Does 5-carboxamidotryptamine-induced turning in guinea-pigs involve 5-HT1D autoreceptors?
Contralateral turning induced by unilateral injection of 5-carboxamidotryptamine (5-CT) into guinea-pig substantia nigra could result from unilaterally reduced inhibition of the dopaminergic pathway as a consequence of a decreased release of inhibitory 5-hydroxytryptamine (5-HT) through stimulation of 5-HT1D autoreceptors. This hypothesis was tested by administering 5-CT unilaterally to freely moving guinea pigs through a microdialysis probe, and simultaneously measuring extracellular 5-HT in the dialysate and rotation. A concentration of 250 mN 5-CT was required to produce significant turning. This also induced a massive increase in extracellular 5-HT, introduced as an impurity of the 5-CT. The presence of high concentrations of extracellular 5-HT makes it unlikely that 5-CT-induced rotation is mediated through decreased 5-HT release resulting from 5-HT1D autoreceptor stimulation.
Moret
C
C
Division of Neurobiology I, Centre de Recherche Pierre Fabre, Castres, France.
Briley
M
M
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003956:Dialysis; D006168:Guinea Pigs; D008297:Male; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism
D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D012701:Serotonin; C047087:5-carboxamidotryptamine