Distinct presynaptic mechanisms underlie firing frequency-dependent modulation of synaptic transmission in the solitary complex

• Yamamoto Kiyofumi

  Lab. Neurophysiol., Dept. Neurosci., Jikei Univ. Sch. Med., Tokyo, Japan

• Yamada Chiaki

  Lab. Neurophysiol., Dept. Neurosci., Jikei Univ. Sch. Med., Tokyo, Japan

• Imura Taiko

  Lab. Neurophysiol., Dept. Neurosci., Jikei Univ. Sch. Med., Tokyo, Japan

• Shigetomi Eiji

  Lab. Neurophysiol., Dept. Neurosci., Jikei Univ. Sch. Med., Tokyo, Japan

• Kato Fusao

  Lab. Neurophysiol., Dept. Neurosci., Jikei Univ. Sch. Med., Tokyo, Japan

Bibliographic Information

Other Title

• 内臓感覚１次求心神経—孤束複合体ニューロン間シナプス伝達効率の周波数依存性

Abstract

The afferent fibers in the vagus nerve transmit visceral information encoded as varying firing frequency to the second-order neurons in the nucleus of the solitary tract (NTS) and dorsal motor nucleus of the vagus (DMX). The purpose of this study was to examine how the firing frequency affects transmission efficiency at these synapses. EPSCs evoked by the solitary tract (TS) stimulation were recorded from DMX and NTS neurons in the thick brainstem slices of young rats. TS stimulation at various frequencies (0.1–20 Hz) revealed distinct frequency-dependent responses in the EPSC amplitude among different types of neurons recorded. When stimulated at 20 Hz, NTS neurons and low-pass type DMX neurons exhibited marked amplitude reduction (<30% of the first EPSC) within 10 pulses, whereas high-fidelity (hi-fi) type DMX neurons presented only modest attenuation (>40%). These neurons exhibited distinct short-term plasticity as revealed by paired-pulse ratio (PPR) evaluation. Surprisingly, unlike the NTS neurons, PPRs in the low-pass DMX neurons were not significantly affected by changes in [Ca²⁺]_o, suggesting distinct mechanisms for their short-term depression. These results indicate that the transmission efficiency between the visceral afferents and second-order neurons depends largely on the firing frequency mostly through distinct target cell-dependent presynaptic mechanisms, which might result in differential activation of distinct components in the solitary complex network. [J Physiol Sci. 2006;56 Suppl:S173]

Journal

• Proceedings of Annual Meeting of the Physiological Society of Japan

  Proceedings of Annual Meeting of the Physiological Society of Japan 2006 (0), 173-173, 2006

  PHYSIOLOGICAL SOCIETY OF JAPAN

Keywords

• transmission
• vagus nerve
• nucleus of the solitary tract
• dorsal motor nucleus of the vagus

Details

• CRID: 1390001205727435776
• NII Article ID: 130005448457
• DOI: 10.14849/psjproc.2006.0_173_3
• Data Source:
  • JaLC
  • CiNii Articles
• Abstract License Flag: Disallowed