Large enhancement of excitatory postsynaptic potentials and currents by thyrotropin-releasing hormone (TRH) in frog spinal motoneurones.
Frog spinal motoneurones were studied in vitro under voltage clamp conditions to examine the effect of the peptide thyrotropin-releasing hormone (TRH). TRH (50 microM) produced a small membrane depolarization, without obvious changes in the neuronal conductance or sensitivity to exogenously applied glutamate. These effects were seen regardless of the presence of 1 mM Mg2+ in the bathing solution. Low- and high-threshold excitatory postsynaptic potentials, induced by dorsal root stimulation, were enhanced by TRH. Under voltage clamp, TRH did not change the cell leak conductance while producing a considerable enhancement of polysynaptic current amplitude, particularly when recorded at a rather negative potential level. It is suggested that TRH might potentiate excitatory neurotransmission by facilitating presynaptic release of the excitatory neurotransmitter(s) onto motoneurones.
Lacey
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Department of Pharmacology, St. Bartholomew's Hospital Medical College, University of London, U.K.
Nistri
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Rhys-Maitland
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D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D066298:In Vitro Techniques; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D011896:Rana temporaria; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D013973:Thyrotropin-Releasing Hormone