Serotonergic excitatory drive to hypoglossal motoneurons in the decerebrate cat.
In decerebrate, paralyzed, vagotomized and artificially ventilated cats, serotonin (5-HT) and its analogues, microinjected into the hypoglossal (XII) motor nucleus, altered the activity of the genioglossal branch of XII nerve. 5-HT, carboxamidotryptamine maleate (5-CT) and DOI (1-5 mM) increased the activity by over 200%. Methysergide reversed this increase. Methysergide, mianserin, or ketanserin (100-250 nl, 1 mM) reduced the spontaneous hypoglossal activity by 20-50%. Buspirone, 8-OH-DPAT and (-)-propranolol were without effect. Thus, 5-HT provides a substantial tonic excitatory drive to XII motoneurons. The 5-HT receptors involved are likely to be type 1C or 2, but uncertainty regarding the affinity profiles of the drugs used in in vivo conditions in the cat precludes a definite identification.
Kubin
L
L
Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104.
Tojima
H
H
Davies
R O
RO
Pack
A I
AI
D000818:Animals; D002415:Cats; D003655:Decerebrate State / Q000378:metabolism*; D005260:Female; D007002:Hypoglossal Nerve / Q000378:metabolism*; D008297:Male; D008845:Microinjections; D009046:Motor Neurons / Q000378:metabolism*; D012121:Respiration, Artificial; D012701:Serotonin / Q000494:pharmacology / Q000502:physiology*; D013268:Stimulation, Chemical; D014628:Vagotomy
D012701:Serotonin