Dorsal horn neurons expressing NK-1 receptors mediate scratching in rats.
Itch is thought to be signaled by pruritogen-responsive neurons in the superficial spinal dorsal horn. Many neurons here express the substance P NK-1 receptor. We investigated whether neurotoxic destruction of spinal NK-1-expressing neurons affected itch-related scratching behavior. Rats received intracisternal substance P conjugated to saporin (SP-SAP), or saporin (SAP) only (controls), and were subsequently tested for scratching behavior elicited by intradermal 5-hydroxytryptamine. SAP controls exhibited dose-related hindlimb scratching, which was significantly attenuated in SP-SAP-treated rats. There was a virtual absence of NK-1 immunoreactive neurons in superficial laminae of the upper cervical and medullary dorsal horn in SP-SAP-treated rats. These results indicate that superficial dorsal horn neurons expressing NK-1 receptors play a key role in spinal itch transmission.
Carstens
Earl E
EE
Department of Neurobiology, Physiology and Behavior, University of California, Davis1 Shields Avenue, Davis, CA 95616, USA. eecarstens@ucdavis.edu
Carstens
Mirela Iodi
MI
Simons
Christopher T
CT
Jinks
Steven L
SL
D000818:Animals; D004338:Drug Combinations; D006614:Hindlimb / Q000187:drug effects / Q000503:physiopathology; D007150:Immunohistochemistry; D007271:Injections, Intradermal; D008297:Male; D008845:Microinjections; D018377:Neurotransmitter Agents / Q000008:administration & dosage / Q000494:pharmacology*; D020671:Posterior Horn Cells / Q000187:drug effects / Q000378:metabolism*; D011537:Pruritus / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018040:Receptors, Neurokinin-1 / Q000187:drug effects / Q000378:metabolism*; D054789:Ribosome Inactivating Proteins, Type 1 / Q000008:administration & dosage / Q000494:pharmacology*; D000076985:Saporins; D012701:Serotonin; D018490:Serotonin Agents; D013373:Substance P / Q000008:administration & dosage / Q000494:pharmacology*
D004338:Drug Combinations; D018377:Neurotransmitter Agents; D018040:Receptors, Neurokinin-1; D054789:Ribosome Inactivating Proteins, Type 1; D018490:Serotonin Agents; D012701:Serotonin; D013373:Substance P; D000076985:Saporins