SEROTONERGIC MODULATION OF CENTRAL RESPIRATORY ACTIVITY IN THE NEONATAL MOUSE - AN IN-VITRO STUDY

In order to determine whether the serotonergic modulation of the centr al respiratory activity previously reported in neonatal rats occurs in species other than the rat, we performed identical in vitro experimen ts on the neonatal mouse to those performed on the neonatal rat. The e ffects of adding serotonin (5-hydroxytryptamine, 5-HT) and related age nts to the superfusate suggested that the respiratory rhythm generator undergoes an excitatory modulation via medullary 5-HT1A receptors. Up on applying the drugs to the spinal cord alone, 5-HT was found to have a dual effect on phrenic motoneuron firing: (i) a facilitatory effect mediated by 5-HT2A receptors and (ii) a depressive effect on their in spiratory discharge mediated by non-5-HT1A, non-5-HT2A non-5-HT3 recep tors, possibly of the 5-HT1B subtype. It was therefore concluded that serotonin modulates the neonatal central respiratory activity in mice as well as in rats, and that similar 5-HT receptor subtypes are involv ed in this process in both species. (C) 1997 Elsevier Science B.V.