title: Connections from the rat dorsal column nuclei (DCN) to the periaqueductal gray matter (PAG).
abstract: Electrical stimulation of the dorsal columns (DCs; spinal cord stimulation; SCS) has been proposed to treat chronic neuropathic pain. SCS may activate a dual mechanism that would affect both the spinal cord and supraspinal levels. Stimulation of DCs or DC nuclei (DCN) in animals where neuropathic pain has been induced causes activation of brainstem centers including the periaqueductal gray (PAG), which is involved in the endogenous pain suppression system. Biotinylated dextran-amine (BDA) was iontophoretically injected into the DCN to analyze the ascending projection directed to the PAG. Separate injections into the gracile nucleus (GrN) and the cuneate nucleus (CunN) showed BDA-positive fibers terminating in different regions of the contralateral PAG. GrN-PAG afferents terminated in the caudal and middle portions of PAG-l, whereas CunN-PAG fibers terminated in the middle and rostral portions of PAG-l. Based on the DCN somatotopic map, the GrN sends information to the PAG from the contralateral hindlimb and the tail and the CunN from the contralateral forelimb, shoulder, neck and ear. This somatotopic organization is consistent with earlier electrophysiological and PAG stimulation studies. These fibers could form part of the DCs-brainstem-spinal cord loop, which may be involved in the inhibitory effects of SCS on neuropathic pain.
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Via Tronto 10/A, Torrette di Ancona, I-60020 Ancona, Italy. Electronic address: p.barbaresi@univpm.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Barbaresi
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Via Tronto 10/A, Torrette di Ancona, I-60020 Ancona, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Mensà
mesh_terms: D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives; D003911:Dextrans; D005456:Fluorescent Dyes; D010487:Periaqueductal Gray / Q000033:anatomy & histology / Q000502:physiology*; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000033:anatomy & histology / Q000502:physiology*; D066127:White Matter / Q000033:anatomy & histology / Q000502:physiology*
chemical_list: D003911:Dextrans; D005456:Fluorescent Dyes; C076397:biotinylated dextran amine; D001710:Biotin
keywords: BDA10kDa; DCN; PAG; Pain; Spinal cord stimulation