Serotonin receptor subtypes involved in vagus nerve stimulation-induced phrenic long-term facilitation in rats.
Episodic vagus nerve stimulation (VNS) induces phrenic long-term facilitation (LTF, a persistent augmentation of phrenic nerve activity after the stimulation ends), sensitive to the serotonin 5-HT(1,2,5,6,7) receptor antagonist methysergide and similar to that elicited by episodic hypoxia or carotid sinus nerve stimulation. This study examined the effect of ketanserin (5-HT(2) antagonist) or clozapine (5-HT(2,6,7) antagonist) on VNS-induced LTF in anesthetized, vagotomized, paralyzed and ventilated rats to determine which receptor subtype(s) is involved. Three episodes of 5 min VNS (50 Hz, 0.1 ms, approximately 500 microA) with 5 min intervals elicited phrenic LTF in control (amplitude: 38% above baseline at 60 min post-VNS) and ketanserin (2 mg x kg(-1), i.p.) pre-treated rats (45%), but not clozapine (3 mg x kg(-1)) rats (8%). These data suggest that unlike hypoxia-induced LTF (5-HT(2) receptor-dependent), VNS-induced LTF requires non-5-HT(2) serotonin receptors, perhaps 5-HT(6) and/or 5-HT(7) subtype(s).
Zhang
Yi
Y
Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
McGuire
Michelle
M
White
David P
DP
Ling
Liming
L
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D003024:Clozapine / Q000494:pharmacology; D004558:Electric Stimulation; D007650:Ketanserin / Q000494:pharmacology; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D010791:Phrenic Nerve / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism*; D012143:Respiratory Physiological Phenomena / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*
D011985:Receptors, Serotonin; C097216:serotonin 6 receptor; C104425:serotonin 7 receptor; D012701:Serotonin; D007650:Ketanserin; D003024:Clozapine