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Adenosine A₂A receptors in striatal glutamatergic terminals and GABAergic neurons oppositely modulate psychostimulant action and DARPP-32 phosphorylation.

Shen HY, Canas PM, Garcia-Sanz P, Lan JQ, Boison D, Moratalla R, Cunha RA, Chen JF - PLoS ONE (2013)

Bottom Line: The inactivation of A2ARs in GABAergic neurons reduced striatal DARPP-32 phosphorylation at Thr-34 and increased its phosphorylation at Thr-75.Conversely, the additional deletion of corticostriatal glutamatergic A2ARs produced opposite effects on DARPP-32 phosphorylation at Thr-34 and Thr-75.We conclude that A2ARs in glutamatergic terminals prominently control the action of psychostimulants and define a novel mechanism by which A2ARs fine-tune striatal activity by integrating GABAergic, dopaminergic and glutamatergic signaling.

View Article: PubMed Central - PubMed

Affiliation: Molecular Neuropharmacology Lab, Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America.

ABSTRACT
Adenosine A2A receptors (A2AR) are located postsynaptically in striatopallidal GABAergic neurons, antagonizing dopamine D2 receptor functions, and are also located presynaptically at corticostriatal terminals, facilitating glutamate release. To address the hypothesis that these two A2AR populations differently control the action of psychostimulants, we characterized A2AR modulation of cocaine-induced effects at the level of DARPP-32 phosphorylation at Thr-34 and Thr-75, c-Fos expression, and psychomotor activity using two lines of cell-type selective A2AR knockout (KO) mice with selective A2AR deletion in GABAergic neurons (striatum-A2AR-KO mice), or with A2AR deletion in both striatal GABAergic neurons and projecting cortical glutamatergic neurons (forebrain-A2AR-KO mice). We demonstrated that striatum-A2AR KO mice lacked A2ARs exclusively in striatal GABAergic terminals whereas forebrain-A2AR KO mice lacked A2ARs in both striatal GABAergic and glutamatergic terminals leading to a blunted A2AR-mediated facilitation of synaptosomal glutamate release. The inactivation of A2ARs in GABAergic neurons reduced striatal DARPP-32 phosphorylation at Thr-34 and increased its phosphorylation at Thr-75. Conversely, the additional deletion of corticostriatal glutamatergic A2ARs produced opposite effects on DARPP-32 phosphorylation at Thr-34 and Thr-75. This distinct modulation of DARPP-32 phosphorylation was associated with opposite responses to cocaine-induced striatal c-Fos expression and psychomotor activity in striatum-A2AR KO (enhanced) and forebrain-A2AR KO mice (reduced). Thus, A2ARs in glutamatergic corticostriatal terminals and in GABAergic striatal neurons modulate the action of psychostimulants and DARPP-32 phosphorylation in opposite ways. We conclude that A2ARs in glutamatergic terminals prominently control the action of psychostimulants and define a novel mechanism by which A2ARs fine-tune striatal activity by integrating GABAergic, dopaminergic and glutamatergic signaling.

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Cocaine-induced psychomotor activity and striatal c-Fos expression were attenuated in forebrain-A2AR KO but enhanced in striatal-A2AR KO mice.Ambulation was recorded for 180 min after injection of a single dose of cocaine (25 mg/kg, i.p.) or vehicle in fb-A2AR KO (n = 12, A) and in st-A2AR KO (n = 9, B) mice and their WT littermates (n = 8–12). The arrow indicates the time of injection and the data are mean ± SEM; *p<0.05, comparing fb-A2AR KO and st-A2AR KO groups to their corresponding WT group using two-way ANOVA and a post hoc Bonferroni test. (C) Cocaine-induced c-Fos expression in the striatum of fb-A2AR KO (n = 12) and st-A2AR KO (n = 9) and their corresponding WT littermates (n = 8–12) # p<0.05, comparing to corresponding wild-types with cocaine treatment, two-way ANOVA post hoc Bonferroni test. (D) Representative co-immunostaining of c-Fos with dynorphin. Black arrows indicate neurons co-stained with dynorphin and c-Fos; white arrow heads indicate neurons stained with dynorphin only (greyish brown) and black arrow heads indicate neurons stained with c-Fos (reddish brown). Scale bar  =  25 µm.
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pone-0080902-g004: Cocaine-induced psychomotor activity and striatal c-Fos expression were attenuated in forebrain-A2AR KO but enhanced in striatal-A2AR KO mice.Ambulation was recorded for 180 min after injection of a single dose of cocaine (25 mg/kg, i.p.) or vehicle in fb-A2AR KO (n = 12, A) and in st-A2AR KO (n = 9, B) mice and their WT littermates (n = 8–12). The arrow indicates the time of injection and the data are mean ± SEM; *p<0.05, comparing fb-A2AR KO and st-A2AR KO groups to their corresponding WT group using two-way ANOVA and a post hoc Bonferroni test. (C) Cocaine-induced c-Fos expression in the striatum of fb-A2AR KO (n = 12) and st-A2AR KO (n = 9) and their corresponding WT littermates (n = 8–12) # p<0.05, comparing to corresponding wild-types with cocaine treatment, two-way ANOVA post hoc Bonferroni test. (D) Representative co-immunostaining of c-Fos with dynorphin. Black arrows indicate neurons co-stained with dynorphin and c-Fos; white arrow heads indicate neurons stained with dynorphin only (greyish brown) and black arrow heads indicate neurons stained with c-Fos (reddish brown). Scale bar  =  25 µm.

Mentions: To evaluate the functional significance of the opposite modulation of striatal DARPP-32 phosphorylation by A2AR in GABAergic striatal neurons and in glutamatergic terminals, we compared cocaine-induced psychomotor activity and c-Fos expression, a measure of MSN activity, in the striatum of st-A2AR KO and fb-A2AR KO mice. Consistent with our previous reports [9], we found that cocaine (25 mg/kg, i.p.)-induced psychomotor activity was enhanced in st-A2AR KO (n = 9) but attenuated in fb-A2AR KO mice (n = 12) compared to their WT littermates (n = 8-12) (two-way ANOVA, drug effect: F(1,24)  = 91.892, p<0.001; genotype effect: F(3,24)  = 8.456, p<0.001; drug x genotype: F(3,24)  = 13.297, p<0.001) (Figure 4A and 4B). The opposite psychomotor effects of cocaine in st-A2AR KO and fb-A2AR KO mice were also paralleled by similar opposite effects of cocaine on c-Fos gene expression in the striatum of these two transgenic mouse strains. As expected, cocaine treatment (25 mg/kg, i.p.) increased c-Fos expression in the striatum of WT mice (st-WT and fb-WT, Figure 4C) to a similar extent. Interestingly, cocaine-induced striatal c-Fos expression was enhanced in st-A2AR KO mice (p<0.05, Student’s t-test, comparing with st-WT) (Figure 4C) but reduced in fb-A2AR KO mice compared to their corresponding WT littermates (p<0.05, Student’s t-test, comparing with fb-WT mice) (Figure 4C). Furthermore, double immunohistochemical analysis showed that the cocaine-induced increase of striatal c-Fos immunoreactivity in st-A2AR KO mice was restricted to dynorphin-positive cells (Figure 4D). As shown in Figure 4D, the majority of c-Fos-positive cells (black arrows) in the striatum were also stained with dynorphin, whereas some neurons were stained with dynorphin (white arrow heads) or c-Fos (black arrow heads) only.


Adenosine A₂A receptors in striatal glutamatergic terminals and GABAergic neurons oppositely modulate psychostimulant action and DARPP-32 phosphorylation.

Shen HY, Canas PM, Garcia-Sanz P, Lan JQ, Boison D, Moratalla R, Cunha RA, Chen JF - PLoS ONE (2013)

Cocaine-induced psychomotor activity and striatal c-Fos expression were attenuated in forebrain-A2AR KO but enhanced in striatal-A2AR KO mice.Ambulation was recorded for 180 min after injection of a single dose of cocaine (25 mg/kg, i.p.) or vehicle in fb-A2AR KO (n = 12, A) and in st-A2AR KO (n = 9, B) mice and their WT littermates (n = 8–12). The arrow indicates the time of injection and the data are mean ± SEM; *p<0.05, comparing fb-A2AR KO and st-A2AR KO groups to their corresponding WT group using two-way ANOVA and a post hoc Bonferroni test. (C) Cocaine-induced c-Fos expression in the striatum of fb-A2AR KO (n = 12) and st-A2AR KO (n = 9) and their corresponding WT littermates (n = 8–12) # p<0.05, comparing to corresponding wild-types with cocaine treatment, two-way ANOVA post hoc Bonferroni test. (D) Representative co-immunostaining of c-Fos with dynorphin. Black arrows indicate neurons co-stained with dynorphin and c-Fos; white arrow heads indicate neurons stained with dynorphin only (greyish brown) and black arrow heads indicate neurons stained with c-Fos (reddish brown). Scale bar  =  25 µm.
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Related In: Results  -  Collection

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pone-0080902-g004: Cocaine-induced psychomotor activity and striatal c-Fos expression were attenuated in forebrain-A2AR KO but enhanced in striatal-A2AR KO mice.Ambulation was recorded for 180 min after injection of a single dose of cocaine (25 mg/kg, i.p.) or vehicle in fb-A2AR KO (n = 12, A) and in st-A2AR KO (n = 9, B) mice and their WT littermates (n = 8–12). The arrow indicates the time of injection and the data are mean ± SEM; *p<0.05, comparing fb-A2AR KO and st-A2AR KO groups to their corresponding WT group using two-way ANOVA and a post hoc Bonferroni test. (C) Cocaine-induced c-Fos expression in the striatum of fb-A2AR KO (n = 12) and st-A2AR KO (n = 9) and their corresponding WT littermates (n = 8–12) # p<0.05, comparing to corresponding wild-types with cocaine treatment, two-way ANOVA post hoc Bonferroni test. (D) Representative co-immunostaining of c-Fos with dynorphin. Black arrows indicate neurons co-stained with dynorphin and c-Fos; white arrow heads indicate neurons stained with dynorphin only (greyish brown) and black arrow heads indicate neurons stained with c-Fos (reddish brown). Scale bar  =  25 µm.
Mentions: To evaluate the functional significance of the opposite modulation of striatal DARPP-32 phosphorylation by A2AR in GABAergic striatal neurons and in glutamatergic terminals, we compared cocaine-induced psychomotor activity and c-Fos expression, a measure of MSN activity, in the striatum of st-A2AR KO and fb-A2AR KO mice. Consistent with our previous reports [9], we found that cocaine (25 mg/kg, i.p.)-induced psychomotor activity was enhanced in st-A2AR KO (n = 9) but attenuated in fb-A2AR KO mice (n = 12) compared to their WT littermates (n = 8-12) (two-way ANOVA, drug effect: F(1,24)  = 91.892, p<0.001; genotype effect: F(3,24)  = 8.456, p<0.001; drug x genotype: F(3,24)  = 13.297, p<0.001) (Figure 4A and 4B). The opposite psychomotor effects of cocaine in st-A2AR KO and fb-A2AR KO mice were also paralleled by similar opposite effects of cocaine on c-Fos gene expression in the striatum of these two transgenic mouse strains. As expected, cocaine treatment (25 mg/kg, i.p.) increased c-Fos expression in the striatum of WT mice (st-WT and fb-WT, Figure 4C) to a similar extent. Interestingly, cocaine-induced striatal c-Fos expression was enhanced in st-A2AR KO mice (p<0.05, Student’s t-test, comparing with st-WT) (Figure 4C) but reduced in fb-A2AR KO mice compared to their corresponding WT littermates (p<0.05, Student’s t-test, comparing with fb-WT mice) (Figure 4C). Furthermore, double immunohistochemical analysis showed that the cocaine-induced increase of striatal c-Fos immunoreactivity in st-A2AR KO mice was restricted to dynorphin-positive cells (Figure 4D). As shown in Figure 4D, the majority of c-Fos-positive cells (black arrows) in the striatum were also stained with dynorphin, whereas some neurons were stained with dynorphin (white arrow heads) or c-Fos (black arrow heads) only.

Bottom Line: The inactivation of A2ARs in GABAergic neurons reduced striatal DARPP-32 phosphorylation at Thr-34 and increased its phosphorylation at Thr-75.Conversely, the additional deletion of corticostriatal glutamatergic A2ARs produced opposite effects on DARPP-32 phosphorylation at Thr-34 and Thr-75.We conclude that A2ARs in glutamatergic terminals prominently control the action of psychostimulants and define a novel mechanism by which A2ARs fine-tune striatal activity by integrating GABAergic, dopaminergic and glutamatergic signaling.

View Article: PubMed Central - PubMed

Affiliation: Molecular Neuropharmacology Lab, Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States of America.

ABSTRACT
Adenosine A2A receptors (A2AR) are located postsynaptically in striatopallidal GABAergic neurons, antagonizing dopamine D2 receptor functions, and are also located presynaptically at corticostriatal terminals, facilitating glutamate release. To address the hypothesis that these two A2AR populations differently control the action of psychostimulants, we characterized A2AR modulation of cocaine-induced effects at the level of DARPP-32 phosphorylation at Thr-34 and Thr-75, c-Fos expression, and psychomotor activity using two lines of cell-type selective A2AR knockout (KO) mice with selective A2AR deletion in GABAergic neurons (striatum-A2AR-KO mice), or with A2AR deletion in both striatal GABAergic neurons and projecting cortical glutamatergic neurons (forebrain-A2AR-KO mice). We demonstrated that striatum-A2AR KO mice lacked A2ARs exclusively in striatal GABAergic terminals whereas forebrain-A2AR KO mice lacked A2ARs in both striatal GABAergic and glutamatergic terminals leading to a blunted A2AR-mediated facilitation of synaptosomal glutamate release. The inactivation of A2ARs in GABAergic neurons reduced striatal DARPP-32 phosphorylation at Thr-34 and increased its phosphorylation at Thr-75. Conversely, the additional deletion of corticostriatal glutamatergic A2ARs produced opposite effects on DARPP-32 phosphorylation at Thr-34 and Thr-75. This distinct modulation of DARPP-32 phosphorylation was associated with opposite responses to cocaine-induced striatal c-Fos expression and psychomotor activity in striatum-A2AR KO (enhanced) and forebrain-A2AR KO mice (reduced). Thus, A2ARs in glutamatergic corticostriatal terminals and in GABAergic striatal neurons modulate the action of psychostimulants and DARPP-32 phosphorylation in opposite ways. We conclude that A2ARs in glutamatergic terminals prominently control the action of psychostimulants and define a novel mechanism by which A2ARs fine-tune striatal activity by integrating GABAergic, dopaminergic and glutamatergic signaling.

Show MeSH
Related in: MedlinePlus