Systemic and intra-amygdala administrations of midazolam reverse anxiety-like behavior induced by cohabiting with a cagemate in chronic pain condition

The affective component of pain may be shared among conspecifics through emotional contagion, a form of empathic expression. In this sense, reverberation of negative emotions could generate distress behavioral responses, such as pathological anxiety. Evidences reported that amygdala and its benzodiazepine receptors are involved in perception of pain in others. However, relatively little is known about the neural processes underlying emotional contagion induced by pain observation. In the present study, we investigated the effects of midazolam, an allosteric GABAergic receptor agonist, in anxiety-like behaviors induced by cohabitation with cagemate submitted to sciatic nerve constriction. For this purpose, we administrated systemic (0.5, 1.0 and 2.0 mg/kg) and intra-amygdala midazolam injections (3.0 and 30.0 nmol) in observer cagemates before elevated plus-maze (EPM) evaluation. We found that mice subjected to nerve constriction and their observer cagemates increased anxiety-like behavior in the EPM. Further, systemically (1.0 and 2.0 mg/kg) and intra-amygdala administration of midazolam (3.0 and 30 nmol) reverse this anxiogenic effect. Collectively, these results suggest that social interaction with a cagemate under chronic pain produces anxiety-like responses that could be blocked through midazolam application.

Anticompulsive effects of novel derivatives of coumarin in rats

BACKGROUND: Until now, the neurotropic effect, in particular the effect on the emotional behavior of oxy-coumarins, has not been adequately studied. There are only few data on their central action. Currently, research is underway on the synthesis of new compounds based on natural oxy-coumarins, which will potentially have a higher biological activity. AIM: Was to study the central action of new oxycoumarin-based compounds IEM-2886, LVM-99, LVM-S144, in particular, on compulsive behavior in rats. MATERIALS AND METHODS: To assess the behavior of Wistar rats, the Marble-test and Elevated plus maze methods were used. Oxycoumarin derivatives (IEM-2886, LVM-99, LVM-S144) were injected intraperitoneally at doses of 1, 10 and 25 mg/kg. The effectiveness of the drugs was judged by the number of balls buried in the Marble test and by the duration of staying in the open and closed sleeves of the Elevated plus maze. Results. It was shown that in the Marble test, oxycoumarin-based compounds (IEM-2886, LVM-99, LVM-S144) caused a decrease in the number of buried balls, which shows their anti-compulsive effect. After administration of IEM-2886, LVM-99, LVM-S144 (125 mg / kg) compounds, dose-dependent effects were observed (p 0.05). The elevated plus maze test did not show the anxiolytic effect typical for tranquilizers. Moreover, after the administration of IEM-2886 and LVM-S144 at a dose of 25 mg / kg, an increase in the time spent in the closed sleeve of the maze (p 0.05) was observed, i.e. an anxiogenic effect. CONCLUSION: Thus, oxy-coumarin-based compounds are selective for the assessment of anticompulsive effects.

The Effects of Brain Serotonin Deficiency on Responses to High Fat Diet in Female Mice

Clinical studies have reported an increased risk of depression and anxiety disorders among individuals who are obese, and women are more likely than men to suffer from depression, anxiety, and obesity. However, the effects of obesity-promoting diets on depression- and anxiety-like behavior remain controversial. A recent study from our group used the tryptophan hydroxylase 2 (R439H) knock-in mouse line to evaluate the impact of genetic brain serotonin (5-HT) deficiency on behavioral responses to high fat diet (HFD) in male mice. That study indicated that chronic exposure to HFD induced pro-anxiety-like effects in the open field test and antidepressant-like effects in the forced swim test in wild-type males. Interestingly, the antidepressant-like effect of HFD, but not the anxiogenic effect, was blocked by brain 5-HT deficiency in males. The current work sought to repeat these studies in females. Our new data suggest that females are less susceptible than males to HFD-induced weight gain and HFD-induced alterations in behavior. In addition, the effects of chronic HFD on the expression of inflammation-related genes in the hippocampus were markedly different in females than we had previously reported in males, and HFD was shown to impact the expression of several inflammation-related genes in a genotype-dependent manner. Together, our findings highlight the importance of brain 5-HT and sex in regulating behavioral and molecular responses to HFD. Our results may have important implications for our understanding of the clinically observed sex differences in the consequences of obesity.

Rosuvastatin revert memory impairment and anxiogenic-like effect in mice infected with the chronic ME-49 strain of Toxoplasma gondii

The aim of this study was to investigate the effect of rosuvastatin treatment on memory impairment, and anxiogenic-like effects in mice chronically infected with Toxoplasma gondii. For this, Balb/c mice were infected orally with chronic ME-49 strain of Toxoplasma gondii. Oral treatment with rosuvastatin (40mg/kg/day) started on the 51st day post-infection and was performed daily for 21 days. After completion of treatment, anxiety-like effects and locomotion were investigated in the open field (OF) test, whereas novel object recognition (NOR) test was used for evaluation of short- and long-term memory. At the end of the experiments, the brain was collected for Toxoplasma gondii DNA quantification and histopathological analysis. Infection with ME-49 strain decreased the time spent in the center of OF, indicating an anxiogenic effect, without affecting total and peripheral locomotion. Rosuvastatin treatment inhibited the change in the center time. Besides, pharmacological treatment increased total and central locomotion in both non-infected and infected animals. Infection also impaired both short- and long-term memory in the NOR test, and these effects were reverted by rosuvastatin treatment. In addition to effects in behavioral changes, rosuvastatin also reduced parasite load in the brain and attenuated signs of brain inflammation such as perivascular cuffs, inflammatory cell infiltration and tissue damage. These findings indicate for the first time the efficacy of rosuvastatin in treatment of memory impairment and anxiogenic effect evoked by infection with Toxoplasma gondii. These effects might be mediated by reduced cyst load, which in turn decrease inflammation and damage in the brain.

THE ROLE OF THYROID HORMONES IN THE FORMATION OF SPATIAL MEMORY OF RATS IN EARLY ONTOGENESIS

Changes in behavioral and mnestic activity, as well as their neurochemical support in thyroid dysfunction were determined in juvenile Wistar rats. Behavioral activity was studied in an elevated cruciform labyrinth, the study of spatial memory was performed by the development of protective avoidance reaction in the Morris water labyrinth, and by the production of food reactions in the 8-beam labyrinth. The content of free amino acids of the neurotransmitter spectrum and serotonin was determined by thin layer chromatography followed by spectrophotometry. It was found that thyroid dysfunction in early ontogenesis was accompanied by significant impairments of emotional and cognitive activity depending on the thyroid status of rats; differences in the mechanisms of the formation of spatial memory with negative and positive reinforcement were also found. At the same time, the anxiolytic type of behavior and formation of spatial memory in juvenile animals with experimental hyperthyroidism are possibly provided by an increase in GABA content in the neocortex by 40% and a decrease in serotonin level in the hippocampus by 32%. Experimental hypothyroidism caused an anxiogenic effect and cognitive impairment, which were accompanied by an excessive increase by 51% in the neocortical serotonin content.

Kisspeptin-8 Induces Anxiety-Like Behavior and Hypolocomotion by Activating the HPA Axis and Increasing GABA Release in the Nucleus Accumbens in Rats

Kisspeptins (Kp) are RF-amide neuropeptide regulators of the reproductive axis that also influence anxiety, locomotion, and metabolism. We aimed to investigate the effects of intracerebroventricular Kp-8 (an N-terminally truncated octapeptide) treatment in Wistar rats. Elevated plus maze (EPM), computerized open field (OF), and marble burying (MB) tests were performed for the assessment of behavior. Serum LH and corticosterone levels were determined to assess kisspeptin1 receptor (Kiss1r) activation and hypothalamic-pituitary-adrenal axis (HPA) stimulation, respectively. GABA release from the nucleus accumbens (NAc) and dopamine release from the ventral tegmental area (VTA) and NAc were measured via ex vivo superfusion. Kp-8 decreased open arm time and entries in EPM, and also raised corticosterone concentration, pointing to an anxiogenic effect. Moreover, the decrease in arm entries in EPM, the delayed increase in immobility accompanied by reduced ambulatory activity in OF, and the reduction in interactions with marbles show that Kp-8 suppressed exploratory and spontaneous locomotion. The increase in GABA release from the NAc might be in the background of hypolocomotion by inhibiting the VTA-NAc dopaminergic circuitry. As Kp-8 raised LH concentration, it could activate Kiss1r and stimulate the reproductive axis. As Kiss1r is associated with hyperlocomotion, it is more likely that neuropeptide FF receptor activation is involved in the suppression of locomotor activity.

Rosmarinus officinalis L. leaf extract improves Anxity impairment induced by tropane alkaloids extracted from Datura stramonium

The alkaloid extract of datura stramonium (rich of atropine, hyoscyamine, scopolamine) is used to evaluate its effect on the central nervous system in rats (locomotion, anxiety). The animals received the alkaloid extract of datura by intraperitoneal injection. However, after the injection a group of rats got an inhibitory treatment contain flavonoids extracted from Rosmarinus officinalis. At the dose of 50 mg/kg/body weight of the alkaloid extract, the female rats have shown a reduction of locomotor activity and an induction of an anxiogenic effect. In the other hand, the mixture of Datura stramonium and Rosmarinus officinalis showed a neuroprotective action with regard to the disorders induced by extracts of Datura stramonium.

Cannabis, a cause for anxiety? A critical appraisal of the anxiogenic and anxiolytic properties

Background Cannabis has been documented for use in alleviating anxiety. However, certain research has also shown that it can produce feelings of anxiety, panic, paranoia and psychosis. In humans, Δ9-tetrahydrocannabinol (THC) has been associated with an anxiogenic response, while anxiolytic activity has been attributed mainly to cannabidiol (CBD). In animal studies, the effects of THC are highly dose-dependent, and biphasic effects of cannabinoids on anxiety-related responses have been extensively documented. A more precise assessment is required of both the anxiolytic and anxiogenic potentials of phytocannabinoids, with an aim towards the development of the ‘holy grail’ in cannabis research, a medicinally-active formulation which may assist in the treatment of anxiety or mood disorders without eliciting any anxiogenic effects. Objectives To systematically review studies assessing cannabinoid interventions (e.g. THC or CBD or whole cannabis interventions) both in animals and humans, as well as recent epidemiological studies reporting on anxiolytic or anxiogenic effects from cannabis consumption. Method The articles selected for this review were identified up to January 2020 through searches in the electronic databases OVID MEDLINE, Cochrane Central Register of Controlled Trials, PubMed, and PsycINFO. Results Acute doses of CBD were found to reduce anxiety both in animals and humans, without having an anxiogenic effect at higher doses. Epidemiological studies tend to support an anxiolytic effect from the consumption of either CBD or THC, as well as whole plant cannabis. Conversely, the available human clinical studies demonstrate a common anxiogenic response to THC (especially at higher doses). Conclusion Based on current data, cannabinoid therapies (containing primarily CBD) may provide a more suitable treatment for people with pre-existing anxiety or as a potential adjunctive role in managing anxiety or stress-related disorders. However, further research is needed to explore other cannabinoids and phytochemical constituents present in cannabis (e.g. terpenes) as anxiolytic interventions. Future clinical trials involving patients with anxiety disorders are warranted due to the small number of available human studies.