Neurokinin-1 receptor expression in dorsal root ganglion neurons of young rats.
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 microm. 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 microM) 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 microM). Intracellular recordings distinguished between Aalpha/beta-, Adelta- and C-sub-types of ganglion neurons. Superfusion of substance P (1 microM) evoked excitatory responses in Adelta- and C-type neurons. These results demonstrate the expression of functional neurokinin-1 receptors on a subpopulation of Adelta- and C-type sensory ganglion neurons. Our data suggest the possible physiological importance of peripheral neurokinin-1 receptors located on dorsal root ganglion neurons.
Szucs
P
P
Department of Anatomy, University Medical School, Debrecen, Hungary.
Polgar
E
E
Spigelman
I
I
Porszasz
R
R
Nagy
I
I
D000818:Animals; D004558:Electric Stimulation; D005727:Ganglia, Spinal / Q000502:physiology*; D007211:Indoles / Q000494:pharmacology; D054833:Isoindoles; D008564:Membrane Potentials / Q000187:drug effects; D064729:Neurokinin-1 Receptor Antagonists; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010525:Peripheral Nerves / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D018040:Receptors, Neurokinin-1 / Q000096:biosynthesis / Q000502:physiology*; D013373:Substance P / Q000096:biosynthesis / Q000494:pharmacology
D007211:Indoles; D054833:Isoindoles; D064729:Neurokinin-1 Receptor Antagonists; D018040:Receptors, Neurokinin-1; C071693:7,7-diphenyl-2-(1-imino-2-(2-methoxyphenyl)ethyl)perhydroisoindol-4-one; D013373:Substance P