Social disruption-induced stress pre-exposure aggravates, while the presence of conspecifics diminishes, acetic acid-induced writhing.

Abstract

RATIONALE AND OBJECTIVE:

This study was undertaken to assess the modulating effects of (1) pre-exposure to repeated social disruption and (2) group testing on writhing associated with visceral pain induced by intraperitoneal administration of acetic acid.

MATERIALS AND METHODS:

Six consecutive days of social disruption were used to prime for stress, while group testing referred to 3 mouse cage-mates receiving the acetic acid-induced writhing test as a group.

RESULTS:

Social disruption-induced stress-pre-exposed mice displayed a greater number acid-induced writhes compared to mice not receiving the pre-exposure. However, mice displayed fewer acid-induced writhes in a triad group vs. individually, suggesting group-mediated writhing-reducing effects. Likewise, group testing prevented the stress pre-exposure escalation in acid-induced writhes. Additional studies revealed that the stress-pre-exposed mice had increased expression in accumbal TRPV1 receptors. Systemic (0.25 mg/kg) and bilateral intra-accumbal (0.2 ng/0.2 µl/side) administration of SB366791, a TRPV1 receptor antagonist, reliably prevented the stress pre-exposure escalation in acid-induced writhing; SB366791 treatment alone did not affect acid-induced writhing, stress pre-exposure anxiety-like behavior, or the group testing effects. Furthermore, lower neuronal activation was found in the medial septal nucleus in group vs. individual tested mice. Intra-medial septum (0.2 µg/0.5 µl) infusion with bicuculline, a GABAA receptor antagonist, effectively prevented group-mediated writhing-reducing effects, but not individual acid-induced writhing effects.

CONCLUSIONS:

These findings suggest that social disruption-induced stress pre-exposure may upregulate accumbal TRPV1 receptor expression and consequently aggravate acid-induced writhing. Group testing prevents such stress pre-exposure escalation of acid-induced writhing most likely by strengthening the GABAergic inhibition on local neural activity in the medial septum.

• Authors: Yi-Han Liao, Yi-Chi Su, Yu-Han Huang, Hao Chen, Ya-Hsuan Chan, Li-Han Sun, Chianfang G Cherng, Ing-Tiau B Kuo, Lung Yu
• Journal: Psychopharmacology (Psychopharmacology (Berl)) Vol. 238 Issue 10 Pg. 2851-2865 (Oct 2021) ISSN: 1432-2072 [Electronic] Germany
• PMID: 34181036 (Publication Type: Journal Article)
• Copyright: © 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Chemical References

• Analgesics
• Acetic Acid

Topics

• Acetic Acid (toxicity)
• Analgesics (therapeutic use)
• Animals
• Dose-Response Relationship, Drug
• Injections, Intraperitoneal
• Mice
• Septal Nuclei
• Stress, Psychological