Signalisation Fonctionnelle des Canaux Ioniques et Récepteurs

Background: An ENDO-European Reference Network (ERN) initiative was launched that was endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology with 22 participants from the ENDO-ERN and the two societies. The aim was to update the practice guidelines for the diagnosis and management of congenital hypothyroidism (CH). A systematic literature search was conducted to identify key articles on neonatal screening, diagnosis, and management of primary and central CH. The evidence-based guidelines were graded with the Grading of Recommendations, Assessment, Development and Evaluation system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. Summary: The recommendations include the various neonatal screening approaches for CH as well as the etiology (also genetics), diagnostics, treatment, and prognosis of both primary and central CH. When CH is diagnosed, the expert panel recommends the immediate start of correctly dosed levothyroxine treatment and frequent follow-up including laboratory testing to keep thyroid hormone levels in their target ranges, timely assessment of the need to continue treatment, attention for neurodevelopment and neurosensory functions, and, if necessary, consulting other health professionals, and education of the child and family about CH. Harmonization of diagnostics, treatment, and follow-up will optimize patient outcomes. Lastly, all individuals with CH are entitled to a well-planned transition of care from pediatrics to adult medicine. Conclusions: This consensus guidelines update should be used to further optimize detection, diagnosis, treatment, and follow-up of children with all forms of CH in the light of the most recent evidence. It should be helpful in convincing health authorities of the benefits of neonatal screening for CH. Further epidemiological and experimental studies are needed to understand the increased incidence of this condition.

In this paper, we present an updated classification of the ubiquitous MIP (Major Intrinsic Protein) family proteins, including 153 fully or partially sequenced members available in public databases. Presently, about 30 of these proteins have been functionally characterized, exhibiting essentially two distinct types of channel properties: (1) specific water transport by the aquaporins, and (2) small neutral solutes transport, such as glycerol by the glycerol facilitators. Sequence alignments were used to predict amino acids and motifs discriminant in channel specificity. The protein sequences were also analyzed using statistical tools (comparisons of means and correspondence analysis). Five key positions were clearly identified where the residues are specific for each functional subgroup and exhibit high dissimilar physico-chemical properties. Moreover, we have found that the putative channels for small neutral solutes clearly differ from the aquaporins by the amino acid content and the length of predicted loop regions, suggesting a substrate filter function for these loops. From these results, we propose a signature pattern for water transport.

BACKGROUND: N,N-Diethyl-3-methylbenzamide (deet) remains the gold standard for insect repellents. About 200 million people use it every year and over 8 billion doses have been applied over the past 50 years. Despite the widespread and increased interest in the use of deet in public health programmes, controversies remain concerning both the identification of its target sites at the olfactory system and its mechanism of toxicity in insects, mammals and humans. Here, we investigated the molecular target site for deet and the consequences of its interactions with carbamate insecticides on the cholinergic system. RESULTS: By using toxicological, biochemical and electrophysiological techniques, we show that deet is not simply a behaviour-modifying chemical but that it also inhibits cholinesterase activity, in both insect and mammalian neuronal preparations. Deet is commonly used in combination with insecticides and we show that deet has the capacity to strengthen the toxicity of carbamates, a class of insecticides known to block acetylcholinesterase. CONCLUSION: These findings question the safety of deet, particularly in combination with other chemicals, and they highlight the importance of a multidisciplinary approach to the development of safer insect repellents for use in public health.

Background: The 1-minute sit-to-stand (STS) test could be valuable to assess the level of exercise tolerance in chronic obstructive pulmonary disease (COPD). There is a need to provide the minimal important difference (MID) of this test in pulmonary rehabilitation (PR). Methods: COPD patients undergoing the 1-minute STS test before PR were included. The test was performed at baseline and the end of PR, as well as the 6-minute walk test, and the quadriceps maximum voluntary contraction (QMVC). Home and community-based programs were conducted as recommended. Responsiveness to PR was determined by the difference in the 1-minute STS test between baseline and the end of PR. The MID was evaluated using distribution and anchor-based methods. Results: Forty-eight COPD patients were included. At baseline, the significant predictors of the number of 1-minute STS repetitions were the 6-minute walk distance (6MWD) ( r =0.574; P <10 -3 ), age ( r =-0.453; P =0.001), being on long-term oxygen treatment ( r =-0.454; P =0.017), and the QMVC ( r =0.424; P =0.031). The multivariate analysis explained 75.8% of the variance of 1-minute STS repetitions. The improvement of the 1-minute STS repetitions at the end of PR was 3.8±4.2 ( P <10 -3 ). It was mainly correlated with the change in QMVC ( r =0.572; P =0.004) and 6MWD ( r =0.428; P =0.006). Using the distribution-based analysis, an MID of 1.9 (standard error of measurement method) or 3.1 (standard deviation method) was found. With the 6MWD as anchor, the receiver operating characteristic curve identified the MID for the change in 1-minute STS repetitions at 2.5 (sensibility: 80%, specificity: 60%) with area under curve of 0.716. Conclusion: The 1-minute STS test is simple and sensitive to measure the efficiency of PR. An improvement of at least three repetitions is consistent with physical benefits after PR. Keywords: sit-to-stand test, COPD, 6-minute walk test, exercise tolerance, pulmonary rehabilitation

Plant volatiles are important cues for many herbivorous insects when choosing a suitable host plant and finding a mating partner. An appropriate behavioural response to sensory cues from plants and other insects is crucial for survival and fitness. As the natural environment can show both large spatial and temporal variability, herbivores may need to show behavioural plasticity to the available cues. By using earlier experiences, insects can adapt to local variation of resources. Experience is well known to affect sensory-guided behaviour in parasitoids and social insects, but there is also increasing evidence that it influences host plant choice and the probability of finding a mating partner in herbivorous insects. In this review, we will focus upon behavioural changes in holometabolous insect herbivores during host plant choice and localization of mating partners, modulated by experience to sensory cues. The experience can be acquired during both the larval and the adult stage and can influence later responses to plant volatiles and other sensory cues not only within the developmental stage but also after metamorphosis. Furthermore, we will address the neurophysiological mechanisms underlying the experience-dependent behavioural adaptations and discuss ecological and evolutionary aspects of insect behavioural plasticity based upon experience.

The Eyguieres 42 strain of Drosophila simulans, obtained by laboratory selection, displayed approximately 20,000-fold resistance to the insecticide fipronil. Molecular cloning of the cDNA encoding the RDL GABA receptor subunit of this strain revealed the presence of two mutations: the Rdl mutation (A301G) and an additional mutation in the third transmembrane domain (T350M). In order to assess the individual and combined roles of the two mutations in fipronil resistance, the functional properties of wild-type, A301G, T350M and A301G/T350M homomultimeric RDL receptors were compared by expression in Xenopus oocytes. In wild-type receptors, the inhibition of GABA (EC(30))-induced currents by fipronil and picrotoxin was enhanced by repeated GABA applications. The A301G mutation nearly abolished this effect, decreased the sensitivity to fipronil and picrotoxin and increased the reversibility of inhibition. The T350M mutation also reduced the sensitivity to both antagonists. Of the four receptor variants tested, the double mutant showed the highest resistance to fipronil, following repeated GABA applications. In conclusion, the present study emphasizes new aspects of the pharmacological alterations induced by the Rdl mutation and shows that resistance to GABA receptor-directed insecticides may implicate a mutation distinct from Rdl.

ZD7288 has been widely used as a tool in the study of hyperpolarization-activated cyclic nucleotide-gated channels (HCN channels), and to test the relationships between HCN channels and heart and brain function. ZD7288 is widely considered a selective blocker of HCN currents. Here we show that ZD7288 inhibits not only HCN channel currents, but also Na(+) currents in DRG neurons and ZD7288 was confirmed to inhibit Na(+) current in HEK293 cells transfected with Na(v)1.4 plasmids. Thus our findings challenge the view that ZD7288 is a selective blocker of HCN channels. Conclusions about the role of NCN channels in neuronal function should be re-evaluated if based exclusively on the effect of ZD7288.

BACKGROUND: In the present study, the effect of thiamethoxam and clothianidin on the locomotor activity of American cockroach, Periplaneta americana (L.), was evaluated. Because it has been proposed that thiamethoxam is metabolised to clothianidin, high-performance liquid chromatography coupled with mass spectrometry was used to evaluate the amount of clothianidin on thiamethoxam-treated cockroaches. RESULTS: One hour after neonicotinoid treatment, the time spent in the open-field-like apparatus significantly increased, suggesting a decrease in locomotor activity. The percentage of cockroaches displaying locomotor activity was significantly reduced 1 h after haemolymph application of 1 nmol g(-1) neonicotinoid, while no significant effect was found after topical and oral administration. However, at 24 and 48 h, all neonicotinoids were able to reduce locomotor activity, depending on their concentrations and the way they were applied. Interestingly, it was found that thiamethoxam was converted to clothianidin 1 h after application, but the amount of clothianidin did not rise proportionately to thiamethoxam, especially after oral administration. CONCLUSION: The data suggest that the effect of thiamethoxam on cockroach locomotor activity is due in part to clothianidin action because (1) thiamethoxam levels remained persistent 48 h after application and (2) the amount of clothianidin in cockroach tissues was consistent with the toxicity of thiamethoxam.

Most animals rely on olfaction to find sexual partners, food or a habitat. The olfactory system faces the challenge of extracting meaningful information from a noisy odorous environment. In most moth species, males respond to sex pheromone emitted by females in an environment with abundant plant volatiles. Plant odours could either facilitate the localization of females (females calling on host plants), mask the female pheromone or they could be neutral without any effect on the pheromone. Here we studied how mixtures of a behaviourally-attractive floral odour, heptanal, and the sex pheromone are encoded at different levels of the olfactory pathway in males of the noctuid moth Agrotis ipsilon. In addition, we asked how interactions between the two odorants change as a function of the males' mating status. We investigated mixture detection in both the pheromone-specific and in the general odorant pathway. We used a) recordings from individual sensilla to study responses of olfactory receptor neurons, b) in vivo calcium imaging with a bath-applied dye to characterize the global input response in the primary olfactory centre, the antennal lobe and c) intracellular recordings of antennal lobe output neurons, projection neurons, in virgin and newly-mated males. Our results show that heptanal reduces pheromone sensitivity at the peripheral and central olfactory level independently of the mating status. Contrarily, heptanal-responding olfactory receptor neurons are not influenced by pheromone in a mixture, although some post-mating modulation occurs at the input of the sexually isomorphic ordinary glomeruli, where general odours are processed within the antennal lobe. The results are discussed in the context of mate localization.

The aim of this work is to evaluate the impact on the rat microbiota of long-term feeding with phenolic compounds (PC) rich grape pomace extracts. Thirty, 2-mo-old rats, were divided into 5 groups. Four groups were treated with different concentrations of PC (2.5, 5, 10, and 20 mg/kg/d diluted in 0.1% DMSO), and 1 group received 0.1% Dimethyl Sulfoxide (DMSO) alone (control group). The daily treatment lasted 14 mo. Major phenolic compounds constituents were characterized by the high-performance liquid chromatography and free radical scavenging capacity was measured by means of the DPPH assay. Fecal samples from young rats (2-mo old), and rats daily fed with PC or DMSO were collected at 6 and 14 mo posttreatment. The gut microbiota composition was analyzed by quantitative polymerase chain reaction. Bifidobacterium was significantly higher in the groups PC 2.5 and PC 5 than in control and young rats. Lactobacillus decreased with time in all treated and untreated groups. Bacteroides, Clostridium leptum subgroup (Clostridium cluster IV), and Enterococcus were not significantly changed by PC at any concentration when compared to control; nevertheless, after 14 mo of treatment all concentrations of PC abolished the increase of Clostridium sensu stricto (cluster I) (Clostridium Cluster I) observed in the control group when compared to young rats. PC do modulate selectively rat gut microbiome to a healthier phenotype in long-term feeding rats, and could counteract the adverse outcomes of aging on gut bacterial population. PRACTICAL APPLICATION: This research shows that phenolic-rich grape pomace extracts exhibiting a high antioxidant activity, selectively modulate rat gut microbiota to a healthier phenotype within age in a long-term feeding rats.

Elongation of the primary root during postgermination of Medicago truncatula seedlings is a multigenic trait that is responsive to exogenous nitrate. A quantitative genetic approach suggested the involvement of the nitrate transporter MtNPF6.8 (for Medicago truncatula NITRATE TRANSPORTER1/PEPTIDE TRANSPORTER Family6.8) in the inhibition of primary root elongation by high exogenous nitrate. In this study, the inhibitory effect of nitrate on primary root elongation, via inhibition of elongation of root cortical cells, was abolished in npf6.8 knockdown lines. Accordingly, we propose that MtNPF6.8 mediates nitrate inhibitory effects on primary root growth in M. truncatula. pMtNPF6.8:GUS promoter-reporter gene fusion in Agrobacterium rhizogenes-generated transgenic roots showed the expression of MtNPF6.8 in the pericycle region of primary roots and lateral roots, and in lateral root primordia and tips. MtNPF6.8 expression was insensitive to auxin and was stimulated by abscisic acid (ABA), which restored the inhibitory effect of nitrate in npf6.8 knockdown lines. It is then proposed that ABA acts downstream of MtNPF6.8 in this nitrate signaling pathway. Furthermore, MtNPF6.8 was shown to transport ABA in Xenopus spp. oocytes, suggesting an additional role of MtNPF6.8 in ABA root-to-shoot translocation. (15)NO3(-)-influx experiments showed that only the inducible component of the low-affinity transport system was affected in npf6.8 knockdown lines. This indicates that MtNPF6.8 is a major contributor to the inducible component of the low-affinity transport system. The short-term induction by nitrate of the expression of Nitrate Reductase1 (NR1) and NR2 (genes that encode two nitrate reductase isoforms) was greatly reduced in the npf6.8 knockdown lines, supporting a role of MtNPF6.8 in the primary nitrate response in M. truncatula.

The nicotinic acetylcholine receptors are ligand-gated ion channels responsible for rapid neurotransmission and are target sites for pesticides in insects. In the honeybee Apis mellifera, pharmacological and electrophysiological studies have shown that different nicotinic acetylcholine receptor subtypes may exist in the brain. Here, we have identified a honeybee cDNA that encodes a 537 amino acid protein with features typical of nicotinic acetylcholine receptor alpha subunit, and sequence homology to human alpha3. In situ hybridization on cryosections shows that the Apisalpha3 mRNA is differently expressed in larvae and adult. In larvae, Apisalpha3 mRNA expression is restricted to the suboesophageal ganglia. In adult, it is further expressed in the optic lobes, the dorsal lobes, the antennal lobes and the calyces of mushroom bodies. Together our results suggest that Apisalpha3 shows a controlled expression pattern during development.

The present article describes a genome database reviewing gene-related knowledge of two model bacteria, Bacillus subtilis and Escherichia coli. The database, Indigo, is open through the World-Wide Web (http://indigo.genetique.uvsq.fr). The concept used for organising the data, the concept of neighbourhood, allows one to explore the database content in an efficient although somewhat unusual way. Here, genes are related to each other by a variety of neighbourhoods, including proximity in the chromosome, phylogenetic kinship, participation in a common metabolic pathway, common presence in an article of the literature, or similar use of the genetic code. Several examples illustrate how this concept of neighbourhood permits one to review the available knowledge about a given gene or gene family, and elaborate unexpected, but revealing, analyses about gene functions.

While there is mounting knowledge about the structure and diversity of insect neuronal nicotinic acetylcholine receptors, less attention has been directed towards their intracellular regulation by calcium-mediated activation or inhibition of protein phosphorylation. The main goal of this work was to delineate the chain of molecular events that lead to the up- and down-regulation by two protein kinase Cs of an insect neuronal alpha-bungarotoxin-resistant nicotinic acetylcholine receptor (called nAChR1). The native nicotinic acetylcholine receptor intracellular regulation was studied on dissociated adult dorsal unpaired median neurons isolated from the terminal abdominal ganglion of the cockroach Periplaneta americana using whole-cell patch-clamp technique and calcium imaging. We report that under 0.5 micro malpha-bungarotoxin treatment, the inward current produced by pressure ejection application of nicotine onto the cell body was differentially sensitive to specific protein kinase C activators and inhibitors. The phorbol ester PMA produced a calcium-dependent increase in current amplitude blocked by chelerythrine. By contrast, the diacylglycerol analogue 1,2-dioctanoyl-sn-glycerol produced a calcium-independent reduction of the nicotinic response, reversed by rottlerin and chelerythrine. This indicated that two protein kinase C isozymes ('classical' and 'novel' protein kinase C, named PKC1 and PKC2, respectively) up- and down-regulated nicotinic acetylcholine receptor function. PMA and 1,2-dioctanoyl-sn-glycerol effects were mimicked by pirenzepine-sensitive M1 muscarinic receptor subtype coupled to phospholipase C second messenger pathway. Low concentration of muscarine elevated internal calcium levels, which thereby activated PKC1. By contrast, a high concentration of muscarine strongly increased [Ca 2+]i, which induced inhibition of PKC1. This effect was reversed by FK506, suggesting the implication of PP2B which unmasked PKC2 activity mediating down-regulation of nicotinic acetylcholine receptor.

In the olfactory system of male moths, a specialized subset of neurons detects and processes the main component of the sex pheromone emitted by females. It is composed of several thousand first-order olfactory receptor neurons (ORNs), all expressing the same pheromone receptor, that contact synaptically a few tens of second-order projection neurons (PNs) within a single restricted brain area. The functional simplicity of this system makes it a favorable model for studying the factors that contribute to its exquisite sensitivity and speed. Sensory information--primarily the identity and intensity of the stimulus--is encoded as the firing rate of the action potentials, and possibly as the latency of the neuron response. We found that over all their dynamic range, PNs respond with a shorter latency and a higher firing rate than most ORNs. Modelling showed that the increased sensitivity of PNs can be explained by the ORN-to-PN convergent architecture alone, whereas their faster response also requires cell-to-cell heterogeneity of the ORN population. So, far from being detrimental to signal detection, the ORN heterogeneity is exploited by PNs, and results in two different schemes of population coding based either on the response of a few extreme neurons (latency) or on the average response of many (firing rate). Moreover, ORN-to-PN transformations are linear for latency and nonlinear for firing rate, suggesting that latency could be involved in concentration-invariant coding of the pheromone blend and that sensitivity at low concentrations is achieved at the expense of precise encoding at high concentrations.

CONTEXT: Shiitake (Lentinula edodes) is an edible mushroom which was initially grown in Japan and China and is now sold on the European market. Flagellate erythema may arise following shiitake consumption and was first described in Japan in 1974. OBJECTIVE: This paper reports a French shiitake dermatitis case series. METHODS: The findings of retrospective study of shiitake dermatitis cases, reported to French Poison Control Centres (PCC) from January 2000 to December 2013, are reported. RESULTS: Among 32 exposed patients, 15 presented flagellate urticarial lesions after raw shiitake consumption. The first case of this series was reported in 2006 and the last nine cases were reported as of 2012. After shared meals, no symptoms were reported among guests, who preferred cooked shiitake to the raw mushroom. In this series, rashes appeared 12 h to 5 days (median: 24 h) after raw shiitake ingestion. Linear and itchy urticarial lesions formed on the trunk, arms, and legs within a few hours and persisted for 3-21 days. In four cases, rash and pruritus were either triggered or worsened by sun exposure. Eleven patients received corticosteroids, antihistamines, or both. All patients completely recovered. CONCLUSION: Due to the rapidly increasing consumption of exotic food in Western countries, it is no surprise that cases of shiitake dermatitis are now appearing in Europe. The mechanism of shiitake dermatitis is thought to be toxic and due to lentinan, a polysaccharide component of the mushroom. There is no specific validated treatment for shiitake dermatitis. Health professionals and the general population should be aware of both the risk associated with raw shiitake consumption and of the good prognosis of this very spectacular and uncomfortable toxic dermatitis.

Most animals including insects rely on olfaction to find their mating partners. In moths, males are attracted by female-produced sex pheromones inducing stereotyped sexual behavior. The behaviorally relevant olfactory information is processed in the primary olfactory centre, the antennal lobe (AL). Evidence is now accumulating that modulation of sex-linked behavioral output occurs through neuronal plasticity via the action of hormones and/or catecholamines. A G-protein-coupled receptor (GPCR) binding to 20-hydroxyecdysone, the main insect steroid hormone, and dopamine, has been identified in Drosophila (DmDopEcR), and was suggested to modulate neuronal signaling. In the male moth Agrotis ipsilon, the behavioral and central nervous responses to pheromone are age-dependent. To further unveil the mechanisms of this olfactory plasticity, we searched for DopEcR and tested its potential role in the behavioral response to sex pheromone in A. ipsilon males. Our results show that A. ipsilon DopEcR (named AipsDopEcR) is predominantly expressed in the nervous system. The corresponding protein was detected immunohistochemically in the ALs and higher brain centers including the mushroom bodies. Moreover, AipsDopEcR expression increased with age. Using a strategy of RNA interference, we also show that silencing of AipsDopEcR inhibited the behavioral response to sex pheromone in wind tunnel experiments. Altogether our results indicate that this GPCR is involved in the expression of sexual behavior in the male moth, probably by modulating the central nervous processing of sex pheromone through the action of one or both of its ligands.

Neonicotinoid insecticides act on nicotinic acetylcholine receptor and are particularly effective against sucking pests. They are widely used in crops protection to fight against aphids, which cause severe damage. In the present study we evaluated the susceptibility of the pea aphid Acyrthosiphon pisum to the commonly used neonicotinoid insecticides imidacloprid (IMI), thiamethoxam (TMX) and clothianidin (CLT). Binding studies on aphid membrane preparations revealed the existence of high and low-affinity binding sites for [3H]-IMI (Kd of 0.16 ± 0.04 nM and 41.7 ± 5.9 nM) and for the nicotinic antagonist [125I]-α-bungarotoxin (Kd of 0.008 ± 0.002 nM and 1.135 ± 0.213 nM). Competitive binding experiments demonstrated that TMX displayed a higher affinity than IMI for [125I]-α-bungarotoxin binding sites while CLT affinity was similar for both [125I]-α-bungarotoxin and [3H]-IMI binding sites. Interestingly, toxicological studies revealed that at 48 h, IMI (LC50 = 0.038 µg/ml) and TMX (LC50 = 0.034 µg/ml) were more toxic than CLT (LC50 = 0.118 µg/ml). The effect of TMX could be associated to its metabolite CLT as demonstrated by HPLC/MS analysis. In addition, we found that aphid larvae treated either with IMI, TMX or CLT showed a strong variation of nAChR subunit expression. Using semi-quantitative PCR experiments, we detected for all insecticides an increase of Apisumα10 and Apisumβ1 expressions levels, whereas Apisumβ2 expression decreased. Moreover, some other receptor subunits seemed to be differently regulated according to the insecticide used. Finally, we also demonstrated that nAChR subunit expression differed during pea aphid development. Altogether these results highlight species specificity that should be taken into account in pest management strategies.

OBJECTIVE: Insulin binds to the alpha-subunit of the insulin receptor (IRalpha) and subsequently exerts its effects in the cells. The soluble ectodomains of several receptors have been found to circulate in the plasma. Therefore, we hypothesized that soluble human insulin receptor (hIR) ectodomain (alpha-subunit and a part of beta-subunit) may exist in the plasma of diabetic patients. RESEARCH DESIGN AND METHODS: We identified soluble hIR ectodomain in human plasma by a two-step purification followed by immunoblotting and gel-filtration chromatography. Furthermore, we established an hIRalpha-specific enzyme-linked immunosorbent assay and measured the plasma IRalpha levels in patients with diabetes. We also investigated this phenomenon in streptozotocin-induced diabetic hIR transgenic mice. RESULTS: Soluble hIRalpha, but not intact hIRbeta or whole hIR, exists in human plasma. The plasma IRalpha levels were significantly higher in type 1 (2.00 +/- 0.60 ng/ml; n = 53) and type 2 (2.26 +/- 0.80; n = 473) diabetic patients than in control subjects (1.59 +/- 0.40 ng/ml; n = 123 (P < 0.001 vs. control). Plasma IRalpha level was positively correlated with blood glucose level, and 10-20% of the insulin in plasma bound to hIRalpha. In the in vivo experiments using diabetic hIR transgenic mice, hyperglycemia was confirmed to increase the plasma hIRalpha level and the half-life estimated to be approximately 6 h. CONCLUSIONS: We propose that the increased soluble IR ectodomain level appears to be a more rapid glycemic marker than A1C or glycoalbumin.

Insect vector-borne diseases remain one of the principal causes of human mortality. In addition to conventional measures of insect control, repellents continue to be the mainstay for personal protection. Because of the increasing pyrethroid-resistant mosquito populations, alternative strategies to reconstitute pyrethroid repellency and knock-down effects have been proposed by mixing the repellent DEET (N,N-Diethyl-3-methylbenzamide) with nonpyrethroid insecticide to better control resistant insect vector-borne diseases. By using electrophysiological, biochemichal, in vivo toxicological techniques together with calcium imaging, binding studies and in silico docking, we have shown that DEET, at low concentrations, interacts with high affinity with insect M1/M3 mAChR allosteric site potentiating agonist effects on mAChRs coupled to phospholipase C second messenger pathway. This increases the anticholinesterase activity of the carbamate propoxur through calciumdependent regulation of acetylcholinesterase. At high concentrations, DEET interacts with low affinity on distinct M1/M3 mAChR site, counteracting the potentiation. Similar dosedependent dual effects of DEET have also been observed at synaptic mAChR level. Additionally, binding and in silico docking studies performed on human M1 and M3 mAChR subtypes indicate that DEET only displays a low affinity antagonist profile on these M1/M3 mAChRs. These results reveal a selective high affinity positive allosteric site for DEET in insect mAChRs. Finally, bioassays conducted on Aedes aegypti confirm the synergistic interaction between DEET and propoxur observed in vitro, resulting in a higher mortality of