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Pharmacological enhancement of mGlu1 metabotropic glutamate receptors causes a prolonged symptomatic benefit in a mouse model of spinocerebellar ataxia type 1.

Notartomaso S, Zappulla C, Biagioni F, Cannella M, Bucci D, Mascio G, Scarselli P, Fazio F, Weisz F, Lionetto L, Simmaco M, Gradini R, Battaglia G, Signore M, Puliti A, Nicoletti F - Mol Brain (2013)

Bottom Line: Spinocerebellar ataxia type 1 (SCA1) is a genetic disorder characterized by severe ataxia associated with progressive loss of cerebellar Purkinje cells.A single injection of Ro0711401 improved motor symptoms for several days, and no tolerance developed to the drug.The prolonged symptomatic benefit caused by Ro0711401 outlasted the time of drug clearance from the cerebellum, and was associated with neuroadaptive changes in the cerebellum, such as a striking reduction of the ectopically expressed mGlu5 receptors in Purkinje cells, increases in levels of total and Ser880-phosphorylated GluA2 subunit of AMPA receptors, and changes in the length of spines in the distal dendrites of Purkinje cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: I,R,C,C,S, Neuromed, Pozzilli, Italy. ferdinandonicoletti@hotmail.com.

ABSTRACT

Background: Spinocerebellar ataxia type 1 (SCA1) is a genetic disorder characterized by severe ataxia associated with progressive loss of cerebellar Purkinje cells. The mGlu1 metabotropic glutamate receptor plays a key role in mechanisms of activity-dependent synaptic plasticity in the cerebellum, and its dysfunction is linked to the pathophysiology of motor symptoms associated with SCA1. We used SCA1 heterozygous transgenic mice (Q154/Q2) as a model for testing the hypothesis that drugs that enhance mGlu1 receptor function may be good candidates for the medical treatment of SCA1.

Results: Symptomatic 30-week old SCA1 mice showed reduced mGlu1 receptor mRNA and protein levels in the cerebellum. Interestingly, these mice also showed an intense expression of mGlu5 receptors in cerebellar Purkinje cells, which normally lack these receptors. Systemic treatment of SCA1 mice with the mGlu1 receptor positive allosteric modulator (PAM), Ro0711401 (10 mg/kg, s.c.), caused a prolonged improvement of motor performance on the rotarod and the paw-print tests. A single injection of Ro0711401 improved motor symptoms for several days, and no tolerance developed to the drug. In contrast, the mGlu5 receptor PAM, VU0360172 (10 mg/kg, s.c.), caused only a short-lasting improvement of motor symptoms, whereas the mGlu1 receptor antagonist, JNJ16259685 (2.5 mg/kg, i.p.), further impaired motor performance in SCA1 mice. The prolonged symptomatic benefit caused by Ro0711401 outlasted the time of drug clearance from the cerebellum, and was associated with neuroadaptive changes in the cerebellum, such as a striking reduction of the ectopically expressed mGlu5 receptors in Purkinje cells, increases in levels of total and Ser880-phosphorylated GluA2 subunit of AMPA receptors, and changes in the length of spines in the distal dendrites of Purkinje cells.

Conclusions: These data demonstrate that pharmacological enhancement of mGlu1 receptors causes a robust and sustained motor improvement in SCA1 mice, and lay the groundwork for the development of mGlu1 receptor PAMs as novel "cerebellum-specific", effective, and safe symptomatic drugs for the treatment of SCA1 in humans.

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Neuroadaptive changes caused by a single injection of Ro0711401 in the cerebellum of SCA1 mice. Levels of total and Ser880-phosphorylated GluA2 subunit of AMPA receptors in the cerebellum of symptomatic SCA1 mice 6 days following a single injection of vehicle or Ro0711401 (10 mg/kg, s.c.) is shown in (A). Densitometric values are means ± S.E.M. of 4–5 mice per group. *p < 0.05 vs. mice treated with vehicle (Student’s t test). t = - 3.192 (total GluA2) and 4.311 (p-GluA2). Spine density in 3–4 dendritic branchlets of Purkinje cells from wild-type or SCA1 mice 6 days after a single injection of vehicle or Ro0711401 is shown in (B), where values are means + S.E.M. of 4 mice per group. The distribution of dendritic spines in relation to their lengths in distal dendrites of Purkinje cells 6 days after a single injection of vehicle or Ro0711401 in symptomatic SCA1 mice or after injection of vehicle in wild-type littermates is shown in (C). The length of 200 spines per mouse was measured. Values are means ± S.E.M. of 5 individual determination for groups. In (C) spines were identified and measured using Image Pro Plus Software. Representative images and distribution spine analysis are shown. Data are means ± S.E.M. of 4 mice per group. *p < 0.05 (Two-Way ANOVA + Bonferroni’s t tests) as indicated in individual groups of columns. F(13,84) = 87.47.
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Figure 8: Neuroadaptive changes caused by a single injection of Ro0711401 in the cerebellum of SCA1 mice. Levels of total and Ser880-phosphorylated GluA2 subunit of AMPA receptors in the cerebellum of symptomatic SCA1 mice 6 days following a single injection of vehicle or Ro0711401 (10 mg/kg, s.c.) is shown in (A). Densitometric values are means ± S.E.M. of 4–5 mice per group. *p < 0.05 vs. mice treated with vehicle (Student’s t test). t = - 3.192 (total GluA2) and 4.311 (p-GluA2). Spine density in 3–4 dendritic branchlets of Purkinje cells from wild-type or SCA1 mice 6 days after a single injection of vehicle or Ro0711401 is shown in (B), where values are means + S.E.M. of 4 mice per group. The distribution of dendritic spines in relation to their lengths in distal dendrites of Purkinje cells 6 days after a single injection of vehicle or Ro0711401 in symptomatic SCA1 mice or after injection of vehicle in wild-type littermates is shown in (C). The length of 200 spines per mouse was measured. Values are means ± S.E.M. of 5 individual determination for groups. In (C) spines were identified and measured using Image Pro Plus Software. Representative images and distribution spine analysis are shown. Data are means ± S.E.M. of 4 mice per group. *p < 0.05 (Two-Way ANOVA + Bonferroni’s t tests) as indicated in individual groups of columns. F(13,84) = 87.47.

Mentions: We reasoned that the long-lasting improvement in motor performance caused by a single injection of Ro0711401 could reflect the induction of adaptive mechanisms associated with activity-dependent synaptic plasticity and cerebellar motor learning. Changes in the expression, Ser-880 phosphorylation, and clustering of the Ca2+-impermeable GluA2 subunit of AMPA receptors, have been associated with the induction and expression of cerebellar LTD [32-37]. Levels of both unphosphorylated and Ser880-phosphorylated GluA2 subunit were found to be significantly elevated in the cerebellum of SCA1 mice 6 days following a single injection of Ro0711401 (Figure 8A). This treatment did not cause changes in the number of dendritic spines in Purkinje cells of SCA1 mice (Figure 8B). However, injection of Ro0711401 did cause changes in the morphology of dendritic spines that might be associated with motor learning. The distribution analysis of a fixed number of dendritic spines of Purkinje cells in relation to their length showed a shift to the right in symptomatic SCA1 mice as compared to age-matched wild-type mice. A single injection of Ro0711401 in SCA1 mice increased the number of “short” dendritic spines (i.e. spines with length between 0.3 and 0.5 μm), changing the pattern of distribution in a way similar to that found in wild-type mice (Figure 8C).


Pharmacological enhancement of mGlu1 metabotropic glutamate receptors causes a prolonged symptomatic benefit in a mouse model of spinocerebellar ataxia type 1.

Notartomaso S, Zappulla C, Biagioni F, Cannella M, Bucci D, Mascio G, Scarselli P, Fazio F, Weisz F, Lionetto L, Simmaco M, Gradini R, Battaglia G, Signore M, Puliti A, Nicoletti F - Mol Brain (2013)

Neuroadaptive changes caused by a single injection of Ro0711401 in the cerebellum of SCA1 mice. Levels of total and Ser880-phosphorylated GluA2 subunit of AMPA receptors in the cerebellum of symptomatic SCA1 mice 6 days following a single injection of vehicle or Ro0711401 (10 mg/kg, s.c.) is shown in (A). Densitometric values are means ± S.E.M. of 4–5 mice per group. *p < 0.05 vs. mice treated with vehicle (Student’s t test). t = - 3.192 (total GluA2) and 4.311 (p-GluA2). Spine density in 3–4 dendritic branchlets of Purkinje cells from wild-type or SCA1 mice 6 days after a single injection of vehicle or Ro0711401 is shown in (B), where values are means + S.E.M. of 4 mice per group. The distribution of dendritic spines in relation to their lengths in distal dendrites of Purkinje cells 6 days after a single injection of vehicle or Ro0711401 in symptomatic SCA1 mice or after injection of vehicle in wild-type littermates is shown in (C). The length of 200 spines per mouse was measured. Values are means ± S.E.M. of 5 individual determination for groups. In (C) spines were identified and measured using Image Pro Plus Software. Representative images and distribution spine analysis are shown. Data are means ± S.E.M. of 4 mice per group. *p < 0.05 (Two-Way ANOVA + Bonferroni’s t tests) as indicated in individual groups of columns. F(13,84) = 87.47.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Figure 8: Neuroadaptive changes caused by a single injection of Ro0711401 in the cerebellum of SCA1 mice. Levels of total and Ser880-phosphorylated GluA2 subunit of AMPA receptors in the cerebellum of symptomatic SCA1 mice 6 days following a single injection of vehicle or Ro0711401 (10 mg/kg, s.c.) is shown in (A). Densitometric values are means ± S.E.M. of 4–5 mice per group. *p < 0.05 vs. mice treated with vehicle (Student’s t test). t = - 3.192 (total GluA2) and 4.311 (p-GluA2). Spine density in 3–4 dendritic branchlets of Purkinje cells from wild-type or SCA1 mice 6 days after a single injection of vehicle or Ro0711401 is shown in (B), where values are means + S.E.M. of 4 mice per group. The distribution of dendritic spines in relation to their lengths in distal dendrites of Purkinje cells 6 days after a single injection of vehicle or Ro0711401 in symptomatic SCA1 mice or after injection of vehicle in wild-type littermates is shown in (C). The length of 200 spines per mouse was measured. Values are means ± S.E.M. of 5 individual determination for groups. In (C) spines were identified and measured using Image Pro Plus Software. Representative images and distribution spine analysis are shown. Data are means ± S.E.M. of 4 mice per group. *p < 0.05 (Two-Way ANOVA + Bonferroni’s t tests) as indicated in individual groups of columns. F(13,84) = 87.47.
Mentions: We reasoned that the long-lasting improvement in motor performance caused by a single injection of Ro0711401 could reflect the induction of adaptive mechanisms associated with activity-dependent synaptic plasticity and cerebellar motor learning. Changes in the expression, Ser-880 phosphorylation, and clustering of the Ca2+-impermeable GluA2 subunit of AMPA receptors, have been associated with the induction and expression of cerebellar LTD [32-37]. Levels of both unphosphorylated and Ser880-phosphorylated GluA2 subunit were found to be significantly elevated in the cerebellum of SCA1 mice 6 days following a single injection of Ro0711401 (Figure 8A). This treatment did not cause changes in the number of dendritic spines in Purkinje cells of SCA1 mice (Figure 8B). However, injection of Ro0711401 did cause changes in the morphology of dendritic spines that might be associated with motor learning. The distribution analysis of a fixed number of dendritic spines of Purkinje cells in relation to their length showed a shift to the right in symptomatic SCA1 mice as compared to age-matched wild-type mice. A single injection of Ro0711401 in SCA1 mice increased the number of “short” dendritic spines (i.e. spines with length between 0.3 and 0.5 μm), changing the pattern of distribution in a way similar to that found in wild-type mice (Figure 8C).

Bottom Line: Spinocerebellar ataxia type 1 (SCA1) is a genetic disorder characterized by severe ataxia associated with progressive loss of cerebellar Purkinje cells.A single injection of Ro0711401 improved motor symptoms for several days, and no tolerance developed to the drug.The prolonged symptomatic benefit caused by Ro0711401 outlasted the time of drug clearance from the cerebellum, and was associated with neuroadaptive changes in the cerebellum, such as a striking reduction of the ectopically expressed mGlu5 receptors in Purkinje cells, increases in levels of total and Ser880-phosphorylated GluA2 subunit of AMPA receptors, and changes in the length of spines in the distal dendrites of Purkinje cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: I,R,C,C,S, Neuromed, Pozzilli, Italy. ferdinandonicoletti@hotmail.com.

ABSTRACT

Background: Spinocerebellar ataxia type 1 (SCA1) is a genetic disorder characterized by severe ataxia associated with progressive loss of cerebellar Purkinje cells. The mGlu1 metabotropic glutamate receptor plays a key role in mechanisms of activity-dependent synaptic plasticity in the cerebellum, and its dysfunction is linked to the pathophysiology of motor symptoms associated with SCA1. We used SCA1 heterozygous transgenic mice (Q154/Q2) as a model for testing the hypothesis that drugs that enhance mGlu1 receptor function may be good candidates for the medical treatment of SCA1.

Results: Symptomatic 30-week old SCA1 mice showed reduced mGlu1 receptor mRNA and protein levels in the cerebellum. Interestingly, these mice also showed an intense expression of mGlu5 receptors in cerebellar Purkinje cells, which normally lack these receptors. Systemic treatment of SCA1 mice with the mGlu1 receptor positive allosteric modulator (PAM), Ro0711401 (10 mg/kg, s.c.), caused a prolonged improvement of motor performance on the rotarod and the paw-print tests. A single injection of Ro0711401 improved motor symptoms for several days, and no tolerance developed to the drug. In contrast, the mGlu5 receptor PAM, VU0360172 (10 mg/kg, s.c.), caused only a short-lasting improvement of motor symptoms, whereas the mGlu1 receptor antagonist, JNJ16259685 (2.5 mg/kg, i.p.), further impaired motor performance in SCA1 mice. The prolonged symptomatic benefit caused by Ro0711401 outlasted the time of drug clearance from the cerebellum, and was associated with neuroadaptive changes in the cerebellum, such as a striking reduction of the ectopically expressed mGlu5 receptors in Purkinje cells, increases in levels of total and Ser880-phosphorylated GluA2 subunit of AMPA receptors, and changes in the length of spines in the distal dendrites of Purkinje cells.

Conclusions: These data demonstrate that pharmacological enhancement of mGlu1 receptors causes a robust and sustained motor improvement in SCA1 mice, and lay the groundwork for the development of mGlu1 receptor PAMs as novel "cerebellum-specific", effective, and safe symptomatic drugs for the treatment of SCA1 in humans.

Show MeSH
Related in: MedlinePlus