IL-17 triggers the onset of cognitive and synaptic deficits in early stages of Alzheimer’s disease

© 2021 The Author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Neuroinflammation in patients with Alzheimer's disease (AD) and related mouse models has been recognized for decades, but the contribution of the recently described meningeal immune population to AD pathogenesis remains to be addressed. Here, using the 3xTg-AD model, we report an accumulation of interleukin-17 (IL-17)-producing cells, mostly γδ T cells, in the brain and the meninges of female, but not male, mice, concomitant with the onset of cognitive decline. Critically, IL-17 neutralization into the ventricles is sufficient to prevent short-term memory and synaptic plasticity deficits at early stages of disease. These effects precede blood-brain barrier disruption and amyloid-beta or tau pathology, implying an early involvement of IL-17 in AD pathology. When IL-17 is neutralized at later stages of disease, the onset of short-memory deficits and amyloidosis-related splenomegaly is delayed. Altogether, our data support the idea that cognition relies on a finely regulated balance of "inflammatory" cytokines derived from the meningeal immune system.This work was funded by the Fundação para a Ciência e Tecnologia (IF/00013/2014, LISBOA-01-0145-FEDER-028241, and PTDC/MED-IMU/1988/2020) to J.C.R., Santa Casa da Misericórdia (MB-7-2018) and Fundacão para a Ciência e Tecnologia (PTDC/BIM-MEC/4778/2014 and IF/00105/2012) to L.V.L., and PD/BD/114103/2015 to H.C.B. The ORCIDs for this article are as follows: 0000-0001-8367-3005 (L.V.L.) and 0000-0002-7852-343X (J.C.R.).info:eu-repo/semantics/publishedVersio

Triggering of BDNF facilitatory action on neuromuscular transmission by adenosine A2A receptors

© 2006 ElsevierMotor nerve terminals possess adenosine A2A receptors and brain derived neurotrophic factor (BDNF) TrkB receptors. In the present work we evaluated how BDNF actions on neuromuscular transmission would be influenced by adenosine A2A receptors activation. BDNF (20–100 ng/ml)on its own was devoid of effect on evoked endplate potentials (EPPs) recorded intracellularly from rat innervated diaphragms paralysed with tubocurarine. However, when BDNF was applied 45 min after a brief (2 min) depolarizing KCl (10 mM) pulse or when the adenosine A2A receptors were activated with CGS 21680 (10 nM), BDNF (20 ng/ml) increased EPPs amplitude without influencing the resting membrane potential of the muscle fibre. The action of BDNF was prevented by the adenosine A2A receptor antagonist, ZM 241385 (50 nM) as well as by the TrkB receptor phosphorylation inhibitor, K252a (200 nM). The PKA inhibitor, H-89 (1 μM), prevented the excitatory effect of CGS 21680 (10 nM) on EPPs as well as prevented its ability to trigger a BDNF effect. The PLCγ inhibitor, U73122 (5 μM), did not prevent the excitatory action of CGS 21680 (10 nM) on neuromuscular transmission, but abolished the action of BDNF in the presence of the A2A receptor agonist. The results suggest the following sequence of events in what concerns cooperativity between A2A receptors and TrkB receptors at the neuromuscular junction: A2A receptor activates the PKA pathway, which promotes the action of BDNF through TrkB receptors coupled to PLCγ, leading to enhancement of neuromuscular transmission.Work supported by Fundação para a Ciência e Tecnologia (FCT), Portuga

The giant miniature endplate potentials frequency is increased in aged rats

© 2014 Elsevier Ireland Ltd. All rights reserved.At the neuromuscular junction, spontaneous giant events (GMEPPs) are enhanced in different conditions when degenerative and/or remodeling processes take place, but no one investigated their incidence upon aging. In the present work, we evaluated evoked and spontaneous neuromuscular transmission events recorded from single muscle fibers. Phrenic-diaphragm preparations of 3-4, 12-16, 36-40 and 70-80 weeks old rat males were used. We found that the occurrence of GMEPPs significantly increases in aged rats. Moreover, in old rats the neuromuscular transmission was significantly impaired due to a significant decrease in the amplitude and quantal content of evoked endplate potentials. Interestingly, the number of observed EPPs failures were ∼ 3 times lower than the predicted value based on the quantal content. This discrepancy was not observed in infant or adult rats. The coincidence of a high GMEPPs frequency with a lower than expected EPPs failure rate suggests that GMEPPs events are needed to preserve effective neuromuscular transmission in aged animals.This work was supported by Fundação do Ministério da Ciência e Tecnologia de Portugal and European Union [Grant NEREPLAS, COST B30]. P.A.P. was the recipient of a Fundação do Ministério de Ciência e Tecnologia de Portugal fellowship [Grant SFRH/BD/28073/2006].info:eu-repo/semantics/publishedVersio

Adenosine A2A receptors activation facilitates neuromuscular transmission in the pre-symptomatic phase of the SOD1(G93A) ALS mice, but not in the symptomatic phase.

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease leading to motor neuron dysfunction resulting in impairment of neuromuscular transmission. A2A adenosine receptors have already been considered as a potential therapeutical target for ALS but their neuromodulatory role at the neuromuscular junction in ALS remains to be clarified. In the present work, we evaluated the effects of A2A receptors on neuromuscular transmission of an animal model of ALS: SOD1(G93A) mice either in the pre-symptomatic (4-6 weeks old) or in the symptomatic (12-14 weeks old) stage. Electrophysiological experiments were performed obtaining intracellular recordings in Mg2+ paralyzed phrenic nerve-hemidiaphragm preparations. Endplate potentials (EPPs), quantal content (q. c.) of EPPs, miniature endplate potentials (MEPPs) and giant miniature endplate potential (GMEPPs) were recorded. In the pre-symptomatic phase of the disease (4-6 weeks old mice), the selective A2A receptor agonist, CGS 21680, significantly enhanced (p<0.05 Unpaired t-test) the mean amplitude and q.c. of EPPs, and the frequency of MEPPs and GMEPPs at SOD1(G93A) neuromuscular junctions, the effect being of higher magnitude (p<0.05, Unpaired t-test) than age-matched control littermates. On the contrary, in symptomatic mice (12-14 weeks old), CGS 21680 was devoid of effect on both the amplitude and q.c. of EPPs and the frequency of MEPPs and GMEPPs (p<0.05 Paired t-test). The results herein reported clearly document that at the neuromuscular junction of SOD1(G93A) mice there is an exacerbation of A2A receptor-mediated excitatory effects at the pre-symptomatic phase, whereas in the symptomatic phase A2A receptor activation is absent. The results thus suggest that A2A receptors function changes with ALS progression

Neuromuscular transmission modulation by adenosine upon aging

© 2012 Elsevier Inc. All rights reserved.In infant rats adenosine A2A receptor-mediated modulation of neuromuscular transmission predominates over A1 receptor-mediated neuromodulation.We investigated whether aging affects this A2A/A1 receptor balance. Evoked (EPPs) and miniature end plate potentials(MEPPs) were recorded from single fibers of (weeks-old) infant (3– 4), young adult (12–16), older (36 –38),and aged (80 –90) male rat-diaphragm. The non A1/A2A selective agonist, 2-chloroadenosine (CADO; 30 nM) and the adenosine kinase inhibitor, iodotubericidin (ITU; 10 M) increased mean amplitude and quantal content of EPPs in infant, young adult, and older adult rats, but not in aged rats. The facilitatory effects were prevented by the A2A receptor antagonist,ZM241385 (50 nM) and mimicked by the A2A receptor agonist,CGS21680 (10 nM). The A1 receptor agonist, 6-cyclopentyladenosine (CPA; 100 nM), decreased EPPs amplitude in all age groups. It is concluded that aging differently influences adenosine A1 receptor and A2A receptor-mediated presynaptic modulation of neuromuscular transmission, so that the facilitatory influence decreases upon aging, whereas the inhibitory influence remains unchanged in aged animals. The reduction of adenosine A2A receptors upon aging may contribute to the age-related changes in neuromuscular function.This work was supported by Fundação para a Ciência e a Tecnologia (FCT), Portugal and European Union (Grant NEREPLAS, COST B30)

APP fragment controls both ionotropic and non-ionotropic signaling of NMDA receptors

NMDA receptors (NMDARs) are ionotropic receptors crucial for brain information processing. Yet, evidence also supports an ion-flux-independent signaling mode mediating synaptic long-term depression (LTD) and spine shrinkage. Here, we identify AETA (Aη), an amyloid-β precursor protein (APP) cleavage product, as an NMDAR modulator with the unique dual regulatory capacity to impact both signaling modes. AETA inhibits ionotropic NMDAR activity by competing with the co-agonist and induces an intracellular conformational modification of GluN1 subunits. This favors non-ionotropic NMDAR signaling leading to enhanced LTD and favors spine shrinkage. Endogenously, AETA production is increased by in vivo chemogenetically induced neuronal activity. Genetic deletion of AETA production alters NMDAR transmission and prevents LTD, phenotypes rescued by acute exogenous AETA application. This genetic deletion also impairs contextual fear memory. Our findings demonstrate AETA-dependent NMDAR activation (ADNA), characterizing AETA as a unique type of endogenous NMDAR modulator that exerts bidirectional control over NMDAR signaling and associated information processing

The neuromuscular transmission of the SOD1(G93A) mice in the pre-symptomatic phase of the disease.

<p>A) Illustrates raw recordings of 5 EPPs from 4–6 week-old WT and pre-symptomatic SOD1(G93A) mice. B) Shows the frequency histogram of MEPPs amplitudes, which pools the amplitude of all MEPPs recorded at WT (2785 MEPPs) and SOD1(G93A) (2270 MEPPs) fibers. WT – Black bars; SOD1(G93A) – Gray bars. C) Presents the nonlinear regression applied to WT and SOD1(G93A) distributions. As illustrated, both distributions were best fitted with a Gaussian function. In D) are shown examples of a MEPP (<1mV) and a GMEPP (>1mV) and in E) examples of spontaneous events recorded in gap free mode across 10s in WT and SOD1(G93A) neuromuscular junctions.</p

The neuromuscular transmission of the SOD1(G93A) mice in the symptomatic phase of the disease.

<p>A) Illustrates raw recordings of 5 EPPs from adult WT mice and the two groups of symptomatic SOD1(G93A) neuromuscular junctions, SOD1a and SOD1b. B) Shows the frequency histogram of MEPPs amplitudes, that pools the amplitude of all MEPPs recorded at WT (2288 events) and SOD1(G93A) (3674 events) fibers. WT – Black bars; SOD1(G93A) – Gray bars. C) Shows the nonlinear regressions that best shape WT (Gaussian function) and SOD1(G93A) (sum of two Gaussians) data As illustrated, SOD1(G93A) data follows a bimodal distribution with two peak amplitudes, pointing to the existence of 2 groups of neuromuscular junctions. D) After categorizing the two groups, the distributions of MEPPs amplitudes from SOD1a and SOD1b groups were drawn and best-fitted with Gaussian functions. As it is visible, the peak amplitude from both distributions matches the two peak amplitudes from the bimodal curve, validating the grouping. E) Shows examples of spontaneous events recorded in gap free mode across 10s in WT, SOD1a and SOD1b neuromuscular junctions.</p

A_2A receptor modulation is lost in symptomatic SOD1(G93A) mice endplates; (A) representative average time-course of mean EPP amplitude change during CGS 21680 (5 nM) bathing and (B) illustrative mean EPP profile facilitation in 12–14 weeks old control (n = 6) and symptomatic mice (n = 6); (C) dose-response alterations in mean EPP amplitude by CGS 21680 (3 nM: n = 8, WT, n = 10, SOD1G93A; 5 nM: n = 10, WT, n = 7, SOD1G93A; 10 nM: n = 11, WT, n = 7, SOD1G93A) were blocked by SCH 58261 at 50 nM in WT mice (n = 4, WT, n = 4, SOD1G93A); (D) SCH 58261 (50 nM) did not affect evoked activity throughout data acquisition (n = 4, WT, n = 7, SOD1G93A); (E) raw recording of spontaneous release variations from a 12–14 weeks old WT and symptomatic SOD1G93A endplate upon CGS 21680 (5 nM) perfusion; effect of A_2A receptor activation by CGS 21680 (5 nM) on (F) MEPP frequency (n = 6, WT, n = 5, SOD1(G93A)) (G) GMEPP frequency (n = 4, WT, n = 4, SOD1(G93A)) and (H) quantal content of

<p>A_2A receptor modulation is lost in symptomatic SOD1(G93A) mice endplates; (A) representative average time-course of mean EPP amplitude change during CGS 21680 (5 nM) bathing and (B) illustrative mean EPP profile facilitation in 12–14 weeks old control (n = 6) and symptomatic mice (n = 6); (C) dose-response alterations in mean EPP amplitude by CGS 21680 (3 nM: n = 8, WT, n = 10, SOD1G93A; 5 nM: n = 10, WT, n = 7, SOD1G93A; 10 nM: n = 11, WT, n = 7, SOD1G93A) were blocked by SCH 58261 at 50 nM in WT mice (n = 4, WT, n = 4, SOD1G93A); (D) SCH 58261 (50 nM) did not affect evoked activity throughout data acquisition (n = 4, WT, n = 7, SOD1G93A); (E) raw recording of spontaneous release variations from a 12–14 weeks old WT and symptomatic SOD1G93A endplate upon CGS 21680 (5 nM) perfusion; effect of A_2A receptor activation by CGS 21680 (5 nM) on (F) MEPP frequency (n = 6, WT, n = 5, SOD1(G93A)) (G) GMEPP frequency (n = 4, WT, n = 4, SOD1(G93A)) and (H) quantal content of EPPs (n = 9, WT, n = 7, SOD1(G93A)); *p<0.05 Unpaired <i>t</i>-test; ^∂p<0.05 one-way ANOVA with Tukey’s pos-hoc; ^#p<0.05 Paired <i>t</i>-test (as compared with control value before drug perfusion); control corresponds to 100% in all cases.</p

Comparison of A_2A receptor function upon disease progression in SOD1(G93A) mice and healthy controls; average time course of mean EPP amplitude facilitation by CGS 21680 (5 nM) in (A) pre-(n = 10) and symptomatic (n = 6) SOD1(G93A) rodents and (B) 4–6 weeks (n = 5) and 12–14 weeks (n = 6) old WT mice; effect of CGS 21680 perfusion at 5 nM on: (C) quantal content of EPPs (4–6 weeks old: n = 13, WT, n = 12, SOD1(G93A); 12–14 weeks old: n = 9, WT, n = 7, SOD1(G93A)); (D) MEPP frequency (4–6 weeks old: n = 10, WT, n = 9, SOD1(G93A); 12–14 weeks old: n = 6, WT, n = 5, SOD1(G93A)); and (E) GMEPP frequency (4–6 weeks old: n = 10, WT, n = 11, SOD1(G93A); 12–14 weeks old: n = 4, WT, n = 4, SOD1(G93A)) in both phases of the study from SOD1(G93A) mice and respective healthy controls; *p<0.05 Unpaired <i>t</i>-test; ^∂p<0.05 one-way ANOVA with Tukey’s pos-hoc; ^#p<0.05 Paired <i>t</i>-test (as compared with control value before drug perfusion); control corresponds to

<p>Comparison of A_2A receptor function upon disease progression in SOD1(G93A) mice and healthy controls; average time course of mean EPP amplitude facilitation by CGS 21680 (5 nM) in (A) pre-(n = 10) and symptomatic (n = 6) SOD1(G93A) rodents and (B) 4–6 weeks (n = 5) and 12–14 weeks (n = 6) old WT mice; effect of CGS 21680 perfusion at 5 nM on: (C) quantal content of EPPs (4–6 weeks old: n = 13, WT, n = 12, SOD1(G93A); 12–14 weeks old: n = 9, WT, n = 7, SOD1(G93A)); (D) MEPP frequency (4–6 weeks old: n = 10, WT, n = 9, SOD1(G93A); 12–14 weeks old: n = 6, WT, n = 5, SOD1(G93A)); and (E) GMEPP frequency (4–6 weeks old: n = 10, WT, n = 11, SOD1(G93A); 12–14 weeks old: n = 4, WT, n = 4, SOD1(G93A)) in both phases of the study from SOD1(G93A) mice and respective healthy controls; *p<0.05 Unpaired <i>t</i>-test; ^∂p<0.05 one-way ANOVA with Tukey’s pos-hoc; ^#p<0.05 Paired <i>t</i>-test (as compared with control value before drug perfusion); control corresponds to 100% in all cases.</p