Fos-expressing neuronal ensembles in rat infralimbic cortex encode initial and maintained oxycodone seeking in rats.

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Addiction Research

Background:

• The infralimbic cortex (IL) and its projections to the nucleus accumbens (NAc) are known to mediate opiate seeking in established addiction models.
• The precise timing of this circuitry's involvement during the initial acquisition of oxycodone self-administration remains largely unexplored.

Purpose of the Study:

• To investigate the recruitment of IL-NAc neuronal ensembles during the early stages of oxycodone self-administration.
• To determine the functional role of IL neuronal ensembles in both the acquisition and maintenance of oxycodone seeking behavior.

Main Methods:

• Retrograde labeling (CTb) and immunohistochemistry were used to identify activated NAc-projecting IL neurons during initial oxycodone seeking.
• Chemogenetic inactivation of IL Fos-expressing neurons using the Daun02 procedure in Fos-LacZ rats at different training phases.

Main Results:

• Daun02 infusions significantly attenuated oxycodone seeking behavior at both early learning and well-trained time points.
• These findings indicate that IL neuronal ensembles are activated during initial oxycodone self-administration learning.

Conclusions:

• IL neuronal ensembles are established during the initial learning phase of oxycodone self-administration.
• These ensembles are essential for both the maintenance and expression of oxycodone seeking behavior, highlighting their importance throughout the addiction process.