Evidence against a hemodynamic role for serotonin in the dorsal motor nucleus of the vagus.
This study was performed to investigate the potential role of serotonin (5-HT) in the dorsal motor nucleus of the vagus (dmnX) in regulating peripheral hemodynamics. Microinjections (5 or 25 nmol in 50 nl) of the monoaminergic neurotransmitter were made into the dorsomedial medulla of the urethaneanesthetized rat during continuous recording of femoral arterial blood pressure. Heart rate was extracted electronically from the pressure waveform. Discrete injections of 5-HT placed directly in the dmnX were found to be entirely without effect on peripheral hemodynamics. In contrast, injections placed in the solitary tract nucleus, lying immediately above the dmnX, were found to have profound depressor and bradycardic effects, while the immediately subjacent hypoglossal nucleus appeared to contain both depressor and unresponsive sites. These findings cast doubt on the involvement of serotonin in the dmnX in the regulation of cardiovascular hemodynamics.
Feldman
P D
PD
Department of Pharmacology and Experimental Therapeutics, Louisiana State University Medical Center, New Orleans 70112-1393, USA.
Galiano
F J
FJ
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D008297:Male; D008526:Medulla Oblongata / Q000033:anatomy & histology / Q000187:drug effects*; D008845:Microinjections; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000187:drug effects; D012154:Reticular Formation / Q000166:cytology / Q000502:physiology; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*; D017552:Solitary Nucleus / Q000166:cytology / Q000502:physiology; D014630:Vagus Nerve / Q000033:anatomy & histology / Q000187:drug effects*
D012701:Serotonin