THE RELEASE OF IMMUNOREACTIVE NEUROPEPTIDE-Y IN THE SPINAL-CORD OF THE ANESTHETIZED RAT AND CAT

The release of immunoreactive (ir-) neuropeptide Y (NYP) was studied i n the anaesthetized rat and cat by means of microprobes bearing immobi lized antibodies to the C terminus of NPY. An extensive basal release of ir-NYP was detected throughout the dorsal and upper ventral horn of the rat. This spontaneous release was not significantly altered by se ctioning the spinal cord at the thoraco-lumbar junction nor by electri cal stimulation of peripheral nerves. Since NPY is virtually absent in primary afferents it is probable that spontaneous release within the spinal cord comes from active NPY-containing intrinsic spinal neurones . In the spinal cat spontaneous release of ir-NPY was detected in the mid-dorsal horn and this was unaltered by peripheral noxious thermal o r noxious mechanical stimuli. As in the rat, release from intrinsic sp inal neurones is most probable, The extensive spontaneous release of i r-NPY in both species suggests a widespread role in spinal cord functi on.