Hypothalamic tanycytes internalize ghrelin from the cerebrospinal fluid: Molecular mechanisms and functional implications.

OBJECTIVE: The peptide hormone ghrelin exerts potent effects in the brain, where its receptor is highly expressed. Here, we investigated the role of hypothalamic tanycytes in transporting ghrelin across the blood-cerebrospinal fluid (CSF) interface. METHODS: We investigated the internalization and transport of fluorescent ghrelin (Fr-ghrelin) in primary cultures of rat hypothalamic tanycytes, mouse hypothalamic explants, and mice. We also tested the impact of inhibiting clathrin-mediated endocytosis of ghrelin in the brain ventricular system on the orexigenic and locomotor effects of the hormone. RESULTS: In vitro, we found that Fr-ghrelin is selectively and rapidly internalized at the soma of tanycytes, via a GHSR-independent and clathrin-dependent mechanism, and then transported to the endfoot. In hypothalamic explants, we also found that Fr-ghrelin is internalized at the apical pole of tanycytes. In mice, Fr-ghrelin present in the CSF was rapidly internalized by hypothalamic ß-type tanycytes in a clathrin-dependent manner, and pharmacological inhibition of clathrin-mediated endocytosis in the brain ventricular system prolonged the ghrelin-induced locomotor effects. CONCLUSIONS: We propose that tanycyte-mediated transport of ghrelin is functionally relevant, as it may contribute to reduce the concentration of this peptide hormone in the CSF and consequently shortens the duration of its central effects.

Hypothyroidism alters the rhythmicity of the central clock, body temperature and metabolism: evidence of Bmal1 transcriptional regulation by T3.

In mammals, the central circadian oscillator is located in the suprachiasmatic nucleus (SCN). Hypothalamus-pituitary-thyroid axis components exhibit circadian oscillation, regulated by both central clock innervation and intrinsic circadian clocks in the anterior pituitary and thyroid glands. Thyroid disorders alter the rhythmicity of peripheral clocks in a tissue-dependent response; however, whether these effects are influenced by alterations in the master clock remains unknown. This study aimed to characterize the effects of hypothyroidism on the rhythmicity of SCN, body temperature (BT) and metabolism, and the possible mechanisms involved in this signalling. C57BL/6J adult male mice were divided into Control and Hypothyroid groups. Profiles of spontaneous locomotor activity (SLA), BT, oxygen consumption ( V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ ) and respiratory quotient (RQ) were determined under free-running conditions. Clock gene expression, and neuronal activity of the SCN and medial preoptic nucleus (MPOM) area were investigated in light-dark (LD) conditions. Triiodothyronine (T3) transcriptional regulation of Bmal1 promoter activity was evaluated in GH3-transfected cells. Hypothyroidism delayed the rhythmicity of SLA and BT, and altered the expression of core clock components in the SCN. The activity of SCN neurons and their outputs were also affected, as evidenced by the loss of circadian rhythmicity in V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ and RQ and alterations in the neuronal activity pattern of MPOM. In GH3 cells, T3 increased Bmal1 promoter activity in a time-dependent manner. Thyroid hormone may act as a temporal cue for the central circadian clock, and the uncoupling of central and peripheral clocks might contribute to a wide range of metabolic and thermoregulatory impairments observed in hypothyroidism. KEY POINTS: Hypothyroidism alters clock gene expression in the suprachiasmatic nucleus (SCN). Thyroid hypofunction alters the phase of spontaneous locomotor activity and body temperature rhythms. Thyroid hormone deficiency alters the daily pattern of SCN and medial preoptic nucleus neuronal activities. Hypothyroidism alterations are extended to daily oscillations of oxygen consumption and metabolism, which might contribute to the development of metabolic syndrome. Triiodothyronine increases Bmal1 promoter activity acting as temporal cue for the central circadian clock.

Mirtazapine decreased cocaine-induced c-fos expression and dopamine release in rats.

Introduction: Chronic cocaine exposure induces an increase in dopamine release and an increase in the expression of the Fos protein in the rat striatum. It has been suggested that both are necessary for the expression of cocaine-induced alterations in behavior and neural circuitry. Mirtazapine dosing attenuated the cocaine-induced psychomotor and reinforcer effects. Methods: The study evaluates the effect of chronic dosing of mirtazapine on cocaine-induced extracellular dopamine levels and Fos protein expression in rats. Male Wistar rats received cocaine (10 mg/Kg; i.p.) during the induction and expression of locomotor sensitization. The mirtazapine (30 mg/Kg; MIR), was administered 30 minutes before cocaine during the cocaine withdrawal. After each treatment, the locomotor activity was recorded for 30 minutes. Animals were sacrificed after treatment administration. Dopamine levels were determined by high-performance liquid chromatographic (HPLC) in the ventral striatum, the prefrontal cortex (PFC), and the ventral tegmental area (VTA) in animals treated with mirtazapine and cocaine. The quantification of c-fos immunoreactive cells was carried out by stereology analysis. Results: Mirtazapine generated a decrease in cocaine-induced locomotor activity. In addition, mirtazapine decreased the amount of cocaine-induced dopamine and the number of cells immunoreactive to the Fos protein in the striatum, PFC, and VTA. Discussion: These data suggest that mirtazapine could prevent the consolidation of changes in behavior and the cocaine-induced reorganization of neuronal circuits. It would explain the mirtazapine-induced effects on cocaine behavioral sensitization. Thus, these data together could support its possible use for the treatment of patients with cocaine use disorder.

Hypoactivity and neurochemical alterations in the basal ganglia of female Sprague-Dawley rats after repeated exposure to atrazine.

The herbicide atrazine (ATR) has been one of the most widely used herbicides worldwide. However, due to its indiscriminate use, it has been considered an environmental contaminant. Several studies have classified ATR as an endocrine disruptor, and it has been found to have neurotoxic effects on behavior, along with alterations in the dopaminergic, GABAergic, and glutamatergic systems in the basal ganglia of male rodents. These findings suggest that these neurotransmitter systems are targets of this herbicide. However, there are no studies evaluating the neurotoxicity of ATR in female rodents. Our study aimed to assess the effects of repeated IP injections of 100 mg ATR/kg or a vehicle every other day for 2 weeks (six injections) on the locomotor activity, content of monoamines, GABA, glutamate, and glutamine in the striatum, nucleus accumbens, ventral midbrain, and prefrontal cortex, and tyrosine hydroxylase (TH) protein levels in striatum and nucleus accumbens of female rats. Repeated 100 mg ATR/kg injections immediately decreased all the locomotor activity parameters evaluated, and such hypoactivity persisted for at least 48 h after the last ATR administration. The ATR administration increased dopamine and DOPAC content in the nucleus accumbens and the dopamine and DOPAC and serotonin and 5-HIAA content in the ventral midbrain. In contrast, the TH protein levels in the striatum and nucleus accumbens were similar between groups. Meanwhile, GABA, glutamine, and glutamate levels remained unaltered in all brain regions evaluated. The observed behavioral alterations could be associated with the monoamine changes presented by the rats. These data reveal that the nucleus accumbens and ventral midbrain are susceptible to repeated ATR exposure in female rats.

Divergent patterns of locomotor activity in cave isopods (Oniscidea: Styloniscidae) in Neotropics.

In cave environments, stable conditions devoid of light-dark cycles and temperature fluctuations sustain circadian clock mechanisms across various species. However, species adapted to these conditions may exhibit disruption of circadian rhythm in locomotor activity. This study examines potential rhythm loss due to convergent evolution in five semi-aquatic troglobitic isopod species (Crustacea: Styloniscidae), focusing on its impact on locomotor activity. The hypothesis posits that these species display aperiodic locomotor activity patterns. Isopods were subjected to three treatments: constant red light (DD), constant light (LL), and light-dark cycles (LD 12:12), totaling 1656 h. Circadian rhythm analysis employed the Sokolove and Bushell periodogram chi-square test, Hurst coefficient calculation, intermediate stability (IS), and activity differences for each species. Predominantly, all species exhibited an infradian rhythm under DD and LL. There was synchronization of the locomotor rhythm in LD, likely as a result of masking. Three species displayed diurnal activity, while two exhibited nocturnal activity. The Hurst coefficient indicated rhythmic persistence, with LD showing higher variability. LD conditions demonstrated higher IS values, suggesting synchronized rhythms across species. Significant individual variations were observed within species across the three conditions. Contrary to the hypothesis, all species exhibited synchronization under light-dark conditions. Analyzing circadian activity provides insights into organism adaptation to non-cyclical environments, emphasizing the importance of exploring underlying mechanisms.

Reestablishment of ad libitum feeding following partial food deprivation: Impact on locomotor activity, visceral fat, food intake, and circadian glycemic curve.

Food deprivation has been associated with the development of metabolic pathologies. Few studies have explored the repercussions of a partial food deprivation following the reestablishment of an ad libitum diet. This study investigates the impact of a partial food deprivation (an 8-hour food intake restriction coupled with a 4-hour feeding window during the active phase) and the subsequent return to ad libitum feeding on the glycemic curve, food intake, and locomotor behavior. Wistar rats aged 45 days were subjected to 6 weeks of a partial food deprivation followed by 6 weeks of ad libitum feeding. Body weight, visceral fat, food intake, circadian glycemia, oral glucose tolerance, and locomotor activity were evaluated. It was found that the partial food deprivation resulted in the reduction of both the body weight and food intake; however, it increased visceral fat by 60%. Circadian glycemic values were altered at all intervals during the light phase, and glucose sensitivity improved at 60 minutes in the oral glucose tolerance test (OGTT). In the food-deprived group, the locomotor activity rhythm was reduced, with an observed delay in the peak of activity, reduction in total activity, and a decrease in the rhythmicity percentage. After the reestablishment of the ad libitum feeding, there was recovery of body weight, no difference in visceral fat, normalization of the food intake pattern, circadian glycemia, and oral glucose tolerance. Additionally, the return to ad libitum feeding restored locomotor activity, although the duration required for its complete recovery warrants further investigation. In conclusion, partial food deprivation induces physio-metabolic changes in rats, most of which are reversed after reestablishing ad libitum feeding.

Effects of association between resveratrol and ketamine on behavioral and biochemical analysis in mice.

Resveratrol (3,5,4'-trihydroxy-trans-stilbene), a phenol commonly found in grapes and wine, has been associated as protective in experimental models involving alterations in different neurotransmitter systems. However, studies are reporting that resveratrol could have adverse effects. This study evaluated if the association of a low dose of ketamine and resveratrol could induce behavioral manifestations associated with biochemical alterations. Moreover, the effects of treatment with resveratrol and/or ketamine on monoamine oxidase (MAO) activity, oxidative stress markers, and IL-6 levels in the brain were also investigated. Male Swiss mice received a low dose of ketamine (20 mg/kg) for 14 consecutive days, and resveratrol (10, 30, or 100 mg/kg) from day 8 up to day 14 of the experimental period, intraperitoneally. Locomotor, stereotyped behavior, Y-maze, novel recognition object test (NORT), and social interaction were quantified as well as ex vivo analysis of MAO activity, IL-6 levels, and oxidative stress markers (TBARS and total thiol levels) in brain tissues. Ketamine per se reduced the number of bouts of stereotyped behavior on day 8 of the experimental period. Resveratrol per se reduced the locomotor and exploratory activity in the open field, the time of exploration of new objects in the NORT, MAO-A activity in the striatum and increased the IL-6 levels in the cortex. These effects were attenuated when the mice were co-treated with ketamine and resveratrol. There was a decrease in MAO-A activity in the cortex of mice treated with ketamine + resveratrol 100 mg/kg. No significant alterations were found in oxidative stress markers. Resveratrol does not appear to cause summative effects with ketamine on behavioral alterations. However, the effect of resveratrol per se, mainly on locomotor and exploratory activity, should be better investigated.

Evaluation of multitarget drugs on the expression of cocaine-induced locomotor sensitization in male rats: A comparative study.

Purpose: - Cocaine use disorder (CUD) is a complex disease. Several studies have shown the efficacy of multitarget drugs used to treat CUD. Here we compare the efficacy of mirtazapine (MIR), pindolol (PIN), fluoxetine (FLX), risperidone (RIS), trazodone (TRZ), ziprasidone (ZPR), ondansetron (OND), yohimbine (YOH), or prazosin (PRZ), to reduce long-term cocaine-induced locomotor activity and the expression of cocaine-induced locomotor sensitization in rats. Methods: - The study consists of four experiments, which were divided into four experimental phases. Induction (10 days), cocaine withdrawal (30 days), expression (10 days), and post-expression phase (10 days). Male Wistar rats were daily dosed with cocaine (10 mg/kg; i.p.) during the induction and post-expression phases. During drug withdrawal, the MIR, PIN, FLX, RIS, TRZ, ZPR, OND, YOH, or PRZ were administered 30 min before saline. In the expression, the multitarget drugs were administered 30 min before cocaine. After each administration, locomotor activity for each animal was recorded for 30 min.During the agonism phase, in experiment four, 8-OH-DPAT, DOI, CP-809-101, SR-57227A, or clonidine (CLO) was administered 30 min before MIR and 60 min before cocaine. After each administration, locomotor activity for each animal was recorded for 30 min. Results: -MIR, FLX, RIS, ZPR, OND, or PRZ attenuated the cocaine-induced locomotor activity and cocaine locomotor sensitization. PIN, TRZ, and YOH failed to decrease cocaine locomotor sensitization. At the optimal doses used, PIN, FLX, RIS, TRZ, ZPR, OND, YOH, or PRZ failed to attenuate long-term cocaine locomotor activation. MIR generated a decrease in cocaine-induced locomotor activity of greater magnitude and duration than the other multitarget drugs evaluated. Conclusion: - At the optimal doses of multitarget drugs evaluated, MIR was the multitarget drug that showed the greatest long-term cocaine-induced behavior effects compared to other multitarget drugs.

Angiotensin II involvement in the development and persistence of amphetamine-induced sensitization: Striatal dopamine reuptake implications.

Amphetamine (AMPH) exposure induces behavioural and neurochemical sensitization observed in rodents as hyperlocomotion and increased dopamine release in response to a subsequent dose. Brain Angiotensin II modulates dopaminergic neurotransmission through its AT1 receptors (AT1-R), positively regulating striatal dopamine synthesis and release. This work aims to evaluate the AT1-R role in the development and maintenance of AMPH-induced sensitization. Also, the AT1-R involvement in striatal dopamine reuptake was analysed. The sensitization protocol consisted of daily AMPH administration for 5 days and tested 21 days after withdrawal. An AT1-R antagonist, candesartan, was administered before or after AMPH exposure to evaluate the participation of AT1-R in the development and maintenance of sensitization, respectively. Sensitization was evaluated by locomotor activity and c-Fos immunostaining. Changes in dopamine reuptake kinetics were evaluated 1 day after AT1-R blockade withdrawal treatment, with or without the addition of AMPH in vitro. The social interaction test was performed as another behavioural output. Repeated AMPH exposure induced behavioural and neurochemical sensitization, which was prevented and reversed by candesartan. The AT1-R blockade increased the dopamine reuptake kinetics. Neither the AMPH administration nor the AT1-R blockade altered the performance of social interaction. Our results highlight the AT1-R's crucial role in AMPH sensitization. The enhancement of dopamine reuptake kinetics induced by the AT1-R blockade might attenuate the neuroadaptive changes that lead to AMPH sensitization and its self-perpetuation. Therefore, AT1-R is a prominent candidate as a target for pharmacological treatment of pathologies related to dopamine imbalance, including drug addiction and schizophrenia.

Influence of maternal high-fat diet on offspring's locomotor activity during anxiety-related behavioral tests: A systematic review.

The aim of this review was to summarize and discuss the impact of a maternal high-fat diet on the locomotor activity of offspring during anxiety-related behavioral tests. A search was performed in the LILACS, Web of Science, SCOPUS and PUMBED databases, using the following inclusion criteria: studies in which rodent dams were submitted to a high-fat diet during gestation and/or lactation and in which the locomotor activity parameters of offspring were evaluated during an anxiety-related test. Twenty-three articles met these criteria and were included. Most studies, 14 out of 23, found that a maternal high-fat diet did not alter offspring locomotor activity. Six articles found that a maternal high-fat diet increased the locomotor activity of offspring, while three found decreased locomotion. This effect may be associated with the initial response to the test and the fact that it was the first day of exposure to the apparatus.

Evaluation of spontaneous exploratory and anxiety-related behaviors of mice treated with gymnopilins obtained from the mushroom Gymnopilus imperialis (Agaricomycetes, Basidiomycota).

Gymnopilins are long chain oligoisoprenoids produced through the condensation of isoprene units from MEV and MEP biosynthetic pathways. In Gymnopilus, these carotenoid-like molecules are recognized as major compounds in some species. In the present study, oligoisoprenoids derived from gymnopilins were dereplicated from Gymnopilus imperialis, a mushroom-forming basidiomycete, using liquid chromatographic coupled with high-resolution mass spectrometry (tandem LC-HRMS/MS) and GNPS. From the dichloromethane extract (Gym-DCM) of G. imperialis we annotated 3 oligoisoprenoids from the GNPS molecular library spectra and 15 analogs from the curation of the molecular networking. Data from NMR spectroscopic of the extract confirmed the annotation of the metabolites. Based on the literature data suggesting the neurotoxic effect of gymnopilins, we investigated the effects of the administering different doses of gymnopilin extracts (1, 4 or 10 mg/kg) and diazepam (4 mg/kg) on the acquisition of object recognition memory (ORM) in mice. By studying novel object recognition memory (ORM), a type of non-aversive memory. ORM was assessed based on the total time of spontaneous exploration of both objects, the discrimination index (DI), and the frequency of contact with both objects. Our present findings reveal, for the first time, that gymnopilins treatment before training modulates ORM in a dose-dependent manner. It is also suggested that differential effects on memory might be related to differential effects on GABAA receptors but do not exclude its effects in other neurotransmitter systems. Another class of secondary metabolites, alkaloids, might modulate AChR, which is essential for maintaining object recognition memory over time.

Evaluation of insemination, blood feeding, and Plasmodium vivax infection effects on locomotor activity patterns of the malaria vector Anopheles darlingi (Diptera: Culicidae).

Circadian behavioral patterns in mosquitoes can be observed through their locomotor activity, which includes fundamental behaviors such as foraging, mating, and oviposition. These habits, which are fundamental to the life cycle of Anopheles mosquitoes, are closely related to pathogen transmission to humans. While rhythmic cycles of locomotor activity have been described in Anopheles species, no studies have been conducted on Anopheles darlingi species, the main malaria vector in the Amazon region. The aim of this study was to investigate how insemination status, blood meal, and Plasmodium vivax infection affect the locomotor activity of An. darlingi. The experiments were performed with 3- to 10-day-old An. darlingi females, which had been fed with 15% honey solution. These mosquitoes were obtained from the Malaria Vector Production and Infection Platform (PIVEM)/FIOCRUZ-RO. The experimental groups were divided into four categories: virgin vs. inseminated, unfed virgin vs. blood-fed virgin, unfed inseminated vs. blood-fed inseminated, and infected blood vs. uninfected blood. Locomotor activity was monitored using the Flybox equipment, capturing images that were subsequently converted into video to measure the insect activity, using PySoLo software. The periodicity and rhythmicity of mosquito locomotor activity were analyzed using MatLab® software. The locomotor activity of An. darlingi females showed a nocturnal and bimodal pattern under LD conditions. When comparing the insemination states and blood meal, there was a reduction in the locomotor activity in inseminated and blood-fed females. However, the P. vivax+ infection did not increase locomotor activity of An. darlingi species.

The Brazilian Toxoplasma gondii strain BRI caused greater inflammation and impairment in anxiogenic behavior in mice, which was reverted by rosuvastatin treatment.

This study aimed to investigate the effect of rosuvastatin treatment on anxiety-related behavior and short- and long-term memory impairment in mice infected with acute RH and BRI strains of Toxoplasma gondii. Balb/C mice were infected intraperitoneally and after 2 h, oral treatment with rosuvastatin (40 mg/kg/day) was initiated for 4 days. Behaviors related to anxiety and locomotion were evaluated in the open field (OF), and short- and long-term memory through the novel object recognition test (NOR). At the end of the experiments, peritoneal fluid, brain, liver, and lung were collected for T. gondii DNA quantification and histopathological analysis. Infection with BRI strain reduced the dwell time and central locomotion in the OF (p < 0.05), indicating anxiogenic type behavior, while treatment with rosuvastatin reversed this response (p < 0.05). RH strain infection did not alter any behavior in the OF (p > 0.05) and both strains impaired short- and long-term memory (NOR test), but with no significant treatment effect (p > 0.05). The BRI strain was shown to be more damaging in relation to anxiogenic type behavior when compared to the RH strain (p < 0.05), whereas rosuvastatin reduced this damaging effect in BRI. The treatment reduced the parasite load in the peritoneal lavage, liver, and lung of animals infected with both acute strains; however, it significantly (p < 0.05) attenuated the inflammatory process only in BRI-infected and treated animals, showing that non-archetypal genotypes are more damaging in rodents. This suggests that rosuvastatin may be a drug with great therapeutic potential against T. gondii mainly to reduce damage from virulent strains.

Antinociceptive effect of Nephelium lappaceum L. fruit peel and the participation of nitric oxide, opioid receptors, and ATP-sensitive potassium channels.

Introduction: Nephelium lappaceum L. (Sapindaceae) is a plant known as rambutan. It is used for various purposes in traditional medicine. Objective: We aimed to evaluate the antinociceptive effects of the ethanol extract of the fruit peel of N. lappaceum (EENL), the mechanisms involved in these effects, and the acute toxicity in zebrafish. Methods: We performed chromatography coupled to mass spectrometry, acute toxicity assay in zebrafish, and evaluation in mice submitted to models of nociception and locomotor activity. Results: We identified (epi)-catechin, procyanidin B, and ellagic acid and its derivatives in EENL. We did not find any toxicity in zebrafish embryos incubated with EENL. The locomotor activity of mice submitted to oral pretreatment with EENL was not changed, but it reduced the abdominal constrictions induced by acetic acid, the licking/biting time in both the first and second phase of formalin testing and capsaicin testing, and carrageenan-induced paw mechanical allodynia. Oral pretreatment with EENL increased latency time in the hot plate test. This antinociceptive effect was significantly reversed by naloxone, L-arginine, and glibenclamide respectively showing the participation of opioid receptors, nitric oxide, and KATP channels as mediators of EENL-induced antinociception. Conclusion: EENL causes antinociception with the participation of opioid receptors, nitric oxide, and KATP channels, and is not toxic to zebrafish.

Suprachiasmatic nucleus promotes hyperglycemia induced by sleep delay.

Short sleep is linked to disturbances in glucose metabolism and may induce a prediabetic condition. The biological clock in the suprachiasmatic nucleus (SCN) regulates the glucose rhythm in the circulation and the sleep-wake cycle. SCN vasopressin neurons (SCNVP) control daily glycemia by regulating the entrance of glucose into the arcuate nucleus (ARC). Thus, we hypothesized that sleep delay may influence SCN neuronal activity. We, therefore, investigated the role of SCNVP when sleep is disrupted by forced locomotor activity. After 2 h of sleep delay, rats exhibited decreased SCNVP neuronal activity, a decrease in the glucose transporter GLUT1 expression in tanycytes lining the third ventricle, lowered glucose entrance into the ARC, and developed hyperglycemia. The association between reduced SCNVP neuronal activity and hyperglycemia in sleep-delayed rats was evidenced by injecting intracerebroventricular vasopressin; this increased GLUT1 immunoreactivity in tanycytes, thus promoting normoglycemia. Following sleep recovery, glucose levels decreased, whereas SCNVP neuronal activity increased. These results imply that sleep-delay-induced changes in SCNVP activity lead to glycemic impairment, inferring that disruption of biological clock function might represent a critical step in developing type 2 diabetes.

Crude saliva of Amblyomma cajennense sensu stricto (Acari: Ixodidae) reduces locomotor activity and increases the hemocyte number in the females of Aedes aegypti (Diptera: Culicidae).

Aedes aegypti are vector insects of arboviruses such as dengue, Zika, and chikungunya. All available vector control methods have limited efficacy, highlighting the urgent need to find alternative ones. Evidence shows that arachnids like ticks are sources of biologically active compounds. Moreover, chemical modulation of the locomotor and immune systems of vector insects can be used to control arbovirus transmission. The present study evaluated the effectiveness of crude saliva of female Amblyomma cajennense sensu stricto (s.s.) ticks in reducing locomotor activity and inducing an immune response in Ae. aegypti females. Additionally, the study evaluated the protein constitution of tick saliva. For this purpose, the crude saliva obtained from several semi-engorged A. cajennense females was used. A volume of 0.2 nL of crude tick saliva was administered to mosquitoes by direct intrathoracic microinjection. The effect of the tick's saliva on the locomotor activity of the mosquito was observed using Flybox, a video-automated monitoring system, and the hemolymph hemocyte levels were quantified by reading slides under a light microscope. The protein concentration of the crude tick saliva was 1.27 µg/µL, and its electrophoretic profile indicates the presence of proteins with a molecular weight ranging between ∼17 and 95 kDa. Microplusins, ixodegrins, cystatin, actins, beta-actin, calponin, albumin, alpha-globulins, and hemoglobin were the main proteins identified by proteomics in the saliva of A. cajennense. The microinjected saliva had low toxicity for Ae. aegypti females and significantly reduced their locomotor activity, especially in the transition between the light and dark phases. The crude tick saliva did not change the period and rhythmicity of the circadian cycle. The tick saliva significantly increased the number of hemocytes two days after injection and reduced it after five days. These results suggest that further evaluation of the biological properties of tick saliva proteins against Ae. aegypti would be of interest.

Activation of a hypothalamus-habenula circuit by mechanical stimulation inhibits cocaine addiction-like behaviors.

BACKGROUND: Mechanoreceptor activation modulates GABA neuron firing and dopamine (DA) release in the mesolimbic DA system, an area implicated in reward and substance abuse. The lateral habenula (LHb), the lateral hypothalamus (LH), and the mesolimbic DA system are not only reciprocally connected, but also involved in drug reward. We explored the effects of mechanical stimulation (MS) on cocaine addiction-like behaviors and the role of the LH-LHb circuit in the MS effects. MS was performed over ulnar nerve and the effects were evaluated by using drug seeking behaviors, optogenetics, chemogenetics, electrophysiology and immunohistochemistry. RESULTS: Mechanical stimulation attenuated locomotor activity in a nerve-dependent manner and 50-kHz ultrasonic vocalizations (USVs) and DA release in nucleus accumbens (NAc) following cocaine injection. The MS effects were ablated by electrolytic lesion or optogenetic inhibition of LHb. Optogenetic activation of LHb suppressed cocaine-enhanced 50 kHz USVs and locomotion. MS reversed cocaine suppression of neuronal activity of LHb. MS also inhibited cocaine-primed reinstatement of drug-seeking behavior, which was blocked by chemogenetic inhibition of an LH-LHb circuit. CONCLUSION: These findings suggest that peripheral mechanical stimulation activates LH-LHb pathways to attenuate cocaine-induced psychomotor responses and seeking behaviors.

A New Bioassay for the Detection of Paralytic and Amnesic Biotoxins Based on Motor Behavior Impairments of Zebrafish Larvae.

The global concern about the increase of harmful algal bloom events and the possible impacts on food safety and aquatic ecosystems presents the necessity for the development of more accessible techniques for biotoxin detection for screening purposes. Considering the numerous advantages that zebrafish present as a biological model and particularly as a toxicants sentinel, we designed a sensitive and accessible test to determine the activity of paralytic and amnesic biotoxins using zebrafish larvae immersion. The ZebraBioTox bioassay is based on the automated recording of larval locomotor activity using an IR microbeam locomotion detector, and manual assessment of four complementary responses under a simple stereoscope: survival, periocular edema, body balance, and touch response. This 24 h acute static bioassay was set up in 96-well microplates using 5 dpf zebrafish larvae. For paralytic toxins, a significant decrease in locomotor activity and touch response of the larvae was detected, allowing a detection threshold of 0.1-0.2 µg/mL STXeq. In the case of the amnesic toxin the effect was reversed, detecting hyperactivity with a detection threshold of 10 µg/mL domoic acid. We propose that this assay might be used as a complementary tool for environmental safety monitoring.

Neuroprotective effects of resistance physical exercise on the APP/PS1 mouse model of Alzheimer's disease.

Introduction: Physical exercise has beneficial effects by providing neuroprotective and anti-inflammatory responses to AD. Most studies, however, have been conducted with aerobic exercises, and few have investigated the effects of other modalities that also show positive effects on AD, such as resistance exercise (RE). In addition to its benefits in developing muscle strength, balance and muscular endurance favoring improvements in the quality of life of the elderly, RE reduces amyloid load and local inflammation, promotes memory and cognitive improvements, and protects the cortex and hippocampus from the degeneration that occurs in AD. Similar to AD patients, double-transgenic APPswe/PS1dE9 (APP/PS1) mice exhibit Αß plaques in the cortex and hippocampus, hyperlocomotion, memory deficits, and exacerbated inflammatory response. Therefore, the aim of this study was to investigate the effects of 4 weeks of RE intermittent training on the prevention and recovery from these AD-related neuropathological conditions in APP/PS1 mice. Methods: For this purpose, 6-7-month-old male APP/PS1 transgenic mice and their littermates, negative for the mutations (CTRL), were distributed into three groups: CTRL, APP/PS1, APP/PS1+RE. RE training lasted four weeks and, at the end of the program, the animals were tested in the open field test for locomotor activity and in the object recognition test for recognition memory evaluation. The brains were collected for immunohistochemical analysis of Aß plaques and microglia, and blood was collected for plasma corticosterone by ELISA assay. Results: APP/PS1 transgenic sedentary mice showed increased hippocampal Aß plaques and higher plasma corticosterone levels, as well as hyperlocomotion and reduced central crossings in the open field test, compared to APP/PS1 exercised and control animals. The intermittent program of RE was able to recover the behavioral, corticosterone and Aß alterations to the CTRL levels. In addition, the RE protocol increased the number of microglial cells in the hippocampus of APP/PS1 mice. Despite these alterations, no memory impairment was observed in APP/PS1 mice in the novel object recognition test. Discussion: Altogether, the present results suggest that RE plays a role in alleviating AD symptoms, and highlight the beneficial effects of RE training as a complementary treatment for AD.

Neonatal treatment with fluoxetine alters locomotor activity and the cortical glial/neuron index in rats with cerebral palsy.

Cerebral palsy (CP) is characterized by motor disorders, including deficits in locomotor activity, coordination, and balance. Selective serotonin reuptake inhibitors have been shown to play an important role in brain plasticity. This study investigates the effect of neonatal treatment using fluoxetine on locomotor activity and histomorphometric parameters of the primary somatosensory cortex (S1) in rats submitted to an experimental model of CP. CP was found to reduce bodyweight and locomotion parameters and also to increase the glia/neuron index in the S1. Administration of fluoxetine 10 mg/kg reduced bodyweight, impaired locomotor activity parameters, and increased the number of glial cells and the glia/neuron ratio in the S1 in rats with CP. However, treatment with fluoxetine 5 mg/kg was not found to be associated with adverse effects on locomotor activity and seems to improve histomorphometric parameters by way of minor changes in the S1 in animals with CP. These results thus indicate that experimental CP, in combination with the use of a high dose of fluoxetine (10 mg/kg), impairs locomotor and histomorphometric parameters in the S1, while treatment with a low dose of fluoxetine (5 mg/kg) averts the negative outcomes associated with a high dose of fluoxetine in relation to these parameters but produces no protective effect.