Modulatory action of serotonin on glutamate-induced excitation of cerebellar Purkinje cells.
The effects of serotonin (5-hydroxytryptamine, 5-HT) on glutamate-induced excitation of Purkinje cells were examined. Pulsatile iontophoretic applications of glutamate (1-25 nA) induced consistent increases in the spontaneous activity of Purkinje cells. When serotonin was applied continuously with currents that elicited minimum changes in the spontaneous rate, it inhibited or blocked glutamate-induced excitations significantly in most Purkinje cells. We also examined the effects of high currents of serotonin on spontaneous activity of Purkinje cells. High currents of serotonin induced 3 different effects: inhibitions, biphasic effects comprising transient inhibition followed by excitation, and excitations. Nonetheless, whether it inhibited or excited the activity of Purkinje cells, serotonin inhibited glutamate-induced excitations consistently. The effect of a putative 5-HT antagonist methysergide (UML) was also examined. Methysergide consistently attenuated or antagonized the inhibitory effects of serotonin on glutamate-induced excitations. This finding suggests strongly that inhibitory effects of 5-HT on glutamate excitations observed in the present study is the specific action of serotonin.
Lee
M
M
Strahlendorf
J C
JC
Strahlendorf
H K
HK
D000818:Animals; D002531:Cerebellum / Q000502:physiology*; D004553:Electric Conductivity; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology*
D005971:Glutamates; D012701:Serotonin; D018698:Glutamic Acid; D008784:Methysergide