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Presynaptic kainate receptors in primary afferents to the superficial laminae of the rat spinal cord.
J Comp Neurol. 2001 Jul 30; 436(3):275-89.JC

Abstract

Subunits of glutamate receptors participate in the regulation of sensory transmission at primary afferent synapses in the superficial laminae of dorsal horn (DH). We report here on the distribution of kainate receptors (GluR5/6/7) in these laminae by using light microscope (LM) and electron microscope (EM) immunocytochemistry. Standard (4%) paraformaldehyde fixation resulted in immunostaining for GluR5/6/7 in perikarya and fine processes in lamina II, especially its inner part (IIi). Preembedding EM revealed immunostaining of dendrites, perikarya, and occasional terminals, presumed to be from primary afferent fibers, at the center of glomerular arrangements. In rats perfused with 0.5% paraformaldehyde, LM showed a more punctate staining, mainly in the ventral part of lamina IIi and lamina III, than in material fixed with 4% paraformaldehyde. Approximately two-thirds of GluR5/6/7 puncta were also immunostained with synaptophysin, suggesting that in material fixed with 0.5% paraformaldehyde, a large fraction of these are synaptic terminals. Double immunostained puncta disappear 4 days after dorsal rhizotomy, suggesting that most of GluR5/6/7-immunopositive terminals are from primary afferent fibers. EM material fixed with 0.5% paraformaldehyde confirmed the expression of GluR5/6/7 in numerous synaptic endings with morphology of primary afferents. To determine the type of primary afferent terminals that express GluR5/6/7, two neuroanatomic tracers were injected in the sciatic nerves. The lectin from Bandeiraea simplicifolia (IB4) is selectively taken up by unmyelinated primary afferent fibers that terminate in the outer part of lamina II (IIo) and dorsal part of lamina IIi, whereas the B subunit of the cholera toxin (CTB) is selectively taken up by a broader class of primary afferents which, in superficial DH, terminate mainly in laminae I, ventral part of IIi, and III. Approximately 20% of GluR5/6/7-immunoreactive puncta colocalized with IB4, whereas approximately 40% of GluR5/6/7-immunoreactive puncta colocalized with CTB. The present study shows that (1) GluR5/6/7 does not have a clear and consistent spatial relation with postsynaptic sites, (2) a large number of primary afferents express GluR5/6/7, and (3) these are not limited to one functional class. Thus, modulation by glutamate of primary afferent terminals by means of kainate receptors in the superficial laminae of DH may predominantly involve presynaptic mechanisms.

Authors+Show Affiliations

Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA. sejin_hwang@med.unc.eduNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

11438930

Citation

Hwang, S J., et al. "Presynaptic Kainate Receptors in Primary Afferents to the Superficial Laminae of the Rat Spinal Cord." The Journal of Comparative Neurology, vol. 436, no. 3, 2001, pp. 275-89.
Hwang SJ, Pagliardini S, Rustioni A, et al. Presynaptic kainate receptors in primary afferents to the superficial laminae of the rat spinal cord. J Comp Neurol. 2001;436(3):275-89.
Hwang, S. J., Pagliardini, S., Rustioni, A., & Valtschanoff, J. G. (2001). Presynaptic kainate receptors in primary afferents to the superficial laminae of the rat spinal cord. The Journal of Comparative Neurology, 436(3), 275-89.
Hwang SJ, et al. Presynaptic Kainate Receptors in Primary Afferents to the Superficial Laminae of the Rat Spinal Cord. J Comp Neurol. 2001 Jul 30;436(3):275-89. PubMed PMID: 11438930.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Presynaptic kainate receptors in primary afferents to the superficial laminae of the rat spinal cord. AU - Hwang,S J, AU - Pagliardini,S, AU - Rustioni,A, AU - Valtschanoff,J G, PY - 2001/7/5/pubmed PY - 2001/8/31/medline PY - 2001/7/5/entrez SP - 275 EP - 89 JF - The Journal of comparative neurology JO - J. Comp. Neurol. VL - 436 IS - 3 N2 - Subunits of glutamate receptors participate in the regulation of sensory transmission at primary afferent synapses in the superficial laminae of dorsal horn (DH). We report here on the distribution of kainate receptors (GluR5/6/7) in these laminae by using light microscope (LM) and electron microscope (EM) immunocytochemistry. Standard (4%) paraformaldehyde fixation resulted in immunostaining for GluR5/6/7 in perikarya and fine processes in lamina II, especially its inner part (IIi). Preembedding EM revealed immunostaining of dendrites, perikarya, and occasional terminals, presumed to be from primary afferent fibers, at the center of glomerular arrangements. In rats perfused with 0.5% paraformaldehyde, LM showed a more punctate staining, mainly in the ventral part of lamina IIi and lamina III, than in material fixed with 4% paraformaldehyde. Approximately two-thirds of GluR5/6/7 puncta were also immunostained with synaptophysin, suggesting that in material fixed with 0.5% paraformaldehyde, a large fraction of these are synaptic terminals. Double immunostained puncta disappear 4 days after dorsal rhizotomy, suggesting that most of GluR5/6/7-immunopositive terminals are from primary afferent fibers. EM material fixed with 0.5% paraformaldehyde confirmed the expression of GluR5/6/7 in numerous synaptic endings with morphology of primary afferents. To determine the type of primary afferent terminals that express GluR5/6/7, two neuroanatomic tracers were injected in the sciatic nerves. The lectin from Bandeiraea simplicifolia (IB4) is selectively taken up by unmyelinated primary afferent fibers that terminate in the outer part of lamina II (IIo) and dorsal part of lamina IIi, whereas the B subunit of the cholera toxin (CTB) is selectively taken up by a broader class of primary afferents which, in superficial DH, terminate mainly in laminae I, ventral part of IIi, and III. Approximately 20% of GluR5/6/7-immunoreactive puncta colocalized with IB4, whereas approximately 40% of GluR5/6/7-immunoreactive puncta colocalized with CTB. The present study shows that (1) GluR5/6/7 does not have a clear and consistent spatial relation with postsynaptic sites, (2) a large number of primary afferents express GluR5/6/7, and (3) these are not limited to one functional class. Thus, modulation by glutamate of primary afferent terminals by means of kainate receptors in the superficial laminae of DH may predominantly involve presynaptic mechanisms. SN - 0021-9967 UR - https://www.unboundmedicine.com/medline/citation/11438930/Presynaptic_kainate_receptors_in_primary_afferents_to_the_superficial_laminae_of_the_rat_spinal_cord_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0021-9967&date=2001&volume=436&issue=3&spage=275 DB - PRIME DP - Unbound Medicine ER -