Modulation of neonatal rat hypoglossal motoneuron excitability by serotonin.
The effects of 5-HT on neonatal rat hypoglossal motoneurons (HMs) were studied in two in vitro slice preparations. Serotonin caused either reversible depolarization or the generation of an inward current (I5-HT) in every cell tested. I5-HT persisted after synaptic blockade. In most of the cells tested, the magnitude of I5-HT was independent of membrane potential (-50 to -120 mV), and 5-HT had little effect on input resistance or slope conductance. In addition, 5-HT significantly reduced the amplitude of the post-spike medium-duration afterhyperpolarization. This reduction probably contributed to the resulting increase in the slope of the relationship describing the steady-state firing frequency response to injected current (f-I) observed in the presence of 5-HT. Thus, 5-HT increases the excitability of neonatal HMs via at least two different postsynaptic mechanisms.
Berger
A J
AJ
Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle 98195.
Bayliss
D A
DA
Viana
F
F
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000831:Animals, Newborn; D003243:Consciousness / Q000502:physiology; D007002:Hypoglossal Nerve / Q000187:drug effects* / Q000502:physiology; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology; D011903:Raphe Nuclei / Q000502:physiology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology*; D013268:Stimulation, Chemical
D012701:Serotonin