title: The majority of dorsal spinal cord gastrin releasing peptide is synthesized locally whereas neuromedin B is highly expressed in pain- and itch-sensing somatosensory neurons.
abstract: BACKGROUND
  Itch is one of the major somatosensory modalities. Some recent findings have proposed that gastrin releasing peptide (Grp) is expressed in a subset of dorsal root ganglion (DRG) neurons and functions as a selective neurotransmitter for transferring itch information to spinal cord interneurons. However, expression data from public databases and earlier literatures indicate that Grp mRNA is only detected in dorsal spinal cord (dSC) whereas its family member neuromedin B (Nmb) is highly expressed in DRG neurons. These contradictory results argue that a thorough characterization of the expression of Grp and Nmb is warranted.
  
  
  RESULTS
  Grp mRNA is highly expressed in dSC but is barely detectable in DRGs of juvenile and adult mice. Anti-bombesin serum specifically recognizes Grp but not Nmb. Grp is present in a small number of small-diameter DRG neurons and in abundance in layers I and II of the spinal cord. The reduction of dSC Grp after dorsal root rhizotomy is significantly different from those of DRG derived markers but similar to that of a spinal cord neuronal marker. Double fluorescent in situ of Nmb and other molecular markers indicate that Nmb is highly and selectively expressed in nociceptive and itch-sensitive DRG neurons.
  
  
  CONCLUSIONS
  The majority of dSC Grp is synthesized locally in dorsal spinal cord neurons. On the other hand, Nmb is highly expressed in pain- and itch-sensing DRG neurons. Our findings provide direct anatomic evidence that Grp could function locally in the dorsal spinal cord in addition to its roles in DRG neurons and that Nmb has potential roles in nociceptive and itch-sensitive neurons. These results will improve our understanding about roles of Grp and Nmb in mediating itch sensation.
authors: Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors: Michael S
authors: MS
authors: Fleming
authors: Daniel
authors: D
authors: Ramos
authors: Seung Baek
authors: SB
authors: Han
authors: Jianyuan
authors: J
authors: Zhao
authors: Young-Jin
authors: YJ
authors: Son
authors: Wenqin
authors: W
authors: Luo
mesh_terms: D000375:Aging / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity / Q000276:immunology; D001839:Bombesin / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D003080:Cold Temperature; D005727:Ganglia, Spinal / Q000378:metabolism / Q000473:pathology; D019886:Gastrin-Releasing Peptide / Q000096:biosynthesis* / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D040542:Mechanotransduction, Cellular; D051379:Mice; D008969:Molecular Sequence Data; D015287:Neurokinin B / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D009619:Nociceptors / Q000378:metabolism / Q000473:pathology; D010146:Pain / Q000150:complications / Q000378:metabolism* / Q000473:pathology*; D017288:Pain Threshold; D010812:Physical Stimulation; D021381:Protein Transport; D011537:Pruritus / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018004:Receptors, Bombesin / Q000235:genetics / Q000378:metabolism; D019051:Rhizotomy; D011984:Sensory Receptor Cells / Q000378:metabolism* / Q000473:pathology; D013116:Spinal Cord / Q000378:metabolism* / Q000473:pathology
chemical_list: D007106:Immune Sera; D012333:RNA, Messenger; D018004:Receptors, Bombesin; D019886:Gastrin-Releasing Peptide; D015287:Neurokinin B; C038393:neuromedin B; D001839:Bombesin