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Naloxone blockade of (-)pentazocine-induced changes in auditory function
T L Sahley1, F E Musiek, R H Nodar
1Department of Speech & Hearing, Cleveland State University, Ohio, USA.
Ear and Hearing
|August 1, 1996
Summary
Opioid receptor blockade with naloxone reversed the auditory effects of (-)pentazocine in chinchillas. This confirms that opioid receptors play a role in auditory neural function and drug-induced changes in hearing.
Area of Science:
- Neuroscience
- Pharmacology
- Auditory Science
Background:
- Previous studies indicated intravenous (-)pentazocine affects auditory sensitivity and compound action potential (CAP) amplitudes.
- The sigma-receptor-selective isomer (+)pentazocine had no effect, suggesting opioid receptor involvement.
Purpose of the Study:
- To investigate if the auditory neural effects of (-)pentazocine are mediated by opioid receptors.
- To determine if naloxone, a non-specific opioid antagonist, can block these effects.
Main Methods:
- Twenty-five chinchillas were used to measure auditory nerve CAP (N1) and cochlear microphonic (CM) responses.
- (-)pentazocine was administered intravenously, alone or with naloxone at two doses.
- Measurements were taken at six stimulus intensities during baseline and post-drug administration.
Main Results:
- (-)pentazocine administration caused significant changes in CAP amplitudes without affecting latencies, CM amplitudes, or blood chemistry.
- Naloxone (5 mg/kg) significantly antagonized the CAP amplitude changes induced by (-)pentazocine.
- These findings indicate a clear blockade of (-)pentazocine's effects.
Conclusions:
- The results strongly suggest that the auditory neural effects of (-)pentazocine are mediated through opioid receptors.
- This study highlights a connection between opioid receptors and auditory neural function.
- Potential implications for understanding stress, hyperacusis, and tinnitus are discussed.