Denervation supersensitivity to 5-hydroxytryptamine in the rat spinal cord is not due to the absence of 5-hydroxytryptamine.
D,L-5-Hydroxytryptophan and 5-HT agonists administered systemically, stimulate motoneuronal discharges as measured by the spontaneous EMG activity of the hindlimbs in paraplegic rats. Denervation supersensitivity is observed after surgical section of the spinal cord or after treatment with 5,7-dihydroxytryptamine (5,7-DHT). Such denervation supersensitivity, however, cannot be reproduced by equivalent depletion of 5-HT by synthesis inhibition or reversed by chronic intrathecal administration of 5-HT agonists. These results suggest that in the anterior horn of the spinal cord, the trigger of denervation supersensitivity to serotonin is not the absence of the neurotransmitter itself but the absence of the terminals or some other compound contained therein.
Tremblay
L E
LE
Bédard
P J
PJ
Maheux
R
R
Di Paolo
T
T
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000818:Animals; D000870:Anterior Horn Cells / Q000187:drug effects; D002818:Cordotomy; D005260:Female; D010134:Fenclonine / Q000494:pharmacology; D008732:Methoxydimethyltryptamines / Q000494:pharmacology; D011814:Quipazine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology*; D013116:Spinal Cord / Q000187:drug effects*
D008732:Methoxydimethyltryptamines; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D011814:Quipazine; D006916:5-Hydroxytryptophan; D010134:Fenclonine