EARLY DECLINE AND LATE RESTORATION OF SPINAL-CORD BINDING AND TRANSGANGLIONIC TRANSPORT OF ISOLECTIN B4 FROM GRIFFONIA-SIMPLICIFOLIA-I AFTER PERIPHERAL-NERVE TRANSECTION OR CRUSH

Isolectin B4 from Griffonia simplicifolia I (B4) has a high binding af finity to a large population of unmyelinated primary sensory neurons ( Wang et al., Neuroscience 62 (1994) 539-551). Using immunohistochemica l techniques, binding and transganglionic transport of B4 in the spina l cord was investigated, both at short and long survival times, after sciatic nerve transection and ligation or crush in the adult rat. Nerv e transection and ligation resulted in nearly complete disappearance o f B4 immunolabelling in the sciatic nerve territory of the superficial dorsal horn after B4 binding, as well as after transganglionic transp ort of B4 by 2 weeks postinjury. Partial recovery of both B4 binding a nd B4 transport was found by 8 months, and nearly complete recovery by 16 months, indicating that reappearance of B4 binding is not critical ly dependent on peripheral reinnervation. Crush injury made by jewelle r's forceps resulted in partial depletion of binding and transport by 2 weeks and a nearly complete recovery by 10 weeks. The results show t hat binding and transganglionic transport of B4 can be used to label d orsal horn connections of unmyelinated primary afferents during the pr ocess of regeneration after crush injury. Furthermore, as B4 binding a nd transport recover along survival times in the absence of reestablis hed peripheral connections, the same techniques can be used to study c entral primary afferent connections at long survival limes after nerve transection. Binding and transganglionic transport of B4 offer altern atives to the use of previous techniques such as transganglionic trans port of wheat germ agglutinin conjugated horseradish peroxidase (WGA-H RP) to study central connections of fine primary afferents after injur y.