AMPA Induces NO-Dependent cGMP Signals in Hippocampal and Cortical Neurons via L-Type Voltage-Gated Calcium Channels

Abstract

The nitric oxide (NO)/cGMP signaling cascade has an established role in synaptic plasticity. However, with conventional methods, the underlying cGMP signals were barely detectable. Here, we set out to confirm the well-known NMDA-induced cGMP increases, to test the impact of AMPA on those signals, and to identify the relevant phosphodiesterases (PDEs) using a more sensitive fluorescence resonance energy transfer (FRET)-based method. Therefore, a “knock-in” mouse was generated that expresses a FRET-based cGMP indicator (cGi-500) allowing detection of cGMP concentrations between 100 nM and 3 μM. Measurements were performed in cultured hippocampal and cortical neurons as well as acute hippocampal slices. In hippocampal and cortical neurons, NMDA elicited cGMP signals half as high as the ones elicited by exogenous NO. Interestingly, AMPA increased cGMP independently of NMDA receptors and dependent on NO synthase (NOS) activation. NMDA- and AMPA-induced cGMP signals were not additive indicating that both pathways converge on the level of NOS. Accordingly, the same PDEs, PDE1 and PDE2, were responsible for degradation of NMDA- as well as AMPA-induced cGMP signals. Mechanistically, AMPAR induced calcium influx through L-type voltage-gated calcium channels leading to NOS and finally NO-sensitive guanylyl cyclase activation. Our results demonstrate that in addition to NMDA also AMPA triggers endogenous NO formation and hence cGMP production.

Modulation of AMPA Receptors by Nitric Oxide in Nerve Cells

“…The latter was demonstrated by using transgenic mice ubiquitously expressing a Förster resonance energy transfer (FRET)-based cGMP indicator to analyze the cGMP responses induced by NO or glutamatergic agonists in cultured hippocampal and cortical neurons. In this study, besides the well-established NMDA-induced cGMP responses, the glutamatergic agonist AMPA independently elicited cGMP signals in hippocampal and cortical neurons by triggering L-type VGCC-dependent Ca 2+ influx [122]. This finding is consistent with previous studies demonstrating that nNOS can be activated by Ca 2+ influx through VDCCs [123] and CP-AMPARs [124].…”

“…Moreover, the blockade of calcium-permeable AMPARs with PhTx-433 reduced the NO production [121], which directly indicates the dependence of NOS on free calcium ions entering not only through the NMDA channels but also through the calcium-permeable AMPARs. This AMPAR-induced calcium influx probably occurs through L-type voltage-gated calcium channels (VDCC) [122]. The latter was demonstrated by using transgenic mice ubiquitously expressing a Förster resonance energy transfer (FRET)-based cGMP indicator to analyze the cGMP responses induced by NO or glutamatergic agonists in cultured hippocampal and cortical neurons.…”

“…Since both NO and AMPARs are involved in multiple aspects of cell life, it is hardly surprising that the relationships between these two molecules have been observed during different physiological and pathophysiological states, such as plasticity [122,125], excitotoxicity [124], hypoxia [162], the effect of cocaine [92,97], inflammation [148], and so on. To conclude, in this review, we demonstrated that two important factors involved in a broad range of cellular mechanisms-NO and AMPARs-are closely interconnected in various aspects of neuronal functioning.…”

IL-17 crosses the blood–brain barrier to trigger neuroinflammation: a novel mechanism in nitroglycerin-induced chronic migraine

“…Nitric oxide (NO), a small gaseous signaling molecule, and its metabolites are widely accepted as important mediators of neurogenic inflammation and neuroinflammation involved in migraine, and these processes are mainly mediated by the NO-cGMP pathways, glutamatergic pathway and NF-κB pathway. Therefore, NTG, a NO-donating agent, has been recognized as a translational model that has been strongly implicated in the pathological mechanisms of migraine [22]. In human subjects, NTG-induced migraine is associated with an increase in the plasma CGRP concentration [27]; increased levels of CGRP, SP and PACAP were also reported in the plasma of rodents treated systemically with NTG [7,26,29].…”

“…Abundant reports have indicated that neurogenic inflammation caused by NTG-induced neural activation leads to migraine-like behavior and an increased sensitivity to pain in an NTG model. NO released from NTG initiate a rather slow process that likely involves the activation of the trigeminovascular system in the dura mater and the subsequent activation of trigeminal fibers and the trigeminal nucleus caudalis (TNC) [22]. Furthermore, the NTG-induced increase in NOS activity is implicated in higher basal CGRP levels and might activate the exudation of blood material synergistically, leading to neurogenic inflammation involving the NF-κB pathway [33,54].…”