Serotonin and cervical respiratory motoneurones: intracellular study in the newborn rat brainstem-spinal cord preparation

✍ Scribed by D. Morin; R. Monteau; G. Hilaire

• Publisher: Springer-Verlag
• Year: 1991
• Tongue: English
• Weight: 429 KB
• Volume: 84
• Category: Article
• ISSN: 0014-4819
• DOI: 10.1007/bf00231779

✦ Synopsis

Previous experiments performed in the in vitro newborn rat brainstem-spinal cord preparation reported that the addition of serotonin (5-HT, 30-50 microM) to the bathing medium induced increases in the respiratory frequency and a large tonic discharge on all the cervical ventral roots. The aim of the present work was to define whether the 5-HT-induced tonic discharge involved respiratory or non-respiratory motoneurones. Intracellular recordings demonstrated that cervical (C2) motoneurones (n = 27) were depolarized by 5-HT but that the 5-HT-induced tonic discharge was mainly due to recruitment of silent motoneurones (n = 18) which fired permanently (15/18; 17 +/- 3 Hz) under 5-HT. The respiratory motoneurones (n = 9) retained a phasic inspiratory discharge (5/9), even if some (4/9) occasionally exhibited a few spikes during expiration. Therefore, it is concluded that the 5-HT-induced tonic discharge is unlikely to have functional significance in respiration.