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Effects of dalargin on excitation induced by L-glutamate agonists in the frog vestibular organs

Andrianov, G N.1,2; Ryzhova, I V.1

Auditory and Vestibular Systems

We have used an electrophysiological approach to investigate the action of a synthetic analog of leu-enkephalin dalargin (DAL) on chemically induced afferent activity in the frog vestibular organs. Administration of 5.0 μM kainic acid (KA), 5.0 μM (AMPA) and 50 μM NMDA produced an increase in the frequency of the resting discharge. Firing evoked by KA, AMPA or NMDA could be depressed by administration of 1 nM Dal by 55.5 ± 9.9% (n = 10, p < 0.05), 64.5 ± 11.2% (n = 13, p < 0.05) and 21.3 ± 11.1% (n = 14, p = 0.051), respectively. Thus, the frequency decrease under NMDA was statistically non-significant. These results show that non-NMDA, but not NMDA subtypes of receptors are mostly involved in opioid action at the vestibular organs of the frog.

1Laboratory of Physiology of Reception, Pavlov Institute of Physiology of the Russian Academy of Sciences, Nab. Makarova 6, St.Petersburg 199034, Russia

2Corresponding Author: G. N. Andrianov

Acknowledgements: The present study was supported by grant No. 99-04-49635 of the Russian Foundation of Basic Researches.

Received 28 September 1999; accepted 3 November 1999

© 2000 Lippincott Williams & Wilkins, Inc.