Cytotoxic targeting of isolectin IB4-binding sensory neurons

Neuroscience. 2001;108(1):143-55. doi: 10.1016/s0306-4522(01)00377-3.


The isolectin I-B4 (IB4) binds specifically to a subset of small sensory neurons. We used a conjugate of IB4 and the toxin saporin to examine in vivo the contribution of IB4-binding sensory neurons to nociception. A single dose of the conjugate was injected unilaterally into the sciatic nerve of rats. The treatment resulted in a permanent selective loss of IB4-binding neurons as indicated by histological analysis of dorsal root ganglia, spinal cord, and skin from treated animals. Behavioral measurements showed that 7-10 days after the injection, conjugate-treated rats had elevated thermal and mechanical nociceptive thresholds. However, 21 days post-treatment the nociceptive thresholds returned to baseline levels. These results demonstrate the utility of the IB4-saporin conjugate as a tool for selective cytotoxic targeting and provide behavioral evidence for the role of IB4-binding neurons in nociception. The decreased sensitivity to noxious stimuli associated with the loss of IB4-binding neurons indicates that these sensory neurons are essential for the signaling of acute pain. Furthermore, the unexpected recovery of nociceptive thresholds suggests that the loss of IB4-binding neurons triggers changes in the processing of nociceptive information, which may represent a compensatory mechanism for the decreased sensitivity to acute pain.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Count
  • Immunotoxins / pharmacology
  • Lectins / metabolism*
  • Lectins / pharmacology
  • Male
  • Myelin Sheath / drug effects
  • N-Glycosyl Hydrolases*
  • Neurons, Afferent / cytology
  • Neurons, Afferent / metabolism*
  • Nociceptors / physiology*
  • Pain Threshold / drug effects
  • Plant Proteins / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Ribosome Inactivating Proteins, Type 1
  • Saporins
  • Schwann Cells / drug effects
  • Schwann Cells / metabolism
  • Sciatic Nerve / cytology
  • Sciatic Nerve / drug effects
  • Sciatic Nerve / metabolism


  • Immunotoxins
  • Lectins
  • Plant Proteins
  • Ribosome Inactivating Proteins, Type 1
  • N-Glycosyl Hydrolases
  • Saporins