Intracellular analysis of cutaneous afferent-induced excitation and inhibition in rat dorsal horn neurones in vitro.
The mechanoreceptive fields of 54 dorsal horn neurones were mapped intracellularly in the rat spinal cord-hindlimb preparation. A quantitative analysis of the parameters of excitation and inhibition was undertaken and a comparison was made between data obtained for innocuous versus noxious cutaneous stimulation. Neurones were classified as wide dynamic range (WDR), nociceptive specific (NS) or low threshold (LT) on the basis of their response to cutaneous stimuli. In WDR neurones, which responded differentially to both types of cutaneous stimuli, the EPSP produced by noxious pinch had a significantly larger amplitude and a longer duration (P < 0.01) compared to the excitatory postsynaptic potentials (EPSPs) produced by touch. A higher total number of spikes was also associated with the postsynaptic response to pinch in WDR neurones. A population of neurones which responded to mechanical stimuli with non-spiking excitation only were identified; their possible relevance to mechanisms of altered central sensitivity is discussed. Inhibitory components to the mechanoreceptive fields were identified; these were complex in form and co-incidental generation of EPSPs and inhibitory postsynaptic potentials (IPSPs) was common. Inhibition of spontaneous firing by cutaneous stimulation was also observed. This technique allows a quantitative intracellular analysis of naturally evoked postsynaptic excitation in physiologically classified dorsal horn neurones in vitro.
King
A E
AE
Department of Physiology, University of Leeds, UK.
Lopez-Garcia
J A
JA
D000818:Animals; D004594:Electrophysiology; D005260:Female; D006614:Hindlimb / Q000294:innervation; D007425:Intracellular Membranes / Q000502:physiology*; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D010146:Pain; D010812:Physical Stimulation; D051381:Rats; D012867:Skin / Q000294:innervation*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*