Acute and chronic administration of the selective 5-HT1A receptor antagonist WAY-405 significantly alters the activity of midbrain dopamine neurons in rats: an in vivo electrophysiological study.

Yoshio Minabe, Lee Schechter, Kenji Hashimoto, Yuhiko Shirayama, Charles R Ashby

Department of Psychiatry and Neurology, Hamamatsu University School of Medicine, Hamamatsu, 431-3192 Shizuoka, Japan.

Synapse (New York, N.Y.) 2003 Dec 1

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In this study, we examined the effect of the acute and chronic administration of WAY-405, a selective 5-HT(1A) receptor antagonist, on the number and firing pattern of spontaneously active substantia nigra pars compacta (A9) and ventral tegmental area (A10) dopamine (DA) neurons in anesthetized rats. This was accomplished using in vivo, extracellular single unit recording. The i.v. administration of WAY-405 (5-640 microg/kg) did not significantly alter the basal firing rate or pattern of spontaneously active A9 and A10 DA neurons. A single injection of 10 microg/kg of WAY-405 decreased the number of spontaneously active A10 DA neurons and the 100 microg/kg dose significantly decreased the number of spontaneously active A9 and A10 DA neurons compared to vehicle-treated animals. A single injection of 1, 10, or 100 microg/kg of WAY-405 significantly decreased the degree of bursting of A10 DA neurons. In contrast, 1 microg/kg i.p. of WAY-405 significantly increased the percent of A9 DA neurons exhibiting a bursting pattern. The repeated administration of 10 or 100 microg/kg i.p. of WAY-405 (21 days) significantly decreased the number of spontaneously active DA neurons in both the A9 and A10 compared to vehicle-treated animals and this decrease was not reversed by i.v. (+)-apomorphine. The repeated administration of WAY-405 significantly altered the firing pattern of DA neurons, particularly those in the A10 area. Overall, these results indicate that the antagonism of the 5-HT(1A) receptor significantly alters the activity of midbrain DA neurons in anesthetized rats. Copyright 2003 Wiley-Liss, Inc.

Citation

Yoshio Minabe, Lee Schechter, Kenji Hashimoto, Yuhiko Shirayama, Charles R Ashby. Acute and chronic administration of the selective 5-HT1A receptor antagonist WAY-405 significantly alters the activity of midbrain dopamine neurons in rats: an in vivo electrophysiological study. Synapse (New York, N.Y.). 2003 Dec 1;50(3):181-90