memory retrieval. Furthermore, applied doses of sulpiride alone were ineffective in modulating memory retrieval. These findings indicate that D2 receptors located in the mPFC play an important role in mediating the impairing effects of glucocorticoids on memory retrieval.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Avoidance Learning / drug effects
  • Avoidance Learning / physiology*
  • Corticosterone / physiology*
  • Dopamine Antagonists / administration & dosage
  • Dopamine D2 Receptor Antagonists
  • Dose-Response Relationship, Drug
  • Male
  • Microinjections
  • Prefrontal Cortex / drug effects
  • Prefrontal Cortex / physiology*
  • Rats
  • Rats, Wistar
  • Receptors, Dopamine D2 / physiology*
  • Retention, Psychology / drug effects
  • Retention, Psychology / physiology*
  • Sulpiride / administration & dosage
  • Time Factors

Substances

  • Dopamine Antagonists
  • Dopamine D2 Receptor Antagonists
  • Receptors, Dopamine D2
  • Sulpiride
  • Corticosterone