Alterations in serotonin binding sites after 5,7-dihydroxytryptamine treatment in the rat spinal cord.
The 5-HT1B subtype of serotonin (5-HT) receptor regulates the release of 5-HT in the rat spinal cord. In an attempt to confirm the presynaptic location of the 5-HT1B receptor, serotonergic nerves were destroyed neurochemically with 5,7-dihydroxytryptamine (5,7-DHT) administered intrathecally. At 3, 7 and 14 days post 5,7-DHT, competitive radioligand binding assays were performed using 2 nM [3H]5-HT and varying concentrations of trifluoromethylphenylpiperazine (TFMPP), a drug which interacts with 5-HT1B and 5-HT1A binding sites (affinity of 5-HT1B site greater than 5-HT1A site for TFMPP). The decrease in 5-HT1B sites that was expected was not observed at any time following the lesion. However, the binding capacity of the 5-HT1B site, as well as the 5-HT1A site, increased significantly by 7 and 14 days postlesion, respectively. Thus, it appears that an up-regulation of 5-HT1B sites occurred that may have obscured the ability to observe a reduction in a small population of sites located on the serotonergic nerve terminals.
West Virginia University Health Sciences Center, Department of Pharmacology/Toxicology, Morgantown 26506.
L M
LM
Brown
D L
DL
Smith
G M
GM
Williams
D J
DJ
Smith
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology*; D000818:Animals; D004102:Dihydroxytryptamines / Q000494:pharmacology*; D009498:Neurotoxins / Q000494:pharmacology*; D010879:Piperazines / Q000378:metabolism; D051381:Rats; D011985:Receptors, Serotonin / Q000378:metabolism*; D012701:Serotonin / Q000031:analogs & derivatives / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*
D004102:Dihydroxytryptamines; D009498:Neurotoxins; D010879:Piperazines; D011985:Receptors, Serotonin; C018406:1-(3-trifluoromethylphenyl)piperazine; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin