Direct stimulatory effect of calcitonin on [3H]5-hydroxytryptamine release from the rat spinal cord.
The in vitro effects of porcine, salmon and human calcitonin on the K+-evoked overflow of [Met5]enkephalin, substance P and [3H]5-HT (previously taken up) were investigated in superfusion experiments with spinal cord slices. Porcine and salmon calcitonin did not affect the release of [Met5]enkephalin and substance P but enhanced that of [3H]5-HT. In contrast, human calcitonin was inactive. The stimulatory effect of porcine and salmon calcitonin on K+-evoked [3H]5-HT overflow was found with slices from the dorsal or the ventral half of the lumbar enlargement but not with hippocampal or hypothalamic slices. The calcitonin effect on [3H]5-HT outflow persisted in the absence of extracellular Ca2+ but was totally suppressed by 5-HT uptake inhibitors such as citalopram and chlorimipramine and by the 5-HT-releasing agent, p-chloroamphetamine. Direct investigation of the possible action of porcine calcitonin on [3H]5-HT uptake and release demonstrated that the enhanced [3H]5-HT overflow resulted from a p-chloramphetamine-like 5-HT-releasing effect of the hormone at the spinal level. This action might be involved in the potent analgesic effect of intrathecal calcitonin.
Bourgoin
S
S
INSERM U.288, Neurobiologie Cellulaire et Fonctionnelle, Faculté de Médecine Pitié-Salpêtrière, Paris, France.
Pohl
M
M
Hirsch
M
M
Mauborgne
A
A
Cesselin
F
F
Hamon
M
M
D000818:Animals; D001921:Brain / Q000378:metabolism; D002116:Calcitonin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D015283:Citalopram / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000032:analysis; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism; D013373:Substance P / Q000032:analysis; D013552:Swine; D010133:p-Chloroamphetamine / Q000494:pharmacology
D015283:Citalopram; D012701:Serotonin; D013373:Substance P; D004744:Enkephalin, Methionine; D010133:p-Chloroamphetamine; C028815:salmon calcitonin; D002116:Calcitonin; D002118:Calcium