Activation of central terminal vanilloid receptor-1 receptors and alpha beta-methylene-ATP-sensitive P2X receptors reveals a converged synaptic activity onto the deep dorsal horn neurons of the spinal cord.
Using a spinal cord slice preparation and patch-clamp recordings from spinal cord dorsal horn neurons, we examined excitatory and inhibitory circuits connecting to lamina V neurons after the activation of afferent central terminal vanilloid receptor-1 (VR1) receptors and P2X receptors. We found that single neurons in lamina V often received excitatory inputs from two chemically defined afferent pathways. One of these pathways was polysynaptic from capsaicin-sensitive afferent terminals. In this pathway the capsaicin-sensitive afferent input first activated interneurons in superficial laminas, and then the excitatory activity was transmitted onto lamina V neurons. The second excitatory input was monosynaptic from alpha(beta)m-ATP-sensitive/capsaicin-insensitive afferent terminals. Both capsaicin-sensitive and alpha(beta)m-ATP-sensitive/capsaicin-insensitive pathways also recruited polysynaptic inhibitory inputs to lamina V neurons. Furthermore, we demonstrated that simultaneous activation of both capsaicin-sensitive afferent pathways and alpha(beta)m-ATP-sensitive/capsaicin-insensitive pathways could generate a temporal summation of excitatory inputs onto single lamina V neurons. These convergent pathways may provide a mechanism of sensory integration for two chemically defined sensory inputs and may have implications in different sensory states.
Nakatsuka
Terumasa
T
McKnight Brain Institute of the University of Florida and Division of Neuroscience, Department of Oral Surgery, College of Dentistry, University of Florida, Gainesville, Florida 32610, USA.
Furue
Hidemasa
H
Yoshimura
Megumu
M
Gu
Jianguo G
JG
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000375:Aging / Q000378:metabolism; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005727:Ganglia, Spinal / Q000502:physiology; D018684:Glycine Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D009415:Nerve Net / Q000187:drug effects / Q000378:metabolism; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D020671:Posterior Horn Cells / Q000187:drug effects / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000187:drug effects / Q000502:physiology; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D011955:Receptors, Drug / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058469:Receptors, Purinergic P2X; D011999:Recruitment, Neurophysiological / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D018684:Glycine Agents; D058919:Purinergic P2 Receptor Antagonists; D011955:Receptors, Drug; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D013779:Tetrodotoxin; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D002211:Capsaicin