Oxytocin and Dopamine Receptor Expression: Cellular Level Implications for Pair Bonding

Area of Science:

• Neuroscience
• Behavioral Genetics
• Molecular Biology

Background:

• Oxytocin (Oxtr) and dopamine (Drd1, Drd2) receptors influence behavioral variation across species.
• Differences in nucleus accumbens (NAc) expression of these receptors are known between prairie and meadow voles.
• The precise cellular organization of these receptor systems remains largely uncharacterized.

Purpose of the Study:

• To map the cellular distribution of Oxtr, Drd1, and Drd2 in the NAc of prairie and meadow voles.
• To investigate species- and pair-bonding-related differences in receptor expression patterns.
• To comprehensively map Oxtr and dopamine receptor (Drd1-5) expression across NAc cell types in prairie voles.

Main Methods:

• Multiplex in situ hybridization was used to visualize Oxtr, Drd1, and Drd2 expression.
• Cellular counts and distribution were analyzed in sexually naïve and mate-paired voles.
• Single-nucleus sequencing provided a molecular map of NAc cell types and receptor expression in prairie voles.

Main Results:

• Prairie voles exhibited higher Oxtr+ cell counts compared to meadow voles.
• Oxtr was enriched in cells co-expressing Drd1 and Drd2 (Drd1+/Drd2+) in prairie voles.
• No significant species or pairing-induced differences were found in Drd1+ or Drd2+ cell counts.

Conclusions:

• Oxytocin receptor expression is generally upregulated in prairie voles, particularly in cells co-expressing dopamine receptors.
• Dopamine receptor cell counts are stable, suggesting expression level differences, not cell number changes, underlie prior findings.
• This study provides a foundational cellular and molecular framework for understanding how oxytocin and dopamine systems shape social behavior in the NAc.