Cannabinoids enhance the Ca²⁺signal to NMDA in acutely isolated granule neurons and granule neurons in cerebellar culture. A-C, Effect ofR(+)-WIN on the Ca²⁺ signals elicited by NMDA in acutely isolated granule neurons. A, Photomicrograph (Hoffman optics) of granule neurons acutely isolated from a postnatal day 5 rat cerebellum. Also shown in the picture is a Purkinje neuron (PN) showing immunostaining for calbindin, a cellular marker for Purkinje neurons. The emerging apical dendrite and axon of the immature Purkinje neuron are evident.B, Representative Ca²⁺ signals evoked by NMDA in granule neurons under control conditions and in the presence of 10 nmR(+)-WIN. Each traceis from a single granule neuron. NMDA was applied as in Figure 1.C, Mean ± SEM peak amplitude of the Ca²⁺ signals evoked by NMDA in all granule neurons studied in three different acutely isolated preparations.Numbers in the bars represent the number of neurons measured for each condition. D–F, Effect ofR(+)-methanandamide on the Ca²⁺signals elicited by NMDA in granule neurons in cerebellar culture.D, Phase-contrast photomicrograph of granule neurons (gran) and a Purkinje neuron (PN) in cerebellar culture. E, Representative Ca²⁺ signals evoked by NMDA under control conditions in the granule neurons and Purkinje neuron depicted in D. Ca²⁺ signals were measured in both the somatic (PN soma) and dendritic (PN dend) regions of the Purkinje neuron; Purkinje neurons did not respond to the NMDA application. NMDA was applied as in Figure 1.F, Mean ± SEM peak amplitude of the Ca²⁺ signals evoked by NMDA in all granule neurons studied in two culture sets. Numbers in thebars represent the number of neurons measured for each condition. *Significant difference from control (p < 0.05, Mann–Whitney Utest).