MSOP

K _D : 51 μM (L-AP4-sensitive presynaptic mGluR).

In the presence of 200 μM MSOP, a rightward parallel shift of the dose-response curve to L-AP4 is observed, with an apparent K _D calculated as 51±6 μM (n=3). MSOP is shown to be selective for the L-APC sensitive presynaptic mGluR, the apparent K _D for the interaction of MSOP with the (1S, 3S)-ACPD sensitive receptor calculated as greater than 700 μM (n=3).

It is found that TBOA-induced antinociceptive effects are significantly blocked by intrathecal co-administration of MSOP (second phase of formalin model: F _3,16 =30.96, P<0.001; CFA model: F _3,16 =30.77, P<0.001). As expected, intrathecal TBOA (10 μg) reduces the number of formalin-induced flinches and shakes by 47% of the value in the saline-treated group in the second phase (P<0.001) and blocked the CFA-induced decrease in ipsilateral paw withdrawal latency by 60% of the value in the saline-treated group (P=0.01). The number of formalin-induced flinches in the second phase in the group treated with MSOP and TBOA is increased by 56% (P=0.04) of the value in the TBOA-treated group. CFA-induced paw withdrawal latency in the group treated with MSOP and TBOA is decreased by 86% (P=0.03) of the value in the TBOA-treated group.