Abstract
BACKGROUND AND PURPOSE
We recently reported that broad spectrum agonist-induced activation of presynaptic group III metabotropic glutamate (mGlu) receptors within the substantia nigra pars compacta using L-2-amino-4-phosphonobutyrate provided functional neuroprotection in the 6-hydroxydopamine lesion rat model of Parkinson's disease. The aim of this study was to establish whether selective activation of the mGlu4 receptor alone could afford similar functional neuroprotection.
EXPERIMENTAL APPROACH
The neuroprotective effects of 8 days of supranigral treatment with a positive allosteric modulator of mGlu4 receptors, (+/−)-cis-2-(3,5-dichlorphenylcarbamoyl)cyclohexanecarboxylic acid (VU0155041), were investigated in rats with unilateral 6-hydroxydopamine lesions. The effects of VU0155041 treatment on motor function were assessed using both habitual (cylinder test) and forced (adjusted stepping, amphetamine-induced rotations) behavioural tests. Nigrostriatal tract integrity was examined by analysis of tyrosine hydroxylase, dopa decarboxylase or dopamine levels in the striatum and tyrosine hydroxylase-positive cell counts in the substantia nigra pars compacta.
KEY RESULTS
VU0155041 provided around 40% histological protection against a unilateral 6-hydroxydopamine lesion as well as significant preservation of motor function. These effects were inhibited by pre-treatment with (RS)-α-cyclopropyl-4-phosphonophenylglycine, confirming a receptor-mediated response. Reduced levels of inflammatory markers were also evident in the brains of VU0155041-treated animals.
CONCLUSIONS AND IMPLICATIONS
Allosteric potentiation of mGlu4 receptors in the substantia nigra pars compacta provided neuroprotective effects in the 6-hydroxydopamine rat model A reduced inflammatory response may contribute, in part, to this action. In addition to the reported symptomatic effects, activation of mGlu4 receptors may also offer a novel approach for slowing the progressive degeneration observed in Parkinson's disease.
We recently reported that broad spectrum agonist-induced activation of presynaptic group III metabotropic glutamate (mGlu) receptors within the substantia nigra pars compacta using L-2-amino-4-phosphonobutyrate provided functional neuroprotection in the 6-hydroxydopamine lesion rat model of Parkinson's disease. The aim of this study was to establish whether selective activation of the mGlu4 receptor alone could afford similar functional neuroprotection.
EXPERIMENTAL APPROACH
The neuroprotective effects of 8 days of supranigral treatment with a positive allosteric modulator of mGlu4 receptors, (+/−)-cis-2-(3,5-dichlorphenylcarbamoyl)cyclohexanecarboxylic acid (VU0155041), were investigated in rats with unilateral 6-hydroxydopamine lesions. The effects of VU0155041 treatment on motor function were assessed using both habitual (cylinder test) and forced (adjusted stepping, amphetamine-induced rotations) behavioural tests. Nigrostriatal tract integrity was examined by analysis of tyrosine hydroxylase, dopa decarboxylase or dopamine levels in the striatum and tyrosine hydroxylase-positive cell counts in the substantia nigra pars compacta.
KEY RESULTS
VU0155041 provided around 40% histological protection against a unilateral 6-hydroxydopamine lesion as well as significant preservation of motor function. These effects were inhibited by pre-treatment with (RS)-α-cyclopropyl-4-phosphonophenylglycine, confirming a receptor-mediated response. Reduced levels of inflammatory markers were also evident in the brains of VU0155041-treated animals.
CONCLUSIONS AND IMPLICATIONS
Allosteric potentiation of mGlu4 receptors in the substantia nigra pars compacta provided neuroprotective effects in the 6-hydroxydopamine rat model A reduced inflammatory response may contribute, in part, to this action. In addition to the reported symptomatic effects, activation of mGlu4 receptors may also offer a novel approach for slowing the progressive degeneration observed in Parkinson's disease.
| Original language | English |
|---|---|
| Pages (from-to) | 2317 - 2330 |
| Number of pages | 14 |
| Journal | British Journal of Pharmacology |
| Volume | 166 |
| Issue number | 8 |
| Early online date | 24 Jul 2012 |
| DOIs | |
| Publication status | Published - Aug 2012 |