Dorsal horn neurons expressing NK-1 receptors mediate... : NeuroReport (original) (raw)

SOMATOSENSORY SYSTEMS, PAIN

Dorsal horn neurons expressing NK-1 receptors mediate scratching in rats

Carstens, Earl E.a; Carstens, Mirela Iodia; Simons, Christopher T.c; Jinks, Steven L.b

aDepartment of Neurobiology, Physiology and Behavior

bDepartment of Anesthesiology and Pain Medicine, University of California, Davis, California, USA

cGivaudan Flavors Corporation, Cincinnati, Ohio

Correspondence to Professor Earl E. Carstens, PhD, Department of Neurobiology, Physiology and Behavior, University of California, Davis1 Shields Avenue, Davis, CA 95616, USA

Tel: +1 530 752 7767; fax: +1 530 752 5582; e-mail: [email protected]

Received 21 December 2009 accepted 4 January 2010

Abstract

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.