Dopaminergic and noradrenergic modulation of stress-induced alterations in brain activation associated with goal-directed behaviour.

BACKGROUND: Acute stress is thought to reduce goal-directed behaviour, an effect purportedly associated with stress-induced release of catecholamines. In contrast, experimentally increased systemic catecholamine levels have been shown to increase goal-directed behaviour. Whether experimentally increased catecholamine function can modulate stress-induced reductions in goal-directed behaviour and its neural substrates, is currently unknown. AIM: To assess whether and how experimentally induced increases in dopamine and noradrenaline contribute to the acute stress effects on goal-directed behaviour and associated brain activation. METHODS: One hundred participants underwent a stress induction protocol (Maastricht acute stress test; MAST) or a control procedure and received methylphenidate (MPH) (40 mg, oral) or placebo according to a 2 × 2 between-subjects design. In a well-established instrumental learning paradigm, participants learnt stimulus-response-outcome associations, after which rewards were selectively devalued. Participants' brain activation and associated goal-directed behaviour were assessed in a magnetic resonance imaging scanner at peak cortisol/MPH concentrations. RESULTS: The MAST and MPH increased physiological measures of stress (salivary cortisol and blood pressure), but only MAST increased subjective measures of stress. MPH modulated stress effects on activation of brain areas associated with goal-directed behaviour, including insula, putamen, amygdala, medial prefrontal cortex, frontal pole and orbitofrontal cortex. However, MPH did not modulate the tendency of stress to induce a reduction in goal-directed behaviour. CONCLUSION: Our neuroimaging data suggest that MPH-induced increases in dopamine and noradrenaline reverse stress-induced changes in key brain regions associated with goal-directed behaviour, while behavioural effects were absent. These effects may be relevant for preventing stress-induced maladaptive behaviour like in addiction or binge eating disorder.

Three regulatory compliant test systems show no signs of MDMA-related genotoxicity.

3,4 Methylenedioxymethamphetamine (MDMA)-assisted therapy has been recently found to be highly effective for treatment of posttraumatic stress disorder (PTSD). Previous studies have been inconclusive in elucidating potential MDMA genotoxicity. We performed three regulatory compliant studies to investigate the potential of genotoxic effects of MDMA treatment in humans: (1) an in vitro bacterial reverse mutation (Ames) assay, (2) an in vitro chromosome aberration test in Chinese hamster ovary cells, and (3) an in vivo micronucleus study in male Sprague Dawley rats. MDMA was found to not have genotoxic effects in any of the assays at or above clinically relevant concentrations.

The Effect of Platelet-Rich Plasma on the Intra-Articular Microenvironment in Knee Osteoarthritis.

Knee osteoarthritis (KOA) represents a clinical challenge due to poor potential for spontaneous healing of cartilage lesions. Several treatment options are available for KOA, including oral nonsteroidal anti-inflammatory drugs, physical therapy, braces, activity modification, and finally operative treatment. Intra-articular (IA) injections are usually used when the non-operative treatment is not effective, and when the surgery is not yet indicated. More and more studies suggesting that IA injections are as or even more efficient and safe than NSAIDs. Recently, research to improve intra-articular homeostasis has focused on biologic adjuncts, such as platelet-rich plasma (PRP). The catabolic and inflammatory intra-articular processes that exists in knee osteoarthritis (KOA) may be influenced by the administration of PRP and its derivatives. PRP can induce a regenerative response and lead to the improvement of metabolic functions of damaged structures. However, the positive effect on chondrogenesis and proliferation of mesenchymal stem cells (MSC) is still highly controversial. Recommendations from in vitro and animal research often lead to different clinical outcomes because it is difficult to translate non-clinical study outcomes and methodology recommendations to human clinical treatment protocols. In recent years, significant progress has been made in understanding the mechanism of PRP action. In this review, we will discuss mechanisms related to inflammation and chondrogenesis in cartilage repair and regenerative processes after PRP administration in in vitro and animal studies. Furthermore, we review clinical trials of PRP efficiency in changing the OA biomarkers in knee joint.

Approach to the Patient with Chronic Pruritus.

Chronic pruritus (itch lasting ≥6 weeks) is a bothersome chief complaint that may present in a broad variety of diseases. Most itch-causing diagnoses fit into 1 of 5 categories (inflammatory, secondary to systemic disease, neuropathic, chronic pruritus of undetermined origin, and psychogenic itch) and this broad differential can be narrowed using key findings in the history and physical. In this article, we discuss which key findings are most pertinent for narrowing this differential and guiding further workup and treatment, as well as how to treat many itchy conditions.

Norepinephrine in the avian auditory cortex enhances developmental song learning.

Sensory learning during critical periods in development has lasting effects on behavior. Neuromodulators like dopamine and norepinephrine (NE) have been implicated in various forms of sensory learning, but little is known about their contribution to sensory learning during critical periods. Songbirds like the zebra finch communicate with each other using vocal signals (e.g., songs) that are learned during a critical period in development, and the first crucial step in song learning is memorizing the sound of an adult conspecific's (tutor's) song. Here, we analyzed the extent to which NE modulates the auditory learning of a tutor's song and the fidelity of song imitation. Specifically, we paired infusions of NE or vehicle into the caudomedial nidopallium (NCM) with brief epochs of song tutoring. We analyzed the effect of NE in juvenile zebra finches that had or had not previously been exposed to song. Regardless of previous exposure to song, juveniles that received NE infusions into NCM during song tutoring produced songs that were more acoustically similar to the tutor song and that incorporated more elements of the tutor song than juveniles with control infusions. These data support the notion that NE can regulate the formation of sensory memories that shape the development of vocal behaviors that are used throughout an organism's life.NEW & NOTEWORTHY Although norepinephrine (NE) has been implicated in various forms of sensory learning, little is known about its contribution to sensory learning during critical periods in development. We reveal that pairing infusions of NE into the avian secondary auditory cortex with brief epochs of song tutoring significantly enhances auditory learning during the critical period for vocal learning. These data highlight the lasting impact of NE on sensory systems, cognition, and behavior.

Neuromodulatory peptides: Orally active anxiolytic-like and antidepressant-like peptides derived from dietary plant proteins.

Mental disorders are a severe health problem, and the number of patients is growing worldwide. Increased anxiety and decreased motivation due to excessive mental stress further accelerated the severity of the problem. Enzymatic digestion of food proteins produces bioactive peptides with various physiological functions, some of which exhibit neuromodulatory effects with oral administration. Recently, studies reported that some peptides produced from plant proteins such as soybeans, leaves, and grains exhibit emotional regulatory functions such as strong anxiolytic-like and antidepressant-like effects comparable to pharmaceuticals. Conventionally, researchers investigated bioactive peptides by fractionation of protein hydrolysates and structure-activity relationship. As a novel methodology for analyzing bioactive peptides, the information obtained by peptidomics simultaneous analysis of the digested fractions of proteins using mass spectrometry has been effectively utilized. Some small-sized peptides such as dipeptides and tripeptides released food-derived proteins show emotional regulating effects. Moreover, some middle-sized peptides produced after intestinal digestion may exhibit the emotional regulating effect via the vagus nerve, and the importance of the gut-brain axis is also focused. As the central mechanism of emotional regulation, it has been found that these plant-derived peptides regulated monoamine neurotransmitter signaling and hippocampal neurogenesis.

Tyramine induces dynamic RNP granule remodeling and translation activation in the Drosophila brain.

Ribonucleoprotein (RNP) granules are dynamic condensates enriched in regulatory RNA binding proteins (RBPs) and RNAs under tight spatiotemporal control. Extensive recent work has investigated the molecular principles underlying RNP granule assembly, unraveling that they form through the self-association of RNP components into dynamic networks of interactions. How endogenous RNP granules respond to external stimuli to regulate RNA fate is still largely unknown. Here, we demonstrate through high-resolution imaging of intact Drosophila brains that Tyramine induces a reversible remodeling of somatic RNP granules characterized by the decondensation of granule-enriched RBPs (e.g. Imp/ZBP1/IGF2BP) and helicases (e.g. Me31B/DDX-6/Rck). Furthermore, our functional analysis reveals that Tyramine signals both through its receptor TyrR and through the calcium-activated kinase CamkII to trigger RNP component decondensation. Finally, we uncover that RNP granule remodeling is accompanied by the rapid and specific translational activation of associated mRNAs. Thus, this work sheds new light on the mechanisms controlling cue-induced rearrangement of physiological RNP condensates.

Effects of intracerebroventricularly administered opioid peptide antagonists on tissue glycogen levels in rats after exercise

Background/aim: Physical exercise is a state of physiological stress that requires adaptation of the organism to physical activity. Glycogen is an important and essential energy source for muscle contraction. Skeletal muscle and liver are two important glycogen stores, and the energy required to maintain exercise in rodents are provided by destruction of this glycogen depot. In this study, the effects of endogenous opioid peptide antagonism at the central nervous system level on tissue glycogen content after exhaustive exercise were investigated. Materials and methods: Rats had intracerebroventricularly (icv) received nonspecific opioid peptide receptor antagonist, naloxone (50 µg/10 µL in saline) and δ-opioid receptor-selective antagonist naltrindole (50 µg/10 µL in saline) and then exercised till exhaustion. After exhaustion, skeletal muscle, heart, and liver were excised immediately. Results: Both opioid peptide antagonists decreased glycogen levels in skeletal muscle. Although, in soleus muscle, this decrease was not statistically significant (p > 0.05), in gastrocnemius muscle, it was significant in the icv naloxone administered group compared with control (p < 0.05). Heart glycogen levels increased significantly in both naloxone and naltrindole groups compared to control and sham-operated groups (p < 0.05). Heart glycogen levels were higher in the naloxone group than naltrindole (p < 0.05). Liver glycogen levels were elevated significantly with icv naloxone administration compared with the control group (p < 0.05). Glycogen levels in the naloxone group was also significantly higher than the naltrindole group (p < 0.05). Conclusion: Our findings indicate that icv administered opioid peptide antagonists may play a role in glycogen metabolism in peripheral tissues such as skeletal muscle, heart, and liver.

Perception-Action Integration Is Modulated by the Catecholaminergic System Depending on Learning Experience.

BACKGROUND: The process underlying the integration of perception and action is a focal topic in neuroscientific research and cognitive frameworks such as the theory of event coding have been developed to explain the mechanisms of perception-action integration. The neurobiological underpinnings are poorly understood. While it has been suggested that the catecholaminergic system may play a role, there are opposing predictions regarding the effects of catecholamines on perception-action integration. METHODS: Methylphenidate (MPH) is a compound commonly used to modulate the catecholaminergic system. In a double-blind, randomized crossover study design, we examined the effect of MPH (0.25 mg/kg) on perception-action integration using an established "event file coding" paradigm in a group of n = 45 healthy young adults. RESULTS: The data reveal that, compared with the placebo, MPH attenuates binding effects based on the established associations between stimuli and responses, provided participants are already familiar with the task. However, without prior task experience, MPH did not modulate performance compared with the placebo. CONCLUSIONS: Catecholamines and learning experience interactively modulate perception-action integration, especially when perception-action associations have to be reconfigured. The data suggest there is a gain control-based mechanism underlying the interactive effects of learning/task experience and catecholaminergic activity during perception-action integration.

Potential antidepressant-like effect of piperazine derivative LQFM212 in mice: Role of monoaminergic pathway and brain-derived neurotrophic factor.

Major depression disorder (MDD) is one of the most widespread and debilitating psychiatric diseases and may be associated with other mental disorders such as anxiety. Despite advances in neurobiology studies, currently no established mechanism can explain all facets of MDD, and available drugs often show therapeutic delay for clinical effectiveness and response rates in patients are around 50 %. Previous activities of piperazine derivatives on CNS are indicators of its therapeutic potential for treating mental disorders. In this regard, we have previously shown that the piperazine derivative 2,6-di-tert-butyl-4-((4-(2-hydroxyethyl)piperazin-1-yl)methyl)phenol (LQFM212) has anxiolytic-like activity which involves serotonergic pathway, nicotinic receptors and BZD-site of GABAA receptor, without cognitive impairments. Herein, was evaluated the potential antidepressant-like effect of LQFM212 on forced swimming test (FST) after a single dose of 54 µmol/kg and after repeated treatment for 15 days in mice. Pretreatment with WAY-100635, PCPA, prazosin, SCH-23390, sulpiride or AMPT reversed the antidepressant-like effect on FST, suggesting that monoaminergic pathway contributes for effects of LQFM212. Furthermore, repeated treatment with LQFM212 increased hippocampal BDNF levels dosed by ELISA kit. In assessment of possible adverse effects, repeated treatment with LQFM212 did not alter the body weight of the animals, glutathione levels in the liver, and serum levels of AST, ALT, urea, and creatinine. Taken together, the results showed that LQFM212 has an antidepressant-like effect that involves monoaminergic pathway and increased BDNF levels. This compound represents promising candidate for prototype of psychoactive drugs for treatment of anxiety and depression disorders since these pathological conditions may exist in comorbidities.

Broad Efficacy of Cariprazine on Depressive Symptoms in Bipolar Disorder and the Clinical Implications.

INTRODUCTION: Bipolar disorder is a complex mood disorder characterized by a chronic and subtle course of fluctuating manic/hypomanic and depressive symptoms. Cariprazine, a dopamine D3-preferring D3/D2 receptor partial agonist with serotonin 5-HT1A receptor partial agonist and serotonin 5-HT2A antagonist properties, is approved to treat manic and depressive episodes of bipolar disorder. Post hoc analyses evaluated efficacy across symptoms in bipolar depression. METHODS: Pooled data were analyzed from 3 phase 2 or 3, randomized, double-blind, placebo-controlled studies of adults with bipolar disorder and a major depressive episode. Mean change from baseline to week 6 in Montgomery-Asberg Depression Rating Scale (MADRS) total score and individual item scores were analyzed in individual dose groups (1.5 mg/d, 3 mg/d) and overall cariprazine (1.5-3 mg/d). Pooled safety was evaluated via adverse events. RESULTS: A significantly greater difference in mean change from baseline in MADRS total score was seen for each cariprazine dose group versus placebo (least squares mean difference vs placebo: 1.5-3 mg/d = -2.6, 1.5 mg/d = -2.8, 3 mg/d = -2.4) (P < .001 all). Significant differences versus placebo were seen on all individual MADRS items except inner tension for the overall cariprazine group (P < .05). Cariprazine was generally well tolerated. CONCLUSIONS: Cariprazine demonstrated broad efficacy across symptoms of depression in bipolar disorder. In previous post hoc analyses, cariprazine also demonstrated broad efficacy across manic symptoms, suggesting that it is effective across the wide range of symptoms on the bipolar spectrum. A 1.5-mg/d starting dose and slow titration resulted in lower rates of some adverse events in the bipolar depression studies versus the mania studies. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT01396447, NCT02670538, NCT02670551.

Efficacy and safety of brexpiprazole in patients with schizophrenia presenting with severe symptoms: Post-hoc analysis of short- and long-term studies.

BACKGROUND: The treatment of patients with severe schizophrenia symptoms can be complicated and expensive. AIMS: The purpose of this study was to evaluate the short- and long-term effects of brexpiprazole in patients with schizophrenia presenting with severe symptoms. METHODS: Data were pooled from three six-week, randomized, double-blind, placebo-controlled studies and two 52-week, open-label extension studies. In the short-term studies, 1405 patients received placebo or brexpiprazole 2-4 mg/day; 412 brexpiprazole-treated patients rolled over into the long-term studies and received brexpiprazole 1-4 mg/day. More severe symptoms were defined as a Positive and Negative Syndrome Scale Total score >95 (median score at baseline). Outcomes included change in Positive and Negative Syndrome Scale Total and Personal and Social Performance scale scores. RESULTS: Brexpiprazole improved Positive and Negative Syndrome Scale Total score over 6 weeks among more severely ill patients, with a least squares mean difference versus placebo of -6.76 (95% confidence limits: -9.80, -3.72; p<0.0001; Cohen's d: 0.43). Brexpiprazole also improved Personal and Social Performance scale score over 6 weeks in more severely ill patients (least squares mean difference: 4.38; limits: 2.14, 6.62; p=0.0001; Cohen's d: 0.38). Improvement of functioning was greatest in the 'Self-care' domain, followed by 'Personal and social relationships'. Among less severely ill patients, brexpiprazole was superior to placebo on Positive and Negative Syndrome Scale Total and Personal and Social Performance scale at Week 6. Improvements were maintained over 58 weeks. No new safety or tolerability concerns were observed. CONCLUSIONS: Brexpiprazole is an efficacious and well-tolerated treatment for schizophrenia in patients with more severe, and less severe, symptoms.

µ Opioid Receptor Agonism for L-DOPA-Induced Dyskinesia in Parkinson's Disease.

Parkinson's disease (PD) is characterized by severe locomotor deficits and is commonly treated with the dopamine precursor L-DOPA, but its prolonged usage causes dyskinesias referred to as L-DOPA-induced dyskinesia (LID). Several studies in animal models of PD have suggested that dyskinesias are associated with a heightened opioid cotransmitter tone, observations that have led to the notion of a LID-related hyperactive opioid transmission that should be corrected by µ opioid receptor antagonists. Reports that both antagonists and agonists of the µ opioid receptor may alleviate LID severity in primate models of PD and LID, together with the failure of nonspecific antagonist to improve LID in pilot clinical trials in patients, raises doubt about the reliability of the available data on the opioid system in PD and LID. After in vitro characterization of the functional activity at the µ opioid receptor, we selected prototypical agonists, antagonists, and partial agonists at the µ opioid receptor. We then showed that both oral and discrete intracerebral administration of a µ receptor agonist, but not of an antagonist as long thought, ameliorated LIDs in the gold-standard bilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned female macaque model of PD and LID. The results call for a reappraisal of opioid pharmacology in the basal ganglia as well as for the development of brain nucleus-targeted µ opioid receptor agonists.SIGNIFICANCE STATEMENT µ opioid receptors have long been considered as a viable target for alleviating the severity of L-DOPA-induced hyperkinetic side effects, induced by the chronic treatment of Parkinson's disease motor symptoms with L-DOPA. Conflicting results between experimental parkinsonism and Parkinson's disease patients, however, dampened the enthusiasm for the target. Here we reappraise the pharmacology and then demonstrate that both oral and discrete intracerebral administration of a µ receptor agonist, but not of an antagonist as long thought, ameliorates LIDs in the gold-standard bilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned macaque model of Parkinson's disease, calling for a reappraisal of the opioid pharmacology as well as for the development of brain nucleus-targeted µ receptor agonists.

Evidence-Based Antiemetic Decision Tool for Management of Postoperative Nausea and Vomiting in Patients at High Risk of QT Prolongation and Patients Receiving Neurotransmitter-Modulating Medications.

Anesthesia providers have a myriad of medication options when developing and implementing a plan for the management of postoperative nausea and vomiting (PONV). However, anesthetists must be aware of the potential side effects, complications, and interactions of those medications, especially when managing high-risk populations. Although guidelines exist for the management of PONV in the general population, an evidence-based antiemetic decision support tool has not been developed for patients at risk of prolonged QT interval or for patients who are routinely receiving neurotransmitter-modulating medications. Safe practice recommendations exist but are scattered throughout the literature. The goal of this project was to develop a tool for anesthetists that concentrates the evidence and provides practice guidelines in these 2 selected populations. The methods for developing this tool were to perform a thorough literature search to gather evidence-based guidelines, organize findings in a convenient easy-to-read format, and validate guidelines by consultation with an expert panel. The product is a quickly accessible clinical tool listing guidelines for 8 commonly used antiemetic agents to assist anesthetists in PONV management.

Neuropeptide S Displays as a Key Neuromodulator in Olfactory Spatial Memory.

Neuropeptide S (NPS) is an endogenous peptide recently recognized to be presented in the brainstem and believed to play an important role in maintaining memory. The deletion of NPS or NPS receptor (NPSR) in mice shows a deficit in memory formation. Our recent studies have demonstrated that central administration of NPS facilitates olfactory function and ameliorates olfactory spatial memory impairment induced by muscarinic cholinergic receptor antagonist and N-methyl-D-aspartate receptor antagonist. However, it remains to be determined if endogenous NPS is an indispensable neuromodulator in the control of the olfactory spatial memory. In this study, we examined the effects of NPSR peptidergic antagonist [D-Val5]NPS (10 and 20 nmol, intracerebroventricular) and nonpeptidergic antagonist SHA 68 (10 and 50 mg/kg, intraperitoneal) on the olfactory spatial memory using computer-assisted 4-hole-board olfactory spatial memory test in mice. Furthermore, immunofluorescence was employed to identify the distributions of c-Fos and NPSR immunoreactive (-ir) neurons in olfactory system and hippocampal formation known to closely relate to the olfactory spatial memory. [D-Val5]NPS dosing at 20 nmol and SHA 68 dosing at 50 mg/kg significantly decreased the number of visits to the 2 odorants interchanged spatially, switched odorants, in recall trial, and simultaneously reduced the percentage of Fos-ir in NPSR-ir neurons, which were densely distributed in the anterior olfactory nucleus, piriform cortex, subiculum, presubiculum, and parasubiculum. These findings suggest that endogenous NPS is a key neuromodulator in olfactory spatial memory.

FG 7142: is this validated tool to study anxiety now forgotten?

We describe the first human experience with FG 7142, a drug which in a phase I study has caused severe anxiety attacks and which therefore could be a validated tool for further experimental studies of anxiety.

Tick-borne encephalitis vaccination in multiple sclerosis: A prospective, multicenter study.

OBJECTIVE: To assess the changes in disease activity after tick-borne encephalitis (TBE) vaccination in patients with multiple sclerosis (MS) on a variety of disease-modifying drugs and to assess the immunogenicity, safety, and clinical tolerability of the vaccine in this patient group. METHODS: We conducted a prospective, multicenter, nonrandomized observational study. We enrolled 20 patients with MS receiving TBE vaccination who had been on disease-modifying treatment (DMT) for at least 6 months. Serum samples were obtained before and after 4 weeks of vaccination to determine the specific TBE antibody response. MS disease activity (Expanded Disability Status Scale and relapse rates) was evaluated for 1 year after immunization. Local and systemic adverse events were registered. RESULTS: In 20 subjects with TBE vaccination, the annualized relapse rate decreased from 0.65 in the year before vaccination to 0.21 in the following year. Expanded Disability Status Scale remained stable during the 2-year period before vaccination and 1 year after vaccination (range: 1.50-1.97). The geometric mean titer (GMT) increased from 169 Vienna units per milliliter (VIEU/mL) to 719 VIEU/mL 4 weeks after vaccination (p = 0.001), and 77.8% had protective antibody titers after vaccination. In 9 patients treated with beta interferons, GMT increased from 181 VIEU/mL to 690 VIEU/mL (p = 0.018). Three subjects treated with glatiramer acetate developed a 2- to 9.6-fold increase. Patients treated with fingolimod developed the lowest increase in antibody titer. CONCLUSION: TBE vaccination showed good tolerability and was safe in patients with MS. MS disease activity was not increased, and annualized relapse rates decreased after vaccination. Vaccine response differs according to the underlying DMT. TRIAL REGISTRATION: ClinicalTrials.gov, clinicaltrials.gov, Identifier: NCT02275741.

Synthetic enhancer compounds, besides acting on biogenic amine system, influence the glutamate transmission and stress response.

Pharmaceutically available enhancer selegiline/(-)-deprenyl (DEP) in the clinically used dose shows antidepressant effect, but nothing is known about this effect in enhancer dose, and its effect on co-morbid anxiety. Moreover, data about the antidepressant/antianxiety effects of the serotonin-influencing enhancer, (2R)-1-(1-benzofuran-2-yl)-N-propylpentane-2-amine (BPAP) are also missing. The aim of the present paper is to establish the role of enhancer regulation in anxiety and follow the changes in the phosphorylation of glutamate subunits in prefrontal cortex as well as stress-related organ and hormonal changes as possible background mechanism. The effect of 3-week-treatment of rats with specific (0.001 mg/kg for DEP, 0.0001 mg/kg for BPAP) and non-specific (0.1 mg/kg for DEP, 0.05 mg/kg for BPAP) enhancer doses were evaluated on anxiety-like behavior in the elevated plus maze (EPM) and open-field (OF) tests. Phosphorylated glutamatergic GluR1 and GluN2B subunits were analyzed by Western blot. Changes in the stress-regulatory system were evaluated by measuring the organ weights and blood corticosterone concentrations. Non-specific enhancer doses had a tendency for anxiolysis on EPM, while only 0.1 mg/kg DEP elevated motility in OF. Specific enhancer doses significantly increased the expression of both glutamatergic receptor subunits; non-specific doses elevated only pGluR1. Treatments had no effects on stress-like organ weights; however, the specific enhancer doses significantly reduced the dark phase resting corticosterone levels. The study proved the enhancer-sensitivity of the glutamatergic transmitter system and suggested enhancer-induced stabilization of stress-hormone levels without major impact on non-stimulated anxiety-like behavior.