Response of neurons in the dorsal motor nucleus of the vagus to thyrotropin-releasing hormone.
Autonomic motoneurons in the dorsal motor nucleus of the vagus (DMX) were recorded intracellularly in an in vitro slice preparation of the guinea pig brainstem. Bath-applied thyrotropin releasing hormone (TRH) (1-10 microM) induced a reversible depolarization of neurons that was typically accompanied by an increase in the spontaneous firing of the cells. In some cells, TRH induced rhythmic bursting activity. The TRH-induced depolarization occurred also in the presence of reduced Ca2+ and TTX. The response was dose-dependent over TRH concentrations of 0.1-10 microM. The TRH-induced depolarization was accompanied by an increase in input resistance. The reversal potential of this effect corresponded to that of K+. Our results indicate that TRH increases the excitability of DMX neurons by reducing a resting K+ conductance.
Livingston
C A
CA
Department of Physiology and Biophysics, School of Medicine, University of Washington, Seattle 98195.
Berger
A J
AJ
D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000187:drug effects*; D004553:Electric Conductivity; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D014630:Vagus Nerve / Q000166:cytology / Q000187:drug effects*
D013973:Thyrotropin-Releasing Hormone