Efficacy of a Spatial Repellent for Control of Malaria in Indonesia: A Cluster-Randomized Controlled Trial.

A cluster-randomized, double-blinded, placebo-controlled trial was conducted to estimate the protective efficacy (PE) of a spatial repellent (SR) against malaria infection in Sumba, Indonesia. Following radical cure in 1,341 children aged ≥ 6 months to ≤ 5 years in 24 clusters, households were given transfluthrin or placebo passive emanators (devices designed to release vaporized chemical). Monthly blood screening and biweekly human-landing mosquito catches were performed during a 10-month baseline (June 2015-March 2016) and a 24-month intervention period (April 2016-April 2018). Screening detected 164 first-time infections and an accumulative total of 459 infections in 667 subjects in placebo-control households, and 134 first-time and 253 accumulative total infections among 665 subjects in active intervention households. The 24-cluster protective effect of 27.7% and 31.3%, for time to first-event and overall (total new) infections, respectively, was not statistically significant. Purportedly, this was due in part to zero to low incidence in some clusters, undermining the ability to detect a protective effect. Subgroup analysis of 19 clusters where at least one infection occurred during baseline showed 33.3% (P-value = 0.083) and 40.9% (P-value = 0.0236, statistically significant at the one-sided 5% significance level) protective effect to first infection and overall infections, respectively. Among 12 moderate- to high-risk clusters, a statistically significant decrease in infection by intervention was detected (60% PE). Primary entomological analysis of impact was inconclusive. Although this study suggests SRs prevent malaria, additional evidence is required to demonstrate the product class provides an operationally feasible and effective means of reducing malaria transmission.

Effects of combined 5-HT2A and cannabinoid receptor modulation on a schizophrenia-related prepulse inhibition deficit in mice.

RATIONALE: Prepulse inhibition of the startle reflex (PPI) is disrupted in several psychiatric disorders including schizophrenia. Understanding PPI pharmacology may help elucidate the pathophysiology of these disorders and lead to better treatments. Given the advantages of multi-target approaches for complex mental illnesses treatment, we have investigated the interaction between receptors known to modulate PPI (5-HT1A and 5-HT2A) and the neuromodulatory endocannabinoid system. OBJECTIVES: To investigate serotonin and cannabinoid receptor (CBR) co-modulation in a model of PPI disruption relevant to schizophrenia METHODS: Male Swiss mice were pretreated with WIN 55,212-2 (CBR agonist), rimonabant (CB1R inverse agonist), 8-OH-DPAT (5-HT1A/7 agonist), and volinanserin (5-HT2A antagonist) or with a combination of a cannabinoid and a serotonergic drug. PPI disruption was induced by acute administration of MK-801. RESULTS: WIN 55,212-2 and rimonabant did not change PPI nor block MK-801-induced deficits. 8-OH-DPAT increased PPI in control mice and, in a higher dose, inhibited MK-801-induced impairments. Volinanserin also increased PPI in control and MK-801-treated mice, presenting an inverted U-shaped dose-response curve. Co-administration of either cannabinoid ligand with 8-OH-DPAT did not change PPI; however, the combination of volinanserin with rimonabant increased PPI in both control and MK-801-exposed mice. CONCLUSIONS: WIN 55,212-2 and rimonabant had similar effects in PPI. Moreover, serotonin and cannabinoid receptors interact to modulate PPI. While co-modulation of CBR and 5-HT1A receptors did not change PPI, a beneficial effect of 5-HT2A and CB1R antagonist combination was detected, possibly mediated through potentiation of 5-HT2A blockade effects by concomitant CB1R blockade.

Field Effectiveness of a Metofluthrin Fan-Based Emanator and Deet as Repellents Against Aedes vigilax in Southeast Queensland, Australia1.

A field study to compare a formulation containing 40% deet (N,N-diethyl-3-methyl benzamide) in ethanol (Bushman™) and a battery-powered fan emanator with a chemical strip containing 31.2% metofluthrin (OFF!® Clip-On™) was conducted at Redcliffe, Queensland, Australia, in February 2016. The 40% deet provided 100% protection against mosquitoes for 5 h until tests ceased, while the OFF! Clip-On device provided only 42.2-60.8% protection against Aedes vigilax during the same period.

Insula serotonin 2A receptor binding and gene expression contribute to serotonin transporter polymorphism anxious phenotype in primates.

Genetic variation in the serotonin transporter gene (SLC6A4) is associated with vulnerability to affective disorders and pharmacotherapy efficacy. We recently identified sequence polymorphisms in the common marmoset SLC6A4 repeat region (AC/C/G and CT/T/C) associated with individual differences in anxiety-like trait, gene expression, and response to antidepressants. The mechanisms underlying the effects of these polymorphisms are unknown, but a key mediator of serotonin action is the serotonin 2A receptor (5HT2A). Thus, we correlated 5HT2A binding potential (BP) and RNA gene expression in 16 SLC6A4 genotyped marmosets with responsivity to 5HT2A antagonism during the human intruder test of anxiety. Voxel-based analysis and RNA measurements showed a reduction in 5HT2A BP and gene expression specifically in the right posterior insula of individuals homozygous for the anxiety-related variant AC/C/G. These same marmosets displayed an anxiogenic, dose-dependent response to the human intruder after 5HT2A pharmacological antagonism, while CT/T/C individuals showed no effect. A voxel-based correlation analysis, independent of SLC6A4 genotype, revealed that 5HT2A BP in the adjacent right anterior insula and insula proisocortex was negatively correlated with trait anxiety scores. Moreover, 5HT2A BP in both regions was a good predictor of the size and direction of the acute emotional response to the human intruder threat after 5HT2A antagonism. Our findings suggest that genetic variation in the SLC6A4 repeat region may contribute to the trait anxious phenotype via neurochemical changes in brain areas implicated in interoceptive and emotional processing, with a critical role for the right insula 5HT2A in the regulation of affective responses to threat.

Self-administration of benzodiazepine and cocaine combinations by male and female rhesus monkeys in a choice procedure: role of α1 subunit-containing GABAA receptors.

RATIONALE: Compounds lacking efficacy at the α1 subunit-containing GABAA (α1GABAA) receptor appear to have reduced abuse potential compared with those having measurable efficacy at this receptor, though their self-administration in nonhuman primates is dependent upon past drug experience. OBJECTIVES: We used a drug vs. drug choice procedure to evaluate the hypothesis that L-838,417, a compound lacking efficacy at αGABAA receptors, would not enhance cocaine choice in monkeys trained to self-administer cocaine. We also hypothesized that zolpidem, a compound with preferential modulation of ⍺1GABAA receptors and midazolam, a nonselective benzodiazepine, would enhance cocaine choice in this procedure. METHODS: One female and three male rhesus monkeys chose between cocaine alone (0.1 mg/kg/injection) vs. the same dose of cocaine combined with midazolam (0.003-0.1 mg/kg/injection), zolpidem (0.003-0.3 mg/kg/injection), or L-838-417 (0.01-0.1 mg/kg/injection). In addition, we evaluated choice between saline and L-838,417 at select doses to determine whether L-838,417 would function as a reinforcer on its own. RESULTS: Consistent with our hypotheses, midazolam- and zolpidem-cocaine mixtures were chosen over cocaine alone at sufficiently high doses. However, L-838,417-cocaine mixtures also were chosen over cocaine alone in three of four subjects with at least one dose. When available alone vs. saline, L-838,417 did not function as a reinforcer in any subject. CONCLUSION: Compounds that lack efficacy at α1GABAA receptors may have low abuse potential compared to classic benzodiazepines, but self-administration of these compounds is context-dependent.

Gone in 60 seconds: Sub-lethal Effects of Metofluthrin Vapors on Behavior and Fitness of Resistant and Field Strains of Aedes aegypti (Diptera: Culicidae).

Spatial repellents can reduce fecundity and interrupt oviposition behavior in Aedes aegypti. Yet, it is unclear if short exposure times, resistant phenotypes, and other aspects of spatial repellents can impact these effects on mosquito reproduction. To address these issues, pyrethroid susceptible, pyrethroid resistant, and field strains of Ae. aegypti were used to evaluate the extent to which fecundity and oviposition behavior are affected following metofluthrin exposure. Mosquitoes were exposed for 60 s to a sub-lethal dose (LC30) of metofluthrin before blood feeding and allowed 72 h to become gravid before evaluation in an oviposition bioassay for an additional 72 h. Metofluthrin-exposed susceptible, field, and to a lesser extent resistant strain Ae. aegypti showed oviposition across fewer containers, less egg yield, less egg viability, and reduced larval survivorship in hatched eggs compared to unexposed cohorts. Susceptible mosquitoes retained some eggs at dissection following bioassays, and in one case, melanized eggs retained in the female. Treated resistant and field strain F1 larvae hatched significantly earlier than unexposed cohorts and resulted in increased larval mortality in the first 3 d after oviposition. Upon laying, the treated field strain had incompletely melanized eggs mixed in with viable eggs. The treated field strain also had the lowest survivorship of larvae reared from bioassay eggs. These results indicate that metofluthrin could succeed in reducing mosquito populations via multiple mechanisms besides acute lethality. With the available safety data, pre-existing spatial repellent registration, and possibilities for other outdoor delivery methods, metofluthrin is a strong candidate for transition into broader mosquito abatement operations.

A combined experimental-computational approach for spatial protection efficacy assessment of controlled release devices against mosquitoes (Anopheles).

This work describes the use of entomological studies combined with in silico models (computer simulations derived from numerical models) to assess the efficacy of a novel device for controlled release of spatial repellents. Controlled Release Devices (CRDs) were tested with different concentrations of metofluthrin and tested against An. quadrimaculatus mosquitoes using arm-in cage, semi-field, and outdoor studies. Arm-in-cage trials showed an approximate mean values for mosquito knockdown of 40% and mosquito bite reduction of 80% for the optimal metofluthrin formulation for a 15-minute trial. Semi-field outdoor studies showed a mean mortality of a 50% for 24 hour trial and 75% for a 48 hour trial for optimal concentrations. Outdoors studies showed an approximate mean mortality rate of 50% for a 24 hour trial for optimal concentrations. Numerical simulations based on Computational Fluid Dynamics (CFD) were performed in order to obtain spatial concentration profiles for 24 hour and 48 hour periods. Experimental results were correlated with simulation results in order to obtain a functional model that linked mosquito mortality with the estimated spatial concentration for a given period of time. Such correlation provides a powerful insight in predicting the effectiveness of the CRDs as a vector-control tool. While CRDs represent an alternative to current spatial repellent delivery methods, such as coils, candles, electric repellents, and passive emanators based on impregnated strips, the presented method can be applied to any spatial vector control treatment by correlating entomological endpoints, i.e. mortality, with in-silico simulations to predict overall efficacy. The presented work therefore presents a new methodology for improving design, development and deployment of vector-control tools to reduce transmission of vector-borne diseases, including malaria and dengue.

5-HT2A receptors modulate dopamine D2-mediated maternal effects.

Serotonin 5-HT2A receptors are expressed throughout the mesolimbic and mesocortical dopamine pathways, and manipulation of this receptor system has a profound impact on dopamine functions and dopamine-mediated behaviors. It is highly likely that 5-HT2A receptors may also modulate the D2-mediated maternal effects. The present study investigated this issue and also explored the possible behavioral mechanisms. We tested the effects of two D2 drugs (an agonist quinpirole: 0.5, 1.0 mg/kg, and a potent D2 antagonist haloperidol: 0.05, 0.10 mg/kg, sc) and their combinations with two 5-HT2A drugs (a selective 5-HT2A agonist TCB-2: 2.5 mg/kg, and 5-HT2A antagonist MDL100907, 1.0 mg/kg, sc) on maternal behavior in Sprague-Dawley postpartum females. Individually, TCB-2 (2.5 mg/kg, sc) and quinpirole (0.5 and 1.0 mg/kg, sc) reduced pup preference and disrupted home-cage maternal behavior. In contrast, haloperidol (0.10 mg/kg, sc) only disrupted home-cage maternal behavior, but did not suppress pup preference. MDL100907 (1.0 mg/kg, sc) by itself had no effect on either pup preference or maternal behavior. When administered in combination, pretreatment of TCB-2 did not alter quinpirole's disruption of pup preference and home-cage maternal behavior (possibly due to the floor effect), however, it did enhance haloperidol's disruption of pup retrieval in the home cage. MDL100907 had no effect both quinpirole's and haloperidol's disruption of pup preference and home-cage maternal behavior. Interestingly, haloperidol attenuated TCB-2's disruptive effect on pup preference. These findings suggest that activation of 5-HT2A receptors tends to enhance D2-mediated maternal disruption, whereas blockade of 5-HT2A receptors is less effective. They also suggest that 5-HT2A receptors may have a direct effect on maternal behavior independent of their interaction with D2 receptors. The possible behavioral and neural mechanisms by which 5-HT2A- and D2-mediated maternal effects and their interaction are discussed.

Effects of acute treatments with the serotonin 2A antagonist M100907 alone or in combination with the serotonin 2C agonist WAY163909 on methamphetamine self-administration in rhesus monkeys.

BACKGROUND: Serotonin 5-HT2A receptor antagonists and 5-HT2C receptor agonists have been proposed as important candidates for the development of pharmacotherapies for psychostimulant abuse, with evidence suggesting that those receptors may act together to control behavior. However, the role of 5-HT2A receptors on the reinforcing effects of psychostimulant drugs has not been fully elucidated. METHODS: In the present study, we investigated the effects of the selective 5HT2A receptor antagonist M100907 alone or in combination with the selective 5HT2C agonist WAY 163909 on intravenous methamphetamine self-administration in rhesus macaques (N = 3). Methamphetamine self-administration (0.01-0.03 mg/kg/inf) was evaluated under a fixed-ratio 20-schedule of reinforcement, and acute pretreatments were conducted 1 h (M100907) or 45 min (WAY 163,909) prior to the beginning of self-administration sessions at the EDMax dose of methamphetamine once stability criteria were met. RESULTS: Pretreatment with M100907 (0.03-0.3 mg/kg, i.m.) dose-dependently attenuated methamphetamine self-administration, with the highest dose significantly decreasing response rates compared to vehicle. Combined administration of ineffective doses of M100907 and WAY 163,909 had no effects on methamphetamine self-administration. CONCLUSIONS: Our study indicates that acute selective 5-HT2A receptor blockade decreases peak methamphetamine intake in nonhuman primates. Combination approaches with sub-threshold doses of 5-HT2A receptor antagonists and 5-HT2C receptor agonists, on the other hand, do not seem to be effective in decreasing methamphetamine reinforcement. Further studies are needed in order to investigate the effects of chronic treatments with M100 on complete METH SA dose-response curves.

Chronic treatment with a metabotropic mGlu2/3 receptor agonist diminishes behavioral response to a phenethylamine hallucinogen.

BACKGROUND: There is evidence that mGlu2/3 receptors regulate 5-HT2A signaling, interactions that have been theorized to play a role in the antipsychotic-like effects of mGlu2/3 agonists as well as the hallucinogenic effects of 5-HT2A agonists. One approach to unraveling this interaction is through the chronic administration of agonists at the two receptors, which should influence the functional properties of the targeted receptor due to receptor downregulation or desensitization and thereby alter crosstalk between the two receptors. In this study, we investigated whether chronic treatment with the mGlu2/3 agonist LY379268 would alter the behavioral response to a phenethylamine hallucinogen, 25CN-NBOH, which acts as a selective 5-HT2A agonist. METHODS: We first conducted a dose response of 25CN-NBOH (0.1, 0.3, 1, 3, or 10 mg/kg) to confirm the effects on head-twitch response (HTR) and then blockade studies with either the M100907 (0.1 mg/kg) or SB242084 (0.1, 0.3, or 1 mg/kg) to determine the contribution of 5-HT2A and 5-HT2C to 25CN-NBOH-induced HTR, respectively. To determine whether an mGlu2/3 agonist could block 25CN-NBOH-induced HTR, mice were pretreated with vehicle or LY379268 (0.1, 1, or 10 mg/kg) prior to 25CN-NBOH, and HTR was assessed. The effects of chronic LY379268 on 5-HT2A agonist-induced HTR were evaluated by treating mice with either vehicle or LY379268 (10 mg/kg) for 21 days and measuring 25CN-NBOH-induced HTR 48 h after the final LY379268 treatment. The following day (72 h after the final LY379268 treatment), the ability of acute LY379268 to block PCP-induced locomotor activity was assessed. RESULTS: 25CN-NBOH dose-dependently increased the HTR, a 5-HT2A-mediated behavior, in mice. The selective 5-HT2A antagonist M100907 completely blocked the HTR induced by 25CN-NBOH, whereas the selective 5-HT2C antagonist SB242084 had no effect on the HTR. Administration of LY379268 (10 mg/kg SC) attenuated the HTR induced by 1 mg/kg 25CN-NBOH by ~ 50%. Chronic treatment (21 days) with LY379268 also attenuated the HTR response to 25CN-NBOH when tested 48 h after the last dose of LY379268. In locomotor tests, acute LY379268 significantly attenuated PCP-induced locomotor activity in the chronic vehicle treatment group; by contrast, there was only a trend for an overall interaction in the chronic LY379268 group, with LY379268 blocking the locomotor-stimulating effects of PCP only during the last 20 min. CONCLUSIONS: These data are consistent with a functional interaction between mGlu2/3 and 5-HT2A receptors, although the specific mechanism for the interaction is not known. These data support the hypothesis that mGlu2/3 receptors play a prominent role in modulating the behavioral response to 5-HT2A receptor activation.

A definite measure of occupancy exposures, seeking with non-radiolabeled in vivo 5-HT2A receptor occupancy and in vitro free fractions.

Unbound drug concentration in the brain would be the true exposure responsible for specific target occupancy. Drug exposures from preclinical are total concentrations of those over/underestimate the clinical dose projection. With the application of mass spectrometry, the current work proposes a definite measure of test drug exposures at serotonin-2A occupancy. The 5-HT2A occupancy of antagonist in the rat brain has determined with non-radiolabeled tracer MDL-100,907 at an optimized dose (3 µg/kg) and treatment time (30 min). Equilibrium dialysis method determines the in vitro free fraction of the test antagonist in untreated rat brain homogenates and plasma. Drug-free fractions derived the unbound concentration (EC50) in plasma and brain at test doses. The corresponding binding affinities (Ki) correlated with the unbound concentrations. Except for quetiapine, the ED50 values in the dose-occupancy curves of antagonists are close and ranged from 1 to 3 mg/kg. The test drug quetiapine, eplivanserin, and clozapine showed high free fractions in plasma, but for ketanserin and olanzapine, the brain free fraction was higher. The correlation between the unbound EC50 of the antagonists and corresponding Ki values was good (r2=0.828). The improved EC50 accuracy with unbound concentrations was 10-250 folds in plasma and 10-170 folds in the brain. Further, the free fractions (fu, plasma/fu, brain) of test drugs had shown a correlation of ∼83% with brain permeability (Ctotal brain/Ctotal plasma), a limiting factor. Thus, correlating the occupancy with unbound exposure and pharmacology would result in an accurate measurement of drug potency and optimizes in selecting the clinical dose.

Intracerebroventricular microinjection of the 5-HT1F receptor agonist LY 344864 inhibits methamphetamine conditioned place preference reinstatement in rats.

Relapse following a prolonged period of drug cessation is a key barrier in the treatment of methamphetamine (METH) addiction, for which pharmacological treatment exhibits little efficacy. Previous studies have suggested that this process involves alterations in levels of serotonin (5-HT) in the brain. Although the 5-HT1F receptor has been implicated in the reward pathway, its physiological functions remain unknown. In the present study, we examined the effect of the 5-HT1F agonist LY 344864 on the reinstatement of METH-seeking behavior in rats using a conditioned place preference (CPP) paradigm. The CPP paradigm was first used to determine the effective doses of LY and METH. Four groups were then conditioned with METH (5 mg/kg; i.p.), while the sham group received saline. METH-induced CPP was subsequently extinguished. On the 13th day of extinction, the rats received either METH (0, 1, or 2.5 mg/kg; i.p.) plus vehicle or priming METH plus LY (2 µg/5 µL; i.c.v.). On reinstatement day, preference scores were calculated as the difference in time spent in the drug-paired and vehicle-paired compartments. Rats conditioned with the lowest effective dose of METH (5 mg/kg) exhibited significant differences in pre- and post-testing preference scores. Preference scores were significantly higher in the saline + METH group than in the control group. Furthermore, preference scores were significantly higher in rats that had received priming METH treatment, and pre-treatment with LY significantly attenuated the reinstatement of METH-seeking behavior. These findings suggest that future studies should evaluate the therapeutic potential of 5-HT1F agonists for preventing relapse in individuals with METH addiction.

Oral Delivery of Highly Lipophilic, Poorly Water-Soluble Drugs: Self-Emulsifying Drug Delivery Systems to Improve Oral Absorption and Enable High-Dose Toxicology Studies of a Cholesteryl Ester Transfer Protein Inhibitor in Preclinical Species.

BMS-A is an inhibitor of cholesteryl ester transfer protein and is a highly lipophilic compound (clogP 10.5) with poor aqueous solubility (<0.0001 mg/mL at pH 6.5). The compound exhibits low oral exposure when dosed as cosolvent solution formulations. The purpose of this study was to evaluate lipid-based formulations for enabling high-dose toxicology studies and enhancing toxicology margins of BMS-A in preclinical studies in nonrodent species. The solubility of BMS-A was screened in lipid and cosolvent/surfactant excipients, and prototype formulations were developed. In vitro tests showed that fine/microemulsions were formed after aqueous dilution of lipid formulations, and BMS-A was transferred from oil phase to aqueous phase with enhanced solubility following lipid digestion. When dosed in dogs at 200 mg/kg, a Gelucire-based formulation exhibited more than 10-fold higher exposure compared to the solution formulation and was thus selected for toxicology studies in dogs. For monkeys, an olive oil formulation was developed, and the exposure was about 7-fold higher than that from the solution. In summary, lipid-based drug delivery could be applied in early stages of drug discovery to enhance oral exposure and enable preclinical toxicology studies of highly lipophilic compounds, while facilitating the candidate selection of a molecule which is more specifically designed for bioperformance in a lipid-based drug delivery strategy.

Gas chromatography/negative chemical ionization mass spectrometry of transfluthrin in rat plasma and brain.

RATIONALE: Transfluthrin is a relatively non-toxic rapid-acting synthetic pyrethroid insecticide. It is widely used in household and hygiene products. A sensitive and accurate bioanalytical method is required for quantification of its concentration in plasma and its potential target organ, the brain for studies to assess its health effects and toxicokinetics in mammals. METHODS: The samples were prepared by liquid-liquid extraction. Gas chromatography mass spectrometry (GC/MS) analysis was performed for the determination of transfluthrin in biological samples with an overall method run time of 15 min. Transfluthrin was quantified using selected-ion monitoring (SIM) in the negative chemical ionization (NCI) mode. Chromatographic separation was achieved using a Zebron® ZB5-MS GC column operating with 1 mL/min constant flow helium. Cis-Permethrin was used as the internal standard. RESULTS: The method was validated to be precise and accurate within the linear range of 1.0-400.0 ng/mL in plasma and 4.0-400.0 ng/mL in brain homogenate, based on a 100 µL sample volume for both matrices. This method was applied to samples following administration of a 10 mg/kg oral dose to male adult rats. The plasma concentrations were observed to be 11.70 ± 5.69 ng/mL and brain concentrations 12.09 ± 3.15 ng/g when measured 2 h post-dose. CONCLUSIONS: A rapid GC/NCI-MS method was demonstrated to be sensitive, specific, precise and accurate for the quantification of transfluthrin in rat plasma and brain. The optimized method was successfully used to quantify the rat plasma and brain concentrations of transfluthrin 2 h after the oral dosing of Sprague-Dawley rats.

Effects of sublethal exposure to metofluthrin on the fitness of Aedes aegypti in a domestic setting in Cairns, Queensland.

BACKGROUND: Metofluthrin is highly effective at reducing biting activity in Aedes aegypti. Its efficacy lies in the rapid onset of confusion, knockdown, and subsequent kill of a mosquito. In the field, there are a variety of scenarios that might result in sublethal exposure to metofluthrin, including mosquitoes that are active at the margins of the chemical's lethal range, brief exposure as mosquitoes fly in and out of treated spaces or decreasing efficacy of the emanators with time. Sublethal effects are key elements of insecticide exposure and selection. METHODS: The metofluthrin dose for each treatment group of male and female Ae. aegypti was controlled using exposure time intervals to a 10% active ingredient (AI) metofluthrin emanator. Room size and distance from the emanator for all groups was maintained at 3 m. In bioassay cages, male Ae. aegypti were exposed at 0, 5, 10, 20, 30 and 40-min intervals. Females were exposed in bioassay cages at 0, 10, 20, 30, 40 and 60-min intervals. Mortality rates and fecundity were observed between the exposure time groups for both sexes. RESULTS: Female Ae. aegypti exposed for 60 min had a significantly higher mortality rate (50%), after a 24-h recovery period, than other exposure times, 10, 20, 30 and 40 min (P < 0.001). An overall difference in fecundity was not observed in females between treatments. A significant effect on male mortality was only observed at 40 min exposure times, three meters from the 10% AI emanator [Formula: see text]. Males that survived metofluthrin exposure were as likely to produce viable eggs with an unexposed female as males that had not been exposed (P > 0.05). CONCLUSION: Regardless of sex, if a mosquito survived exposure, it would be as biologically successful as its unexposed counterpart. Portability of the metofluthrin emanator and delayed knockdown effects create opportunities for sublethal exposure and potential pyrethroid resistance development in Ae. aegypti, and should be taken into consideration in recommendations for field application of this product, including minimum exposure periods and a prescribed number of emanators per room based on volume.

The acute social defeat stress and nest-building test paradigm: A potential new method to screen drugs for depressive-like symptoms.

Psychosocial stress can cause mental conditions such as depression in humans. To develop drug therapies for the treatment of depression, it is necessary to use animal models of depression to screen drug candidates that exhibit anti-depressive effects. Unfortunately, the present methods of drug screening for antidepressants, the forced-swim test and tail-suspension test, are limiting factors in drug discovery because they are not based on the constructive validity of objective phenotypes in depression. Previously, we discovered that the onset of nest building is severely delayed in mice exposed to subchronic mild social defeat stress (sCSDS). Therefore, a novel paradigm combining acute social defeat stress (ASDS) and the nest-building test (SNB) were established for the efficient screening of drugs for depressive-like symptoms. Since ASDS severely delayed the nest-building process as shown in chronically social defeated mice, we sought to rescue the delayed nest-building behavior in ASDS mice. Injecting a specific serotonin 2a receptor antagonist (SR-46349B), the nest-building deficit exhibited by ASDS mice was partially rescued. On the other hand, a selective serotonin reuptake inhibitor (fluoxetine) did not rescue the nest-building deficit in ASDS mice. Therefore, we conclude that the SNB paradigm is an another potential behavioral method for screening drugs for depressive-like symptoms including attention deficit, anxiety, low locomotion, and decreased motivation.

Discriminative stimulus properties of 1.25mg/kg clozapine in rats: Mediation by serotonin 5-HT2 and dopamine D4 receptors.

The atypical antipsychotic drug clozapine remains one of most effective treatments for schizophrenia, given a lack of extrapyramidal side effects, improvements in negative symptoms, cognitive impairment, and in symptoms in treatment-resistant schizophrenia. The adverse effects of clozapine, including agranulocytosis, make finding a safe clozapine-like a drug a goal for drug developers. The drug discrimination paradigm is a model of interoceptive stimulus that has been used in an effort to screen experimental drugs for clozapine-like atypical antipsychotic effects. The present study was conducted to elucidate the receptor-mediated stimulus properties that form this clozapine discriminative cue by testing selective receptor ligands in rats trained to discriminate a 1.25mg/kg dose of clozapine from vehicle in a two choice drug discrimination task. Full substitution occurred with the 5-HT2A inverse agonist M100907 and the two preferential D4/5-HT2/α1 receptor antagonists Lu 37-114 ((S)-1-(3-(2-(4-(1H-indol-5-yl)piperazin-1-yl)ethyl)indolin-1-yl)ethan-1-one) and Lu 37-254 (1-(3-(4-(1H-indol-5-yl)piperazin-1-yl)propyl)-3,4-dihydroquinolin-2(1H)-one). Partial substitution occurred with the D4 receptor antagonist Lu 38-012 and the α1 adrenoceptor antagonist prazosin. Drugs selective for 5-HT2C, 5-HT6 muscarinic, histamine H1, and benzodiazepine receptors did not substitute for clozapine. The present findings suggest that 5-HT2A inverse agonism and D4 receptor antagonism mediate the discriminative stimulus properties of 1.25mg/kg clozapine in rats, and further confirm that clozapine produces a complex compound discriminative stimulus.

M100907 attenuates elevated grooming behavior in the BTBR mouse.

Individuals with autism spectrum disorder (ASD) exhibit social-communication deficits along with restricted interests and repetitive behaviors (RRBs). To date, there is a lack of effective treatments to alleviate RRBs. A recent study found that treatment with the 5HT2A receptor antagonist M100907 attenuates a reversal learning deficit in the BTBR mouse model of autism. The BTBR mouse also exhibits elevated grooming behavior which may model stereotyped motor behaviors also observed in ASD. The present study examined whether 5HT2A receptor blockade with M100907 at either 0.01 or 0.1mg/kg can reduce repetitive grooming in BTBR mice compared to that of vehicle-treated BTBR and C57BL6/J (B6) mice. M100907 at 0.1mg/kg, but not 0.01mg/kg, significantly attenuated repetitive grooming in BTBR mice compared to that of vehicle-treated BTBR mice. M100907 at either dose did not affect grooming behavior in B6 mice. To determine whether 0.1mg/kg M100907 had a more general effect on activity in BTBR mice, a second experiment determined whether M100907 at 0.1mg/kg affected locomotor activity in BTBR mice. M100907 treatment in BTBR and B6 mice did not alter locomotor activity compared to that of vehicle-treated BTBR and B6 mice. The present findings taken together with past results suggest that treatment with a 5HT2A receptor antagonist may be effective in ameliorating RRBs in ASD.

The α5 subunit containing GABAA receptors contribute to chronic pain.

It has been recently proposed that α5-subunit containing GABAA receptors (α5-GABAA receptors) that mediate tonic inhibition might be involved in pain. The purpose of this study was to investigate the contribution of α5-GABAA receptors in the loss of GABAergic inhibition and in formalin-induced, complete Freund's adjuvant (CFA)-induced and L5 and L6 spinal nerve ligation-induced long-lasting hypersensitivity. Formalin or CFA injection and L5 and L6 spinal nerve ligation produced long-lasting allodynia and hyperalgesia. Moreover, formalin injection impaired the rate-dependent depression of the Hofmann reflex. Peripheral and intrathecal pretreatment or post-treatment with the α5-GABAA receptor antagonist, L-655,708 (0.15-15 nmol), prevented and reversed, respectively, these long-lasting behaviors. Formalin injection increased α5-GABAA receptor mRNA expression in the spinal cord and dorsal root ganglia (DRG) mainly at 3 days. The α5-GABAA receptors were localized in the dorsal spinal cord and DRG colabeling with NeuN, CGRP, and IB4 which suggests their presence in peptidergic and nonpeptidergic neurons. These receptors were found mainly in small and medium sized neurons. Formalin injection enhanced α5-GABAA receptor fluorescence intensity in spinal cord and DRG at 3 and 6 days. Intrathecal administration of L-655,708 (15 nmol) prevented and reversed formalin-induced impairment of rate-dependent depression. These results suggest that α5-GABAA receptors play a role in the loss of GABAergic inhibition and contribute to long-lasting secondary allodynia and hyperalgesia.

OFF! Clip-on Repellent Device With Metofluthrin Tested on Aedes aegypti (Diptera: Culicidae) for Mortality at Different Time Intervals and Distances.

The OFF! Clip-on mosquito-repellent device was tested outdoors against Aedes aegypti (L.). A single treatment device was used against batches of caged adult, nonblood fed Ae. aegypti at multiple locations 0.3m from treatment center. Another set of cages was stationed 0.6m from treatment. A final set of cages was placed 0.9m away. Trials ran for durations of 5, 15, 30, and 60 min. Initial knockdown and mortality after 24 h was recorded. The devices had effective knockdown and mortality. This was not sustained at distances greater than 0.3m from the device.