Differential regulation of motor control and response to dopaminergic drugs by D1R and D2R neurons in distinct dorsal striatum subregions

Abstract

The dorsal striatum is critically involved in a variety of motor behaviours, including regulation of motor activity, motor skill learning and motor response to psychostimulant and neuroleptic drugs, but contribution of D(2)R-striatopallidal and D(1)R-striatonigral neurons in the dorsomedial (DMS, associative) and dorsolateral (DLS, sensorimotor) striatum to distinct functions remains elusive. To delineate cell type-specific motor functions of the DMS or the DLS, we selectively ablated D(2)R- and D(1)R-expressing striatal neurons with spatial resolution. We found that associative striatum exerts a population-selective control over locomotion and reactivity to novelty, striatopallidal and striatonigral neurons inhibiting and stimulating exploration, respectively. Further, DMS-striatopallidal neurons are involved only in early motor learning whereas gradual motor skill acquisition depends on striatonigral neurons in the sensorimotor striatum. Finally, associative striatum D(2)R neurons are required for the cataleptic effect of the typical neuroleptic drug haloperidol and for amphetamine motor response sensitization. Altogether, these data provide direct experimental evidence for cell-specific topographic functional organization of the dorsal striatum.

Figure 1

Characterization of D1R-striatonigral neuron ablation after full striatum DT injections in D1-DTR⁺ mice. (A) In-situ hybridization autoradiograms (coronal sections, level +1.2 mm relative to bregma) of D₁R-striatonigral (D₁R, SP) and D₂R-striatopallidal (D₂R, Enk and A_2AR) neuron mRNAs and respective levels in the striatum of D₁-DTR⁻ and D₁-DTR⁺ mice 2 weeks after bilateral full DT injections (n=6 per group). (B) Autoradiograms (coronal sections, level +1.2 mm relative to bregma) of D₁ and A_2A receptors and respective striatal binding levels of D₁-DTR⁻ and D₁-DTR⁺ mice 2 weeks after bilateral full striatum DT injections (n=5–6 per group). Scale bars=1 mm. Data are reported as mean±s.e.m. ^***P<0.001.

Figure 2

Preservation of striatal interneurons after ablation of striatonigral neurons in D₁-DTR⁺ mice. (A–D) Immunostaining and quantitative analysis of (A) choline acetyltransferase (ChAT), (B) parvalbumin (PV), (C) neuropeptide Y (NPY) and (D) calretinin (CR)-positive cells in full DT-injected striatum as compared with uninjected striatum of D₁-DTR⁺ mice (day 22 after unilateral full DT injections). Scale bars=100 μm. Columns represent the mean±s.e.m. (n=7).

Figure 3

Reduction of striatal DARPP-32-positive neurons in DT-injected D₁-DTR⁺ or A_2A-DTR⁺ mice. (A, B) DARPP-32 immunostaining 1 month after unilateral DT injection in the entire striatum showing a 44.5±2.5 and 42.9±2.62% reduction of DARPP-32-positive cells in the injected striatum as compared with the uninjected striatum of D₁-DTR⁺ (A) (6870±244 cells versus 3807±40 cells, n=2) and A_2A-DTR⁺ (B) (6046±1094 cells versus 3481.5±783.5 cells, n=2) mice, respectively. Scale bars=200 μm.

Figure 4

Motor activity and rotarod learning in D₁R and D₂R MSN full ablation mice. (A, B) In-situ hybridization for substance P (SP) (A) and enkephalin (Enk) (B) mRNA and respective quantitation, in rostral (bregma +1.2 mm) and caudal (bregma −0.1 mm) coronal brain sections of full striatum DT-injected D₁-DTR⁻/D₁-DTR⁺ (A) and A_2A-DTR⁻/A_2A-DTR⁺ (B) mice. Data are expressed as optical density values of the injected striatum in DTR⁺ as a percentage of the respective DTR⁻ mice. Scale bars represent 1 mm. (C, E) Locomotor activity over 60 min in an open field of D₁-DTR⁺ (C) and A_2A-DTR⁺ (E) mice, and respective controls, 1 week after full DT injections. (D, F) Rotarod performance in D₁-DTR⁻/D₁-DTR⁺ (D) and A_2A-DTR⁻/A_2A-DTR⁺ (F) mice 1 week after full DT injections (n=6–10 per group). (G, H) Ten days of rotarod training and three days of performance recall one week after full DT injections in D₁-DTR⁻/D₁-DTR⁺ (G) and A_2A-DTR⁻/A_2A-DTR⁺ (H) mice (n=6–8 per group). Data are reported as mean±s.e.m. Statistical comparisons were made between DTR⁺ and respective DTR⁻ control mice. ^*P<0.05, ^**P<0.01, ^***P<0.001.

Figure 5

Ablation of D₁R and D₂R MSNs in the dorsomedial (DMS) or dorsolateral (DLS) striatum. (A–D) In-situ hybridization and quantitation of substance P (SP) (A, C) and enkephalin (Enk) (B, D) mRNA in rostral (bregma +1.2 mm) and caudal (bregma −0.1 mm) coronal brain sections of DMS (A, B) or DLS (C, D) DT-injected D₁-DTR⁻/D₁-DTR⁺ (A, C) and A_2A-DTR⁻/A_2A-DTR⁺ (B, D) mice (topographical representation of lesions can be found on Figure 6A, C, E and G). Data are expressed as optical density values of the injected striatum in DTR⁺ as a percentage of respective DTR⁻ mice. Scale bars represent 1 mm. Data are reported as mean±s.e.m. (n=7–9 per group). Statistical comparisons were made between DTR⁺ and respective DTR⁻ control mice. ^*P<0.05, ^***P<0.001.

Figure 6

Locomotor behaviour after ablation of D₁R or D₂R MSNs in the dorsomedial (DMS) or dorsolateral (DLS) striatum. (A, C, E, G) Topographic representation of the lesioned areas in D₁-DTR⁺ (A, E) and A_2A-DTR⁺ (C, G) DT-injected mice into the DMS (A, C) or the DLS (E, G). Colours represent percent of superimposed lesioned areas. (B, D, F, H) Locomotion of DMS DT-injected D₁-DTR⁺ (B) and A_2A-DTR⁺ (D) or DLS DT-injected D₁-DTR⁺ (F) and A_2A-DTR⁺ (H) mice, and respective controls over 60 min in an open field; histograms represent mean ambulation during the first 10 min and the 10 last minutes of the open field. Data are reported as mean±s.e.m. (n=19–28 per group). Statistical comparisons were made between DTR⁺ and respective DTR⁻ control mice (dot chart) or between first and last open field 10 min for the same genotype (histograms). ^*P<0.05, ^**P<0.01, ^***P<0.001.

Figure 7

Object recognition task of DMS or DLS D₁R- and D₂R-MSN ablated mice. (A) Decoupled delayed spontaneous object recognition task, in which time spent in an open field core zone (dot line) is recorded without object, with novel object or repeated object. (B, F, J, N) Topographic representation of the lesioned areas in D₁-DTR⁺ (B, J) and A_2A-DTR⁺ (F, N) DT-injected mice into the DMS (B, F) or the DLS (J, N). Colours represent percent of superimposed lesioned areas. (C–E, G–I, K–M, O–Q) Time spent in the open field core in the absence of object (C, G, K, O), time spent in open field core in the presence of novel objects divided by the time spent in the open field core without object (D, H, L, P) and time spent in the open field core during the test phase divided by time spent in the open field core during the study phase in novel or repeated conditions (F, I, M, Q) of DMS D₁-DTR (C–E) and A_2A-DTR (G–I) or DLS D₁-DTR (K–M) and A_2A-DTR (O–Q) DT-injected mice. Data are reported as mean±s.e.m. (n=6–10 per group). Statistical comparisons were made as described in Materials and methods. ^*P<0.05, ^**P<0.01, ^***P<0.001.

Figure 8

Rotarod performance after ablation of D₁R and D₂R MSNs in the DMS or DLS. (A, C, E, G) Topographic representation of the lesioned areas in D₁-DTR⁺ (A, E) and A_2A-DTR⁺ (C, G) DT-injected mice into the DMS (A, D) or the DLS (E, G). Colours represent percent of superimposed lesioned areas. (B, D, F, H) Rotarod performance of DMS D₁-DTR⁺ (B) and A_2A-DTR⁺ (D) and DLS D₁-DTR⁺ (F) and A_2A-DTR⁺ (H) DT-injected mice and respective controls. (I, J) Ten days of rotarod training and three days of performance recall one week after DT injections in DLS of D₁-DTR (I) and DMS of A_2A-DTR (J) mice; respective topographic representation of the lesioned areas can be found on Figure 5F and J. Data are reported as mean±s.e.m. (n=7–9 per group). Statistical comparisons were made between DTR⁺ and respective DTR⁻ control mice. ^*P<0.05, ^**P<0.01, ^***P<0.001.

Figure 9

Haloperidol-induced immobility and catalepsy in mice lacking D₁R or D₂R MSNs in the DMS or DLS. (A, B, D, E, G, H, J, K) Locomotor activity in a 60-min open field after saline or haloperidol (1.5 mg/kg) administration in DMS D₁-DTR (A, B) and A_2A-DTR (D, E) or DLS D₁-DTR (G, H) and A_2A-DTR (J, K) DT-injected mice. (C, F, I, L) Catalepsy score (latency to move) 30 min after haloperidol (1.5 mg/kg) administration in D₁-DTR⁺ (C, I) and A_2A-DTR⁺ (F, L) DT-injected mice into the DMS (C, F) or the DLS (I, L). Respective topographic representation of the lesioned areas can be found on Figure 5B, F, J and N. Data are reported as mean±s.e.m. (n=6–11 per group). Statistical comparisons were made between haloperidol and saline treatment (dot chart) or DTR⁺ and respective DTR⁻ control mice (histograms). ^*P<0.05, ^**P<0.01, ^***P<0.001.

Figure 10

Amphetamine locomotor sensitization after D₁R or D₂R MSN ablation in the DMS or DLS. (A, D, G, J) Topographic representation of the lesioned areas in D₁-DTR⁺ (A, G) and A_2A-DTR⁺ (D, J) DT-injected mice into the DMS (A, D) or the DLS (G, J). Colours represent percent of superimposed lesioned areas. (B, C, E, F, H, I, K, L) Locomotor activity in a 60-min open field after repeated d-amphetamine (3 mg/kg) administration in DMS D₁-DTR (B, C) and A_2A-DTR (E, F) or DLS D₁-DTR (H, I) and A_2A-DTR (K, L) DT-injected mice. Histograms represent ambulation following first and last d-amphetamine administration. Data are reported as mean±s.e.m. (n=10–17 per group). Statistical comparisons were made between DTR⁺ and respective DTR⁻ control mice (dot chart) or between first and last amphetamine injection (histograms). ^*P<0.05, ^**P<0.01.