Somatic and visceral afferents to the 'vasodepressor region' of the caudal midline medulla in the rat.
Previous research has found that the integrity of a restricted region of the caudal midline medulla (including caudal portions of nucleus raphé obscurus and nucleus raphé pallidus) was critical for vasodepression (hypotension, bradycardia, decreased cardiac contractility) evoked either by haemorrhage or deep pain. In this anatomical tracing study we found that the vasodepressor part of the caudal midline medulla (CMM) receives inputs arising from spinal cord, spinal trigeminal nucleus (SpV) and nucleus of the solitary tract (NTS). Specifically: (i) a spinal-CMM projection arises from neurons of the deep dorsal horn, medial ventral horn and lamina X at all spinal segmental levels, with approximately 60% of the projection originating from the upper cervical spinal cord (C1-C4); (ii) a SpV-CMM projection arises primarily from neurons at the transition between subnucleus caudalis and subnucleus interpolaris; (iii) a NTS-CMM projection arises primarily from neurons in ventrolateral and medial subnuclei. In combination, the specific spinal, SpV and NTS regions which project to the CMM receive the complete range of somatic and visceral afferents known to trigger vasodepression. The role(s) of each specific projection is discussed.
Potas
Jason R
JR
Department of Anatomy and Histology, The University of Sydney, NSW, Australia 2006.
Keay
Kevin A
KA
Henderson
Luke A
LA
Bandler
Richard
R
D000344:Afferent Pathways / Q000033:anatomy & histology*; D000818:Animals; D001919:Bradycardia / Q000473:pathology; D001931:Brain Mapping; D007022:Hypotension / Q000473:pathology; D008297:Male; D008526:Medulla Oblongata / Q000033:anatomy & histology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000033:anatomy & histology*; D013116:Spinal Cord / Q000033:anatomy & histology*; D014279:Trigeminal Nucleus, Spinal / Q000033:anatomy & histology*; D017833:Visceral Afferents / Q000033:anatomy & histology