Forty-kHz ultrasonic vocalizations of rat pups predict adult behavior in the elevated plus-maze behavior but not the effect of cocaine on 50-kHz ultrasonic vocalizations.

Ultrasonic vocalizations (USV) are emitted by both young pups and adult rats to convey positive or negative emotional states. These USV manifestations are contingent on factors including developmental stage, situational requirements, and individual dispositions. Pups emit 40-kHz USV when separated from their mother and litter, which function to elicit maternal care. Conversely, adult rats can produce 50-kHz USV in response to stimuli that elicit reward-related states, including natural rewards, stimulant drugs, and reward-predictive stimuli. The present study aims to investigate whether pup 40-kHz USV can serve as predictors of behaviors related to positive or negative states in adult rats. Both male and female Wistar pups were initially tested on the 11th postnatal day and subsequently in adulthood. There was no significant difference in the number of 40-kHz ultrasonic vocalizations between male and female pups. However, cocaine elicited more 50-kHz USV and hyperactivity in adult females compared to males. Notably, cocaine increased the proportion of step and trill USV subtypes in both adult males and females. Interestingly, this effect of cocaine was stronger in females that were in the diestrus, compared to the estrus phase. In males, a significant positive correlation was found between pup 40-kHz USV and lower anxiety scores in adult male but not female rats tested on the elevated plus-maze test. Furthermore, no significant correlation was found between pup 40-kHz and adult 50-kHz USV in both males and females, whether in undrugged (saline) or in cocaine-treated rats. It is possible that the 40-kHz USV emitted by pups predicted reduced anxiety-like behavior only for male rats because they could elicit maternal care directed specifically to male pups. These findings suggest that 40-kHz USV can serve as an indicator of the emotional link between the rat mother and male pups. Indeed, this suggests that maternal care exerts a positive influence on the emotional state during adulthood.

Characterization of Depression- and Anxiety-Like Behaviours in a Mouse Model of Relapsing-Remitting Multiple Sclerosis.

Relapsing-remitting multiple sclerosis (RRMS) is an autoimmune neurological disease and is the most common subtype of MS. In addition, it is associated with the development of depression and anxiety. To date, depressive- and anxiety-like behaviours were only studied using models of progressive MS, which causes severe motor alterations. Thus, we sought to standardise the depressive and anxiety-like behaviours in an RRMS model induced by experimental autoimmune encephalomyelitis (RR-EAE) in mice. The RR-EAE model was induced in C57BL/6 female mice using myelin oligodendrocyte glycoprotein (MOG35-55) antigen and Quillaja saponin (Quil A) as an adjuvant. The immunisation of RR-EAE did not induce locomotor alteration but caused relapsing-remitting induction of clinical scores in mice until 35 post-immunization (p.i.). Also, increased levels of tumour necrosis factor alpha (TNF-α), astrocyte marker (GFAP), and microglial markers (IBA-1) were detected in the prefrontal cortex at 35 p.i. of RR-EAE. In the open field test, RR-EAE mice showed decreased time spent at the centre and sniffing behaviour (at days 21 and 34 p.i.). Also, on day 35 p.i. the RR-EAE group spent less time in the open arms and had decreased open-arm entries compared to control mice in the elevated plus maze (EPM) test, confirming the anxiety-like behaviour. At day 36° p.i. in the tail suspension test, mice showed depression-like behaviour with decreased latency time and increased immobility time. Thus, the RR-EAE model mimics the neuroinflammatory and behavioural features of the RRMS, including depression- and anxiety-like symptoms.

The insula mediates the effects of glucocorticoids in anxiety.

Increased activity in the insula has been consistently reported to be associated with anxiety and anxiety-related disorders. However, little is known on how the insula regulates anxiety. The present study aims at determining the role of the insula on the effects of glucocorticoids in anxiety. A combination of pharmacological manipulations, including blockade of adrenal GC synthesis by metyrapone and intra-insular microinjections of corticosterone, corticosterone-BSA, mineralocorticoid receptor (MR) antagonist spironolactone and glucocorticoid receptor (GR) antagonist mifepristone, were used to assess the short-term (5 min) effects of intra-insular corticosterone in two anxiety-like behaviors in male Sprague-Dawley rats. The elevated plus maze (EPM) and Novelty Suppressed Feeding (hyponeophagia) were utilized. We found that corticosterone in the insula is sufficient to prevent the anxiolytic effects corticosterone synthesis blockade in anxiety, and that intra-insular corticosterone has anxiolytic or anxiogenic effects depending on the amount of corticosterone microinjected and the arousal associated to the test, without affecting the HPA axis. Glucocorticoid anxiolytic effects in the insula are mediated by MRs, while its anxiogenic effects are dependent on a mifepristone-sensitive membrane-bound mechanism. Anxiety appears to be modulated at the insula through a competition between fast MR-dependent anxiolytic and membrane-associated anxiogenic signaling pathways that orchestrate the behavioral response to stress and determines the resulting level of anxiety.

Neonatal olfactory bulbectomy induces anxiety-related behavior and modifies dopaminergic receptor expression in post-pubertal rats.

Olfaction is a complex physiological process producing effects in the central nervous system (CNS) and implicated in emotional processes. Indeed, the olfactory bulbs (OB) send projections to various CNS regions including the nucleus accumbens (NAcc) and caudate-putamen (CPu). Both the NAcc and CPu receive important dopaminergic input. Emerging evidence suggests that dopamine (DA) is related to anxiety-related behaviors. Therefore, we aimed to investigate the consequences of neonatal olfactory bulbectomy (nOBX) to anxiety-related behavior as assayed in the elevated plus maze (EPM) as well as the expression of dopaminergic receptors (D1-like, D2-like, and D3) in the NAcc and CPu at pre- and post-pubertal ages in the rat. The results show that nOBX increased the number of entries in the open arm of the EPM post-pubertally, suggesting an anxiolytic-related effect. nOBX increased the D2-like binding in the NAcc shell and D3 binding in the NAcc core pre-pubertally. At post-pubertal ages, the D3 binding was reduced at the olfactory tubercle and islands of Calleja in nOBX rats. Alterations in the DA receptor expression may be one mechanism responsible for the observed behavioral modifications in nOBX rats.

Comparative analysis between Open Field and Elevated Plus Maze tests as a method for evaluating anxiety-like behavior in mice.

Anxiety is being increasingly diagnosed in the elderly population. In this sense, epidemiologic data have linked late-life anxiety disorders to increased cognitive decline, morbidity, and even mortality. In addition, studies have already reported the influence of the environment on the association between aging and anxiety. Therefore, the present study aimed to conduct a comparative analysis between Elevated Plus Maze (EPM) and Open Field (OF) tests as methods for evaluating mice's anxiety-like behavior, considering environmental and age variables. For this, eighty Female albino Swiss mice aged 6, 12, and 18 months were housed in an impoverished environment (IE) and enriched environment (EE). Following this, the animals were tested in EPM and OF tests. The environment and age affect the anxiety-like behavior of the mice in the OF, with a difference between the animals of 6 and 18 months, only in the EE (p < 0.021). However, in the EPM, it does not occur. Despite that, the environment affected the distance traveled by the mice in the EPM, where the IE animals showed greater exploratory activity than the EE, only in the 18-month group (p < 0.001). No environmental influences were detected in the OF. Concerning age, in the EPM, animals in the 18-month-old group traveled shorter distances compared to the 6-month group (p < 0.001) and the 12-month group (p < 0.001), only in EE. In turn, in the OF there was a decrease in the distance traveled in the 18-month group compared to the 6-month group (p = 0.012), only in the IE. Thus, the divergences between the results of EPM and OF instigate a better evaluation of the parameters analyzed in each test.

The Estrous Cycle Influences the Effects of Fatty Acid Amide Hydrolase and Monoacylglycerol Lipase Inhibition in the Anxiety-Like Behavior in Rats.

Background: Sex differences in the response to the anxiety-related effects of cannabinoid drugs have been reported, with females being more sensitive than males. Evidence suggests that, according to sex and estrous cycle phase (ECP), the content of the endocannabinoids (eCBs) N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) varies in brain areas involved in the anxiety-like behavior. Methods: Considering the lack of studies evaluating sex and ECP differences in the eCB system in anxiety, using URB597, a fatty acid amide hydrolase inhibitor, or MJN110, a monoacylglycerol lipase inhibitor, we explored the effects of increasing AEA or 2-AG levels, respectively, in cycling and ovariectomized (OVX) female adult Wistar rats, as well as males, subjected to the elevated plus maze. Results: The administration of URB597 (0.1 or 0.3mg/kg; intraperitoneally) either increased or reduced the percentage of open arms time (%OAT) and open arms entries (%OAE), being anxiolytic in diestrus and anxiogenic in estrus. No effects were observed in proestrus or when all ECPs were analyzed together. Both doses produced anxiolytic-like effects in males. In OVX females, the anxiolytic-like effect of URB597 0.1 was associated with low levels of estradiol, whereas the anxiogenic-like effect of URB597 0.3 was spared by estradiol pretreatment. The systemic administration of MJN110 3.0 mg/kg reduced the risk assessment behavior (RAB), suggesting an anxiolytic-like effect independent of the ECP. When considering the ECP, MJN110 3.0 increased the %OAT and reduced the RAB, being anxiolytic in estrus and diestrus. No effects were observed in proestrus. Both doses of MJN110 were anxiogenic in males. In OVX females, the anxiolytic-like effect of MJN110 was dependent on low estradiol levels. Conclusion: Together, our findings support the evidence that females react differently to the effects of cannabinoids in the anxiety-like behavior; in addition, AEA and 2-AG modulation elicits anxiety-like responses that are closely influenced by hormone levels, mainly estradiol.

Systematic review on the anxiolytic and hypnotic effects of flower extracts in in vivo pre-clinical studies published from 2010 to 2020.

Anxiety disorders are prevalent conditions in the world population, whose standard approaches include pharmacotherapy, psychotherapy, and combinations of these interventions. Different classes of psychopharmaceuticals are recommended as the first line of drugs to treat these disorders, which can have several adverse effects, treatment resistance, dependence, and drug-drug interactions making it necessary to search for new therapeutic agents. In particular, diazepam (DZP), a prototype drug from the group of benzodiazepines, has been commonly used and evaluated for its efficacy and safety in different anxiety disorders in clinical trials. DZP is also the most widely used reference standard in in vivo pharmacological assays of natural compounds. However, translating the results obtained in different rodent species and physiological anxiety tests instead of psychopathological animal models that can be of clinical application remains challenging. A systematic review of scientific articles published between 2010 and 2020 that included in vivo pre-clinical tests to define the anxiolytic, sedative and/or hypnotic effect of flower extracts is proposed. PRISMA and Rayyan were used for the selection of studies using four databases (Pubmed, Scopus, Web of Science, and QInsight), using the keywords: "Animals," "Anxiolytic," "Diazepam," "Elevated Plus Maze," "Flower Extracts," "Insomnia," "In vivo," "Mice," "Open Field Test," "Pre clinical" and "Sedative." The characteristics of anxiety studies in animal models, other studies related to locomotor activity, and the hypnotic effect of the extracts were compiled. Twenty-four articles were included, 21 of them performed the animal model of anxiety-like behavior of the elevated plus maze, seven the open field test, and six the light-dark box test. The locomotor activity was evaluated in 10 studies after the administration of the extracts to the animals to define their sedative effect, where only one defined that the extract (Matricaria chamomilla) had a sedative effect. The plants declared with this type of activity were Achyranthes aspera, Alcea aucheri, Brassica nigra, Cananga odorata, Carthamus tinctorius, Chrysanthemum indicum, Citrus aurantium, Couroupita guianensis, Echium amoenum, Erythrina berteroana, Gardenia jasminoides, Hibiscus tilliaceus, Lavandula officinalis, Lawsonia inermis, Matricaria chamomilla, Melia azedarach, Nerium oleander, Passiflora incarnata, Plumeria rubra, Salix aegyptiaca, Syzygium aromaticum, Tagetes erecta, Tilia americana. Although this review showed that some flower extracts have an anxiolytic effect as effective as diazepam, their therapeutic utility in anxiety disorders remains to be extensively demonstrated. Hence, more reliable and predictive behavioral tests and appropriate strategies for the experimental designs are needed to obtain more conclusive evidence with clinical significance.

Individual differences in the effects of midazolam on anxiety-like behavior, learning, reward, and choice behavior in male mice.

Introduction: The aim of the present study was to investigate the behavioral effects of the benzodiazepine midazolam in male mice, in models of anxiolysis, learning, and abuse-related effects. Methods: In a first set of experiments, male Swiss mice were submitted to the training session of a discriminative avoidance (DA) task on the elevated plus maze to evaluate anxiety-like behavior and learning after vehicle or midazolam (1, 2 or 5 mg/kg, i.g.) administration. The same animals were submitted to a conditioned place preference (CPP) protocol with midazolam (1, 2 or 5 mg/kg, i.g.). In a second experiment, outbred (Swiss) and inbred (C57BL/6) male mice were submitted to a two-bottle choice (TBC) oral midazolam drinking procedure. Animals were exposed to one sucrose bottle and one midazolam (0.008, 0.016 or 0.032 mg/ml) plus sucrose bottle. Results: Midazolam (1 and 2 mg/kg) induced anxiolytic-like effects, and all doses of midazolam prevented animals from learning to avoid the aversive closed arm during the DA training session. Assessment of midazolam reward via the CPP procedure and choice via the TBC procedure showed notable variability. A 2-step cluster analysis for the CPP data showed that midazolam data were well-fitted to 2 separate clusters (preference vs. aversion), albeit with the majority of mice showing preference (75%). Correlational and regression analyses showed no relationship between midazolam reward and anxiolytic-like effects (time spent in the open arms in the DA test) or learning/memory. Two-step cluster analysis of the TBC data also demonstrated that, regardless of strain, mice overall fell into two clusters identified as midazolam-preferring or midazolam-avoiding groups. Both midazolam preference and avoidance were concentration-dependent in a subset of mice. Discussion: Our findings show that midazolam preference is a multifactorial behavior, and is not dependent solely on the emergence of therapeutic (anxiolytic-like) effects, learning impairments, or on genetic factors (inbred vs. outbred animals).

Cannabidiol modulates contextual fear memory consolidation in animals with experimentally induced type-1 diabetes mellitus.

OBJECTIVES: In view of the neuroprotective characteristic of cannabidiol (CBD) and its beneficial action on aversive memory in non-diabetic animals, we aimed to investigate in animals with experimentally induced type-1 diabetes mellitus (T1DM) whether CBD treatment would be able to impair the contextual fear memory consolidation, its generalisation and whether the effect would be lasting. We also investigated the CBD effect on anxiety-like responses. METHODS: After T1DM induction, animals received single or more prolonged treatment with CBD and were submitted to the contextual fear conditioning test. As expression of activity-regulated cytoskeletal-associated (Arc) protein is necessary for memory consolidation, we evaluated its expression in the dorsal hippocampus (DH). For evaluating anxiety-related responses, animals were submitted to the elevated plus maze test (EPMT), in which the time and number of entries in the open arms were used as anxiety index. RESULTS: A single injection of CBD impaired the contextual fear memory consolidation and its generalisation, which was evaluated by exposing the animal in a neutral context. This single injection was able to reduce the elevated expression of Arc in the DH from these animals. Interestingly, more prolonged treatment with CBD also impaired the persistence of context-conditioned fear memory and induced an anxiolytic-like effect, as the treated group spent more time in the open arms of the EPMT. CONCLUSION: CBD interferes with contextual fear memory and the dosage regimen of treatment seems to be important. Moreover, we cannot rule out the involvement of emotional aspects in these processes related to fear memory.

Water deprivation induces hypoactivity in rats independently of oxytocin receptor signaling at the central amygdala.

Introduction: Vasopressin (AVP) and oxytocin (OXT) are neuropeptides produced by magnocellular neurons (MCNs) of the hypothalamus and secreted through neurohypophysis to defend mammals against dehydration. It was recently demonstrated that MCNs also project to limbic structures, modulating several behavioral responses. Methods and Results: We found that 24 h of water deprivation (WD) or salt loading (SL) did not change exploration or anxiety-like behaviors in the elevated plus maze (EPM) test. However, rats deprived of water for 48 h showed reduced exploration of open field and the closed arms of EPM, indicating hypoactivity during night time. We evaluated mRNA expression of glutamate decarboxylase 1 (Gad1), vesicular glutamate transporter 2 (Slc17a6), AVP (Avpr1a) and OXT (Oxtr) receptors in the lateral habenula (LHb), basolateral (BLA) and central (CeA) amygdala after 48 h of WD or SL. WD, but not SL, increased Oxtr mRNA expression in the CeA. Bilateral pharmacological inhibition of OXTR function in the CeA with the OXTR antagonist L-371,257 was performed to evaluate its possible role in regulating the EPM exploration or water intake induced by WD. The blockade of OXTR in the CeA did not reverse the hypoactivity response in the EPM, nor did it change water intake induced in 48-h water-deprived rats. Discussion: We found that WD modulates exploratory activity in rats, but this response is not mediated by oxytocin receptor signaling to the CeA, despite the upregulated Oxtr mRNA expression in that structure after WD for 48 h.

Antidepressant- and anxiolytic-like actions of Cajanus cajan seed extract mediated through monoaminergic, nitric oxide-cyclic GMP and GABAergic pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: The seeds of Cajanus cajan (L) Millsp, are used in Traditional medicine for the treatment of anxiety and other neurological disorders. Hence, this study is designed to investigate the antidepressant- and anxiolytic-like properties of ethanol seed extract of Cajanus cajan (CC) in mice. MATERIALS AND METHODS: CC (50, 100 or 200 mg/kg, p.o.) was administered 1h before subjecting the animals to different behavioral models: forced swim test (FST) and tail suspension test (TST) (depressive-like behaviour), open field test (OFT), elevated plus maze (EPM), light-dark test (LDT) and hole-board test (HBT) for anxiety-like behaviour. To ascertain the pharmacodynamic of CC mice were pretreated with monoaminergic, nitrergic and GABAergic receptors antagonists. As well as molecular docking analysis of about 19 flavonoids present in CC on GABAA, α2 adrenoceptors and 5-HT2A receptors. RESULTS: CC (50, 100 or 200 mg/kg, p.o.) treatment significantly reduced immobile time in both FST and TST when compared with vehicle-treated control. However, the pretreatment of mice with prazosin/yohimbine (α1/2 adrenoceptor antagonists, respectively), WAY100635 (5-HT1A receptor antagonist), ketanserin (5-HT2A receptor antagonist), sulpiride (dopamine D2 receptor antagonist), L-NG-Nitro arginine methyl ester (L-NAME), or methylene blue reversed the antidepressant-like effect of CC. In anxiety model, CC produced significant (p < 0.05) increase in open arms exploration and head dipping behavior which was reversed by flumazenil (benzodiazepine receptor antagonist) in the EPM. Docking analysis showed significant binding affinity of orientin, vitexin, pinostrobin and quercetin with 5HT2A, α2-adrenoceptor and GABAA receptors. CONCLUSION: Findings from this study showed that C.cajan seeds extract exerts antidepressant-like effect through participation of monoaminergic systems (5-HT2 receptor, α1/α2-adrenoceptors, and dopamine D2-receptors), nitric oxide-cyclic GMP pathway and anxiolytic-like effect via GABAA benzodiazepine receptors. Moreso, presence of flavonoids with significant binding energies with monoaminergic and GABAergic systems support the potential of the extract in the management of mixed anxiety-depressive illness.

The resilience of adolescent male rats to acute stress-induced delayed anxiety is age-related and glucocorticoid release-dependent.

Studies investigated how stressful experiences modulate physiological and behavioral responses and the consequences of stress-induced corticosterone release in anxiety-like behavior. Adolescence is crucial to brain maturation, and several neurobiological changes in this period lead individuals to increased susceptibility or resilience to aversive situations. Despite the effects of stress in adults, information about adolescents' responses to acute stress is lacking. We aimed to understand how adolescence affects acute stress responses. Male adolescent rats (30 days old) were 2 h restrained, and anxiety-like behaviors were measured immediately or 10 days after stress in the elevated plus-maze (EPM) and the light-dark box (LDB) tests. To verify the importance of CORT modulation in stress-induced anxiety, another group of rats was treated, 30 min before restraint, with metyrapone to blunt the stress-induced CORT peak and tested immediately after stress. To show that stress effects on behavior were age-dependent, another set of rats was tested in two different periods - early adolescence (30 days old) and mid-adolescence (40 days old) and were treated or not with metyrapone before the stress session and tested immediately or ten days later in the LDB test. Only early adolescent male rats were resilient to delayed anxiety-like behavior in EPM and LDB tests. Metyrapone treatment increased the rats' exploration immediately and ten days after stress. These data suggest a specific age at which adolescent rats are resilient to the delayed effects of acute restraint stress and that the metyrapone treatment has long-term behavioral consequences.

Long-term treatment with roflumilast improves learning of fear extinction memory and anxiety-like response in a type-1 diabetes mellitus animal model.

Diabetic encephalopathy is related to serious damage to the Central Nervous System leading to several disturbances in memory processing and emotions. It is known that the cyclic adenosine 3',5'-monophosphate (cAMP) responsive element-binding protein (CREB) pathway participates in neuronal plasticity and prevention of neuroinflammation, as well as the mediation of learning/memory processes and emotions in brain areas such as the hippocampus (HIP) and prefrontal cortex (PFC). We aimed to investigate the effect of acute (one injection) and long-term treatment (21 days) with roflumilast (ROF; i.p.; 0, 0.01, 0.03, 0.1 mg/kg), a drug able to inhibit the enzyme phosphodiesterase-4 (PDE-4) responsible for cAMP hydrolysis, on parameters related to the acquisition of fear extinction memory and anxiety-like responses in animals with type-1 diabetes mellitus (T1DM) induced through one injection of streptozotocin (60 mg/kg; ip; STZ animals). When we performed acute treatment, no difference was observed between all the groups when resubmitted to the same context paired with an aversive stimulus (footshock) or to a neutral context. In contrast, long-term treatment was able to improve learning of extinction fear memory and discriminating between a conditioned and neutral context. Moreover, this treatment decreased the pronounced anxiety-like response of STZ animals. In addition, there was an increase in the product of the CREB signaling pathway, the pro brain-derived neurotrophic factor, in the HIP and PFC of these animals. The treatment did not impair glycemic control, whereas it decreased the animal's blood glucose levels. To conclude, these findings suggest that ROF treatment repositioning has potential for future translational investigations involving diabetic patients considering its beneficial effects on emotional processes related to fear memory and anxiety, in addition to improvement of glycemic control.

Static magnetic field blocked alprazolam-induced behavior of Wistar rats in the elevated plus-maze test.

Studies have shown that psychotropic drugs change rat behavior in the elevated plus-maze test (EPM). This study investigated whether static magnetic fields could alter alprazolam-induced rat behavior in the EPM. 66 male Wistar rats (270-300 g weight) were assigned to one of the following groups: Sham Magnetic + Saline (SMS), North Pole + Saline (NPS), South Pole + Saline (SPS), Sham magnetic + alprazolam (SMA), NP + alprazolam (NPA), and SP + alprazolam (SPA). After five days of static magnetic stimulation (3200 Gauss), they received alprazolam or saline (1 mg/kg), and their behavior was evaluated. Two-way ANOVA and Holm-Sidak post-hock were used, with a significant P value of <0.05. The SMA and NPA groups showed an increased number of entries and time in the open arms compared with the SMS group. SPA showed a decrease in these measures when compared to SMA [F(2,61) = 6.43 and F(2,61) = 3.72, respectively]. The SMA and NPA groups showed increased head dipping and end-arm activity compared with the SMS group. SPA showed a decrease in these measures when compared to SMA [F(2,61) = 3.37 and [F(2,61) = 4.72, respectively]. These results show that the south magnetic pole of a static magnetic field blocked the alprazolam effect in the space-time variables of the open arms and ethological anxiolytic-like behavior in the EPM.

Effects of Δ9-THC and Type-1 Cannabinoid Receptor Agonists in the Elevated Plus Maze Test of Anxiety: A Systematic Review and Meta-Analysis.

Δ9-THC (the main active compound from Cannabis sativa) and related cannabinoids have been used as drugs of abuse and as medications. They induce a complex set of emotional responses in humans and experimental animals, consisting of either anxiolysis or heightened anxiety. These discrepant effects pose a major challenge for data reproducibility and for developing new cannabinoid-based medicines. In this study, we review and analyze previous data on cannabinoids and anxiety-like behavior in experimental animals. Systematic review and meta-analysis on the effects of type-1 cannabinoid receptor agonists (full or partial, selective or not) in rodents exposed to the elevated plus maze, a widely used test of anxiety-like behavior. Cannabinoids tend to reduce anxiety-like behavior if administered at low doses. THC effects are moderated by the dose factor, with anxiolytic- and anxiogenic-like effects occurring at low-dose (0.075-1 mg/kg) and high-dose (1-10 mg/kg) ranges, respectively. However, some studies report no effect at all regardless of the dose tested. Finally, motor impairment represents a potential confounding factor when high doses are administered. The present analysis may contribute to elucidate the experimental factors underlying cannabinoid effects on anxiety-like behavior and facilitate data reproducibility in future studies.

The Anxiolytic Activity of Schinus terebinthifolia Leaf Lectin (SteLL) Is Dependent on Monoaminergic Signaling although Independent of the Carbohydrate-Binding Domain of the Lectin.

The potential of plant lectins (carbohydrate-binding proteins) for the treatment of neurological disorders such as anxiety and depression has started to be reported in the last few years. Schinus terebinthifolia leaves contain a lectin called SteLL, which has displayed antimicrobial, immunomodulatory, antitumor, and analgesic activities. However, the effects of SteLL on the Central Nervous System (CNS) have not yet been determined. In this study, we investigated the in vivo anxiolytic effect of SteLL in mice using the open field (OF) and elevated plus maze (EPM) tests. In the OF, SteLL (1, 2, and 4 mg/kg, i.p.) did not interfere with the number of crossings but significantly reduced the number of rearings. In the EPM, SteLL 4 mg/kg and the combination SteLL (1 mg/kg) plus diazepam (1 mg/kg) significantly increased the time spent in the open arms while reducing the time spent in the closed arms. The anxiolytic effect of SteLL did not seem to be dependent on the carbohydrate-binding domain of the lectin. Nevertheless, the SteLL effect in the EPM was reversed by the pretreatment with the pharmacological antagonists of the α2-adrenoceptor, 5-HT2A/2C serotonin receptor, and the D1 dopamine receptor. Overall, our results suggest that the anxiolytic effect of SteLL is dependent on the monoaminergic signaling cascade.

Anxiolytic-like activity of Aloysia virgatavar. platyphylla leaves extract in mice / Actividad ansiolítica del extracto de hojas de Aloysia virgatavar. platyphylla en ratones

Background: Medicinal plants are part of traditional medicine and should be considered a therapeutic alternative for mental diseases. Several plants belonging to the Verbenaceae family have proved useful in treating general anxiety disorders, the most prevalent psychiatric disorders. Objective: This research aimed to verify the extract's safety, the effect on general behavior, and the effect on sleeping time, as well as to evaluate the anxiolytic-like effect of the methanol extract of Aloysia virgata var. platyphylla (Avp), in mice. Methodology: The toxicity test was done according to the OECD guide (mice groups n=5), and general behavior was observed during the assay. Sleeping time was assessed using the pentobarbital-induced hypnosis method (n=8). Male Swiss albino mice (n=6) were treated with 50 to 400 mg/kg of Avp extract and diazepam as a control. The anxiolytic-like effect was tested through the hole board and elevated plus-maze test. Results: The Avp extract has no side effects in tested doses, and no central nervous system depressant activity was noted. A. virgatavar. platyphyllaincreased exploration (number and time) in the hole board. In the elevated plus-maze, increased number and time into open arms were evidenced compared to the control group. Conclusion: With all these results, we concluded that the Avp extract is safe and has a potential anxiolytic-like activity in the animal model used

Antecedentes: Las plantas medicinales forman parte de la medicina tradicional y deben ser consideradas una alternativa terapéutica para las enfermedades mentales. Varias plantas pertenecientes a la familia Verbenaceae han demostrado su utilidad en el tratamiento de los trastornos de ansiedad, uno de los trastornos psiquiátricos más prevalentes. Objetivo: Esta investigación tuvo como objetivo verificar la seguridad del extracto, el efecto sobre el comportamiento general y el efecto sobre el tiempo de sueño, así como evaluar el efecto tipo ansiolítico del extracto metanólico de Aloysia virgata var. platyphylla(Avp), en ratones. Metodología: La prueba de toxicidad se realizó de acuerdo con la guía de la OCDE (grupos de ratones n=5), y se observó el comportamiento general durante el ensayo. El tiempo de sueño se evaluó mediante el método de hipnosis inducida por pentobarbital (n=8). Se trataron ratones albinos suizos macho (n=6) con 50 a 400 mg/kg de extracto de Avp y diazepam como control. El efecto ansiolítico se probó a través de la placa perforada y prueba del laberinto en cruz elevado. Resultados: El extracto de Avp no tiene efectos secundarios en las dosis probadas y no se observó actividad depresora del sistema nervioso central. A. virgata var. platyphylla aumentó la exploración (número y tiempo) en el tablero de agujeros. En el laberinto en cruz elevado, se evidenció un mayor número y tiempo en los brazos abiertos en comparación con el grupo de control. Conclusión: Con todos estos resultados, concluimos que el extracto de Avp es seguro y tiene una potencial actividad ansiolítica en el modelo animal utilizado

Resolvin D5 disrupts anxious- and depressive-like behaviors in a type 1 diabetes mellitus animal model.

Type 1 diabetes mellitus (T1DM) is a chronic disease related to a persistent inflammatory process reaching the central nervous system, which leads to psychiatric comorbidities such as depression and anxiety. The search for new therapeutic agents effective in alleviating the psychiatric condition associated with T1DM becomes critical. Using an animal model of T1DM, we aimed to evaluate the effect of a specific specialized pro-resolving lipid mediator Resolvin D5 (RvD5), in preventing behaviors related to depression and anxiety, investigating its influence on inflammasome in interleukin (IL)-1ß in the hippocampus and prefrontal cortex. After experimental T1DM induction with streptozotocin (60 mg/kg, i.p.), these animals were treated for 23 days and randomly divided into 6 subgroups according to the treatment: vehicle (VEH), the antidepressant Fluoxetine (FLX; 10 mg/kg), the nonsteroidal anti-inflammatory Ibuprofen (IBU; 30 mg/kg) or Resolvin D5 (RvD5; 1 3, or 10 ng/animal). As a control group for the experimental-T1DM condition, a group of normoglycemic animals treated with VEH underwent the same behavioral tests: elevated plus maze, open field, and modified forced swimming tests. In the end, hippocampus and prefrontal cortex samples were processed to analyze the pro-inflammatory cytokine IL-1ß levels. Our data showed that RvD5 treatment prevented the more pronounced anxious-like and reduced the depressive-like behaviors of experimental-T1DM animals and significantly improved the plasma glucose levels. Additionally, RvD5 treatment prevented the increased level of pro-inflammatory cytokine IL-1ß in the hippocampus and prefrontal cortex of experimental-T1DM rats. To conclude, RvD5 presents a preventive therapeutic potential in impairing the development of the emotional complications resulting from T1DM. This potential may be related to its protective profile, as demonstrated in this study by its pro-resolutive action on neuroinflammation in the hippocampus and prefrontal cortex.

Chronic rapid eye movement sleep restriction during juvenility has long-term effects on anxiety-like behaviour and neurotransmission of male Wistar rats.

Modernity imposes a toll on the sleep time of young population, with concomitant increase in symptoms of anxiety and depression. Whether there is a causal relationship between these events are only now being experimentally tested in humans and rodents. In a previous study, we showed that chronic sleep deprivation in juvenile-adolescent male rats led to increased anxiety-like behaviour and changes in noradrenaline and serotonin in the amygdala and hippocampus. In the present study we investigated whether early chronic sleep restriction affects emotional behaviour, stress response and neurochemistry in adulthood. From 21 to 42 days of age, Wistar male rats were submitted to sleep restriction by the multiple platform method or allowed to sleep freely. Forty-five days after this period, rats were tested in the elevated plus maze (EPM) and blood samples were collected from non-tested rats or 30 and 60 min after the EPM for determination of plasma corticosterone levels. Levels of monoamines were determined in the frontal cortex, hippocampus, amygdala and hypothalamus 60 min after the EPM. Sleep restriction resulted in increased anxiety-like behaviour, decreased noradrenaline levels in the amygdala and dopamine levels in the ventral hippocampus. Anxiety index was positively correlated with increased serotonin metabolism in the frontal cortex and greater dopamine metabolism in the ventral hippocampus, and negatively correlated with dopamine levels in the ventral hippocampus. These results suggest that sleep restriction in juvenility and adolescence induces persistent changes in emotional behaviour in adult male rats and that levels of anxiety are correlated with increased serotonin and dopamine metabolism in specific brain areas.

A single injection of pregabalin induces short- and long-term beneficial effects on fear memory and anxiety-like behavior in rats with experimental type-1 diabetes mellitus.

Anxiety Disorders and Posttraumatic Stress Disorders (PTSD) associated with type-1 diabetes mellitus (T1DM) are increasingly common comorbidities and the treatment is quite challenging. In that sense, evidence indicates that the anticonvulsant pregabalin is highly effective in treating severe cases of anxiety, as well as PTSD and diabetic neuropathic pain which is also very prevalent in T1DM. Herein, the short- and long-term effects of a single injection of pregabalin on the acquisition of a fear extinction memory and parameters of anxiety in induced-T1DM animals were investigated. For that, we used the contextual fear conditioning (CFC) and elevated plus maze paradigms, respectively. A putative antioxidant activity was also evaluated. Our findings demonstrated that induced-T1DM animals presented greater expression of fear memory, difficulty in extinguishing this fear memory, associated with a more pronounced anxiety-like response. Pregabalin was able to induce a short and long-lasting effect by facilitating the acquisition of the fear extinction memory and inducing a later anxiolytic-like effect. Also, the increased lipid peroxidation levels in the hippocampus and prefrontal cortex of induced-T1DM rats were reduced after pregabalin injection, while the decreased levels of reduced glutathione were increased in the hippocampus. Despite the need for more studies to understand the mechanism of action of pregabalin under these conditions, our data demonstrate for the first time that a single injection of pregabalin in a specific time window was able to improve behavioral parameters in addition to inducing neuroprotective effect. Thus, pregabalin has potential worth exploring for the treatment of PTSD and/or Anxiety associated with T1DM.