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Endogenous 5-HT inhibits firing activity of hippocampal CA1 pyramidal neurons during conditioned fear stress-induced freezing behavior through stimulating 5-HT1A receptors

  1. Koji Tada*,
  2. Kimihiro Kasamo,
  3. Tadashi Suzuki,
  4. Yamato Matsuzaki,
  5. Takuya Kojima

Article first published online: 12 JAN 2004

DOI: 10.1002/hipo.10178

Issue

Hippocampus

Hippocampus

Volume 14, Issue 2, pages 143–147, 2004

Additional Information

How to Cite

Tada, K., Kasamo, K., Suzuki, T., Matsuzaki, Y. and Kojima, T. (2004), Endogenous 5-HT inhibits firing activity of hippocampal CA1 pyramidal neurons during conditioned fear stress-induced freezing behavior through stimulating 5-HT1A receptors. Hippocampus, 14: 143–147. doi: 10.1002/hipo.10178

Author Information

  1. Department of Neuropsychiatry, Nihon University, School of Medicine, Tokyo, Japan

*Department of Neuropsychiatry, Nihon University, School of Medicine, Oyaguchi Kamimachi 30-1, Itabashi, Tokyo 173-8610, Japan

Publication History

  1. Issue published online: 9 MAR 2004
  2. Article first published online: 12 JAN 2004
  3. Manuscript Accepted: 9 DEC 2002

Funded by

  • Pharmacopsychiatry Research Foundation

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Keywords:

  • hippocampus;
  • unit recording;
  • unanesthetized;
  • WAY-100635;
  • PCPA

Abstract

This study examines the activity of hippocampal CA1 pyramidal neurons during conditioned fear stress (CFS)-induced freezing behavior in unanesthetized, unrestrained rats. The firing frequency of hippocampal CA1 pyramidal neurons was significantly decreased when conditioned rats exhibited freezing behavior. Firing frequency returned to the baseline after freezing behavior disappeared. The selective 5-hydroxytryptamine (5-HT)1A antagonists, N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclohexanecarboxamide (WAY-100635), and N-tert-butyl-3-[4-(2-methoxyphenyl)piperazine-1-yl]-2-phenylpropamide (WAY-100135) and 5-HT depletion with parachlorophenylalanine (PCPA) completely abolished the decrease in firing frequency during CFS-induced freezing behavior. These results suggested that endogenous 5-HT inhibited the firing activity of hippocampal CA1 pyramidal neurons during CFS-induced freezing behavior mainly through stimulating 5-HT1A receptors. © 2004 Wiley-Liss, Inc.

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