Neuropeptide Y and Y1 receptor like immunoreactivities in dorsal root ganglia and spinal cord after colchicine application to the sciatic nerve in the rat

M.F. CORONEL; P.R. BRUMOVSKY; J.B. AQUINO; T. HÖKFELT; M.J. VILLAR

San Diego, USA

Congreso; Society for Neuroscience; 2001

Society for Neuroscience

Neuropeptide Y (NPY) is normally present in very few neurons in dorsal root ganglia (DRG) and in layers I-III of the spinal cord. However, following a peripheral injury, NPY is up regulated in medium and large primary sensory neurons and to a lesser extent in small sized cells, with increased transport to the dorsal horn. Y1 receptor (Y1r) is expressed in the soma of some small and medium sized ganglion neurons in DRGs and in local neurons of layers II-III of the spinal cord. To further determine a possible regulation of NPY by peripheral trophic factors and explore a similar regulatory mechanism for the Y1r in DRG and spinal cord, the immunoreactivity of both molecules was examined after colchicine application to the intact sciatic nerve of adult male rats. Colchicine (5, 10, 20 mM) or saline were either injected to the nerve or applied using a cotton bud. After different survival times the ipsilateral and contralateral DRGs (L4-5), as well as the corresponding levels of the spinal cord were removed. The tissue was then processed for standard ABC immunohistochemistry and immunofluorescence techniques using NPY and Y1r antibodies. Colchicine induced an increase in the number of NPY-immunoreactive (IR) neurons in DRGs as well as in layers I-III of the lumbar spinal cord. A decrease in the number of neuronal profiles exhibiting Y1r-like immunoreactivity in DRGs was also detected. The mechanism by which peripheral administration of colchicine induced a reduction in the number of Y1r-IR neurons is unknown. However, a regulation by NGF and other trophic molecules should be further analyzed.