Article Figures & Data
Figures
- Figure 1.
In vivo classification of direct and indirect pathway murine MSNs and confirmation of S2 projections to MSNs. A, Confirmation of substantial S2 projections to the DLS via BDA (red) injection in S2, showing axonal boutons present in the striatum (showed with white arrows). Str, striatum; WM, white matter; LV, lateral ventricle. B, Schematic representation of the stimulation electrode placement in S2, optopatch pipette in dorsal striatum, and LFP electrode in the contralateral S2. In total 38 MSNs (21 D1 MSNs and 17 D2 MSNs) have been recorded. C, Representatives of LFP traces in S2 and of whole-cell optopatch–clamp traces in the striatum. D, Classification of D2 (ChR2+, top) and D1 (ChR2−, bottom) MSNs based on the presence or absence of membrane depolarization in response to pulsed blue light (vertical shading). E, Postmortem validation of D1 (ChR2−) or D2 (ChR2+) MSN identity through immunostaining against biocytin with streptavidin-Cy3 (red) and DAPI (blue) to unveil the recorded neuron and the neuronal nuclei, respectively. Notice how D2 ChR2+ cells display fluorescence for YFP (green), showing its positiveness for ChR2.
- Figure 2.
LY IP injection reduces evoked PSP amplitude in direct and indirect MSNs in vivo. A, Representative trace of whole-cell recordings in DLS and of contralateral S2 LFP following an electrical stimulation in ipsilateral S2 (red line). B, Average (thick line) and variance (shading) MSN PSPs in downstate before and after injection of CCK2R antagonist LY (orange line). C, Effect of LY injection on MSN PSPs amplitude in cells from both direct (D1) and indirect (D2) MSNs (n = 12). D, On normalized PSP amplitude in direct (D1, n = 8) and indirect (D2) MSNs (n = 4). Significant diminution of the PSP slope in both direct (D1) or indirect (D2, n = 4) MSNs and on E, PSP slope in combined D1 and D2 MSNs (n = 12). Dots and squares are individual cells before (black) and after (orange) LY application; **p < 0.01; ***p < 0.001.
- Figure 3.
CCK2R antagonist LY application modulates MSN membrane properties ex vivo. A, Left, Schematic representation of the horizontal corticostriatal rat brain slice preparation with the recording electrode in the striatum (Str). Right, Schematic representation of the experience timeline. B, Effect of LY application on MSN spike and rheobase (n = 6). B, Example traces of MSN responses to current injections of increasing amplitude before and after LY application. C,D, Effect of CCK2R antagonist LY application on MSN spike threshold and rheobase (n = 5). Dots and squares are individual cells before (black) and after LY (orange). E,F, Effect of CCK1R antagonist Lorg application on MSNs spike threshold and rheobase (n = 14). Dots and squares are individual cells before (black) and after Lorg (pink) application; *p < 0.05.
- Figure 4.
Ex vivo LY application decreases glutamatergic transmission and alters EPSC properties at the S2→MSN synapse. A, Left, Schematic representation of the horizontal rat corticostriatal brain slice preparation with the recording electrode in the striatum and the stimulation electrode placed in S2. Right, Schematic representation of the experience timeline. B, Stimulation protocol (repeated every 10 s, i.e., 0.1 Hz) and evoked glutamatergic response from a representative recorded MSN before (control) and after (LY) LY infusion. C,D, Effect of LY application on S2→MSNs EPSC duration and amplitude (n = 18). E, Stimulation protocol and evoked glutamatergic response from a representative recorded MSN before (control) and after Lorg application. F,G, Effect of Lorg application on S2→MSN EPSC duration and amplitude (n = 7). Dots and squares are individual cells before (black) and after LY (orange) or Lorg (pink) application; *p < 0.05.
- Figure 5.
CCK2R blocker LY switches long-term STDP from potentiation to depression. A, STDP protocol, with post–pre pairing repeated 100 times at 1 Hz (top), and evoked EPSCs from a representative MSN during baseline and long-term conditions under control, LY, or Lorg application. B,C, Normalized EPSC amplitude (top and right) and input resistance (bottom) to preplasticity induction in control and LY conditions (black control n = 10; orange LY n = 9). D, Normalized 1/CV2 of control condition and LY condition. E,F, Normalized EPSC amplitude (top and right) and input resistance (bottom) to preplasticity induction in control and Lorg conditions (black control n = 10; pink Lorg n = 9). Dots/squares are mean, and error bars are ±SEM; ****p < 0.0001.
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