Altered prelimbic cortex output during cue-elicited drug seeking

Area of Science:

• Neuroscience
• Addiction Research
• Molecular Biology

Background:

• Environmental cues paired with cocaine establish conditioned place preference (CPP).
• This preference is associated with elevated immediate early gene (IEG) expression in brain regions like the prelimbic cortex (PrL), basolateral amygdala (BLC), and nucleus accumbens core (NAcc).
• These regions are implicated in a circuit contributing to cue-elicited craving and drug-seeking behavior.

Purpose of the Study:

• To investigate the functional roles of specific neuron classes within the PrL, BLC, and NAcc during cue-elicited cocaine-seeking.
• To differentiate immediate early gene (IEG) activation in GABAergic versus non-GABAergic neurons in response to cocaine-associated cues.

Main Methods:

• Combined Fos immunohistochemistry with GAD67 (GABAergic marker) or CAMKII (excitatory neuron marker) immunohistochemistry in rats.
• Quantified Fos immunoreactivity overlap with GAD67 and CAMKII in the PrL, BLC, and NAcc of animals exhibiting CPP versus controls.

Main Results:

• No significant differences in Fos/GAD67 overlap were found in the BLC or NAcc between groups.
• No significant differences in Fos/CAMKII overlap were observed in the BLC.
• In the PrL, a significantly higher percentage of Fos-immunoreactive cells co-expressed GAD67 in cocaine-paired animals compared to controls.
• Conversely, Fos/CAMKII overlap was significantly lower in the entire PrL and layer V of drug-paired animals.

Conclusions:

• Cocaine-seeking behavior is associated with preferential activation of GABAergic interneurons in the PrL.
• Attenuated PrL output, possibly via increased inhibition of layer V pyramidal neurons, may occur during CPP expression.
• These findings suggest a dynamic shift in prefrontal cortex neuronal population activity during cocaine-seeking.