The expression of neurokinin-1 receptors was studied in the fourth lumbar dorsal root ganglia of young rats using immunohistochemical and electrophysiological techniques. Use of a specific immunoserum raised against the C-terminal fragment of rat neurokinin-1 receptor revealed immunoreactivity in 32 ± 1.5% of dorsal root ganglion neurons. The diameter of the majority of the neurokinin-1 receptor immunostained neurons was smaller than 30 μm. Double immunohistochemical labelling using neurokinin-1 receptor and substance P antibodies revealed that about 1/3 of the neurokinin-1 receptor expressing neuron contains substance P. Likewise, about 1/3 of the substance P producing DRG cells expressed the neurokinin-1 receptor. Superfusion of substance P (1 μM) to an in vitro preparation of the fourth lumbar dorsal root ganglion induced a reversible long-lasting depolarization as measured by extracellular suction electrodes attached to the dorsal roots. This response to substance P was only partially antagonized by the selective neurokinin-1 receptor antagonist RP 67580 (1 μM). Intracellular recordings distinguished between Aα/β-, Aδ- and C-sub-types of ganglion neurons. Superfusion of substance P (1 μM) evoked excitatory responses in Aδ- and C-type neurons. These results demonstrate the expression of functional neurokinin-1 receptors on a subpopulation of Aδ- and C-type sensory ganglion neurons. Our data suggest the possible physiological importance of peripheral neurokinin-1 receptors located on dorsal root ganglion neurons.
|Number of pages||9|
|Journal||Journal of the Peripheral Nervous System|
|Publication status||Published - Dec 1 1999|
- Sensory neuron
- Substance P
ASJC Scopus subject areas
- Clinical Neurology