Impact of short-term oral dose of cinnamtannin A2, an (-)-epicatechin tetramer, on spatial memory and adult hippocampal neurogenesis in mouse

Recent epidemiological and intervention studies have suggested that polyphenol-rich plant food consumption reduced the risk of cognitive decline. However, the findings were tentative and by no means definitive. In the present study, we examined the impact of short-term oral administration of cinnamtannin A2 (A2), an (-)-epicatechin tetramer, on adult hippocampal neurogenesis and cognitive function in mice. Mice received supplementation with vehicle (20% glycerol) or 100 μg/kg A2 for 10 days. Then, we conducted the open field test, the object location test, and the novel object test. In the open field test, the A2-treated group tended to spend more time in the center of the arena, compared to the vehicle-treated group. The A2-treated group spent significantly more time exploring objects placed in different locations, compared to the vehicle-treated group. There were no significant differences between groups in the object preference index or in the novel object test. In addition, A2 administration significantly increased the number of hippocampal bromodeoxyuridine-labeled cells in the dentate gyrus, but not in the CA1 or CA3 regions. These results suggested that short-term administration of A2 may impact spatial memory by enhancing neurogenesis in the dentate gyrus of adult mice.

Zebrafish Model for Studying Dexamethasone-Induced Muscle Atrophy and Preventive Effect of Maca (Lepidium meyenii)

Loss of myofibers during muscle atrophy affects functional capacity and quality of life. Dexamethasone, an inducer of rapid atrophy of skeletal myofibers, has been studied as a glucocorticoid receptor in muscle atrophy or motor neurodegeneration. In this study, we examined dexamethasone-induced muscle atrophy using zebrafish (Danio rerio), a vertebrate model, and assessed whether administration of Lepidium meyenii (maca) as a dietary supplement can prevent muscle atrophy. Changes in skeletal myofibers in zebrafish were evaluated after exposure to dexamethasone for different periods and at different concentrations. Under optimized conditions, zebrafish pre-fed with maca for 3 days were exposed to 0.01% dexamethasone for 1 h/day for 7 days. Thereafter, myofiber loss, damaged muscle contractile proteins, and abnormal exploratory behavior due to the structural and functional impairment of skeletal muscle associated with muscle atrophy were investigated using hematoxylin-eosin, immunofluorescence staining, and behavioral analyses. Our findings suggest that dexamethasone induces muscle atrophy in zebrafish, inhibiting exploratory behavior by inducing myofiber loss, inhibiting muscle contraction, and causing changes in endurance and velocity. Thus, the zebrafish model can be used to screen pharmaceutical agents and to study muscle atrophy. Furthermore, maca is a potential dietary supplement to prevent muscle atrophy, as it protects muscle fibers.

Contribution of the Adenosine 2A Receptor to Behavioral Effects of Tetrahydrocannabinol, Cannabidiol and PECS-101

The cannabis-derived molecules, ∆⁹ tetrahydrocannabinol (THC) and cannabidiol (CBD), are both of considerable therapeutic interest for a variety of purposes, including to reduce pain and anxiety and increase sleep. In addition to their other pharmacological targets, both THC and CBD are competitive inhibitors of the equilibrative nucleoside transporter-1 (ENT-1), a primary inactivation mechanism for adenosine, and thereby increase adenosine signaling. The goal of this study was to examine the role of adenosine A2A receptor activation in the effects of intraperitoneally administered THC alone and in combination with CBD or PECS-101, a 4′-fluorinated derivative of CBD, in the cannabinoid tetrad, elevated plus maze (EPM) and marble bury assays. Comparisons between wild-type (WT) and A2AR knock out (A2AR-KO) mice were made. The cataleptic effects of THC were diminished in A2AR-KO; no other THC behaviors were affected by A2AR deletion. CBD (5 mg/kg) potentiated the cataleptic response to THC (5 mg/kg) in WT but not A2AR-KO. Neither CBD nor THC alone affected EPM behavior; their combination produced a significant increase in open/closed arm time in WT but not A2AR-KO. Both THC and CBD reduced the number of marbles buried in A2AR-KO but not WT mice. Like CBD, PECS-101 potentiated the cataleptic response to THC in WT but not A2AR-KO mice. PECS-101 also reduced exploratory behavior in the EPM in both genotypes. These results support the hypothesis that CBD and PECS-101 can potentiate the cataleptic effects of THC in a manner consistent with increased endogenous adenosine signaling.

A Reliable High-Throughput Screening Model for Antidepressant

Depression is the most frequent affective disorder and is the leading cause of disability worldwide. In order to screen antidepressants and explore molecular mechanisms, a variety of animal models were used in experiments, but there is no reliable high-throughput screening method. Zebrafish is a common model organism for mental illness such as depression. In our research, we established chronic unpredictable mild stress (CUMS) models in C57BL/6 mice and zebrafish; the similarities in behavior and pathology suggest that zebrafish can replace rodents as high-throughput screening organisms. Stress mice (ip., 1 mg/kg/d, 3 days) and zebrafish (10 mg/L, 20 min) were treated with reserpine. As a result, reserpine caused depression-like behavior in mice, which was consistent with the results of the CUMS mice model. Additionally, reserpine reduced the locomotor ability and exploratory behavior of zebrafish, which was consistent with the results of the CUMS zebrafish model. Further analysis of the metabolic differences showed that the reserpine-induced zebrafish depression model was similar to the reserpine mice model and the CUMS mice model in the tyrosine metabolism pathway. The above results showed that the reserpine-induced depression zebrafish model was similar to the CUMS model from phenotype to internal metabolic changes and can replace the CUMS model for antidepressants screening. Moreover, the results from this model were obtained in a short time, which can shorten the cycle of drug screening and achieve high-throughput screening. Therefore, we believe it is a reliable high-throughput screening model.

LPS tolerance prevents anxiety-like behavior and amygdala inflammation of high-fat-fed dams' adolescent offspring

Maternal high-fat diets (HFD) can generate inflammation in the offspring's amygdala, which can lead to anxiety-like behaviors. Conversely, lipopolysaccharide (LPS) tolerance can reduce neuroinflammation in the offspring caused by maternal high-fat diets. This study evaluated the combination of LPS tolerance and high-fat maternal diet on amygdala's inflammatory parameters and the anxiety-like behavior in adolescent offspring. Female pregnant Wistar rats received randomly a standard diet or a high-fat diet during gestation and lactation. On gestation days 8, 10, and 12, half of the females in each group were intraperitonially injected with LPS (0.1 mg.kg-1). After weaning, the male offspring (n = 96) were placed in individual boxes in standard conditions, and when 6 weeks-old, the animals underwent: Open-Field, Light/Dark Box, Elevated Plus-Maze, and Rotarod tests. When 50 days-old the offspring were euthanized and the amygdala removed for cytokine and redox status analysis. The offspring in the HFD group showed lower amygdala IL-10 levels, high IL-6/IL-10 ratio, and anxiety-like behaviors. These effects were attenuated in the HFD offspring submitted to LPS tolerance, which showed an anti-inflammatory compensatory response in the amygdala. Also, this group showed a higher activity of the enzyme catalase in the amygdala. In addition, receiving the combination of LPS tolerance and maternal HFD did not lead to anxiety-like behavior in the offspring. The results suggest that LPS tolerance attenuated amygdala inflammation through an anti-inflammatory compensatory response besides preventing anxiety-like behavior caused by the high-fat maternal diet.

Incorporating inter-individual variability in experimental design improves the quality of results of animal experiments

Inter-individual variability in quantitative traits is believed to potentially inflate the quality of results in animal experimentation. Yet, to our knowledge this effect has not been empirically tested. Here we test whether inter-individual variability in emotional response within mouse inbred strains affects the outcome of a pharmacological experiment. Three mouse inbred strains (BALB/c, C57BL/6 and 129S2) were behaviorally characterized through repeated exposure to a mild aversive stimulus (modified Hole Board, five consecutive trials). A multivariate clustering procedure yielded two multidimensional response types which were displayed by individuals of all three strains. We show that systematic incorporation of these individual response types in the design of a pharmacological experiment produces different results from an experimental pool in which this variation was not accounted for. To our knowledge, this is the first study that empirically confirms that inter-individual variability affects the interpretation of behavioral phenotypes and may obscure experimental results in a pharmacological experiment.

Testosterone ameliorates age-related brain mitochondrial dysfunction

Brain mitochondrial dysfunction and reduced testosterone levels are common features of aging in men. Although evidence suggests that the two phenomena are interrelated, it is unclear whether testosterone supplementation ameliorates mitochondrial dysfunction in the aging male brain. Here, we show that testosterone supplementation significantly alleviates exploratory behavioral deficits and oxidative damage in the substantia nigra and hippocampus of aging male rats. These effects were consistent with improved mitochondrial function, reflected by testosterone-induced increases in mitochondrial membrane potential (MMP), antioxidant enzyme (GSH-PX, catalase, and Mn-SOD) expression/activity, and mitochondrial respiratory complex activities in both brain regions. Furthermore, elevated PGC-1α, NRF-1, and TFAM expression (suggestive of enhanced mitochondrial biogenesis), increased citrate synthase activity, mtDNA copy number, and ND1, COX1, and ATP6 expression (indicative of increased mitochondrial content), as well as increased PINK1/Parkin and decreased P62 expression (suggesting mitophagy activation), were detected in the substantial nigra and hippocampus of aged male rats after testosterone supplementation. These findings suggest that testosterone supplementation may be a viable approach to ameliorating brain mitochondrial dysfunction and thus prevent or treat cognitive-behavioral deficits and neurodegenerative conditions associated with aging.

Effects of the aqueous extract of Phyllanthus niruri Linn during pregnancy and lactation on neurobehavioral parameters of rats' offspring

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus niruri L. (Phyllanthaceae) is a plant used in traditional medicine, mainly to treat kidney stones. However, the effects of maternal exposure to P. niruri remain poorly explored.

AIM OF THE STUDY

The objective of this study was to investigate the effects of administration of aqueous extract of P. niruri (AEPN) during pregnancy and lactation, in maternal toxicity, reflex maturation, and offspring memory.

MATERIALS AND METHODS

Pregnant rats were divided into three groups (n = 8/group): Control (vehicle), AEPN 75, and AEPN 150 (each respectively treated with P. niruri at a dose of 75 and 150 mg/kg/day). The animals were treated via intragastric gavage during pregnancy and lactation. Weight gain, feed intake, and reproductive performance were analyzed in the mothers. In the offspring, the following tests were performed: Neonatal Reflex Ontogeny, Open Field Habituation Test and the Object Recognition Test in adulthood.

RESULTS

Maternal exposure to AEPN did not influence weight gain, feed intake, or reproductive parameters. In the offspring, anticipation of reflex ontogenesis (time of completion) was observed (p < 0.05). During adulthood, the AEPN groups presented decreases in exploratory activity upon their second exposure to the Open Field Habituation Test (in a dose-dependent manner) (p < 0.05). In the Object Recognition Test, administration of the extract at 75 and 150 mg/kg induced significant dose-dependent improvements in short and long-term memory (p < 0.05).

CONCLUSION

Administration of the AEPN accelerated the reflex maturation in neonates, and improved offspring memory while inducing no maternal or neonatal toxicity.

Effects of olanzapine on anxiety-related behaviour in male and female rats assessed after 21-24 and 42-45 days of chronic treatment

Olanzapine can decrease anxiety and impair memory, but there is limited information about length of treatment or sex differences in its effectiveness. Therefore, effects of 21-24 and 41-45 days of treatment and sex differences on anxiety-related behaviour and spatial memory were assessed in PVG/c (PVG/c is the internationally recognised way of referring to this rat strain) male and female rats. From 70 days after birth (PND70), all rats received no drug or 6, 11 or 15 mg/kg/day olanzapine via drinking water. From PND91, they were given four daily tests in an open field, light-dark box, zero maze and Y maze, and then again 21 days later from PND112. At PND91-94, all olanzapine doses decreased open-field ambulation and walking, and 6 and 15 mg/kg/day decreased rearing, increased immobility while 15 mg/kg/day decreased shuttles in the light/dark box (all suggesting higher anxiety). At PND112-115, 11 mg/kg/day increased open-field ambulation, walking, rearing, centre occupancy and light/dark-box shuttles and light-side entries while decreasing open-field immobility and corner occupancy (all suggesting lower anxiety). There were also several results in the open field and light/dark box suggesting olanzapine decreased anxiety for males but increased it for females. A significant olanzapine-related preference for the novel Y-maze arm either improved spatial memory, or decreased anxiety. Olanzapine thus appeared anxiogenic after 21 days' treatment, becoming anxiolytic after 42 days. This could depend on the sex of the rats (females more responsive to lower doses), and the dose (11 mg/kg/day being most effective). Therefore, while olanzapine was generally anxiolytic, it also had some treatment length- and sex-related anxiogenic effects.

Dexmedetomidine and Clonidine Attenuate Sevoflurane-Induced Tau Phosphorylation and Cognitive Impairment in Young Mice via α-2 Adrenergic Receptor

BACKGROUND

Anesthetic sevoflurane induces tau phosphorylation and cognitive impairment in young mice. The underlying mechanism and the targeted interventions remain largely unexplored. We hypothesized that dexmedetomidine and clonidine attenuated sevoflurane-induced tau phosphorylation and cognitive impairment by acting on α-2 adrenergic receptor.

METHODS

Six-day-old mice received anesthesia with 3% sevoflurane 2 hours daily on postnatal days 6, 9, and 12. Alpha-2 adrenergic receptor agonist dexmedetomidine and clonidine were used to treat the mice with and without the α-2 adrenergic receptor antagonist yohimbine. Mouse hippocampi were harvested and subjected to western blot analysis. The New Object Recognition Test and Morris Water Maze were used to measure cognitive function. We analyzed the primary outcomes by using 2- and 1-way analysis of variance (ANOVA) and Mann-Whitney U test to determine the effects of sevoflurane on the amounts of phosphorylated tau, postsynaptic density-95, and cognitive function in young mice after the treatments with dexmedetomidine, clonidine, and yohimbine.

RESULTS

Both dexmedetomidine and clonidine attenuated the sevoflurane-induced increase in phosphorylated tau amount (94 ± 16.3% [dexmedetomidine plus sevoflurane] versus 240 ± 67.8% [vehicle plus sevoflurane], P < .001; 125 ± 13.5% [clonidine plus sevoflurane] versus 355 ± 57.6% [vehicle plus sevoflurane], P < .001; mean ± standard deviation), sevoflurane-induced reduction in postsynaptic density-95 (82 ± 6.6% [dexmedetomidine plus sevoflurane] versus 31 ± 12.4% [vehicle plus sevoflurane], P < .001; 95 ± 6.4% [clonidine plus sevoflurane] versus 62 ± 18.4% [vehicle plus sevoflurane], P < .001), and cognitive impairment in the young mice. Interestingly, yohimbine reversed the effects of dexmedetomidine and clonidine on attenuating the sevoflurane-induced changes in phosphorylated tau, postsynaptic density-95, and cognitive function.

CONCLUSIONS

Dexmedetomidine and clonidine could inhibit the sevoflurane-induced tau phosphorylation and cognitive impairment via activation of α-2 adrenergic receptor. More studies are needed to confirm the results and to determine the clinical relevance of these findings.

The antidepressant-like effects of the water extract of Panax ginseng and Polygala tenuifolia are mediated via the BDNF-TrkB signaling pathway and neurogenesis in the hippocampus

ETHNOPHARMACOLOGY RELEVANCE

The water extract of Panax ginseng (GT) and Polygala tenuifolia (YT), the main constituents of the commonly used kai-xin-san formula of traditional Chinese medicine, represents SY. It possesses strong neuroprotective effects. Using behavioural tests, we have previously established that the SY formulation exerts superior antidepressant activity than that of GT or YT.

AIM

To elucidate the impact of SY treatment on chronic unpredictable mild stress (CUMS)-induced depressive-like behaviours and the prospective mechanism related to hippocampal neurogenesis and the BDNF signaling pathway.

METHODS

We exposed Sprague-Dawley rats (male; 180-200 g) to CUMS for 35 days. The rats in the experimental treatment groups were daily treated with either fluoxetine (10 mg kg-1d-1) or SY (67.5, 135, or 270 mg kg-1d-1) orally until the behavioural tests (tail suspension test [TST], novelty-suppressed feeding test [NSFT], sucrose preference test [SPT], and forced swim test [FST]) were completed. We assessed the modifications in the hippocampal neurogenesis and the BDNF signaling pathway post-treatment with CUMS and SY. Additionally, K252a, a tyrosine protein kinase inhibitor, was utilized to evaluate the antidepressant mechanisms of SY.

RESULT

s: The results of SPT, NSFT, FST, and TST in CUMS-exposed rats confirmed the antidepressant actions of SY. Additionally, SY treatment induced the BDNF signaling pathway and reversed the hippocampal neurogenesis caused by CUMS. Moreover, we found that the TrkB antagonist K252a blocked SY effects on behavioural improvement, inhibited the incremental effects of SY on hippocampal neurogenesis, and eliminated the impact of SY on BDNF-TrkB signaling activation. Thus, the impact of SY treatment on BDNF signaling molecules (pAkt, pERK1/2, and pCREB) were significantly inhibited by K252a.

CONCLUSIONS

This study showed that SY acted as an antidepressant in rats exhibiting CUMS-induced depressive-like behaviours, and was facilitated by promoting hippocampal neurogenesis and the BDNF signaling pathway activation. Thus, SY could act as a potential novel supplement or adjuvant to prevent or treat clinical depressive disorders.

A 20-hydroxyecdysone-enriched fraction from Pfaffia glomerata (Spreng.) pedersen roots alleviates stress, anxiety, and depression in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Pfaffia glomerata roots are widely used in Brazil to treat various pathological conditions, particularly psychological disorders. 20-hydroxyecdysone, a phytosteroid present in the plant, can promote greater body resistance against exogenous and endogenous stressors. The objective of this study was to evaluate the possible neuroprotective effect of a 20-hydroxyecdysone-enriched fraction (20E-EF), obtained from P. glomerata roots, in an acute murine stress model.

MATERIAL AND METHODS

The 20E-EF was obtained by partitioning the methanol extract from P. glomerata roots with dichloromethane. Mice were treated by gavage with three doses of 20E-EF (3, 10, and 30 mg/kg) and parameters of stress, anxiety, and depression were evaluated. Biomarkers of oxidative stress (enzymes, antioxidant profile, and oxidized molecules) were evaluated in the cortex, striatum (basal ganglia), and hippocampus of animals treated with 30 mg/kg of 20E-EF.

RESULTS

Mass spectrometry revealed that 20E was the main compound in the dichloromethane fraction. At a dose of 30 mg/kg, 20E-EF reduced stress, anxiety, and depression, while stimulating antioxidant enzymes (catalase, superoxide dismutase, and glutathione peroxidase), promoting antioxidant activity (antioxidant capacity, sulfhydryl groups, and reduced glutathione), and reducing oxidative markers (lipid peroxidation). In addition, 20E increased the concentration of NO in the striatum, possibly improving memory function and antioxidant activity.

CONCLUSION

A 30 mg/kg dose of 20E-EF was able to reduce stress, anxiety, and depression, in addition to maintaining antioxidant defenses of the cortex and striatum. These findings open new perspectives for understanding the therapeutic properties of P. glomerata and the underlying mechanism(s).

Flavonoid compounds isolated from Tibetan herbs, binding to GABAA receptor with anxiolytic property

ETHNOPHARMACOLOGICAL RELEVANCE

Previously, the phytochemical constituents of Biebersteinia heterostemon Maxim (BHM) and Arenaria kansuensis Maxim (AKM) were studied and the evaluation of anxiolytic effect based on their extracts was also investigated. The two traditional Tibetan herbs, BHM and AKM, have been widely used in Qinghai-Tibet Plateau for cardiopulmonary disorders and neuropsychiatric diseases. The anxiolytic activities of a number of agents mediated by α2/3-containing GABAA receptors (GABAARs) have been demonstrated through the genetic and pharmacological studies. Flavonoids, such as flavones and flavanols, are a class of ligands that act at GABAARs and exhibit anxiolytic effects in vivo. Here, the flavonoids are the predominant constituents isolated from BHM and AKM. And our purpose is to investigate structure-activity relationships of the flavonoid compounds with binding to BZ-S of GABAAR complexes, and to search for anxiolytic constituents that lack undesirable-effects such as sedation and myorelaxation.

MATERIALS AND METHODS

The flavonoid constituents were separated and purified through the repeatedly silica gel or/and C18 column chromatography. The affinities of the compounds for BZ-S of GABAARs were detected by the radioreceptor binding assay with bovine cerebellum membranes, in which the different recombinant subunits-containing GABAARs were expressed in HEK 293T cells. The behavior tests, including elevated plus maze, locomotor activity, holeboard, rotarod and horizontal wire, were used to determine and evaluate the anxiolytic, sedative, and myorelaxant effects of these flavonoids.

RESULTS

Eleven total flavonoid compounds were obtained from the Tibetan herbs (BHM and AKM). The flavones with 6-and/or 8-OMe possessed the most potent binding affinity to GABAARs, which were based on the result of structure-activity relationships analysis. Demethoxysudachitin (DMS, Ki = 0.59 μM), a flavone that binds to recombinant α1-3/5 subunit-containing GABAARs, was isolated from BHM, and exhibited high anxiolytic activity, without inducing sedation and myorelaxation. Moreover, the anxiolytic effect of DMS was antagonized by flumazenil, suggesting that a mode of action was mediated via the BZ-S of GABAARs.

CONCLUSIONS

This present study indicated that the flavones, especially DMS, are novel GABAAR ligands and therapeutic potential candidates for anxiety.

A mixture of quercetin 4'-O-rhamnoside and isoquercitrin from Tilia americana var. mexicana and its biotransformation products with antidepressant activity in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The aerial parts of Tilia americana var. mexicana (Malvaceae, formerly Tiliaceae) or "sirimo" are used in Mexican traditional medicine for the relief of mild symptoms of mental stress, commonly referred to as "nerve diseases". Individuals use this plant to fall asleep, to calm states of nervous excitement, headaches, mood disorders, and general discomfort. Recent studies indicated that fractions standardized in their flavonoid content possess antidepressant activity in behavioral assays in mice. The present study aims to focus on the evaluation of the antidepressant effect of the mixture of two flavonoids (FMix), and its interaction with serotonergic drugs. Also, the pharmacological effect of the products of the metabolism of aglycone, quercetin, was evaluated in mice subjected to forced swimming test (FST) and open field test (OFT).

MATERIALS AND METHODS

A methanol-soluble extract obtained from leaves of Tilia americana was fractionated in an open column chromatographic separation. One of the fractions contained FMix wich is constituted of the mixture of quercetin 4'-O-rhamnoside (1, 47%) y isoquercitrin (2, 53%). The mice were divided into the several following groups: FMix (0.01, 0.1, 0.5, 1.0, and 2 mg/kg); FMix (1.0 mg/kg) and agonist DOI (2.0 mg/kg); FMix (1.0 mg/kg) and antagonist ketanserin (KET, 0.03 mg/kg) of 5-HT2A receptors; FMix (1.0 mg/kg) and selective agonist 8-OH-DPAT (8-OH, 0.01 mg/kg); FMix (1.0 mg/kg) and antagonist WAY100635 (WAY, 0.5 mg/kg) of 5HT1 receptors; Phloroglucinol (PHL); 3,4-dihydroxy-phenyl acid (DOPAC); p-hydroxyphenyl acetic acid (p-HPAA); and m-hydroxyphenyl acetic acid (m-HPAA) were tested in FST or OFT.

RESULTS

FMix induced dependent-dose antidepressant activity and, at the highest dose administered, a sedative effect was also observed. The 8-OH-DPAT, or the DOI, or the KET combination with FMix (1.0 mg/kg) induced a higher antidepressant effect than compounds alone; there was no effect exerted with WAY. The activity on OFT increased only with the FMix and KET combination. At the same time, the products of the aglycone metabolism of quercetin, that is, DOPAC and p-HPAA, decreased the immobility time of the mice in FST at 1.0 mg/kg, and a dose-curve was formed for these.

CONCLUSION

The antidepressant effect of FMix could depend, at least in part, on the degradation products of quercetin and with a possible action mode through interaction with the serotoninergic system.

Paternal exposure to a common pharmaceutical (Ritalin) has transgenerational effects on the behaviour of Trinidadian guppies

Evidence is emerging that paternal effects, the nongenetic influence of fathers on their offspring, can be transgenerational, spanning several generations. Methylphenidate hydrochloride (MPH; e.g. Ritalin) is a dopaminergic drug that is highly prescribed to adolescent males for the treatment of Attention-deficit/hyperactivity disorder. It has been suggested that MPH could cause transgenerational effects because MPH can affect the male germline in rodents and because paternal effects have been observed in individuals taking similar drugs (e.g. cocaine). Despite these concerns, the transgenerational effects of paternal MPH exposure are unknown. Therefore, we exposed male and female Trinidadian guppies (Poecilia reticulata) to a low, chronic dose of MPH and observed that MPH affected the anxiety/exploratory behaviour of males, but not females. Because of this male-specific effect, we investigated the transgenerational effects of MPH through the paternal line. We observed behavioural effects of paternal MPH exposure on offspring and great-grandoffspring that were not directly administered the drug, making this the first study to demonstrate that paternal MPH exposure can affect descendants. These effects were not due to differential mortality or fecundity between control and MPH lines. These results highlight the transgenerational potential of MPH.

Erythromycin in the aquatic environment: deleterious effects on the initial development of zebrafish

Due to the large volume of erythromycin continuously reaching waterbodies and its high persistence, this antibiotic drug has been detected in the aquatic environment at elevated concentrations. Although the problem of the presence of erythromycin in the environment is evident due to its influence in development of antimicrobial resistance, the toxicological consequences on non-target organisms remain to be determined. There are no apparent data on the impact of environmentally relevant concentrations of erythromycin on developing fish. Data on toxic effects during development are essential for evaluation of environmental risk to organisms. Therefore, the aim of this study was to investigate the effects of exposure to erythromycin on certain parameters including hatchability, survival rate, heart rate, and behavior in developing zebrafish. Zebrafish were exposed to a range of environmentally relevant concentrations of antibiotic (0.001, 0.01, 0.1, 1 μg/L) and one concentration 10-fold higher (10 μg/L). Exposure to erythromycin at 0.1 μg/L delayed hatching and decreased survival rate. Exposure to all tested concentrations increased heart rate. Further, exposure to erythromycin at 1 or 10 μg/L enhanced swimming activity. Our results indicated that erythromycin present in the aquatic environment might lead to disabling consequences in developing fish organisms and subsequently may result in ecological imbalance in the natural environment.

Calcium channels blockers toxins attenuate abdominal hyperalgesia and inflammatory response associated with the cerulein-induced acute pancreatitis in rats

Agents that modulate the activity of high-voltage gated calcium channels (HVCCs) exhibit experimentally and clinically significant effect by relieving visceral pain. Among these agents, the toxins Phα1β and ω-conotoxin MVIIA effectively reduce chronic pain in rodent models. The molecular mechanisms underlying the chronic pain associated with acute pancreatitis (AP) are poorly understood. Hypercalcemia is a risk factor; the role of cytosolic calcium is considered to be a modulator of pancreatitis. Blockade of Ca2+ signals may be useful as a prophylactic treatment of pancreatitis. We explored the pathophysiological roles of three peptide toxins: Phα1β and its recombinant form CTK 01512-2-blockers of TRPA1 receptor and HVCCs and ω-conotoxin MVIIA, a specific blocker of N-type calcium channels in cerulein-induced AP. Cerulein injection elicits AP in rats, evidenced by an increase in hyperalgesic pain, inflammatory infiltration, amylase and lipase secretion, and reactive oxygen species, TNF-α, and p65 NF-κB levels. These effects of cerulein-induced AP were abolished by Phα1β and its recombinant form CTK 01512-2, whereas ω-conotoxin MVIIA had no effect on the induced increase in pancreatic enzyme secretion. Our results demonstrate that Phα1β and CTK 01512-2 toxins-antagonists of HVCCs and TRPA1 receptor presented an effective response profile, in the control of nociception and inflammatory process in the AP model in rats, without causing changes in spontaneous locomotion of the rats.

LL-00066471, a novel positive allosteric modulator of α7 nicotinic acetylcholine receptor ameliorates cognitive and sensorimotor gating deficits in animal models: Discovery and preclinical characterization

α7 nicotinic acetylcholine receptor (α7 nAChR) is an extensively validated target for several neurological and psychiatric conditions namely, dementia and schizophrenia, owing to its vital roles in cognition and sensorimotor gating. Positive allosteric modulation (PAM) of α7 nAChR represents an innovative approach to amplify endogenous cholinergic signaling in a temporally restricted manner in learning and memory centers of brain. α7 nAChR PAMs are anticipated to side-step burgeoning issues observed with several clinical-stage orthosteric α7 nAChR agonists, related to selectivity, tolerance/tachyphylaxis, thus providing a novel dimension in therapeutic strategy and pharmacology of α7 nAChR ion-channel. Here we describe a novel α7 nAChR PAM, LL-00066471, which potently amplified agonist-induced Ca2+ fluxes in neuronal IMR-32 neuroblastoma cells in a α-bungarotoxin (α-BTX) sensitive manner. LL-00066471 showed excellent oral bioavailability across species (mouse, rat and dog), low clearance and good brain penetration (B/P ratio > 1). In vivo, LL-00066471 robustly attenuated cognitive deficits in both procognitive and antiamnesic paradigms of short-term episodic and recognition memory in novel object recognition task (NORT) and social recognition task (SRT), respectively. Additionally, LL-00066471 mitigated apomorphine-induced sensorimotor gating deficits in acoustic startle reflex (ASR) and enhanced antipsychotic efficacy of olanzapine in conditioned avoidance response (CAR) task. Further, LL-00066471 corrected redox-imbalances and reduced cortico-striatal infarcts in stroke model. These finding together suggest that LL-00066471 has potential to symptomatically alleviate cognitive deficits associated with dementias, attenuate sensorimotor gating deficits in schizophrenia and correct redox-imbalances in cerebrovascular disorders. Therefore, LL-00066471 presents potential for management of cognitive impairments associated with neurological and psychiatric conditions.

Neurochemical and behavioral effects of lorazepam: A dose related study

Present study was designed to monitor the dose dependent effects of lorazepam; a benzodiazepine (CNS depressant). It is the primary drug of choice for treatment of anxiety and to produce calming effects. However, repeated administration of this lorazepam causes dependence and this might be caused by increased dopaminergic neurotransmission. Besides dopamine, 5-hydroxy tryptamine (5-HT) has also been reported to have pivotal role in the pathophysiology as well as treatment of anxiety and addiction. Repeated administration of lorazepam might involve altered 5-HT metabolism as well. Present study was therefore designed to monitor dose-dependent effects of lorazepam and to select its optimum dose for further experiments and pharmacological interventions. Effects of lorazepam were monitored on food intake, growth rate, activities in familiar and novel environments, light dark box activity, forced swim test and metabolism of dopamine and 5-HT. oral administration of lorazepam was done at the doses of 0mg/kg, 2mg/kg, 4mg/kg and 6mg/kg. Behaviors parameters were monitored following single administration of lorazepam. Rats were decapitated and whole brain samples were collected and stored at -70°C until neurochemical analysis by HPLC-EC. Findings from the present study could be implicated to increased therapeutic utility of lorazepam and related benzodiazepines.

The cardioprotective and anxiolytic effects of Chaihujialonggumuli granule on rats with anxiety after acute myocardial infarction is partly mediated by suppression of CXCR4/NF-κB/GSDMD pathway

AIMS

Over-expression of CXCR4 activates nuclear translocation of NF-κB, induces high expression of NLRP3, GSDMD, IL-1β and IL-18, which promotes severe inflammatory response following myocardial infarction. Previous studies revealed inflammation induces anxiety after myocardial infarction. The Chaihujialonggumuli granule has anti-inflammatory properties and could tranquillize mind. But the mechanism of its efficacy remains unknown. This study was to investigate the possible mechanism of BFG on cardioprotective and anxiolytic.

METHODS

The expression of CXCR4, NF-κB, NLRP3and GSDMD was measured with western-blot, QRT-PCR. The expression location of CXCR4, NLRP3, GSDMD were determined by immunohistochemistry. IL-1β、IL-18 in the peripheral blood were measured by ELISA. HE staining, Masson staining and transmission electron microscopy were used to observe morphological changes of cardiomyocytes. Echocardiography was used to assess cardiac function after cardiac surgery. Elevated cross maze test and open field test were used to evaluate behaviours. Western blot was used to detect the protein expressions of 5-HT, DA, IL-1β, IL-18 and neuron damage was investigated by Nissl staining in the hippocampus.

RESULTS

The up-regulation of CXCR4, NF-κB, NLRP3 and GSDMD were found in the infarcted area after left coronary artery ligation. Pathological staining and analysis showed that more severe inflammatory cytokines infiltration, myocardial fibrosis, were found in myocardial tissue of the complex group rats. And when compared to the sham group, the levels of IL-1β, IL-18 was increased of the complex group in both peripheral blood and brain. Behavioural test and echocardiography indicated that the rats in complex group exploration behaviours was significantly reduced, and with poor cardiac functional recovery. The AMD3100 had an inhibitory impact of CXCR4 on the activition of its downstream effectors, alleviating inflammatory reaction. Furthermore, the BFG decreased the expression level of CXCR4, NF-κB, GSDMD, NLRP3 in the infarcted area after myocardial infarction, when compared to the complex group. The assays in the brain indicated the BFG suppressed expression and activity of IL-1β, IL-18, and improved 5-HT and DA synthesis.

CONCLUSIONS

In sum, our study indicated that BFG may reduce inflammation, treat co-existing anxiety after myocardial infarction through inhibition of CXCR4/NF-κB/GSDMD signalling.

Neurotoxicity of different amyloid beta subspecies in mice and their interaction with isoflurane anaesthesia

Background

The aim of this study was to assess different amyloid beta subspecies’ effects on behaviour and cognition in mice and their interaction with isoflurane anaesthesia.

Methods

After governmental approval, cannulas were implanted in the lateral cerebral ventricle. After 14 days the mice were randomly intracerebroventricularly injected with Aβ 1–40 (Aβ40), Aβ 1–42 (Aβ42), 3NTyr10-Aβ (Aβ nitro), AβpE3-42 (Aβ pyro), or phosphate buffered saline. Four days after the injection, 30 mice (6 animals per subgroup) underwent general anaesthesia with isoflurane. A “sham” anaesthetic procedure was performed in another 30 mice (6 animals per subgroup, 10 subgroups in total). During the next eight consecutive days a blinded assessor evaluated behavioural and cognitive performance using the modified hole-board test. Following the testing we investigated 2 brains per subgroup for insoluble amyloid deposits using methoxy staining. We used western blotting in 4 brains per subgroup for analysis of tumour-necrosis factor alpha, caspase 3, glutamate receptors NR2B, and mGlu5. Data were analysed using general linear modelling and analysis of variance.

Results

Aβ pyro improved overall cognitive performance (p = 0.038). This cognitive improvement was reversed by isoflurane anaesthesia (p = 0.007), presumably mediated by decreased exploratory behaviour (p = 0.022 and p = 0.037). Injection of Aβ42 was associated with increased anxiety (p = 0.079). Explorative analysis on a limited number of brains did not reveal insoluble amyloid deposits or differences in the expression of tumour-necrosis factor alpha, NR2B, mGlu5, or caspase 3.

Conclusions

Testing cognitive performance after intracerebroventricular injection of different amyloid beta subspecies revealed that Aβ pyro might be less harmful, which was reversed by isoflurane anaesthesia. There is minor evidence for Aβ42-mediated neurotoxicity. Preliminary molecular analysis of biomarkers did not clarify pathophysiological mechanisms.

A selective effect of dopamine on information-seeking

Humans are motivated to seek information from their environment. How the brain motivates this behavior is unknown. One speculation is that the brain employs neuromodulatory systems implicated in primary reward-seeking, in particular dopamine, to instruct information-seeking. However, there has been no causal test for the role of dopamine in information-seeking. Here, we show that administration of a drug that enhances dopamine function (dihydroxy-L-phenylalanine; L-DOPA) reduces the impact of valence on information-seeking. Specifically, while participants under Placebo sought more information about potential gains than losses, under L-DOPA this difference was not observed. The results provide new insight into the neurobiology of information-seeking and generates the prediction that abnormal dopaminergic function (such as in Parkinson's disease) will result in valence-dependent changes to information-seeking.

Fetal Bisphenol-A Induced Changes in Murine Behavior and Brain Gene Expression Persisted in Adult-aged Offspring

In utero Bisphenol A (BPA) exposure has been linked to many deficits during brain development, including sexual differentiation, behavior, and motor coordination. Yet, how BPA induces these disorders and whether its effects are long lasting are largely unknown. In this study, using a mouse model, we demonstrated that in utero exposure to an environmentally relevant dose of BPA induced locomotor deficits, anxiety-like behavior, and declarative memory impairments that persisted into old age (18 months). Compared to the control animals, the BPA-exposed mice had a significant decrease in locomotor activity, exploratory tendencies, and long-term memory, and an increase in anxiety. The global brain gene expression profile was altered permanently by BPA treatment and showed regional and sexual differences. The BPA-treated male mice had more changes in the hippocampus, while female mice experienced more changes in the cortex. Overall, we demonstrate that in utero exposure to BPA induces permanent changes in brain gene expression in a region-specific and sex-specific manner, including a significant decrease in locomotor activity, learning ability, long-term memory, and an increase in anxiety. Fetal/early life exposures permanently affect neurobehavioral functions that deteriorate with age; BPA exposure may compound the effects of aging.

In utero exposure to protease inhibitor-based antiretroviral regimens delays growth and developmental milestones in mice

Antiretroviral therapy (ART) in pregnancy has dramatically reduced HIV vertical transmission rates. Consequently, there is a growing number of children that are HIV exposed uninfected (CHEUs). Studies suggest that CHEUs exposed in utero to ART may experience developmental delays compared to their peers. We investigated the effects of in utero ART exposure on perinatal neurodevelopment in mice, through assessment of developmental milestones. Developmental milestone tests (parallel to reflex testing in human infants) are reflective of brain maturity and useful in predicting later behavioral outcomes. We hypothesized that ART in pregnancy alters the in utero environment and thereby alters developmental milestone outcomes in pups. Throughout pregnancy, dams were treated with boosted-atazanavir combined with either abacavir/lamivudine (ATV/r/ABC/3TC), or tenofovir/emtricitabine (ATV/r/TDF/FTC), or water as control. Pups were assessed daily for general somatic growth and on a battery of tests for primitive reflexes including surface-righting, negative-geotaxis, cliff-aversion, rooting, ear-twitch, auditory-reflex, forelimb-grasp, air-righting, behaviors in the neonatal open field, and olfactory test. In utero exposure to either ART regimen delayed somatic growth in offspring and evoked significant delays in the development of negative geotaxis, cliff-aversion, and ear-twitch reflexes. Exposure to ATV/r/ABC/3TC was also associated with olfactory deficits in male and forelimb grasp deficits in female pups. To explore whether delays persisted into adulthood we assessed performance in the open field test. We observed no significant differences between treatment arm for males. In females, ATV/r/TDF/FTC exposure was associated with lower total distance travelled and less ambulatory time in the centre, while ATV/r/ABC/3TC exposure was associated with higher resting times compared to controls. In utero PI-based ART exposure delays the appearance of primitive reflexes that involve vestibular and sensory-motor pathways in a mouse model. Our findings suggest that ART could be disrupting the normal progress/maturation of the underlying neurocircuits and encourage further investigation for underlying mechanisms.

Apigenin as a Candidate Prenatal Treatment for Trisomy 21: Effects in Human Amniocytes and the Ts1Cje Mouse Model

Human fetuses with trisomy 21 (T21) have atypical brain development that is apparent sonographically in the second trimester. We hypothesize that by analyzing and integrating dysregulated gene expression and pathways common to humans with Down syndrome (DS) and mouse models we can discover novel targets for prenatal therapy. Here, we tested the safety and efficacy of apigenin, identified with this approach, in both human amniocytes from fetuses with T21 and in the Ts1Cje mouse model. In vitro, T21 cells cultured with apigenin had significantly reduced oxidative stress and improved antioxidant defense response. In vivo, apigenin treatment mixed with chow was administered prenatally to the dams and fed to the pups over their lifetimes. There was no significant increase in birth defects or pup deaths resulting from prenatal apigenin treatment. Apigenin significantly improved several developmental milestones and spatial olfactory memory in Ts1Cje neonates. In addition, we noted sex-specific effects on exploratory behavior and long-term hippocampal memory in adult mice, and males showed significantly more improvement than females. We demonstrated that the therapeutic effects of apigenin are pleiotropic, resulting in decreased oxidative stress, activation of pro-proliferative and pro-neurogenic genes (KI67, Nestin, Sox2, and PAX6), reduction of the pro-inflammatory cytokines INFG, IL1A, and IL12P70 through the inhibition of NFκB signaling, increase of the anti-inflammatory cytokines IL10 and IL12P40, and increased expression of the angiogenic and neurotrophic factors VEGFA and IL7. These studies provide proof of principle that apigenin has multiple therapeutic targets in preclinical models of DS.

Noradrenergic circuits in the forebrain control affective responses to novelty

RATIONALE

In rodents, exposure to novel environments elicits initial anxiety-like behavior (neophobia) followed by intense exploration (neophilia) that gradually subsides as the environment becomes familiar. Thus, innate novelty-induced behaviors are useful indices of anxiety and motivation in animal models of psychiatric disease. Noradrenergic neurons are activated by novelty and implicated in exploratory and anxiety-like responses, but the role of norepinephrine (NE) in neophobia has not been clearly delineated.

OBJECTIVE

We sought to define the role of central NE transmission in neophilic and neophobic behaviors.

METHODS

We assessed dopamine β-hydroxylase knockout (Dbh -/-) mice lacking NE and their NE-competent (Dbh +/-) littermate controls in neophilic (novelty-induced locomotion; NIL) and neophobic (novelty-suppressed feeding; NSF) behavioral tests with subsequent quantification of brain-wide c-fos induction. We complimented the gene knockout approach with pharmacological interventions.

RESULTS

Dbh -/- mice exhibited blunted locomotor responses in the NIL task and completely lacked neophobia in the NSF test. Neophobia was rescued in Dbh -/- mice by acute pharmacological restoration of central NE with the synthetic precursor L-3,4-dihydroxyphenylserine (DOPS), and attenuated in control mice by the inhibitory α2-adrenergic autoreceptor agonist guanfacine. Following either NSF or NIL, Dbh -/- mice demonstrated reduced c-fos in the anterior cingulate cortex, medial septum, ventral hippocampus, bed nucleus of the stria terminalis, and basolateral amygdala.

CONCLUSION

These findings indicate that central NE signaling is required for the expression of both neophilic and neophobic behaviors. Further, we describe a putative noradrenergic novelty network as a potential therapeutic target for treating anxiety and substance abuse disorders.

14,15-Epoxyeicosatrienoic Acid Alleviates Pathology in a Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is the leading cause of late-onset dementia, and there exists an unmet medical need for effective treatments for AD. The accumulation of neurotoxic amyloid-β (Aβ) plaques contributes to the pathophysiology of AD. EPHX2 encoding soluble epoxide hydrolase (sEH)-a key enzyme for epoxyeicosatrienoic acid (EET) signaling that is mainly expressed in lysosomes of astrocytes in the adult brain-is cosited at a locus associated with AD, but it is unclear whether and how it contributes to the pathophysiology of AD. In this report, we show that the pharmacologic inhibition of sEH with 1-trifluoromethoxyphenyl- 3-(1-propionylpiperidin-4-yl) urea (TPPU) or the genetic deletion of Ephx2 reduces Aβ deposition in the brains of both male and female familial Alzheimer's disease (5×FAD) model mice. The inhibition of sEH with TPPU or the genetic deletion of Ephx2 alleviated cognitive deficits and prevented astrocyte reactivation in the brains of 6-month-old male 5×FAD mice. 14,15-EET levels in the brains of these mice were also increased by sEH inhibition. In cultured adult astrocytes treated with TPPU or 14,15-EET, astrocyte Aβ clearance was increased through enhanced lysosomal biogenesis. Infusion of 14,15-EET into the hippocampus of 5×FAD mice prevented the aggregation of Aβ. Notably, a higher concentration of 14,15-EET (200 ng/ml) infusion into the hippocampus reversed Aβ deposition in the brains of 6-month-old male 5×FAD mice. These results indicate that EET signaling, especially 14,15-EET, plays a key role in the pathophysiology of AD, and that targeting this pathway is a potential therapeutic strategy for the treatment of AD.SIGNIFICANCE STATEMENT There are limited treatment options for Alzheimer's disease (AD). EPHX2 encoding soluble epoxide hydrolase (sEH) is located at a locus that is linked to late-onset AD, but its contribution to the pathophysiology of AD is unclear. Here, we demonstrate that sEH inhibition or Ephx2 deletion alleviates pathology in familial Alzheimer's disease (5×FAD) mice. Inhibiting sEH or increasing 14,15-epoxyeicosatrienoic acid (EET) enhanced lysosomal biogenesis and amyloid-β (Aβ) clearance in cultured adult astrocytes. Moreover, the infusion of 14,15-EET into the hippocampus of 5×FAD mice not only prevented the aggregation of Aβ, but also reversed the deposition of Aβ. Thus, 14,15-EET plays a key role in the pathophysiology of AD and therapeutic strategies that target this pathway may be an effective treatment.

Metabolomics analysis of the antidepressant prescription Danzhi Xiaoyao Powder in a rat model of Chronic Unpredictable Mild Stress (CUMS)

ETHNOPHARMACOLOGICAL RELEVANCE

Danzhi Xiaoyao Powder (DZXY) is a classical prescription, that has been extensively used in traditional Chinese medicine (TMC) to treat depression for many years. However, the mechanism of DZXY is still unclear.

AIM OF THE STUDY

The aim was to investigate the mechanism of the antidepressant effect of DZXY on a rat model of chronic unpredictable mild stress (CUMS).

MATERIALS AND METHODS

Forty male SD (Sprague-Dawley) rats with similar open field test (OFT) results were randomLy divided into a control group (n = 10) and an experimental group (n = 30). A depression model was established in the experimental group using the CUMS method. After the CUMS model was established successfully, the rats were randomLy divided into a depression model group and a DZXY group. The DZXY group was fed DZXY, while the depression model group and control group were given an equal amount of 0.5% sodium carboxymethyl cellulose suspension. Intragastric administration was performed once daily for 14 consecutive days. Animal weight, the sugar preference test, the open field test and the forced swimming test were used to evaluate the modeling effect and the antidepressant effect of DZXY. After the experiment, the plasma of rats was collected and the changes in plasma metabolites were analyzed by UPLC/Q-TOF-MS. The UPLC/Q-TOF-MS spectra data were evaluated by pattern recognition analysis to determine the changes in endogenous metabolites in the rat plasma samples.

RESULTS

The results of the behavioral investigation showed that the rat model of depression was successfully replicated and that DZXY had an antidepressant effect. Using the UPLC-MS/MS metabolomics platform, partial least squares (PLS) and orthogonal partial least squares (OPLS), metabolic profile models (R2 and Q2 ≥ 0.5) of rat plasma were successfully constructed. The model could distinguish among the control group, the depression model group and the DZXY group. Finally, 38 differential metabolites were identified in the plasma. According to KEGG (http://www.kegg.jp) pathway analysis, amino acid metabolism, lipid metabolism, purine metabolism, the prolactin signaling pathway and bile secretion were enriched and represented the main metabolic pathways influenced in the plasma.

CONCLUSIONS

This study successfully established a CUMS depression model. A total of 38 differential metabolites associated with depression were identified in the plasma of rats, 24 of which were modulated by DZXY. These results suggest that DZXY can improve excitability and play an antidepressant role by regulating phenylalanine metabolism, arachidonic acid metabolism, porphyrin metabolism, D-arginine and D-ornithine metabolism, steroid hormone biosynthesis, unsaturated fatty acid biosynthesis and steroid biosynthesis.

Fear expression is reduced after acute and repeated nociceptin/orphanin FQ (NOP) receptor antagonism in rats: therapeutic implications for traumatic stress exposure

RATIONALE

Evaluation of pharmacotherapies for acute stress disorder (ASD) or post-traumatic stress disorder (PTSD) is challenging due to robust heterogeneity of trauma histories and limited efficacy of any single candidate to reduce all stress-induced effects. Pursuing novel mechanisms, such as the nociceptin/orphanin FQ (NOP) system, may be a viable path for therapeutic development and of interest as it is involved in regulation of relevant behaviors and recently implicated in PTSD and ASD.

OBJECTIVES

First, we evaluated NOP receptor antagonism on general behavioral performance and again following a three-species predator exposure model (Experiment 1). Then, we evaluated effects of NOP antagonism on fear memory expression (Experiment 2).

METHODS

Adult, male rats underwent daily administration of NOP antagonists (J-113397 or SB-612,111; 0-20 mg/kg, i.p.) and testing in acoustic startle, elevated plus maze, tail-flick, and open field tests. Effects of acute NOP antagonism on behavioral performance following predator exposure were then assessed. Separately, rats underwent fear conditioning and were later administered SB-612,111 (0-3 mg/kg, i.p.) prior to fear memory expression tests.

RESULTS

J-113397 and SB-612,111 did not significantly alter most general behavioral performance measures alone, suggesting minimal off-target behavioral effects of NOP antagonism. J-113397 and SB-612,111 restored performance in measures of exploratory behavior (basic movements on the elevated plus maze and total distance in the open field) following predator exposure. Additionally, SB-612,111 significantly reduced freezing behavior relative to control groups across repeated fear memory expression tests, suggesting NOP antagonism may be useful in dampening fear responses. Other measures of general behavioral performance were not significantly altered following predator exposure.

CONCLUSIONS

NOP antagonists may be useful as pharmacotherapeutics for dampening fear responses to trauma reminders, and the present results provide supporting evidence for the implication of the NOP system in the neuropathophysiology of dysregulations in fear learning and memory processes observed in trauma- and stress-related disorders.

Glaucacetalin E and galphimidin B from Galphimia glauca and their anxiolytic activity

ETHNOPHARMACOLOGICAL RELEVANCE

Galphimia glauca is a Mexican medicinal plant used to treat anxiety, fear, phobia and stress as it possesses sedative properties which produce a calming effect. Although some chemical and pharmacological studies have already been carried out on G. glauca, there are still new chemical entities from this plant whose anxiolytic activity should be established.

AIM OF THE STUDY

To validate the use of G. glauca growing in Cuernavaca, Morelos, as an anti-stress agent, through the purification and structural identification of its extracts' chemical constituents; the analysis of the biogenetic relationship of its chemical compounds, and its biological evaluation to demonstrate its traditional use as anxiolytic agents.

MATERIALS AND METHODS

The structures of all isolated compounds were established based on their spectroscopic and spectrometric data. The structure of compound 2 was corroborated through X-Ray. The anxiolytic and sedative-like activities were assessed by the open-field, hole-board and exploration cylinder test.

RESULTS

The nor-triterpenes glaucacetalin E (1) and galphimidin B (2) were isolated for the first time along with seven other known compounds, one of them galphimidin (3), from the CHCl₃ fraction of the aerial parts of Galphimia glauca. The biogenesis of the natural nor-triterpenes isolated from Galphimia glauca is delineated for the first time starting from the taraxasteryl cation. Oral administration of CHCl₃ fraction and 1-3 compounds produced significant attenuation in the anxiety-response in cylinder activity, decrease in the ambulatory activity and in head dipping when compared to the vehicle. However, only the extract enhanced the pentobarbital-induced hypnosis. Diazepam was used as a positive control.

CONCLUSION

Our results suggest that G. glauca growing in Cuernavaca, Morelos, exerts anxiolytic-like activity due to the presence of the nor-triterpenes 1-3. These results reinforce the potential use of this species in the treatment of anxiety.

Early-Life Supplementation of Bovine Milk Osteopontin Supports Neurodevelopment and Influences Exploratory Behavior

Introduction: Osteopontin (OPN) is a whey protein found at high concentration in human milk and is involved in processes such as bone cell proliferation and differentiation. Milk OPN has shown to be involved in various aspects of development, including the immune system and gut health. However, the influence of dietary bovine milk OPN inclusion on brain and cognitive development has not been studied extensively until recently. This research examines whether dietary supplementation of bovine milk OPN supports brain and cognitive development in the translational pig model. Methods: From postnatal day (PND) 2 to 34, twenty-one intact male pigs were provided ad libitum access to one of two dietary treatments, a standard soy protein isolate-based milk replacer to serve as a control diet (n = 11) and the same base diet supplemented with bovine milk OPN to serve as a test diet (n = 10). In addition to growth and health outcomes, recognition memory was tested using the novel object recognition (NOR) task from PND 28 to 32, and magnetic resonance imaging was conducted at PND 34 to evaluate brain development. Results: No dietary effects were observed for growth performance or health indices. For the behavioral analysis, pigs that received the test diet exhibited shorter (p < 0.05) latency to the first object visited compared with pigs fed the control diet. Although the control group exhibited novelty preference, there was no difference in recognition index between dietary groups. Neuroimaging outcomes revealed increased (p < 0.05) relative brain volumes of the corpus callosum, lateral ventricle, left and right internal capsule, left and right putamen-globus pallidus, and right hippocampus, and right cortex in the test group. Diffusion tensor imaging revealed higher (p < 0.05) radial diffusivity in the corpus callosum and lower (p < 0.05) fractional anisotropy in pigs provided the test diet. Conclusion: Dietary supplementation of bovine milk OPN increased the relative volume of several brain regions and altered behaviors in the NOR task. Underlying mechanisms of bovine milk OPN influencing the development of brain structures and additional behaviors warrant further investigation.

Playback of 50-kHz ultrasonic vocalizations overcomes psychomotor deficits induced by sub-chronic haloperidol treatment in rats

RATIONALE

In rodents, acute haloperidol treatment induces psychomotor impairments known as catalepsy, which models akinesia in humans and is characterized as an animal model of acute Parkinsonism, whereas sub-chronic haloperidol reduces exploratory behavior, which resembles bradykinesia. Haloperidol-induced catalepsy in rats can be ameliorated by playback of 50-kHz ultrasonic vocalizations (USV), an emotionally and motivationally relevant appetitive auditory stimulus, representing an animal model of paradoxical kinesia. In a condition like PD where patients suffer from chronic motor impairments, it is paramount to assess the long-term symptom relief in an animal model of Parkinsonism.

OBJECTIVES

We investigated whether 50-kHz USV playback ameliorates psychomotor deficits induced by haloperidol in a sub-chronic dosing regimen.

METHODS

In phase 1, distance traveled and number of rearing behavior were assessed in an activity chamber in order to investigate whether sub-chronic haloperidol treatment induced psychomotor impairments. In phase 2, we investigated whether 50-kHz USV playback could overcome these impairments by assessing exploratory behaviors and approach behavior towards the sound source in the 50-kHz USV radial maze playback paradigm.

RESULTS

Sub-chronic haloperidol treatment led to psychomotor deficits since the distance traveled and number of rearing behavior were reduced as compared to saline control group or baseline. These psychomotor impairments were ameliorated during playback of 50-kHz USV, with haloperidol treated rats showing a clear social approach behavior towards the sound source exclusively during playback.

CONCLUSIONS

This study provides evidence that 50-kHz USV playback induces paradoxical kinesia in rats exhibiting motor deficits after sub-chronic haloperidol, as we previously showed after acute haloperidol treatment.

Chronic harmine treatment has a delayed effect on mobility in control and socially defeated rats

INTRODUCTION

Depression is characterized by behavioral, cognitive and physiological changes, imposing a major burden on the overall wellbeing of the patient. Some evidence indicates that social stress, changes in growth factors (e.g., brain-derived neurotrophic factor (BDNF)), and neuroinflammation are involved in the development and progression of the disease. The monoamine oxidase A inhibitor drug harmine was suggested to have both antidepressant and anti-inflammatory properties and may, therefore, be a potential candidate for treatment of depression.

AIM

The goal of this study was to assess the effects of harmine on behavior, brain BDNF levels, and microglia activation in control rats and a rat model of social stress.

MATERIAL AND METHODS

Rats were submitted to 5 consecutive days of repeated social defeat (RSD) or control conditions. Animals were treated daily with harmine (15 mg/kg) or vehicle from day 3 until the end of the experiment. To assess the effects of harmine treatment on behavior, the sucrose preference test (SPT) was performed on days 1, 6, and 15, the open field test (OFT) on days 6 and 14, and the novel object recognition test (NOR) on day 16. Brain microgliosis was assessed using [11C]PBR-28 PET on day 17. Animals were terminated on day 17, and BDNF protein concentrations in the hippocampus and frontal cortex were analyzed using ELISA.

RESULTS

RSD significantly decreased bodyweight and increased anxiety and anhedonia-related parameters in the OFT and SPT on day 6, but these behavioral effects were not observed anymore on day 14/15. Harmine treatment caused a significant reduction in bodyweight gain in both groups, induced anhedonia in the SPT on day 6, and significantly reduced the mobility and exploratory behavior of the animals in the OFT mainly on day 14. PET imaging and the NOR test did not show any significant effects on microglia activation and memory, respectively. BDNF protein concentrations in the hippocampus and frontal cortex were not significantly affected by either RSD or harmine treatment.

DISCUSSION

Harmine was not able to reverse the acute effects of RSD on anxiety and anhedonia and even aggravated the effect of RSD on bodyweight loss. Moreover, harmine treatment caused unexpected side effects on general locomotion, both in RSD and control animals, but did not influence glial activation status and BDNF concentrations in the brain. In this model, RSD-induced stress was not strong enough to induce long-term effects on the behavior, neuroinflammation, or BDNF protein concentration. Thus, the efficacy of harmine treatment on these delayed parameters needs to be further evaluated in more severe models of chronic stress.

Blockade of the endovanilloid receptor, TRPV1, and of the endocannabinoid enzyme, FAAH, within the nucleus accumbens shell elicits anxiolytic-like effects in male rats

RATIONALE

The functional role of the endocannabinoid system (ECS) and Transient Receptor Potential Vanilloid type-1 (TRPV1) within the Nucleus Accumbens shell (NAc shell) remains unknown. Preclinical studies in rodents have reported that the ECS modulates emotional responses such as anxiety. The NAc shell has a high density of synaptically co-localized cannabinoid receptor type-1 (CB1R) and TRPV1, suggesting a potential involvement in the modulation of anxiety.

OBJECTIVES

The present study aims to establish the role of ECS-TRPV1 interactions within the NAc shell and its effects on anxiety. It is hypothesized that the neurochemical regulation elicited by ECS within the NAc shell mediates anxiety-like behaviors in rodents.

METHODS

In this study, male Sprague Dawley rats were implanted with bilateral brain cannula targeting the NAc shell. Following recovery from surgery, animals received microinfusion pretreatments (0, 0.125, 0.5 nmol/0.4 μl) of N-arachidonoyl-serotonin (AA-5-HT), a dual blocker of the endocannabinoid-inactivating enzyme, fatty acid amide hydrolase (FAAH) and a TRPV1 antagonist in the NAc shell. Following treatment, animals were tested in an elevated plus maze (EPM) paradigm for a period of 5 minutes. At the end of the experiment, animals were sacrificed and their brains collected for histological and biochemical analysis.

RESULTS

Results showed that animals treated with AA-5-HT in a dose dependent manner spent significantly more time in the open arms than vehicle-treated animals. In addition, AA-5-HT administration induced a significant downregulation of CB1R expression in the NAc shell.

CONCLUSIONS

The present findings suggest that the ECS within the NAc shell modulates anxiety-like behaviors via FAAH and CB1R activity.

A mouse model of chemotherapy-related cognitive impairments integrating the risk factors of aging and APOE4 genotype

Some cancer survivors experience marked cognitive impairment, referred to as cancer-related cognitive impairment (CRCI). CRCI has been linked to the genetic factor APOE4, the strongest genetic risk factor for Alzheimer's disease (AD). We used APOE knock-in mice to test whether the relationship between APOE4 and CRCI can be demonstrated in a mouse model, to identify associations of chemotherapy with behavioural and structural correlates of cognition, and to test whether chemotherapy affects markers of AD. Twelve-month old C57BL/6 J female APOE3 (n = 30) and APOE4 (n = 31) knock-in mice were randomized to treatment with either doxorubicin (10 mg/kg) or saline. Behavioural assays at 2-21 weeks-post exposure included open field maze, elevated zero maze, pre-pulse inhibition, Barnes maze, and fear conditioning. Ex-vivo magnetic resonance imaging was used to determine regional volume differences at 31-35 weeks-post exposure, and tissue sections were analyzed for markers of AD pathogenesis. Minimal toxicities were observed in the aged mice after doxorubicin exposure. In the Barnes maze assay, APOE3 mice did not exhibit impairment in spatial learning after doxorubicin treatment, but APOE4 mice demonstrated significant impairments in both the initial identification of the escape hole and the latency to full escape at 6 weeks post-exposure. Both APOE3 and APOE4 mice treated with doxorubicin showed impairment of spatial memory. Grey matter volume in the frontal cortex decreased in APOE4 mice treated with doxorubicin vs. APOE3 mice. This study demonstrates cognitive impairments in aged APOE4 knock-in mice after doxorubicin treatment and establishes this system as a novel and powerful model of CRCI.

Spontaneous appetence for wheel-running: a model of dependency on physical activity in rat

According to human observations of a syndrome of physical activity dependence and its consequences, we tried to examine if running activity in a free activity paradigm, where rats had a free access to activity wheel, may present a valuable animal model for physical activity dependence and most generally to behavioral dependence. The pertinence of reactivity to novelty, a well-known pharmacological dependence predictor was also tested. Given the close linkage observed in human between physical activity and drugs use and abuse, the influence of free activity in activity wheels on reactivity to amphetamine injection and reactivity to novelty were also assessed. It appeared that (1) free access to wheel may be used as a valuable model for physical activity addiction, (2) two populations differing in activity amount also differed in dependence to wheel-running. (3) Reactivity to novelty did not appeared as a predictive factor for physical activity dependence (4) activity modified novelty reactivity and (5) subjects who exhibited a high appetence to wheel-running, presented a strong reactivity to amphetamine. These results propose a model of dependency on physical activity without any pharmacological intervention, and demonstrate the existence of individual differences in the development of this addiction. In addition, these data highlight the development of a likely vulnerability to pharmacological addiction after intense and sustained physical activity, as also described in man. This model could therefore prove pertinent for studying behavioral dependencies and the underlying neurobiological mechanisms. These results may influence the way psychiatrists view behavioral dependencies and phenomena such as doping in sport or addiction to sport itself.

Paternal exposure to a common herbicide alters the behavior and serotonergic system of zebrafish offspring

Increasingly, studies are revealing that endocrine disrupting chemicals (EDCs) can alter animal behavior. Early life exposure to EDCs may permanently alter phenotypes through to adulthood. In addition, the effects of EDCs may not be isolated to a single generation − offspring may indirectly be impacted, via non-genetic processes. Here, we analyzed the effects of paternal atrazine exposure on behavioral traits (distance moved, exploration, bottom-dwelling time, latency to enter the top zone, and interaction with a mirror) and whole-brain mRNA of genes involved in the serotonergic system regulation (slc6a4a, slc6a4b, htr1Aa, htr1B, htr2B) of zebrafish (Danio rerio). F0 male zebraFIsh were exposed to atrazine at 0.3, 3 or 30 part per billion (ppb) during early juvenile development, the behavior of F1 progeny was tested at adulthood, and the effect of 0.3 ppb atrazine treatment on mRNA transcription was quantified. Paternal exposure to atrazine significantly reduced interactions with a mirror (a proxy for aggression) and altered the latency to enter the top zone of a tank in unexposed F1 offspring. Bottom-dwelling time (a proxy for anxiety) also appeared to be somewhat affected, and activity (distance moved) was reduced in the context of aggression. slc6a4a and htr1Aa mRNA transcript levels were found to correlate positively with anxiety levels in controls, but we found that this relationship was disrupted in the 0.3 ppb atrazine treatment group. Overall, paternal atrazine exposure resulted in alterations across a variety of behavioral traits and showed signs of serotonergic system dysregulation, demonstrating intergenerational effects. Further research is needed to explore transgenerational effects on behavior and possible mechanisms underpinning behavioral effects.

Pre-adult aggression and its long-term behavioural consequences in crickets

Social experience, particularly aggression, is considered a major determinant of consistent inter-individual behavioural differences between animals of the same species and sex. We investigated the influence of pre-adult aggressive experience on future behaviour in male, last instar nymphs of the cricket Gryllus bimaculatus. We found that aggressive interactions between male nymphs are far less fierce than for adults in terms of duration and escalation. This appears to reflect immaturity of the sensory apparatus for releasing aggression, rather than the motor system controlling it. First, a comparison of the behavioural responses of nymphs and adults to mechanical antennal stimulation using freshly excised, untreated and hexane-washed antennae taken from nymphs and adults, indicate that nymphs neither respond to nor produce sex-specific cuticular semiochemicals important for releasing aggressive behaviour in adults. Second, treatment with the octopamine agonist chlordimeform could at least partially compensate for this deficit. In further contrast to adults, which become hyper-aggressive after victory, but submissive after defeat, such winner and loser effects are not apparent in nymphs. Aggressive competition between nymphs thus appears to have no consequence for future behaviour in crickets. Male nymphs are often attacked by adult males, but not by adult females. Furthermore, observations of nymphs raised in the presence, or absence of adult males, revealed that social subjugation by adult males leads to reduced aggressiveness and depressed exploratory behaviour when the nymphs become adult. We conclude that social subjugation by adults during pre-adult development of nymphs is a major determinant of consistent inter-individual behavioural differences in adult crickets.

Protective effects of losartan on some type 2 diabetes mellitus-induced complications in Wistar and spontaneously hypertensive rats

Diabetes mellitus type 2 (T2DM) is characterized by resistance of insulin receptors and/or inadequate insulin secretion resulting in metabolic and structural complications including vascular diseases, arterial hypertension and different behavioral alterations. We aimed to study the effects of the antihypertensive angiotensin AT1 receptor antagonist losartan on the T2DM-induced changes of exploratory behavior, anxiety, nociception and short term memory in normotensive Wistar and spontaneously hypertensive rats (SHRs). The experimental model of T2DM induced by a combination of high fat diet and streptozotocin, decreased exploratory activity and increased the level of carbonylated proteins in selected brain structures in both strains; as well it increased corticosterone level, pain threshold, anxiety-like behavior, and decline short term memory only in SHRs. Losartan treatment alleviated some of the T2DM- induced metabolic complications, abolished the T2DM-induced hypo activity, and normalized the corticosterone level, carbonylated proteins in brain, nociception and memory. Losartan did not exert effect on the anxiety behavior in both strains. We showed that T2DM exerted more pronounced negative effects on the rats with comorbid hypertension as compared to normotensive rats. Overall effects on the studied behavioral parameters are related to decreased exploration of the new environment, increased anxiety-like behavior, and decline in short-term memory. The systemic sub-chronic treatment with an angiotensin AT1 receptor antagonist losartan ameliorated most of these complications.

Prepubertal gonadectomy reveals sex differences in approach-avoidance behavior in adult mice

Adolescence is a developmental period that is associated with physical, cognitive, and affective maturation and a time when sex biases in multiple psychiatric diseases emerge. While puberty onset marks the initiation of adolescence, it is unclear whether the pubertal rise in gonadal hormones generates sex differences in approach-avoidance behaviors that may impact psychiatric vulnerability. To examine the influence of pubertal development on adult behavior, we removed the gonads or performed sham surgery in male and female mice just prior to puberty onset and assessed performance in an odor-guided foraging task and anxiety-related behaviors in adulthood. We observed no significant sex differences in foraging or anxiety-related behaviors between intact adult male and female mice but found significant differences between adult male and female mice that had been gonadectomized (GDX) prior to puberty onset. GDX males failed to acquire the odor-guided foraging task, showed reduced locomotion, and exhibited increased anxiety-like behavior, while GDX females showed the opposite pattern of behavior. These data suggest that puberty may minimize rather than drive differences in approach-avoidance phenotypes in male and female mice.

Sexual motivation: problem solved and new problems introduced

Background During the past 50 years, motivational studies have evolved from the logical inference of logically required "intervening variables" to explain behavioral change, to electrophysiological and molecular analyses of the mechanisms causing such changes. Aim The purpose of this review article is two-fold: first to describe the logic of sexual motivation in a way that applies to laboratory animals as well as humans, and the second is to address some of the problems of sexual motivation experienced by men. Results When problems of motivational mechanisms are stripped down to their essentials, as performed in the laboratory animal models and are available for reductionistic studies, then the problems can be solved with certainty, as illustrated in the first part of this review. However, with respect to human sexual motivation, the various determinants which include so many behavioral routes and so many brain states come into play, that definite conclusions are harder to come by, as illustrated in the second part of this review. Conclusions This review highlights a number of key questions that merit further investigation. These include (a) What mechanisms do cultural and experiential influences interact with androgenic hormone influences on human sexual motivation? (b) How would epigenetic effects in the human brain related to changes in motivation be investigated? (c) What are the effects of unpredictable traumatic and stressful human experiences on sexual motivation; (d) How such mechanisms are activated upon unpredictable traumatic and stressful insults? (e) What are the outstanding differences between sexual motivational drive and motivations driven by homeostatic systems such as hunger and thirst?

Behavioral Impairments and Oxidative Stress in the Brain, Muscle, and Gill Caused by Chronic Exposure of C70 Nanoparticles on Adult Zebrafish

There is an imperative need to develop efficient whole-animal-based testing assays to determine the potential toxicity of engineered nanomaterials. While previous studies have demonstrated toxicity in lung and skin cells after C70 nanoparticles (NPs) exposure, the potential detrimental role of C70 NPs in neurobehavior is largely unaddressed. Here, we evaluated the chronic effects of C70 NPs exposure on behavior and alterations in biochemical responses in adult zebrafish. Two different exposure doses were used for this experiment: low dose (0.5 ppm) and high dose (1.5 ppm). Behavioral tests were performed after two weeks of exposure of C70 NPs. We found decreased locomotion, exploration, mirror biting, social interaction, and shoaling activities, as well as anxiety elevation and circadian rhythm locomotor activity impairment after ~2 weeks in the C70 NP-exposed fish. The results of biochemical assays reveal that following exposure of zebrafish to 1.5 ppm of C70 NPs, the activity of superoxide dismutase (SOD) in the brain and muscle tissues increased significantly. In addition, the concentration of reactive oxygen species (ROS) also increased from 2.95 ± 0.12 U/ug to 8.46 ± 0.25 U/ug and from 0.90 ± 0.03 U/ug to 3.53 ± 0.64 U/ug in the muscle and brain tissues, respectively. Furthermore, an increased level of cortisol was also observed in muscle and brain tissues, ranging from 17.95 ± 0.90 pg/ug to 23.95 ± 0.66 pg/ug and from 3.47 ± 0.13 pg/ug to 4.91 ± 0.51 pg/ug, respectively. Increment of Hif1-α level was also observed in both tissues. The elevation was ranging from 11.65 ± 0.54 pg/ug to 18.45 ± 1.00 pg/ug in the muscle tissue and from 4.26 ± 0.11 pg/ug to 6.86 ± 0.37 pg/ug in the brain tissue. Moreover, the content of DNA damage and inflammatory markers such as ssDNA, TNF-α, and IL-1β were also increased substantially in the brain tissues. Significant changes in several biomarker levels, including catalase and malondialdehyde (MDA), were also observed in the gill tissues. Finally, we used a neurophenomic approach with a particular focus on environmental influences, which can also be easily adapted for other aquatic fish species, to assess the toxicity of metal and carbon-based nanoparticles. In summary, this is the first study to illustrate the adult zebrafish toxicity and the alterations in several neurobehavior parameters after zebrafish exposure to environmentally relevant amounts of C70 NPs.

Noradrenergic and dopaminergic involvement in novelty modulation of aversive memory generalization of adult rats

The generalization of aversive memory can be defined as the phenomenon in which a situation similar to (but distinctive from) a previous aversive event triggers an avoidance response. This phenomenon has been suggested to play a role in several psychological disorders. In this study, we investigate the effects of novelty on the generalization of fear memories, and the involvement of noradrenergic and dopaminergic systems in this process. For this study we used male Wistar rats (3 months old, 300-400 g). The participation of each neurotransmitter system was evaluated separately (two set of experiments). In each experimental set, the animals were divided in groups (8 animals each): (i) control, (ii) novelty, and, (iii) antagonist + novelty group (timolol, a β-adrenergic antagonist, or SCH23390, a D1/D5 dopaminergic antagonist, in the first and in the second set of experiments, respectively). Additionaly, to investigate whether novelty exposure increases the levels of noradrenaline and/or dopamine in the hippocampus fifteen animals were divided in three groups (5 animals each).: (i) naïve, (ii) control; and, (iii) novelty. To examine aversive memory, and generalization of aversive memory, we trained adult male Wistar rats in an inhibitory avoidance (IA) memory task and after in a modified inhibitory avoidance (MIA). Before the MIA training some of the animals were exposed to environmental novelty (open field). Immediately before this novelty exposure, some animals received intrahippocampal infusion of timolol (β-adrenergic antagonist), SCH23390 (D1/D5 antagonist) or vehicle to evaluate the involvement of noradrenergic and dopaminergic systems. Finally, to evaluate aversive memory and generalization of aversive memory respectively, half of the animals in each group were tested on IA and half on MIA. We confirmed that the exposure to novelty blocks the generalization of aversive memory, but moreover, demonstrated that this process involves activation of β-adrenergic and dopaminergic D1/D5 pathways. We additionally observed that exposure to novelty raises hippocampal levels of noradrenaline and dopamine. This suggests that these neurotransmitters not only influence long-term memory (LTM) as such, but also aversive memory generalization.

Prophylactic neuroprotective propensity of Crocin, a carotenoid against rotenone induced neurotoxicity in mice: behavioural and biochemical evidence

Previously we have demonstrated the potential neuroprotective propensity of saffron and Crocin (CR) employing a Drosophila model of Parkinsonism. Rotenone (ROT) has been extensively used as a model neurotoxin to induce Parkinson's disease (PD) like symptoms in mice. In the present study, as a proof of concept we evaluated the efficacy of CR prophylaxis (25 mg/ kg bw/d, 7d) to attenuate ROT(0.5 mg/Kg bw/d,7d) -induced neurotoxic effects in male mice focussing on neurobehavioural assessments and biochemical determinants in the striatum. CR prophylaxis significantly alleviated ROT-induced behavioural alterations such as increased anxiety, diminished exploratory behaviour, decreased motor co-ordination, and grip strength. Concomitantly, we evidenced diminution of oxidative stress markers, enhanced levels of antioxidant enzyme and mitochondrial enzyme function in the striatal region. Further, varying degree of restoration of cholinergic function, dopamine and α-synuclein levels were discernible suggesting the possible mechanism/s of action of CR in this model. Based on our earlier data in flies and in worm model, we propose its use as an adjuvant therapeutic agent in oxidative stress-mediated neurodegenerative conditions such as PD.

Btbd3 expression regulates compulsive-like and exploratory behaviors in mice

BTB/POZ domain-containing 3 (BTBD3) was identified as a potential risk gene in the first genome-wide association study of obsessive-compulsive disorder (OCD). BTBD3 is a putative transcription factor implicated in dendritic pruning in developing primary sensory cortices. We assessed whether BTBD3 also regulates neural circuit formation within limbic cortico-striato-thalamo-cortical circuits and behaviors related to OCD in mice. Behavioral phenotypes associated with OCD that are measurable in animals include compulsive-like behaviors and reduced exploration. We tested Btbd3 wild-type, heterozygous, and knockout mice for compulsive-like behaviors including cage-mate barbering, excessive wheel-running, repetitive locomotor patterns, and reduced goal-directed behavior in the probabilistic learning task (PLT), and for exploratory behavior in the open field, digging, and marble-burying tests. Btbd3 heterozygous and knockout mice showed excessive barbering, wheel-running, impaired goal-directed behavior in the PLT, and reduced exploration. Further, chronic treatment with fluoxetine, but not desipramine, reduced barbering in Btbd3 wild-type and heterozygous, but not knockout mice. In contrast, Btbd3 expression did not alter anxiety-like, depression-like, or sensorimotor behaviors. We also quantified dendritic morphology within anterior cingulate cortex, mediodorsal thalamus, and hippocampus, regions of high Btbd3 expression. Surprisingly, Btbd3 knockout mice only showed modest increases in spine density in the anterior cingulate, while dendritic morphology was unaltered elsewhere. Finally, we virally knocked down Btbd3 expression in whole, or just dorsal, hippocampus during neonatal development and assessed behavior during adulthood. Whole, but not dorsal, hippocampal Btbd3 knockdown recapitulated Btbd3 knockout phenotypes. Our findings reveal that hippocampal Btbd3 expression selectively modulates compulsive-like and exploratory behavior.

Propionate relieves pentylenetetrazol-induced seizures, consequent mitochondrial disruption, neuron necrosis and neurological deficits in mice

The present research was designed to evaluate the protective effects and underlying mechanisms of propionate, a bioactive food additive, on mitochondrial disruption, neuron necrosis and neurological deficits after epilepsy seizures. Epilepsy seizures was induced by repetitive injections of pentylenetetrazol at a dose of 37 mg per kg. Propionate (37.5, 50 and 75 mg/kg) as well as sodium valproate (300 mg/kg) were administrated intragastrically (i.g.) 1 h before each PTZ injection and continued for 40 days. The influence of propionate was assessed by many biochemical assays and neurobehavioral experiments. The results of gas chromatography (GC) analysis indicated that increased concentration of propionate can be explored in hippocampus area of propionate + PTZ treated animals. Propionate decreased epilepsy seizure intensity, increased latency of seizures. Meanwhile, propionate treatment reversed the structure disruption of the mitochondria, improved ATP level and lessened 8-OHdG level in the brains of animals with seizures. In addition, we find propionate pretreated can increase activities of the antioxidant enzymes (CAT, SOD, as well as GSH-Px) in mitochondria. Additionally, propionate reduced neuronal loss in hippocampus and our results suggest that HIF-1α/ERK pathway and neuron necrosis exists potential linkage during epileptogenesis. Moreover, as a result, propionate administration can significantly improve the neurological function estimated by a battery of functional tests. In conclusion, treatment with propionate attenuates mitochondrial disruption, hippocampal apoptosis and neurological deficits in a mouse model of epilepsy seizures. Therefore, propionate, currently used as a food preservative, has a potential additional advantage of ameliorating epilepsy seizures.

Late glucocorticoid receptor antagonism changes the outcome of adult life stress

BACKGROUND

Stressors activate a wide spectrum of interacting hormonal and neuronal systems resulting in behavioral and physiological responses, with consequences for the development of psychopathology. Several recent studies demonstrated that treatment with the glucocorticoid receptor (GR) antagonist RU486 during adulthood normalized effects of early life stress. We aimed to evaluate the potential of RU486 to reverse stress-induced changes in an animal model of adult stress.

METHOD

We employed the single-prolonged stress (SPS) model as a multimodal stress exposure protocol in male rats. SPS rats and unstressed controls were treated with RU486 on days 8, 9, 10 after stress exposure and the effects of treatment were evaluated after another 4 days. We determined body weight gain, corticosterone levels, behavioral reactivity in anxiety tests, and brain gene expression of c-fos, corticosteroid receptors, drivers of the stress response and genes (epi-)genitally linked to PTSD.

RESULTS

RU486 affected body weight gain, corticosterone levels and open field behavior only in SPS rats. RU486 had history-independent effects in reducing fear in the elevated plus maze and fear conditioning behavior. Gene expression analysis showed a diversity of in- and interdependent effects of stress and RU486.

CONCLUSION

The effects of RU486 applied 1 week after stress and measured 4 days after treatment demonstrate that in the state of post-SPS the GR-dependence of homeostatic processes has changed. This suggests that GR-mediated processes are part of allostatic regulation after adult stress. The normalization of a number of SPS-effects after RU486 treatment reinforces the potential of targeting GR for treatment of stress-related psychopathologies.

The effects of fluorene-9-bisphenol on female zebrafish (Danio rerio) reproductive and exploratory behaviors

Endocrine disruptor chemicals induce adverse effects to animals' development, reproduction and behavior in environment. We investigated the effects of fluorene-9-bisphenol (BHPF), one substitute of bisphenol A, on courtship behavior and exploratory behavior of adult zebrafish. Customized apparatus was used to evaluate courtship behavior. The result showed that the male spent less time with BHPF and anti-oestrogenic fulvestrant (FULV) treated female in region of approaching (ROA). Courtship index between BHPF-exposed female and male decreased. The body orientation of BHPF- and FULV-exposed female to male decreased. Furthermore, BHPF exposure downregulated the expression of genes related to estrogen receptor, steroidogenesis and upregulated oxidative stress related genes. It indicated that BHPF exposure interfered the preference of male and female in courtship, and induced detrimental effects on reproduction. BHPF treatment decreased locomotor activity and time spent in top, increased freezing bouts, and induced anxiety/depression-like behavior. The tyrosine hydroxylase in brain decreased under BHPF exposure. Here we showed the potential adverse effects of BHPF on reproduction and exploratory behaviors.

Behavioral and neurological analyses of adult mice carrying null and distinct loss-of-receptor function mutations in protein tyrosine phosphatase receptor type Z (PTPRZ)

Protein tyrosine phosphatase receptor type Z (PTPRZ) is preferentially expressed in the central nervous system as two transmembrane receptor isoforms PTPRZ-A/B and one secretory isoform PTPRZ-S. Ptprz-knockout mice lacking the expression of all three isoforms show behavioral, learning, and neurological abnormalities, including increased exploratory activities to novelty, deficits in spatial and contextual learning, and reduced responses to methamphetamine, relative to wild-type mice. To investigate whether PTPRZ isoforms play distinct physiological roles, we herein performed behavioral studies on two knock-in mouse lines: One expresses the catalytically inactive Cys-1930 to Ser (CS) mutants of PTPRZ-A/B, while the other generated in the present study expresses catalytically active mutants of PTPRZ-A/B lacking the negative regulatory PTP-D2 domain and C-terminal PDZ-binding motif (ΔD2) instead of wild-type PTPRZ-A/-B. In contrast to Ptprz-knockout mice, neither increased responses to novelty in the open field nor memory impairments in the inhibitory-avoidance task were observed in Ptprz-CS or Ptprz-ΔD2 mice. However, the effects of methamphetamine on locomotor activity were significantly weaker in Ptprz-KO mice and CS mutant mice than in wild-type mice, but were normal in ΔD2 mutant mice. Furthermore, microdialysis experiments revealed that methamphetamine-evoked dopamine release in the nucleus accumbens was reduced in Ptprz-KO mice and CS mutant mice. These results suggest that the extracellular region of PTPRZ, including the secretory isoform, is crucial for behavioral responses to novelty and the formation of aversive memories, whereas the PTPase activities of PTPRZ receptor isoforms are involved in regulating the dopaminergic system.

Sexually Dimorphic Regulation of Behavioral States by Dopamine in Caenorhabditis elegans

Sex differences in behavior allow animals to effectively mate and reproduce. However, the mechanism by which biological sex regulates behavioral states, which underlie the regulation of sex-shared behaviors, such as locomotion, is largely unknown. In this study, we studied sex differences in the behavioral states of Caenorhabditis elegans and found that males spend less time in a low locomotor activity state than hermaphrodites and that dopamine generates this sex difference. In males, dopamine reduces the low activity state by acting in the same pathway as polycystic kidney disease-related genes that function in male-specific neurons. In hermaphrodites, dopamine increases the low activity state by suppression of octopamine signaling in the sex-shared SIA neurons, which have reduced responsiveness to octopamine in males. Furthermore, dopamine promotes exploration both inside and outside of bacterial lawn (the food source) in males and suppresses it in hermaphrodites. These results demonstrate that sexually dimorphic signaling allows the same neuromodulator to promote adaptive behavior for each sex.SIGNIFICANCE STATEMENT The mechanisms that generate sex differences in sex-shared behaviors, including locomotion, are not well understood. We show that there are sex differences in the regulation of behavioral states in the model animal Caenorhabditis elegans Dopamine promotes the high locomotor activity state in males, which must search for mates to reproduce, and suppresses it in self-fertilizing hermaphrodites through distinct molecular mechanisms. This study demonstrates that sex-specific signaling generates sex differences in the regulation of behavioral states, which in turn modulates the locomotor activity to suit reproduction for each sex.