Serotonin-like actions of quipazine and CPP on spinal motoneurones.
The actions of iontophoretically applied quipazine (QPZ) and 6-chloro-2-[1-piperazinyl]-pyrazine (CPP) were compared with those of serotonin (5-HT) on rat spinal motoneurones. QPZ and CPP qualitatively resembled 5-HT in that both facilitated single unit activity evoked by glutamate. Like 5-HT, the facilitation they produced could be antagonized by metergoline or methysergide. These observations are compatible with the suggestion that the actions of QPZ and CPP are mediated by 5-HT receptors. In rats pretreated with the neurotoxin 5,7-dihydroxytryptamine (5,7-DHT), QPZ and CPP remained effective in facilitating the glutamate evoked activity, whereas p-chloroamphetamine (PCA), a known releaser of 5-HT, was without effect. In contrast, PCA produced a long lasting facilitation in untreated rats. These data, taken together, suggest that QPZ and CPP are direct agonists at 5-HT receptors, but do not preclude the possibility that they might also act indirectly.
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D005971:Glutamates / Q000494:pharmacology; D008297:Male; D008711:Metergoline / Q000494:pharmacology; D008784:Methysergide / Q000494:pharmacology; D009046:Motor Neurons / Q000187:drug effects*; D011719:Pyrazines / Q000494:pharmacology*; D011804:Quinolines / Q000494:pharmacology*; D011814:Quipazine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology*; D013116:Spinal Cord / Q000187:drug effects*; D010133:p-Chloroamphetamine / Q000494:pharmacology
D005971:Glutamates; D011719:Pyrazines; D011804:Quinolines; D008711:Metergoline; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D011814:Quipazine; C014896:6-chloro-2-(1-piperazinyl)pyrazine; D010133:p-Chloroamphetamine; D008784:Methysergide