Scopolamine attenuates auditory cortex response

Abstract

Conclusion: Scopolamine, a tropane alkaloid drug that mainly acts as an antagonist of muscarinic acetylcholine receptors, was found to reduce the local field potentials (LFP) of auditory cortex (AC) evoked by tone and gap-offsets whose effects may compensate the cortical hyperexcitability related to tinnitus. Objective: To study the effects of scopolamine on the AC and the inferior colliculus (IC) of awake rats in order to understand scopolamine’s effect on tinnitus and gap detection. Method: Silent gaps (duration varied from 2–100 ms) embedded in otherwise continuous noise were used to elicit AC and IC response. Gap evoked AC and IC field potentials were recorded from awake rats before and after treatment of scopolamine (3 mg/kg, i.m.). Results: Acute injection of scopolamine (3 mg/kg, i.m.) induced a significant reduction of the AC response, but not the IC response, to the offset of the gaps embedded in white noise. The results suggest that scopolamine may reduce AC neural synchrony.

Keywords:

• Scopolamine
• acetylcholine
• gap detection
• tinnitus
• auditory cortex

Acknowledgments

The project was supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (SRF for ROCS, SEM), Chongqing Natural Science Foundation (CSTC 2010BB5032).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.