Weak effect of neuromodulators on climbing fiber-activated [Ca2+](i) increases in rat cerebellar Purkinje neurons

The effect of several neuromodulators (carbachol (CCh), serotonin (5- HT), noradrenaline (NE), and dopamine (DA)) on the climbing fiber (CF)- induced [Ca²⁺](i) increase in the dendrites of cerebellar Purkinje cells was examined in slices from the rat cerebellum. Purkinje cells were filled with the Ca²⁺ indicator bis-fura-2 with patch electrodes on the soma. [Ca²⁺](i) changes were measured from regions of interest in the dendrites with a high speed camera. Changes evoked by one or three responses were measured in control conditions and with neuromodulators added to the bath. None of these four classic modulators caused a significant change in the CF- induced [Ca²⁺](i) amplitude. Buspirone, a partial 5-HT(1A) agonist and a weak DA receptor antagonist caused a small (10-15%) reduction in the response.