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Updated: May 23, 2026
A Conditioned Place Preference Protocol for Measuring Incubation of Craving in Rats
Published on: November 6, 2018
Different current intensities electrical stimulation of prelimbic cortex of mPFC produces different effects on
AliAkbar Kargari1, Effat Ramshini, HojjatAllah Alaei
1Department of Physiology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Abstract:
The medial prefrontal cortex (mPFC) is a part of brain reward system involved in higher cognitive functions such as learning and memory. The mPFC receives strong dopaminergic innervations from ventral tegmental area (VTA) that comprises a portion of the mesolimbic dopaminergic system (MLDS), and in turn sends glutamate projection to both the VTA and nucleus accumbens (NAc). In the present study, we investigated the influence of electrical stimulation with different current intensities on prelimbic cortex (PL, subdivision of mPFC) (25, 50, 100, and 150 μA) with and without an effective dose of morphine (0.5 and 5 mg/kg) on CPP during conditioning and post-conditioning phases. Subcutaneous administration of morphine 5mg/kg produced significant CPP in comparison with saline group. Our findings also showed that electrical stimulation of PL (100 μA) suppressed morphine-induced CPP that reveals impaired learning and memory formation in the process of conditioning through the blocking connection from the hippocampus to the prelimbic cortex of mPFC. A lowest current intensity (25 μA) in combination with ineffective dose of morphine (0.5 mg/kg) increased morphine-induced CPP probability via the prove reward system.
Insights
Electrical stimulation of the prelimbic cortex (PL) impacts morphine-induced conditioned place preference (CPP). High PL stimulation (100 μA) suppressed CPP, impairing learning, while low stimulation (25 μA) enhanced it.
Area of Science:
- Neuroscience
- Neurobiology
- Cognitive Science
Background:
- The medial prefrontal cortex (mPFC) is integral to the brain's reward system, supporting learning and memory.
- The mPFC, specifically the prelimbic cortex (PL), receives dopaminergic input from the ventral tegmental area (VTA) and projects to the VTA and nucleus accumbens (NAc).
Purpose of the Study:
- To investigate the effects of varying electrical stimulation intensities on the prelimbic cortex (PL) on morphine-induced conditioned place preference (CPP).
- To determine how PL stimulation, with and without morphine, influences learning and memory during conditioning and post-conditioning.
Main Methods:
- Morphine (0.5 and 5 mg/kg) or saline was administered subcutaneously.
- Electrical stimulation of the PL was applied at intensities of 25, 50, 100, and 150 μA.
- Conditioned place preference (CPP) was assessed during conditioning and post-conditioning phases.
Main Results:
- Morphine (5 mg/kg) significantly induced CPP compared to saline.
- PL electrical stimulation at 100 μA suppressed morphine-induced CPP, suggesting impaired learning and memory formation.
- Low PL stimulation (25 μA) combined with a low morphine dose (0.5 mg/kg) increased CPP probability, indicating potentiation of the reward system.
Conclusions:
- Electrical stimulation of the PL modulates morphine-induced CPP, affecting learning and memory processes.
- High-intensity PL stimulation can disrupt reward-related learning, potentially by blocking hippocampal-prefrontal pathways.
- Low-intensity PL stimulation may enhance reward system activity, increasing CPP likelihood.
