Thealpha2C subclass of adrenergic receptor ( @entity69430 ) mediates some of the antinociceptive actions of @entity1063 in the spinal cord. Axon terminals, which possess this receptor, are concentrated in the superficial dorsal horn and originate from spinal interneurons. We performed a series of combined tract-tracing and immunocytochemical studies to determine whether @entity69430 -immunoreactive axons target projection neurons that possess the neurokinin-1 ( @entity16325 because such cells are likely to transmit nociceptive information to the brain. Spinomedullary neurons were labeled by stereotaxic injection of the B-subunit of cholera toxin ( @entity34981 ) into the caudal ventrolateral medulla of three anesthetized adult @entity35 . After 3 d, the animals were anesthetized again and fixed by perfusion. Sections were cut from midlumbar segments and reacted with antibodies to reveal alpha2C-ARs, @entity34981 , and NK-1 receptors. Retrogradely labeled neurons possessing the @entity16325 (n = 45) were examined with confocal microscopy to investigate their relationship with @entity69430 -immunoreactive axons. Numerous @entity69430 axons were apposed to cell bodies and proximal dendrites of cells in lamina I and also to distal dendrites that originate from labeled cell bodies in lamina III/IV. A combined confocal and electron microscopic method confirmed that these appositions were synaptic. Additional experiments showed that virtually all @entity69430 terminals in contact with labeled cells are also immunoreactive for the vesicular @entity2227 transporter 2 and therefore are glutamatergic. These data suggest that @entity1063 can modulate excitatory synaptic transmission from spinal interneurons to projection cells by acting at alpha2C-ARs. This could be one of the mechanisms that underlie the antinociceptive actions of @entity1063 .

Neurokinin-1 projection cells in the XXXX dorsal horn receive synaptic contacts from axons that possess alpha2C-adrenergic receptors.

@entity2227 :: ('CHEBI:29987', 'Chemical') :: ['glutamate'] @entity16325 :: ('24807(Tax:10116)', 'Gene') :: ['NK-1 receptor', 'NK-1) receptor'] @entity35 :: ('10116', 'Species') :: ['rats'] @entity69430 :: ('24175(Tax:10116)', 'Gene') :: ['alpha2C-AR'] @entity1063 :: ('MESH:D009638', 'Chemical') :: ['norepinephrine'] @entity34981 :: ('286936(Tax:10116)', 'Gene') :: ['CTb']
@entity35 :: (10116,Species) :: ['rat']
