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Endocannabinoids Mediate Muscarinic Acetylcholine Receptor-Dependent Long-Term Depression in the Adult Medial Prefrontal Cortex.

Martin HG, Bernabeu A, Lassalle O, Bouille C, Beurrier C, Pelissier-Alicot AL, Manzoni OJ - Front Cell Neurosci (2015)

Bottom Line: Cholinergic inputs into the prefrontal cortex (PFC) are associated with attention and cognition; however there is evidence that acetylcholine also has a role in PFC dependent learning and memory.Yet, when endogenous acetylcholine was released from local cholinergic afferents in the PFC using optogenetics, it failed to trigger eCB-LTD.Together these results shed new light on the mechanisms of synaptic plasticity in the adult PFC and expand on the actions of endogenous cholinergic signaling.

View Article: PubMed Central - PubMed

Affiliation: Aix-Marseille Université Marseille, France ; Institut de Neurobiologie de la Méditerranée UMR_S 901 Marseille, France ; INMED UMR_S 901 Marseille, France.

ABSTRACT
Cholinergic inputs into the prefrontal cortex (PFC) are associated with attention and cognition; however there is evidence that acetylcholine also has a role in PFC dependent learning and memory. Muscarinic acetylcholine receptors (mAChR) in the PFC can induce synaptic plasticity, but the underlying mechanisms remain either opaque or unresolved. We have characterized a form of mAChR mediated long-term depression (LTD) at glutamatergic synapses of layer 5 principal neurons in the adult medial PFC. This mAChR LTD is induced with the mAChR agonist carbachol and inhibited by selective M1 mAChR antagonists. In contrast to other cortical regions, we find that this M1 mAChR mediated LTD is coupled to endogenous cannabinoid (eCB) signaling. Inhibition of the principal eCB CB1 receptor blocked carbachol induced LTD in both rats and mice. Furthermore, when challenged with a sub-threshold carbachol application, LTD was induced in slices pretreated with the monoacylglycerol lipase (MAGL) inhibitor JZL184, suggesting that the eCB 2-arachidonylglyerol (2-AG) mediates M1 mAChR LTD. Yet, when endogenous acetylcholine was released from local cholinergic afferents in the PFC using optogenetics, it failed to trigger eCB-LTD. However coupling patterned optical and electrical stimulation to generate local synaptic signaling allowed the reliable induction of LTD. The light-electrical pairing induced LTD was M1 mAChR and CB1 receptor mediated. This shows for the first time that connecting excitatory synaptic activity with coincident endogenously released acetylcholine controls synaptic gain via eCB signaling. Together these results shed new light on the mechanisms of synaptic plasticity in the adult PFC and expand on the actions of endogenous cholinergic signaling.

No MeSH data available.


Related in: MedlinePlus

Adult mice show M1 mAChR dependent LTD in mPFC mediated by CB1R. (A) Time course of normalized field EPSPs in response to acute carbachol (10 μM, 10 min) stimulation in presence of M1 mAChR antagonist pirenzepine (0.5 μM, n = 6; control, n = 14). (B) Individual experiments (gray) and group average, pre (baseline) and post (40 min washout) carbachol treatment (**P < 0.01). Below, example traces pre (black) and post (orange) carbachol treatment (scale bar: 5 ms, 0.1 mV). (C) Similar plot with highly selective M1 mAChR antagonist VU0255035 treated group before (Pre) and after (Post) carbachol challenge; group averages in red (10 μM, n = 4). Below, example traces. (D) Time course showing normalized field EPSPs in response to carbachol stimulation in presence of CB1R antagonist AM251 (4 μM, n = 6). (E) Before-after carbachol challenge plot of individual experiments in presence of AM251, group average in green. Below, example traces. (F) Summary bar chart of percent LTD 40 min after carbachol washout (*P < 0.05).
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Figure 4: Adult mice show M1 mAChR dependent LTD in mPFC mediated by CB1R. (A) Time course of normalized field EPSPs in response to acute carbachol (10 μM, 10 min) stimulation in presence of M1 mAChR antagonist pirenzepine (0.5 μM, n = 6; control, n = 14). (B) Individual experiments (gray) and group average, pre (baseline) and post (40 min washout) carbachol treatment (**P < 0.01). Below, example traces pre (black) and post (orange) carbachol treatment (scale bar: 5 ms, 0.1 mV). (C) Similar plot with highly selective M1 mAChR antagonist VU0255035 treated group before (Pre) and after (Post) carbachol challenge; group averages in red (10 μM, n = 4). Below, example traces. (D) Time course showing normalized field EPSPs in response to carbachol stimulation in presence of CB1R antagonist AM251 (4 μM, n = 6). (E) Before-after carbachol challenge plot of individual experiments in presence of AM251, group average in green. Below, example traces. (F) Summary bar chart of percent LTD 40 min after carbachol washout (*P < 0.05).

Mentions: Our findings and those of others suggest that M1 mAChR mediated LTD is a robust phenomenon found throughout development in the rat mPFC. However it is unclear if these findings can be generalized, especially in light of reported interspecies differences in cholinergic innervation and AChR synaptic modulation (Gil et al., 1997; Van der Zee and Keijser, 2011). Therefore we repeated our LTD experiments in the adult mouse mPFC. Recording layer 5 field potentials we challenged mPFC neurons with an identical 10 min carbachol (10 μM) protocol. Similar to the rat, carbachol induced a strong acute depression of field EPSPs, that after washout remain depressed and was absent in the presence of M1 mAChR antagonist pirenzepine (Figure 4A). Compared to baseline responses were significantly depressed 40 min after carbachol washout (86.1 ± 3.6%; t(12) = 4.34, P = 0.001; Figure 4B). Furthermore in the presence of the highly selective M1 muscarinic receptor antagonist VU 0255,035 carbachol induced depression was also absent. Plotting individual experiments before and 40 min after carbachol washout in the presence of VU 0255,035, average responses were not different to baseline values (Figure 4C; 103.6 ± 2.6%, n = 4). Furthermore, compared to control experiments VU0255035 significantly interacted with the carbachol induced LTD (two-way repeat measure ANOVA F(1,15) = 8.93, P = 0.009), due to an inhibition of the carbachol induced LTD (P < 0.01, Holm-Sidak’s multiple comparisons test). Thus a M1 mAChR mediated LTD is also found in the adult mouse mPFC.


Endocannabinoids Mediate Muscarinic Acetylcholine Receptor-Dependent Long-Term Depression in the Adult Medial Prefrontal Cortex.

Martin HG, Bernabeu A, Lassalle O, Bouille C, Beurrier C, Pelissier-Alicot AL, Manzoni OJ - Front Cell Neurosci (2015)

Adult mice show M1 mAChR dependent LTD in mPFC mediated by CB1R. (A) Time course of normalized field EPSPs in response to acute carbachol (10 μM, 10 min) stimulation in presence of M1 mAChR antagonist pirenzepine (0.5 μM, n = 6; control, n = 14). (B) Individual experiments (gray) and group average, pre (baseline) and post (40 min washout) carbachol treatment (**P < 0.01). Below, example traces pre (black) and post (orange) carbachol treatment (scale bar: 5 ms, 0.1 mV). (C) Similar plot with highly selective M1 mAChR antagonist VU0255035 treated group before (Pre) and after (Post) carbachol challenge; group averages in red (10 μM, n = 4). Below, example traces. (D) Time course showing normalized field EPSPs in response to carbachol stimulation in presence of CB1R antagonist AM251 (4 μM, n = 6). (E) Before-after carbachol challenge plot of individual experiments in presence of AM251, group average in green. Below, example traces. (F) Summary bar chart of percent LTD 40 min after carbachol washout (*P < 0.05).
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Figure 4: Adult mice show M1 mAChR dependent LTD in mPFC mediated by CB1R. (A) Time course of normalized field EPSPs in response to acute carbachol (10 μM, 10 min) stimulation in presence of M1 mAChR antagonist pirenzepine (0.5 μM, n = 6; control, n = 14). (B) Individual experiments (gray) and group average, pre (baseline) and post (40 min washout) carbachol treatment (**P < 0.01). Below, example traces pre (black) and post (orange) carbachol treatment (scale bar: 5 ms, 0.1 mV). (C) Similar plot with highly selective M1 mAChR antagonist VU0255035 treated group before (Pre) and after (Post) carbachol challenge; group averages in red (10 μM, n = 4). Below, example traces. (D) Time course showing normalized field EPSPs in response to carbachol stimulation in presence of CB1R antagonist AM251 (4 μM, n = 6). (E) Before-after carbachol challenge plot of individual experiments in presence of AM251, group average in green. Below, example traces. (F) Summary bar chart of percent LTD 40 min after carbachol washout (*P < 0.05).
Mentions: Our findings and those of others suggest that M1 mAChR mediated LTD is a robust phenomenon found throughout development in the rat mPFC. However it is unclear if these findings can be generalized, especially in light of reported interspecies differences in cholinergic innervation and AChR synaptic modulation (Gil et al., 1997; Van der Zee and Keijser, 2011). Therefore we repeated our LTD experiments in the adult mouse mPFC. Recording layer 5 field potentials we challenged mPFC neurons with an identical 10 min carbachol (10 μM) protocol. Similar to the rat, carbachol induced a strong acute depression of field EPSPs, that after washout remain depressed and was absent in the presence of M1 mAChR antagonist pirenzepine (Figure 4A). Compared to baseline responses were significantly depressed 40 min after carbachol washout (86.1 ± 3.6%; t(12) = 4.34, P = 0.001; Figure 4B). Furthermore in the presence of the highly selective M1 muscarinic receptor antagonist VU 0255,035 carbachol induced depression was also absent. Plotting individual experiments before and 40 min after carbachol washout in the presence of VU 0255,035, average responses were not different to baseline values (Figure 4C; 103.6 ± 2.6%, n = 4). Furthermore, compared to control experiments VU0255035 significantly interacted with the carbachol induced LTD (two-way repeat measure ANOVA F(1,15) = 8.93, P = 0.009), due to an inhibition of the carbachol induced LTD (P < 0.01, Holm-Sidak’s multiple comparisons test). Thus a M1 mAChR mediated LTD is also found in the adult mouse mPFC.

Bottom Line: Cholinergic inputs into the prefrontal cortex (PFC) are associated with attention and cognition; however there is evidence that acetylcholine also has a role in PFC dependent learning and memory.Yet, when endogenous acetylcholine was released from local cholinergic afferents in the PFC using optogenetics, it failed to trigger eCB-LTD.Together these results shed new light on the mechanisms of synaptic plasticity in the adult PFC and expand on the actions of endogenous cholinergic signaling.

View Article: PubMed Central - PubMed

Affiliation: Aix-Marseille Université Marseille, France ; Institut de Neurobiologie de la Méditerranée UMR_S 901 Marseille, France ; INMED UMR_S 901 Marseille, France.

ABSTRACT
Cholinergic inputs into the prefrontal cortex (PFC) are associated with attention and cognition; however there is evidence that acetylcholine also has a role in PFC dependent learning and memory. Muscarinic acetylcholine receptors (mAChR) in the PFC can induce synaptic plasticity, but the underlying mechanisms remain either opaque or unresolved. We have characterized a form of mAChR mediated long-term depression (LTD) at glutamatergic synapses of layer 5 principal neurons in the adult medial PFC. This mAChR LTD is induced with the mAChR agonist carbachol and inhibited by selective M1 mAChR antagonists. In contrast to other cortical regions, we find that this M1 mAChR mediated LTD is coupled to endogenous cannabinoid (eCB) signaling. Inhibition of the principal eCB CB1 receptor blocked carbachol induced LTD in both rats and mice. Furthermore, when challenged with a sub-threshold carbachol application, LTD was induced in slices pretreated with the monoacylglycerol lipase (MAGL) inhibitor JZL184, suggesting that the eCB 2-arachidonylglyerol (2-AG) mediates M1 mAChR LTD. Yet, when endogenous acetylcholine was released from local cholinergic afferents in the PFC using optogenetics, it failed to trigger eCB-LTD. However coupling patterned optical and electrical stimulation to generate local synaptic signaling allowed the reliable induction of LTD. The light-electrical pairing induced LTD was M1 mAChR and CB1 receptor mediated. This shows for the first time that connecting excitatory synaptic activity with coincident endogenously released acetylcholine controls synaptic gain via eCB signaling. Together these results shed new light on the mechanisms of synaptic plasticity in the adult PFC and expand on the actions of endogenous cholinergic signaling.

No MeSH data available.


Related in: MedlinePlus