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

1. Exp Brain Res. 1991;84(1):229-32.

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

Morin D(1), Monteau R, Hilaire G.

Author information:
(1)Equipe Biologie des Rythmes et du Développement, URA-CNRS 0205, Faculté des
Sciences et Techniques St Jérôme, Marseille, France.

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.

DOI: 10.1007/BF00231779
PMID: 1855561 [Indexed for MEDLINE]

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