Limits...
Nicotinic α7 receptor activation selectively potentiates the function of NMDA receptors in glutamatergic terminals of the nucleus accumbens.

Zappettini S, Grilli M, Olivero G, Chen J, Padolecchia C, Pittaluga A, Tomé AR, Cunha RA, Marchi M - Front Cell Neurosci (2014)

Bottom Line: Pre-exposure to the α4-nAChR agonists 5IA85380 (10 nM) or RJR2429 (1 µM) did not modify NMDA-evoked ([(3)H]D-Asp) outflow and calcium transients.In conclusion, our results show that the GluN2A-NMDA receptor function can be positively regulated in NAc terminals in response to a brief incubation with α7 but not α4 nAChRs agonists.This might be a general feature in different brain areas since a similar nAChR-mediated bolstering of NMDA-induced ([(3)H]D-Asp) overflow was also observed in hippocampal synaptosomes.

View Article: PubMed Central - PubMed

Affiliation: Faculté de Médecine, Institut de Neurosciences des Systèmes Inserm UMR1106, Aix Marseille Université La Timone Marseille, France.

ABSTRACT
We here provide functional and immunocytochemical evidence supporting the co-localization and functional interaction between nicotinic acetylcholine receptors (nAChRs) and N-methyl-D-aspartic acid receptors (NMDARs) in glutamatergic terminals of the nucleus accumbens (NAc). Immunocytochemical studies showed that a significant percentage of NAc terminals were glutamatergic and possessed GluN1 and α7-containing nAChR. A short-term pre-exposure of synaptosomes to nicotine (30 µM) or choline (1 mM) caused a significant potentiation of the 100 µM NMDA-evoked [(3)H]D-aspartate ([(3)H]D-Asp) outflow, which was prevented by α-bungarotoxin (100 nM). The pre-exposure to nicotine (100 µM) or choline (1 mM) also enhanced the NMDA-induced cytosolic free calcium levels, as measured by FURA-2 fluorescence imaging in individual NAc terminals, an effect also prevented by α-bungarotoxin. Pre-exposure to the α4-nAChR agonists 5IA85380 (10 nM) or RJR2429 (1 µM) did not modify NMDA-evoked ([(3)H]D-Asp) outflow and calcium transients. The NMDA-evoked ([(3)H]D-Asp) overflow was partially antagonized by the NMDAR antagonists MK801, D-AP5, 5,7-DCKA and R(-)CPP and unaffected by the GluN2B-NMDAR antagonists Ro256981 and ifenprodil. Notably, pre-treatment with choline increased GluN2A biotin-tagged proteins. In conclusion, our results show that the GluN2A-NMDA receptor function can be positively regulated in NAc terminals in response to a brief incubation with α7 but not α4 nAChRs agonists. This might be a general feature in different brain areas since a similar nAChR-mediated bolstering of NMDA-induced ([(3)H]D-Asp) overflow was also observed in hippocampal synaptosomes.

No MeSH data available.


Related in: MedlinePlus

Different impact of choline (1 mM) pre-treatment on the ability of NMDAR agonists to trigger calcium transients in different individual terminals from the rat NAc. (A) Time course of FURA-2 fluorescence emission in different individual nerve terminals (terminal 1–terminal 4), which were challenged twice with NMDAR agonists (100 µM NMDA and 10 µM glycine), before and 60 s after pre-treatment with 1 mM choline. Drugs were applied for 60 s, at the end of the wash out of the previous application and the arrows identify the peaks. (B) Fluorescence image of a field of FURA- 2-labelled synaptosomes including terminals 1–4. (C) Immunocytochemical co-localization of α7-nAChR, vGLUT and GluN1 in terminal 1. (D) Average co-localization of α7-nAChR, vGLUT and GluN1 in nerve terminals from the rat NAc. Values are mean ± S.E.M of at least four experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4199379&req=5

Figure 3: Different impact of choline (1 mM) pre-treatment on the ability of NMDAR agonists to trigger calcium transients in different individual terminals from the rat NAc. (A) Time course of FURA-2 fluorescence emission in different individual nerve terminals (terminal 1–terminal 4), which were challenged twice with NMDAR agonists (100 µM NMDA and 10 µM glycine), before and 60 s after pre-treatment with 1 mM choline. Drugs were applied for 60 s, at the end of the wash out of the previous application and the arrows identify the peaks. (B) Fluorescence image of a field of FURA- 2-labelled synaptosomes including terminals 1–4. (C) Immunocytochemical co-localization of α7-nAChR, vGLUT and GluN1 in terminal 1. (D) Average co-localization of α7-nAChR, vGLUT and GluN1 in nerve terminals from the rat NAc. Values are mean ± S.E.M of at least four experiments.

Mentions: We next carried out an immunocytochemical characterization of NAc nerve endings to gauge the extent of the co-localization between α7 nAChR and NMDAR in glutamatergic nerve terminals. As shown in Figure 3, we identified individual nerve terminals (e.g., terminal 1) that were glutamatergic (vGluT1-positive) and endowed with both GluN1 and α7 subunits (Figures 3B,C), where the pre-treatment with choline (1 mM) potentiated the NMDA (100 µM)-induced calcium transient (Figure 3A). In fact, this analysis revealed that more than 40% of glutamatergic nerve terminals (vGluT1-positive) possessed GluN1 and α7 subunits (Figure 3D), thus confirming that the co-localization of NMDAR and α7 nAChR on the same glutamatergic terminal is a generalized feature in the NAc. The analysis of individual NAc terminals further revealed non-glutamatergic (vGluT1-negative) NAc terminals (e.g., terminal 2) containing both GluN1 and α7 subunits (Figures 3B,C), where choline (1 mM) failed to modify the NMDA (100 µM)-induced calcium transient (Figure 3A). We also found terminals that responded only to the α7 nAChR agonist (e.g., terminal 3 in Figure 3A) or to NMDA (e.g., terminal 4 in Figure 3A).


Nicotinic α7 receptor activation selectively potentiates the function of NMDA receptors in glutamatergic terminals of the nucleus accumbens.

Zappettini S, Grilli M, Olivero G, Chen J, Padolecchia C, Pittaluga A, Tomé AR, Cunha RA, Marchi M - Front Cell Neurosci (2014)

Different impact of choline (1 mM) pre-treatment on the ability of NMDAR agonists to trigger calcium transients in different individual terminals from the rat NAc. (A) Time course of FURA-2 fluorescence emission in different individual nerve terminals (terminal 1–terminal 4), which were challenged twice with NMDAR agonists (100 µM NMDA and 10 µM glycine), before and 60 s after pre-treatment with 1 mM choline. Drugs were applied for 60 s, at the end of the wash out of the previous application and the arrows identify the peaks. (B) Fluorescence image of a field of FURA- 2-labelled synaptosomes including terminals 1–4. (C) Immunocytochemical co-localization of α7-nAChR, vGLUT and GluN1 in terminal 1. (D) Average co-localization of α7-nAChR, vGLUT and GluN1 in nerve terminals from the rat NAc. Values are mean ± S.E.M of at least four experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4199379&req=5

Figure 3: Different impact of choline (1 mM) pre-treatment on the ability of NMDAR agonists to trigger calcium transients in different individual terminals from the rat NAc. (A) Time course of FURA-2 fluorescence emission in different individual nerve terminals (terminal 1–terminal 4), which were challenged twice with NMDAR agonists (100 µM NMDA and 10 µM glycine), before and 60 s after pre-treatment with 1 mM choline. Drugs were applied for 60 s, at the end of the wash out of the previous application and the arrows identify the peaks. (B) Fluorescence image of a field of FURA- 2-labelled synaptosomes including terminals 1–4. (C) Immunocytochemical co-localization of α7-nAChR, vGLUT and GluN1 in terminal 1. (D) Average co-localization of α7-nAChR, vGLUT and GluN1 in nerve terminals from the rat NAc. Values are mean ± S.E.M of at least four experiments.
Mentions: We next carried out an immunocytochemical characterization of NAc nerve endings to gauge the extent of the co-localization between α7 nAChR and NMDAR in glutamatergic nerve terminals. As shown in Figure 3, we identified individual nerve terminals (e.g., terminal 1) that were glutamatergic (vGluT1-positive) and endowed with both GluN1 and α7 subunits (Figures 3B,C), where the pre-treatment with choline (1 mM) potentiated the NMDA (100 µM)-induced calcium transient (Figure 3A). In fact, this analysis revealed that more than 40% of glutamatergic nerve terminals (vGluT1-positive) possessed GluN1 and α7 subunits (Figure 3D), thus confirming that the co-localization of NMDAR and α7 nAChR on the same glutamatergic terminal is a generalized feature in the NAc. The analysis of individual NAc terminals further revealed non-glutamatergic (vGluT1-negative) NAc terminals (e.g., terminal 2) containing both GluN1 and α7 subunits (Figures 3B,C), where choline (1 mM) failed to modify the NMDA (100 µM)-induced calcium transient (Figure 3A). We also found terminals that responded only to the α7 nAChR agonist (e.g., terminal 3 in Figure 3A) or to NMDA (e.g., terminal 4 in Figure 3A).

Bottom Line: Pre-exposure to the α4-nAChR agonists 5IA85380 (10 nM) or RJR2429 (1 µM) did not modify NMDA-evoked ([(3)H]D-Asp) outflow and calcium transients.In conclusion, our results show that the GluN2A-NMDA receptor function can be positively regulated in NAc terminals in response to a brief incubation with α7 but not α4 nAChRs agonists.This might be a general feature in different brain areas since a similar nAChR-mediated bolstering of NMDA-induced ([(3)H]D-Asp) overflow was also observed in hippocampal synaptosomes.

View Article: PubMed Central - PubMed

Affiliation: Faculté de Médecine, Institut de Neurosciences des Systèmes Inserm UMR1106, Aix Marseille Université La Timone Marseille, France.

ABSTRACT
We here provide functional and immunocytochemical evidence supporting the co-localization and functional interaction between nicotinic acetylcholine receptors (nAChRs) and N-methyl-D-aspartic acid receptors (NMDARs) in glutamatergic terminals of the nucleus accumbens (NAc). Immunocytochemical studies showed that a significant percentage of NAc terminals were glutamatergic and possessed GluN1 and α7-containing nAChR. A short-term pre-exposure of synaptosomes to nicotine (30 µM) or choline (1 mM) caused a significant potentiation of the 100 µM NMDA-evoked [(3)H]D-aspartate ([(3)H]D-Asp) outflow, which was prevented by α-bungarotoxin (100 nM). The pre-exposure to nicotine (100 µM) or choline (1 mM) also enhanced the NMDA-induced cytosolic free calcium levels, as measured by FURA-2 fluorescence imaging in individual NAc terminals, an effect also prevented by α-bungarotoxin. Pre-exposure to the α4-nAChR agonists 5IA85380 (10 nM) or RJR2429 (1 µM) did not modify NMDA-evoked ([(3)H]D-Asp) outflow and calcium transients. The NMDA-evoked ([(3)H]D-Asp) overflow was partially antagonized by the NMDAR antagonists MK801, D-AP5, 5,7-DCKA and R(-)CPP and unaffected by the GluN2B-NMDAR antagonists Ro256981 and ifenprodil. Notably, pre-treatment with choline increased GluN2A biotin-tagged proteins. In conclusion, our results show that the GluN2A-NMDA receptor function can be positively regulated in NAc terminals in response to a brief incubation with α7 but not α4 nAChRs agonists. This might be a general feature in different brain areas since a similar nAChR-mediated bolstering of NMDA-induced ([(3)H]D-Asp) overflow was also observed in hippocampal synaptosomes.

No MeSH data available.


Related in: MedlinePlus