|
(2R,4R)-APDC |
DCG-IV | |||
EC 50 Values (µM) | ||||
Group I |
mGlu 1 |
>300 |
>100 |
>1000 (Ant) |
mGlu 5 |
>300 |
>100 |
389-360 (Ant) | |
Group II |
mGlu 2 |
0.005 - 0.01 |
0.4 |
0.3 |
mGlu 3 |
0.024 - 0.04 |
0.4 |
0.2 | |
Group III |
mGlu 4 |
>100 |
>300 |
23 (Ant) |
mGlu 6 |
3 |
110 |
40 (Ant) | |
mGlu 7 |
>100 |
>300 |
40 (Ant) | |
mGlu 8 |
12 - 36 |
>100 |
32 (Ant) |
Group III mGlu Receptor Agonists The most widely used group III mGlu receptor agonist is L-AP4, a glutamate analogue that was used in the early 1980's to suggest the involvement of pre-synaptic glutamate receptors in controlling glutamate release. In addition, this compound, and the closely releated L-AP3, were shown to block the 'metabotropic' actions of ibotentate (a broad spectrum glutamate receptor agonist) and were instrumental in the development of the notion of metabotropic glutamate receptors long before they were cloned. Other widely used agonists are L-SOP and more recently (RS)-PPG. Within the group III receptors, (RS)-PPG shows an ~20-fold selectivity for mGlu8 over mGlu4 or mGlu6 receptors. More recently still, a highly potent mGlu8 receptor selective agonist has been reported from Dr David Jane's laboratory, (S)-3,4-DCPG. This compound activates mGlu8a receptors with nanomolar potency and shows >280 fold selectivity over any other centrally expressed mGlu receptor subtype. (S)-3,4-DCPG is therfore likely to become the agonist of choice for the study of mGlu8 receptor function. Other agonists show no particular selectivity for any of the group III receptors, although (S)-HomoAMPA appears to selectively activate mGlu6 receptors ( it possesses neither agonist or antagonist activity in cell lines expressing either group I or group II mGlu receptor subtypes but no information is available regarding the activity of this compound on mGlu8 receptors). |
L-AP4 |
L-SOP |
(RS)-4PPG |
(S)-3,4-DCPG | ||
EC 50 Values (µM) | |||||
Group I |
mGlu 1 |
>1000 |
- |
>200 |
IC50 = 32 ± 1 |
mGlu 5 |
>1000 |
- |
>200 |
>100 | |
Group II |
mGlu 2 |
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