Effects of the potassium ion channel modulators BMS-204352 Maxipost and its R-enantiomer on salicylate-induced tinnitus in rats.
Summary of "Effects of the potassium ion channel modulators BMS-204352 Maxipost and its R-enantiomer on salicylate-induced tinnitus in rats."
Currently, there are no effective pharmacological therapies for chronic tinnitus despite a number of efforts from clinical studies and more recently, studies in animals using compounds to enhance endogenous inhibition or reduce central hyperactivity. The purpose of the current study was to evaluate the therapeutic efficacy of a novel anxiolytic with potassium channel activity in suppressing salicylate induced tinnitus in animals. Kv7 potassium channels are present in the peripheral and central auditory system where they are believed to modulate neural activity. Maxipost, a compound which attenuates hyperexcitability via positive modulation of Kv7.2-Kv7.5 channels, was administered to rats with behavioral evidence of salicylate induced tinnitus. Tinnitus was measured using our previously established animal model, Schedule Induced Polydipsia Avoidance Conditioning, a paradigm where rats were conditioned to drink only during quiet and suppress drinking in the presence of sound. Salicylate alone significantly suppressed licks in quiet but had no effect on licks in sound; results consistent with the presence of tinnitus. Maxipost at 10mg/kg suppressed behavioral evidence of tinnitus as it completely reversed salicylate's suppression of licks in quiet. Unexpectedly, the R-enantiomer of Maxipost, R-Maxipost, which has no anxiolytic effects and negatively modulates Kv7.2-Kv7.5, also suppressed behavioral evidence of tinnitus. Our original hypothesis was that Kv7.2-Kv7.5 channels might play a key role in tinnitus generation and that Maxipost but not R-Maxipost would suppress tinnitus; however, it appears that a shared mechanism between Maxipost and R-xMaxipost, such as inhibition of Kv7.1 channels or activation of BK channels or some novel mechanism common to both compounds, underlies salicylate induced tinnitus as both compounds completely abolished behavioral evidence of tinnitus in a dose-dependent manner. Further studies with specific BK channel agonists/antagonists are necessary to determine the contribution of these channels to other forms of tinnitus or determine novel targets that could be related to tinnitus.
Affiliation
State University of New York at Buffalo, Center for Hearing and Deafness, United States.
Journal Details
This article was published in the following journal.
Name: Physiology & behavior
ISSN: 1873-507X
Pages: 873-9
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21640740
- DOI: http://dx.doi.org/10.1016/j.physbeh.2011.05.022
Medical and Biotech [MESH] Definitions
Kcnq3 Potassium Channel
A very slow opening and closing voltage-gated potassium channel that is expressed in NEURONS and is closely related to KCNQ2 POTASSIUM CHANNEL. It is commonly mutated in BENIGN FAMILIAL NEONATAL CONVULSIONS.
Kv1.3 Potassium Channel
A delayed rectifier subtype of shaker potassium channels that is the predominant VOLTAGE-GATED POTASSIUM CHANNEL of T-LYMPHOCYTES.
Kcnq1 Potassium Channel
A voltage-gated potassium channel that is expressed primarily in the HEART.
Kcnq2 Potassium Channel
A very slow opening and closing voltage-gated potassium channel that is expressed in NEURONS and is commonly mutated in BENIGN FAMILIAL NEONATAL CONVULSIONS.
Sodium Salicylate
A non-steroidal anti-inflammatory agent that is less effective than equal doses of ASPIRIN in relieving pain and reducing fever. However, individuals who are hypersensitive to ASPIRIN may tolerate sodium salicylate. In general, this salicylate produces the same adverse reactions as ASPIRIN, but there is less occult gastrointestinal bleeding. (From AMA Drug Evaluations Annual, 1992, p120)
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