Serotonin innervation of enkephalin containing neurones in the rat spinal trigeminal nucleus.
Light and electron microscopic immunocytochemistry was used to examine the serotonin (5-HT) innervation of the rat spinal trigeminal subnucleus caudalis. 5-HT-immunoreactive fibres form a dense plexus in lamina I and outer lamina II and synapse with the cell bodies and proximal dendrites of local neurones. Light microscopic double labelling revealed that the 5-HT axons contact enkephalin immunoreactive neurones in both laminae. The 5-fHT electron microscopic results indicate that at least some of these contacts are likely to be synapses. 5-HT axons are therefore in a position to exert a direct action on enkephalinergic interneurones and this may contribute to the analgesic actions of the 5-HT system.
Department of Physiology, UMDS St Thomas's Hospital, London, UK.
J J
JJ
López Costa
S
S
Averill
J P
JP
Saavedra
J V
JV
Priestley
D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D004745:Enkephalins / Q000032:analysis*; D007150:Immunohistochemistry; D008297:Male; D016253:Microscopy, Immunoelectron; D009412:Nerve Fibers / Q000502:physiology* / Q000648:ultrastructure; D009474:Neurons / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D012701:Serotonin / Q000032:analysis*; D013569:Synapses / Q000502:physiology / Q000648:ultrastructure; D014279:Trigeminal Nucleus, Spinal / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure
D004745:Enkephalins; D012701:Serotonin