Long-term potentiation and long-term depression of primary afferent neurotransmission in the rat spinal cord.
Synaptic transmission between dorsal root afferents and neurons in the superficial laminae of the spinal dorsal horn (laminae I-III) was examined by intracellular recording in a transverse slice preparation of rat spinal cord. Brief high-frequency electrical stimulation (300 pulses at 100 Hz) of primary afferent fibers produced a long-term potentiation (LTP) or a long-term depression (LTD) of fast (monosynaptic and polysynaptic) EPSPs in a high proportion of dorsal horn neurons. Both the AMPA and the NMDA receptor-mediated components of synaptic transmission at the primary afferent synapses with neurons in the dorsal horn can exhibit LTP and LTD of the synaptic responses. In normal and neonatally capsaicin-treated rats, the induction of LTP requires the activation of NMDA receptor-gated conductances. The induction of LTP or LTD, however, was not abolished in the presence of bicuculline, a GABAA receptor antagonist. The results demonstrate that distinct and long-lasting modulation in synaptic efficiency can be induced at primary afferent synapses with neurons in the superficial laminae of spinal dorsal horn by high-frequency stimulation of dorsal root afferents and that these changes may be physiologically relevant for transmission and integration of sensory information, including pain.
Randić
M
M
Department of Veterinary Physiology and Pharmacology, Iowa State University, Ames 50011.
Jiang
M C
MC
Cerne
R
R
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D005260:Female; D018756:GABA Antagonists; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D016202:N-Methylaspartate / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D013116:Spinal Cord / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
D018756:GABA Antagonists; D011810:Quinoxalines; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; D016202:N-Methylaspartate; D002211:Capsaicin