Figure 1.

Effects of (±) DOI and of LY379268 on the 15 mM KCl-evoked release of preloaded [³H]D-aspartate ([³H]D-asp) from synaptosomes isolated from the prefrontal cortex (PFc) of adult rats. (a) (±) DOI (0.1–30 μM) inhibits the exocytosis of ([³H]D-asp) elicited by 15 mM KCl-enriched medium. Synaptosomes were exposed in superfusion to the depolarizing stimulus for 90 s in the absence or in the presence of the 5-HT_2A receptor agonist. When indicated, the 5-HT_2A antagonist MDL11,939 (0.1 μM) was added concomitantly to (±) DOI. The release of [³H]D-asp in the first 3 min fraction collected (b1) amounted to 0.33 ± 0.02 nCi and represents the 0.90 ± 0.05% of the total tritium synaptosomal content. (b) PFc synaptosomes are endowed with the 5-HT_2A receptor protein. Synaptosomal lysates were immunoblotted and probed with anti-5-HT2A and anti-β-actin antibodies. (c) LY379268 concentration-dependently (0.003–3 μM) reduced the [³H]D-asp exocytosis elicited by high K⁺ from synaptosomes isolated from the PFc of adult rats. The release of [³H]D-asp in the first 3 min fraction collected (b1) amounted to 0.49 ± 0.06 nCi and and represents the 0.77 ± 0.12% of the total tritium synaptosomal content. (d) Western blot analysis confirming the presence of mGlu2 receptor protein in the PFc lysates. Synaptosomal lysates were immunoblotted and probed with anti-mGlu2 and anti-β-actin antibodies. (a,c) results are expressed as induced overflow; data are the means ± SEM of four to six experiments run in triplicate (three superfusion chambers for each experimental conditions). * p < 0.05 vs. respective 15 mM KCl; ** p < 0.01 vs. respective 15 mM KCl; *** p < 0.001 vs. respective 15 mM KCl; ^^ p < 0.01 vs. 15 mM KCl/30 μM (±) DOI. The blots in (b,d) are representative of 5 to 7 blots run in different days using different samples.