Autoradiographic evidence of serotonin1 binding sites on primary afferent fibres in the dorsal horn of the rat spinal cord.
Spinal serotonin1 (5-HT1)(labelled by [3H]5-HT), 5-HT1A (labelled by [3H]8-hydroxy-2-(di-n-propylamino)tetralin ([3H]8-OH-DPAT)), mu- (labelled by [3H]Tyr-D-Ala-Gly-(Me)Phe-Gly-ol ([3H]DAGO) and [3H]naloxone) and delta-opiate (labelled by [3H]Tyr-D-Ser-Gly-Phe-Leu-Thr [( 3H]DSTLE] receptor binding sites were studied in adult rats using quantitative autoradiography after either neonatal treatment with capsaicin or unilateral cervical dorsal rhizotomy. Both treatments produced a significant loss of 5-HT (-20 to -30%) and opiate (-30 to -45%) binding sites within the superficial layers of the dorsal horn, suggesting they are partly located presynaptically on primary afferent fibres. Thus, 5-HT, as well as opiates, might generate analgesia by acting--at least partly--on primary afferent nociceptive fibres at the spinal level.
Département de Cytologie, C.N.R.S. U.A. 4199, Université Pierre et Marie Curie, Paris, France.
G
G
Daval
D
D
Vergé
A I
AI
Basbaum
S
S
Bourgoin
M
M
Hamon
D000344:Afferent Pathways / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D002211:Capsaicin / Q000494:pharmacology; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism*
D012701:Serotonin; D002211:Capsaicin