Bruton's tyrosine kinase drives neuroinflammation and anxiogenic behavior in mouse models of stress

BACKGROUND

Current therapies targeting several neurotransmitter systems are only able to partially mitigate the symptoms of stress- and trauma-related disorder. Stress and trauma-related disorders lead to a prominent inflammatory response in humans, and in pre-clinical models. However, mechanisms underlying the induction of neuroinflammatory response in PTSD and anxiety disorders are not clearly understood. The present study investigated the mechanism underlying the activation of proinflammatory NLRP3 inflammasome and IL1β in mouse models of stress.

METHODS

We used two mouse models of stress, i.e., mice subjected to physical restraint stress with brief underwater submersion, and predator odor stress. Mice were injected with MCC950, a small molecule specific inhibitor of NLRP3 activation. To pharmacologically inhibit BTK, a specific inhibitor ibrutinib was used. To validate the observation from ibrutinib studies, a separate group of mice was injected with another BTK-specific inhibitor LFM-A13. Seven days after the induction of stress, mice were examined for anxious behavior using open field test (OFT), light-dark test (LDT), and elevated plus maze test (EPM). Following the behavior tests, hippocampus and amygdale were extracted and analyzed for various components of NLRP3-caspase 1-IL1β pathway. Plasma and peripheral blood mononuclear cells were also used to assess the induction of NLRP3-Caspase 1-IL-1β pathway in stressed mice.

RESULTS

Using two different pre-clinical models of stress, we demonstrate heightened anxious behavior in female mice as compared to their male counterparts. Stressed animals exhibited upregulation of proinflammatory IL1β, IL-6, Caspase 1 activity and NLRP3 inflammasome activation in brain, which were significantly higher in female mice. Pharmacological inhibition of NLRP3 inflammasome activation led to anxiolysis as well as attenuated neuroinflammatory response. Further, we observed induction of activated Bruton's tyrosine kinase (BTK), an upstream positive-regulator of NLRP3 inflammasome activation, in hippocampus and amygdala of stressed mice. Next, we conducted proof-of-concept pharmacological BTK inhibitor studies with ibrutinib and LFM-A13. In both sets of experiments, we found BTK inhibition led to anxiolysis and attenuated neuroinflammation, as indicated by significant reduction of NLRP3 inflammasome and proinflammatory IL-1β in hippocampus and amygdala. Analysis of plasma and peripheral blood mononuclear cells indicated peripheral induction of NLRP3-caspase 1-IL1β pathway in stressed mice.

CONCLUSION

Our study identified BTK as a key upstream regulator of neuroinflammation, which drives anxiogenic behavior in mouse model of stress. Further, we demonstrated the sexually divergent activation of BTK, providing a clue to heightened neuroinflammation and anxiogenic response to stress in females as compared to their male counterparts. Our data from the pharmacological inhibition studies suggest BTK as a novel target for the development of potential clinical treatment of PTSD and anxiety disorders. Induction of pBTK and NLRP3 in peripheral blood mononuclear cells of stressed mice suggest the potential effect of stress on systemic inflammation.

Causal roles of stress kinase JNK2 in DNA methylation and binge alcohol withdrawal-evoked behavioral deficits

Excessive binge alcohol intake is a common drinking pattern in humans, especially during holidays. Cessation of the binge drinking often leads to aberrant withdrawal behaviors, as well as serious heart rhythm abnormalities (clinically diagnosed as Holiday Heart Syndrome (HHS)). In our HHS mouse model with well-characterized binge alcohol withdrawal (BAW)-induced heart phenotypes, BAW leads to anxiety-like behaviors and cognitive impairment. We have previously reported that stress-activated c-Jun NH(2)-terminal kinase (JNK) plays a causal role in BAW-induced heart phenotypes. In the HHS brain, we found that activation of JNK2 (but not JNK1 and JNK3) in the prefrontal cortex (PFC), but not hippocampus and amygdala, led to anxiety-like behaviors and impaired cognition. DNA methylation mediated by a crucial DNA methylation enzyme, DNA methyltransferase1 (DNMT1), is known to be critical in alcohol-associated behavioral deficits. In HHS mice, JNK2 in the PFC (but not hippocampus and amygdala) causally enhanced total genomic DNA methylation via increased DNMT1 expression, which was regulated by enhanced binding of JNK downstream transcriptional factor c-JUN to the DNMT1 promoter. JNK2-specific inhibition either by an inhibitor JNK2I or JNK2 knockout completely offset c-JUN-regulated DNMT1 upregulation and restored the level of DNA methylation in HHS PFC to the baseline levels seen in sham controls. Strikingly, either JNK2-specific inhibition or genetic JNK2 depletion or DNMT1 inhibition (by an inhibitor 5-Azacytidine) completely abolished BAW-evoked behavioral deficits. In conclusion, our studies revealed a novel mechanism by which JNK2 drives BAW-evoked behavioral deficits through a DNMT1-regulated DNA hypermethylation. JNK2 could be a novel therapeutic target for alcohol withdrawal treatment and/or prevention.

7,8-Dihydroxyflavone Alleviates Anxiety-Like Behavior Induced by Chronic Alcohol Exposure in Mice Involving Tropomyosin-Related Kinase B in the Amygdala

Alcohol use-associated disorders are highly comorbid with anxiety disorders; however, their mechanism remains unknown. The amygdala plays a central role in anxiety. We recently found that 7,8-dihydroxyflavone (7,8-DHF) significantly reduces withdrawal symptoms in a rat model of chronic intermittent alcohol (ethanol) exposure. This study aimed to determine the role of 7,8-DHF in regulating anxiety induced by chronic alcohol exposure and its associated underlying mechanism. Male C57BL/6J mice were exposed to chronic intermittent alcohol for 3 weeks followed by alcohol withdrawal for 12 h with or without 7,8-DHF administered intraperitoneally. All mice were tested using an open field test and elevated plus maze to assess anxiety-like behaviors. Synaptic activity and intrinsic excitability in basal and lateral amygdala (BLA) neurons were assessed using electrophysiological recordings. 7,8-DHF alleviated alcohol-induced anxiety-like behavior and attenuated alcohol-induced enhancement of activities in BLA pyramidal neurons. Furthermore, 7,8-DHF prevented alcohol withdrawal-evoked augmentation of glutamatergic transmission in the amygdala and had no effect on GABAergic transmission in the amygdala, as demonstrated by unaltered frequency and amplitude of spontaneous inhibitory postsynaptic currents. Microinjection of K252a, a tropomyosin-related kinase B (TrkB) antagonist, into the BLA blocked the effects of 7,8-DHF on anxiety-like behavior and neuronal activity in the BLA. Our findings suggest that 7,8-DHF alleviates alcohol-induced anxiety-like behavior induced by chronic alcohol exposure through regulation of glutamate transmission involving TrKB in the BLA.

The Role of Brain Cyclooxygenase-2 (Cox-2) Beyond Neuroinflammation: Neuronal Homeostasis in Memory and Anxiety

Cyclooxygenases are a group of heme-containing isozymes (namely Cox-1 and Cox-2) that catalyze the conversion of arachidonic acid to largely bioactive prostaglandins (PGs). Cox-1 is the ubiquitous housekeeping enzyme, and the mitogen-inducible Cox-2 is activated to cause inflammation. Interestingly, Cox-2 is constitutively expressed in the brain at the postsynaptic dendrites and excitatory terminals of the cortical and spinal cord neurons. Neuronal Cox-2 is activated in response to synaptic excitation to yield PGE₂, the predominant Cox-2 metabolite in the brain, which in turn stimulates the release of glutamate and neuronal firing in a retrograde fashion. Cox-2 is also engaged in the metabolism of new endocannabinoids from 2-arachidonoyl-glycerol to modulate their actions at presynaptic terminals. In addition to these interactions, the induction of neuronal Cox-2 is coupled to the trans-synaptic activation of the dopaminergic mesolimbic system and some serotoninergic receptors, which might contribute to the development of emotional behavior. Although much of the focus regarding the induction of Cox-2 in the brain has been centered on neuroinflammation-related neurodegenerative and psychiatric disorders, some evidence also suggests that Cox-2 release during neuronal signaling may be pivotal for the fine tuning of cortical networks to regulate behavior. This review compiles the evidence supporting the homeostatic role of neuronal Cox-2 in synaptic transmission and plasticity, since neuroinflammation is originally triggered by the induction of glial Cox-2 expression. The goal is to provide perspective on the roles of Cox-2 beyond neuroinflammation, such as those played in memory and anxiety, and whose evidence is still scant.

Anxiety and Depression Are Related to Higher Activity of Sphingolipid Metabolizing Enzymes in the Rat Brain

Changes in sphingolipid metabolism have been suggested to contribute to the pathophysiology of major depression. In this study, we investigated the activity of acid and neutral sphingomyelinases (ASM, NSM) and ceramidases (AC, NC), respectively, in twelve brain regions of female rats selectively bred for high (HAB) versus low (LAB) anxiety-like behavior. Concomitant with their highly anxious and depressive-like phenotype, HAB rats showed increased activity of ASM and NSM as well as of AC and NC in multiple brain regions associated with anxiety- and depressive-like behavior, including the lateral septum, hypothalamus, ventral hippocampus, ventral and dorsal mesencephalon. Strong correlations between anxiety-like behavior and ASM activity were found in female HAB rats in the amygdala, ventral hippocampus and dorsal mesencephalon, whereas NSM activity correlated with anxiety levels in the dorsal mesencephalon. These results provide novel information about the sphingolipid metabolism, especially about the sphingomyelinases and ceramidases, in major depression and comorbid anxiety.

Rosmarinic acid protects rat hippocampal neurons from cerebral ischemia/reperfusion injury via the Akt/JNK3/caspase-3 signaling pathway

Cerebral ischemia/reperfusion injury can result in neuronal death, which further results in brain damage and can even lead to death. Although recent studies showed that rosmarinic acid (RA) exerts neuroprotective effects and attenuates ischemia-induced brain injury and neuronal cell death, little is known about the precise mechanisms that occur during cerebral ischemia/reperfusion (I/R). Therefore, the aim of this study was to examine the underlying mechanism of the neuroprotective effects of RA against ischemic brain injury induced by cerebral I/R. Transient global brain ischemia was induced by 4-vessel occlusion in adult male Sprague-Dawley rats. We randomly divided rats into five groups: sham, I/R, I/R+RA, I/R+Vehicle and I/R+RA+LY. Open-field, closed-field and Morris water maze tests were carried our separately to examine the anxiety and cognitive behavior of each group. Cresyl violet staining was used to examine the survival of hippocampal CA1 pyramidal neurons. The levels of p-Akt, p-JNK3 and cleaved caspase-3 in the hippocampus were also examined by Western blotting. Our results showed that administration of RA protected locomotive ability, relieved anxiety behavior and protected cognitive ability in cerebral I/R-injured rats. Additionally, RA significantly protected neurons in the hippocampal CA1 region against cerebral I/R-induced damage. Furthermore, RA increased the phosphorylation of Akt1, downregulated the phosphorylation of JNK3 and reduced the expression of cleaved caspase-3. Finally, the Akt inhibitor LY294002 reversed all the protective effects of RA, indicating that RA protects neurons in the hippocampal CA1 region from ischemic damage through the Akt/JNK3/caspase-3 signaling pathway.

Role of Acid Sphingomyelinase in the Regulation of Social Behavior and Memory

Major depressive disorder is often associated with deficits in social and cognitive functioning. Mice transgenic for acid sphingomyelinase (t-ASM) were previously shown to have a depressive-like phenotype, which could be normalized by antidepressant treatment. Here, we investigated whether t-ASM mice show deficits in social behavior and memory performance, and whether these possible deficits might be normalized by amitriptyline treatment. Our results revealed that ASM overexpression altered the behavior of mice in a sex-dependent manner. As such, t-ASM female, but not male, mice showed an impaired social preference and a depressive- and anxiogenic-like phenotype, which could be normalized by amitriptyline treatment. Both male and female t-ASM mice showed unaltered preference for social novelty, novel object recognition, and social and object discrimination abilities. Amitriptyline treatment impaired novel object recognition and object discrimination abilities in female, but not in male, wild-type mice, while female t-ASM mice showed unaltered novel object recognition and object discrimination abilities. This study suggests that female t-ASM mice represent a model of depression with comorbid anxiety and social deficits, without memory impairments. It further suggests that ASM overexpression has a protective role against the detrimental effects of amitriptyline on female, but not on male, non-social (object) memory.

Type 2 Deiodinase Disruption in Astrocytes Results in Anxiety-Depressive-Like Behavior in Male Mice

Millions of levothyroxine-treated hypothyroid patients complain of impaired cognition despite normal TSH serum levels. This could reflect abnormalities in the type 2 deiodinase (D2)-mediated T4-to-T3 conversion, given their much greater dependence on the D2 pathway for T3 production. T3 normally reaches the brain directly from the circulation or is produced locally by D2 in astrocytes. Here we report that mice with astrocyte-specific Dio2 inactivation (Astro-D2KO) have normal serum T3 but exhibit anxiety-depression-like behavior as found in open field and elevated plus maze studies and when tested for depression using the tail-suspension and the forced-swimming tests. Remarkably, 4 weeks of daily treadmill exercise sessions eliminated this phenotype. Microarray gene expression profiling of the Astro-D2KO hippocampi identified an enrichment of three gene sets related to inflammation and impoverishment of three gene sets related to mitochondrial function and response to oxidative stress. Despite normal neurogenesis, the Astro-D2KO hippocampi exhibited decreased expression of four of six known to be positively regulated genes by T3, ie, Mbp (∼43%), Mag (∼34%), Hr (∼49%), and Aldh1a1 (∼61%) and increased expression of 3 of 12 genes negatively regulated by T3, ie, Dgkg (∼17%), Syce2 (∼26%), and Col6a1 (∼3-fold) by quantitative real-time PCR. Notably, in Astro-D2KO animals, there was also a reduction in mRNA levels of genes known to be affected in classical animal models of depression, ie, Bdnf (∼18%), Ntf3 (∼43%), Nmdar (∼26%), and GR (∼20%), which were also normalized by daily exercise sessions. These findings suggest that defects in Dio2 expression in the brain could result in mood and behavioral disorders.

[Effects of Electroacupuncture on Hippocampal nNOS Expression in Rats with Anxiety-like Behavior]

OBJECTIVE

To compare the effects of electroacupuncture (EA) preconditioning and post-conditioning on hippocampal neuronal nitric oxide synthase (nNOS) expression in rats with anxiety-like behavior, so as to explore the reasonable EA intervention time.

METHODS

Forty-two SD rats were randomly divided into 6 groups:normal 1, normal 2, anxiety model 1, an-xiety model 2, EA-pre-conditioning and EA-post-conditioning. The anxiety model was established by giving the rats with repeated foot shock stimulation (0.8 mA, 2-25 s/time, 10 times in 5 min) combined with isolation-raising. Before or after modeling, EA stimulation was applied to "Baihui" (GV 20) and "Yintang" (GV 29) for 20 min, once a day for 7 days. Elevated plus maze (EPM) tests were performed to determine the percentages of time spent in the open arms and the percentages of entries into the open arms in 5 min for evaluating the animals' anxiety-like behavioral activities. The reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect hippocampal nNOS mRNA expression and the immunohistochemical staining adopted to detect the expression of nNOS protein in the hippocampal CA 1 and CA 3 areas, respectively.

RESULTS

Compared with their own normal control group 1 and 2, both the percentage of time spent in the open arms and the percentage of entries into the open arms were significantly decreased in model group 1 and 2 (P<0.05, P<0.01). After pre- and post-conditioning of EA, the decreased proportions of time spent and entries into the open arms were considerably increased (P<0.05), suggesting an improvement of anxiety-like behavior activities after EA intervention. The expression levels of hippocampal nNOS mRNA and nNOS protein in the hippocampal CA 3 region were significantly higher in the model group 1 and 2 than in their own normal control group 1 and 2 (P<0.01), but those of nNOS protein in the CA 1 area were markedly lower in the model group 1 and 2 than in their own normal control group 1 and 2 (P<0.01). Following pre- and post-conditioning of EA, the increased expression levels of nNOS mRNA and protein of CA 3 area and the decreased level of nNOS protein of CA 1 area were all notably reversed (P<0.05, P<0.01).

CONCLUSIONS

Both pre- and post-conditioning of EA can improve anxiety-like behavior in anxiety rats, which may be associated with its effects in down-regulating hippocampal nNOS expression.

Calcium activated adenylyl cyclase AC8 but not AC1 is required for prolonged behavioral anxiety

BACKGROUND

Anxiety disorder is a state of mental discomfort while acute anxiety induces an enhancement of vigilance/arousal or increased anxious responses. Most of the previous studies investigated basic mechanisms for acute anxiety, while less information is available for prolonged or repetitive anxiety.

RESULTS

In the present study, we wanted to examine possible molecular mechanisms for behavioral anxiety after repeated exposures. Performing a paradigm of five sessions of the elevated plus-maze (EPM), we show that the repeated exposure to the EPM induces a long-lasting anxiety causing a gradual increase of anxiolytic activity, which is maintained for at least 21 days. Genetic deletion of AC8 (adenylyl cyclase 8) but not AC1 abolished long-lasting anxiety.

CONCLUSIONS

Our results suggest that calcium-stimulated AC8 is required to sustain the long-lasting anxiety caused by repeated EPM testing, and we can identify in AC8 a novel target for treating anxiety-related mood disorders.

Ethanol withdrawal induces anxiety-like effects: Role of nitric oxide synthase in the dorsal raphe nucleus of rats

Nitric oxide (NO) mediated transmission in the dorsal raphe nucleus (DRN) has been shown to be involved in the modulation of anxiety-like behaviors. We investigated whether inhibition of nitric oxide synthase (NOS) in the DRN would prevent anxiety-like behavior induced by ethanol withdrawal. Male Wistar rats were treated with ethanol 2-6% (v/v) for a period of 21 days. Ethanol withdrawal was induced by abrupt discontinuation of the treatment. Experiments were performed 48 h after ethanol discontinuation. Rats with a guide cannula aimed at the DRN received intra-DRN injections of the non-selective NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME), selective neuronal NOS (nNOS) inhibitor N(ω)-propyl-l-arginine (NPLA), or selective inhibitor of inducible NOS (iNOS) N-([3-(aminomethyl)phenyl] methyl) ethanimidamidedihydrochloride (1400W). Five minutes later, the animals were tested in the elevated plus maze (EPM). Plasma ethanol levels were determined by gas chromatography. There was a reduction in plasma ethanol levels 48 h after ethanol withdrawal. Rats from the ethanol withdrawal group showed decreased exploration of the open arms of the EPM with no change in the exploration of enclosed arms. Intra-DRN treatment with l-NAME (100 nmoles/0.2 μL) and 1400W (1 nmol/0.2 μL), but not NPLA (10 nmoles/0.2 μL) in the DRN attenuated the decrease in the exploration of the open arms of the EPM induced by ethanol withdrawal. The major new finding of the present study is that iNOS in the DRN plays a role in the anxiety-like behavior induced by ethanol withdrawal.

Increasing brain angiotensin converting enzyme 2 activity decreases anxiety-like behavior in male mice by activating central Mas receptors

Over-activation of the brain renin-angiotensin system (RAS) has been implicated in the etiology of anxiety disorders. Angiotensin converting enzyme 2 (ACE2) inhibits RAS activity by converting angiotensin-II, the effector peptide of RAS, to angiotensin-(1-7), which activates the Mas receptor (MasR). Whether increasing brain ACE2 activity reduces anxiety by stimulating central MasR is unknown. To test the hypothesis that increasing brain ACE2 activity reduces anxiety-like behavior via central MasR stimulation, we generated male mice overexpressing ACE2 (ACE2 KI mice) and wild type littermate controls (WT). ACE2 KI mice explored the open arms of the elevated plus maze (EPM) significantly more than WT, suggesting increasing ACE2 activity is anxiolytic. Central delivery of diminazene aceturate, an ACE2 activator, to C57BL/6 mice also reduced anxiety-like behavior in the EPM, but centrally administering ACE2 KI mice A-779, a MasR antagonist, abolished their anxiolytic phenotype, suggesting that ACE2 reduces anxiety-like behavior by activating central MasR. To identify the brain circuits mediating these effects, we measured Fos, a marker of neuronal activation, subsequent to EPM exposure and found that ACE2 KI mice had decreased Fos in the bed nucleus of stria terminalis but had increased Fos in the basolateral amygdala (BLA). Within the BLA, we determined that ∼62% of GABAergic neurons contained MasR mRNA and expression of MasR mRNA was upregulated by ACE2 overexpression, suggesting that ACE2 may influence GABA neurotransmission within the BLA via MasR activation. Indeed, ACE2 overexpression was associated with increased frequency of spontaneous inhibitory postsynaptic currents (indicative of presynaptic release of GABA) onto BLA pyramidal neurons and central infusion of A-779 eliminated this effect. Collectively, these results suggest that ACE2 may reduce anxiety-like behavior by activating central MasR that facilitate GABA release onto pyramidal neurons within the BLA.

The Role of Protein Kinase A in Anxiety Behaviors

This review focuses on the genetic and other evidence supporting the notion that the cyclic AMP (cAMP) signaling pathway and its mediator, the protein kinase A (PKA) enzyme, which respond to environmental stressors and regulate stress responses, are central to the pathogenesis of disorders related to anxiety. We describe the PKA pathway and review in vitro animal studies (mouse) and other evidence that support the importance of PKA in regulating behaviors that lead to anxiety. Since cAMP signaling and PKA have been pharmacologically exploited since the 1940s (even before the identification of cAMP as a second messenger with PKA as its mediator) for a number of disorders from asthma to cardiovascular diseases, there is ample opportunity to develop therapies using this new knowledge about cAMP, PKA, and anxiety disorders.

Anxiety is associated with higher levels of global DNA methylation and altered expression of epigenetic and interleukin-6 genes

OBJECTIVES

Anxiety is associated with elevated levels of the inflammatory cytokine interleukin-6 (IL-6) and an increased risk for diseases with an inflammatory aetiology. In cancer, higher levels of IL-6 have been associated with increased expression of the epigenetic enzymes DNMT1 and Enhancer of Zeste Homolog 2 (EZH2). However, the relationship between IL-6 and DNA methyltransferases (DNMTs) and EZH2 expression has not previously been examined in anxious individuals.

METHODS

Global DNA methylation levels were measured using the Methylflash Methylated DNA Quantification Kit and gene expression levels of the DNMT and EZH2 genes in anxious (n=25) and nonanxious individuals (n=22) were compared using quantitative real-time PCR. Specifically, we investigated whether global DNA methylation or aberrant expression of these genes was correlated with IL-6 mRNA and protein serum levels in anxious individuals.

RESULTS

Anxious participants had significantly higher levels of global DNA methylation compared with controls (P=0.001). There were no differences in the mean mRNA expression levels of the DNMT1/3A/3B, EZH2 and IL-6 genes in anxious individuals compared with controls. However, the expression of DNMT1/3A, EZH2 and IL-6 genes increases with increasing Hospital Anxiety and Depression Scale-Anxiety scores in the anxious cohort only. Interestingly, IL-6 gene expression was correlated strongly with DNMT1/3A/3B and EZH2 expression, highlighting a potential relationship between IL-6 and important epigenetic regulatory enzymes.

CONCLUSION

This study provides novel insight into the relationship between anxiety, epigenetics and IL-6. Moreover, our findings support the hypothesis that changes in DNA methylation profiles may contribute to the biology of anxiety.

Essential elements in depression and anxiety. Part II

In this paper we continue to discuss the involvement of essential elements in depression and anxiety, and the possible mechanisms that link elements to the neurobiology underlying depression/anxiety. The present paper is focused on copper, selenium, manganese, iodine and vanadium. Different aspects of relationship between elements and depression or anxiety are reviewed, e.g. the association of the amount of an element in a diet or the serum level of an element and depressive or anxiety-like symptoms. Moreover, the relation of selected elements to the pathophysiology of depression or anxiety is discussed in the context of enzymes which require these elements as co-factors and are involved in the underlying pathophysiology of these disorders.

Generation and behavior characterization of CaMKIIβ knockout mice

The calcium/calmodulin-dependent protein kinase II (CaMKII) is abundant in the brain, where it makes important contributions to synaptic organization and homeostasis, including playing an essential role in synaptic plasticity and memory. Four genes encode isoforms of CaMKII (α, β, δ, γ), with CaMKIIα and CaMKIIβ highly expressed in the brain. Decades of molecular and cellular research, as well as the use of a large number of CaMKIIα mutant mouse lines, have provided insight into the pivotal roles of CaMKIIα in brain plasticity and cognition. However, less is known about the CaMKIIβ isoform. We report the development and extensive behavioral and phenotypic characterization of a CaMKIIβ knockout (KO) mouse. The CaMKIIβ KO mouse was found to be smaller at weaning, with an altered body mass composition. The CaMKIIβ KO mouse showed ataxia, impaired forelimb grip strength, and deficits in the rotorod, balance beam and running wheel tasks. Interestingly, the CaMKIIβ KO mouse exhibited reduced anxiety in the elevated plus maze and open field tests. The CaMKIIβ KO mouse also showed cognitive impairment in the novel object recognition task. Our results provide a comprehensive behavioral characterization of mice deficient in the β isoform of CaMKII. The neurologic phenotypes and the construction of the genotype suggest the utility of this KO mouse strain for future studies of CaMKIIβ in brain structure, function and development.

Experimental gastritis leads to anxiety- and depression-like behaviors in female but not male rats

Human and animals studies support the idea that there is a gender-related co-morbidity of pain-related and inflammatory gastrointestinal (GI) diseases with psychological disorders. This co-morbidity is the evidence for the existence of GI-brain axis which consists of immune (cytokines), neural (vagus nerve) and neuroendocrine (HPA axis) pathways. Psychological stress causes disturbances in GI physiology, such as altered GI barrier function, changes in motility and secretion, development of visceral hypersensitivity, and dysfunction of inflammatory responses. Whether GI inflammation would exert impact on psychological behavior is not well established. We examined the effect of experimental gastritis on anxiety- and depression-like behaviors in male and female Sprague-Dawley rats, and evaluated potential mechanisms of action. Gastritis was induced by adding 0.1% (w/v) iodoacetamide (IAA) to the sterile drinking water for 7 days. Sucrose preference test assessed the depression-like behavior, open field test and elevated plus maze evaluated the anxiety-like behavior. IAA treatment induced gastric inflammation in rats of either gender. No behavioral abnormality or dysfunction of GI-brain axis was observed in male rats with IAA-induced gastritis. Anxiety- and depression-like behaviors were apparent and the HPA axis was hyperactive in female rats with IAA-induced gastritis. Our results show that gastric inflammation leads to anxiety- and depression-like behaviors in female but not male rats via the neuroendocrine (HPA axis) pathway, suggesting that the GI inflammation can impair normal brain function and induce changes in psychological behavior in a gender-related manner through the GI-to-brain signaling.

Maternal prenatal symptoms of depression and down regulation of placental monoamine oxidase A expression

OBJECTIVE

Maternal prenatal symptoms of depression and anxiety have been associated with altered neurodevelopmental outcomes in the child. These effects may be mediated in part by altered placental function, with increased fetal 5-hydroxytryptamine (5-HT) exposure being one possible mechanism. The current study aimed to determine whether maternal symptoms of depression or anxiety were associated with decreased placental expression of monoamine oxidase A (MAO A), the enzyme which metabolises 5-HT into 5-hydroxyindoleacetic acid. The localisation of MAO A in the placenta was also investigated.

METHODS

Pregnant women were recruited one day prior to elective caesarean and assessed using psychometric tests for symptoms of depression (Edinburgh Depression Scale) and anxiety (Spielberger State/Trait Index). Villous trophoblast tissue was extracted from each placenta and used for subsequent gene expression analysis (N=62). Localisation was studied using immunohistochemistry, with a specific polyclonal antibody.

RESULTS

Increasing symptoms of maternal depression were associated with a reduction in placental MAO A expression (r=-0.339, p=0.007, N=62). There was a trend for a similar correlation with symptoms of maternal trait anxiety, but not with state anxiety. MAO A was localised to the syncytiotrophoblast, the tissue between maternal and fetal blood.

CONCLUSIONS

These findings support the hypothesis that maternal mood is associated with altered placental function. A reduction in placental MAO A expression is consistent with a subsequent increase in fetal exposure to 5-HT.

Monoacylglycerol lipase inhibition-induced changes in plasma corticosterone levels, anxiety and locomotor activity in male CD1 mice

The hypothalamus-pituitary-adrenal-axis is strongly controlled by the endocannabinoid system. The specific impact of enhanced 2-arachidonoylglycerol signaling on corticosterone plasma levels, however, was not investigated so far. Here we studied the effects of the recently developed monoacylglycerol lipase inhibitor JZL184 on basal and stress-induced corticosterone levels in male CD1 mice, and found that this compound dramatically increased basal levels without affecting stress responses. Since acute changes in corticosterone levels can affect behavior, JZL184 was administered concurrently with the corticosterone synthesis inhibitor metyrapone, to investigate whether the previously shown behavioral effects of JZL184 are dependent on corticosterone. We found that in the elevated plus-maze, the effects of JZL184 on "classical" anxiety-related measures were abolished by corticosterone synthesis blockade. By contrast, effects on the "ethological" measures of anxiety (i.e. risk assessment) were not affected by metyrapone. In the open-field, the locomotion-enhancing effects of the compound were not changed either. These findings show that monoacylglycerol lipase inhibition dramatically increases basal levels of corticosterone. This endocrine effect partly affects the anxiolytic, but not the locomotion-enhancing effects of monoacylglycerol lipase blockade.

Enhanced hippocampus-dependent memory and reduced anxiety in mice over-expressing human catalase in mitochondria

Oxidative stress (OS) and reactive oxygen species (ROS) play a modulatory role in synaptic plasticity and signaling pathways. Mitochondria (MT), a major source of ROS because of their involvement in energy metabolism, are important for brain function. MT-generated ROS are proposed to be responsible for a significant proportion of OS and are associated with developmental abnormalities and aspects of cellular aging. The role of ROS and MT function in cognition of healthy individuals is relatively understudied. In this study, we characterized behavioral and cognitive performance of 5- to 6-month-old mice over-expressing mitochondrial catalase (MCAT). MCAT mice showed enhancements in hippocampus-dependent spatial learning and memory in the water maze and contextual fear conditioning, and reduced measures of anxiety in the elevated zero maze. Catalase activity was elevated in MCAT mice in all brain regions examined. Measures of oxidative stress (glutathione, protein carbonyl content, lipid peroxidation, and 8-hydroxyguanine) did not significantly differ between the groups. The lack of differences in these markers of oxidative stress suggests that the differences observed in this study may be due to altered redox signaling. Catalase over-expression might be sufficient to enhance cognition and reduce measures of anxiety even in the absence of alteration in levels of OS.

Differences in salivary alpha-amylase and cortisol responsiveness following exposure to electrical stimulation versus the Trier Social Stress Tests

Background

Cortisol is an essential hormone in the regulation of the stress response along the HPA axis, and salivary cortisol has been used as a measure of free circulating cortisol levels. Recently, salivary alpha-amylase (sAA) has also emerged as a novel biomarker for psychosocial stress responsiveness within the sympathetic adrenomedullary (SAM) system.

Principal Findings

We measured sAA and salivary cortisol in healthy volunteers after exposure to the Trier Social Stress Test (TSST) and electric stimulation stress. One hundred forty-nine healthy volunteers participated in this study. All subjects were exposed to both the TSST and electric stimulation stress on separate days. We measured sAA and salivary cortisol levels three times immediately before, immediately after, and 20 min after the stress challenge. The State (STAI-S) and Trait (STAI-T) versions of the Spielberger Anxiety Inventory test and the Profile of Mood State (POMS) tests were administered to participants before the electrical stimulation and TSST protocols. We also measured HF, LF and LF/HF Heart Rate Variability ratio immediately after electrical stimulation and TSST exposure. Following TSST exposure or electrical stimulation, sAA levels displayed a rapid increase and recovery, returning to baseline levels 20 min after the stress challenge. Salivary cortisol responses showed a delayed increase, which remained significantly elevated from baseline levels 20 min after the stress challenge. Analyses revealed no differences between men and women with regard to their sAA response to the challenges (TSST or electric stimulations), while we found significantly higher salivary cortisol responses to the TSST in females. We also found that younger subjects tended to display higher sAA activity. Salivary cortisol levels were significantly correlated with the strength of the applied electrical stimulation.

Conclusions

These preliminary results suggest that the HPA axis (but not the SAM system) may show differential response patterns to distinct kinds of stressors.

RETRACTED: Salivary amylase and stress during stressful environment: three Mars analog mission crews study

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief based on the outcome of an investigatory report conducted by the Executive Board at Vrije Universiteit Amsterdam that was recently brought to the attention of the journal. Investigating allegations, the Executive Board found evidence of significant plagiarism in multiple sections of this article with an article published in the American Journal of Human Biology (24:468-472 (2012), https://onlinelibrary.wiley.com/doi/full/10.1002/ajhb.22247). One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of Neuroscience Letters that this was not detected during the submission process. The investigatory report conducted by the Executive Board at Vrije Universiteit Amsterdam can be found here.

Differential contribution of hypothalamic MAPK activity to anxiety-like behaviour in virgin and lactating rats

The c-Raf – MEK1/2 – ERK1/2 mitogen-activated protein kinase (MAPK) intracellular signalling cascade in neurons plays important roles in the control of a variety of behaviours, including social behaviours and anxiety. These roles partially overlap with those described for oxytocin (OXT), and it has been shown that OXT activates the MAPK pathway in the hypothalamus (of male), and hippocampus (of female) rats. Here, by combining behavioural (light/dark box) and biochemical analyses (western blotting), we tested two hypotheses: (i) that OXT is anxiolytic within the hypothalamus of females, and (ii) that this effect, as well as that of lactation-associated anxiolysis, depends on the recruitment of the MAPK pathway. We found that, when injected bilaterally into the hypothalamic paraventricular nucleus (PVN), OXT decreased anxiety-like behaviour in virgins, and that this effect depended on phosphorylation of MEK1/2. MAPK pathway activation in lactation was evident by high phosphorylated (p) MEK1/2 levels, and nuclear translocation of ERK1. The high pMEK1/2 levels were necessary for the anxiolytic phenotype typically observed during lactation. Interestingly, exogenous OXT in lactating rats reduced pMEK1/2 levels without a concomitant effect on anxiety, indicating that OXT receptor activation can lead to recruitment of additional intracellular pathways to modulate MEK activity. Still other pathways could include MEK, but without subsequent activation of ERK, as we did not observe any increase in OXT-induced ERK phosphorylation. Together the results demonstrate that the MAPK pathway, especially MEK1/2, is critically involved in the regulation of anxiety-like behaviour in female rats.

Hypoxic-ischemic injury decreases anxiety-like behavior in rats when associated with loss of tyrosine-hydroxylase immunoreactive neurons of the substantia nigra

Neonatal Sprague-Dawley rats were randomly divided into normal control, mild hypoxia-ischemia (HI), and severe HI groups (N = 10 in each group at each time) on postnatal day 7 (P7) to study the effect of mild and severe HI on anxiety-like behavior and the expression of tyrosine hydroxylase (TH) in the substantia nigra (SN). The mild and severe HI groups were exposed to hypoxia (8% O2/92% N2) for 90 and 150 min, respectively. The elevated plus-maze (EPM) test was performed to assess anxiety-like behavior by measuring time spent in the open arms (OAT) and OAT%, and immunohistochemistry was used to determine the expression of TH in the SN at P14, P21, and P28. OAT and OAT% in the EPM were significantly increased in both the mild (1.88-, 1.99-, and 2.04-fold, and 1.94-, 1.51-, and 1.46-fold) and severe HI groups (1.69-, 1.68-, and 1.87-fold, and 1.83-, 1.43-, and 1.39-fold, respectively; P < 0.05). The percent of TH-positive cells occupying the SN area was significantly and similarly decreased in both the mild (17.7, 40.2, and 47.2%) and severe HI groups (16.3, 32.2, and 43.8%, respectively; P < 0.05). The decrease in the number of TH-positive cells in the SN and the level of protein expression were closely associated (Pearson correlation analysis: r = 0.991, P = 0.000 in the mild HI group and r = 0.974, P = 0.000 in the severe HI group) with the impaired anxiety-like behaviors. We conclude that neonatal HI results in decreased anxiety-like behavior during the juvenile period of Sprague-Dawley rats, which is associated with the decreased activity of TH in the SN. The impairment of anxiety and the expression of TH are not likely to be dependent on the severity of HI.

Effect of honokiol on activity of GAD(65) and GAD(67) in the cortex and hippocampus of mice

Honokiol, an active agent extracted from magnolia bark, has been reported that induces anxiolytic action in a mouse elevated plus-maze test. However, the mechanism of anxiolytic action induced by honokiol remains unclear. This study was to investigate the change in two forms of glutamic acid decarboxylase (GABA synthesized enzymes) GAD(65) and GAD(67) in the cortex and hippocampus areas while the anxiolytic actions induced by chronic administration of honokiol in mice. Mice treated with 7 daily injection of honokiol (1mg/kg, p.o.) caused anxiolytic action which was similar to that was induced by 7 daily injection of diazepam (2mg/kg, p.o.) in the elevated plus-maze test. In addition, the activity of hippocampal GAD(65) of honokiol treated mice was significantly increased than that of the vehicle or diazepam treated groups. These data suggest that honokiol causes diazepam-like anxiolytic action, which may be mediated by altering the synthesis of GABA in the brain of mice.

Smoking related diseases: the central role of monoamine oxidase

Smoking is a major risk factor of morbidity and mortality. It is well established that monoamine oxidase (MAO) activity is decreased in smokers. Serotonin (5-HT), a major substrate for MAO that circulates as a reserve pool stored in platelets, is a marker of platelet activation. We recently reported that smoking durably modifies the platelet 5-HT/MAO system by inducing a demethylation of the MAO gene promoter resulting in high MAO protein concentration persisting more than ten years after quitting smoking. The present data enlarges the results to another MAO substrate, norepinephrine (NE), further confirming the central role of MAO in tobacco use-induced diseases. Thus, MAO could be a readily accessible and helpful marker in the risk evaluation of smoking-related diseases, from cardiovascular and pulmonary diseases to depression, anxiety and cancer. The present review implements the new finding of epigenetic regulation of MAO and suggests that smoking-induced MAO demethylation can be considered as a hallmark of smoking-related cancers similarly to other aberrant DNA methylations.

Comt1 genotype and expression predicts anxiety and nociceptive sensitivity in inbred strains of mice

Catechol-O-methyltransferase (COMT) is a ubiquitously expressed enzyme that maintains basic biologic functions by inactivating catechol substrates. In humans, polymorphic variance at the COMT locus has been associated with modulation of pain sensitivity and risk for developing psychiatric disorders. A functional haplotype associated with increased pain sensitivity was shown to result in decreased COMT activity by altering mRNA secondary structure-dependent protein translation. However, the exact mechanisms whereby COMT modulates pain sensitivity and behavior remain unclear and can be further studied in animal models. We have assessed Comt1 gene expression levels in multiple brain regions in inbred strains of mice and have discovered that Comt1 is differentially expressed among the strains, and this differential expression is cis-regulated. A B2 short interspersed nuclear element (SINE) was inserted in the 3'-untranslated region (3'-UTR) of Comt1 in 14 strains generating a common haplotype that correlates with gene expression. Experiments using mammalian expression vectors of full-length cDNA clones with and without the SINE element show that strains with the SINE haplotype (+SINE) have greater Comt1 enzymatic activity. +SINE mice also exhibit behavioral differences in anxiety assays and decreased pain sensitivity. These results suggest that a haplotype, defined by a 3'-UTR B2 SINE element, regulates Comt1 expression and some mouse behaviors.

[Anxiety, depression and polymorphism of the gene encoding superoxide dismutase in patients with chronic obstructive pulmonary disease]

Chronic obstructive pulmonary disease (COPD) is a severe systemic disease leading to circulatory and respiratory failure. COPD is also a risk factor for the onset of anxiety and mood disturbances. Identification of the correlates of emotional disturbances in the course of COPD can make it possible, on the one hand, to prevent mental and behavioral disorders early in the course of this serious somatic disease, and on the other hand, to institute appropriate treatment. The aim of the study was to determine the correlation between the polymorphism of manganese superoxide dismutase signal peptide and the severity of anxiety and depression in COPD patients.

MATERIAL AND METHODS

The study group consisted of 57 patients with grade I, II and III COPD according to GOLD criteria. The control group consisted of 63 healthy nicotine addicts. In all the subjects, the genotype of position 9 of manganese superoxide dismutase signal peptide was determined, depression severity was measured with Beck Depression Scale, and anxiety as a trait and as a state was measured with Spielberg State/Trait Anxiety Inventory (STAI).

RESULTS

Among COPT patients, 16 subjects were found to have Ala/Ala genotype, 23 Val/Ala and 18 Val/Val. In the smokers' group Ala/Ala genotype was found in 29 cases, Val/Ala in 27 and Val/Val in 7. The distribution of genotype frequencies differed between the groups. In COPD patients, the mean depression severity assessed according to Beck Scale amounted to (16.52 +/- 5.63) and was higher than in smokers without COPD (13.85 +/- 4.24, p = 0.003828). The average severity of anxiety as a trait and as a state did not differ significantly in both groups. Among COPD patients, the mean severity of depressive disorders in subjects with Val/ Val genotype was 21.27 +/- 4.32 and was significantly higher than in those with Val/Ala (15.22 +/- 5.29) and Ala/Ala (12.87 +/- 3.72) genotypes. The severity of anxiety as a trait in COPD patients reached 7.72 +/- 1.21 in the subgroup with Val/Val genotype and was also higher than in those with Val/Ala genotype (6.69 +/- 1.48) and with Ala/Ala genotype (5.87 +/- 1.14). A similar correlation was observed for anxiety as a state (subjects with Val/Val genotype 6.78 +/- 1.06, with Val/Ala genotype 6.18 +/- 1.01 and with Ala/ Ala genotype 5.88 +/- 1.41). Among healthy smokers, the mean severities of depression, anxiety as a trait and anxiety as a state did not differ in subjects with different genotypes.

CONCLUSIONS

The study has demonstrated that the severity of depression is higher in COPD patients than in the group of healthy smokers. In the group of patients with COPD, Val/Val genotype at position 9 of MnSOD signal peptide is associated with more severe depression, anxiety as a trait and anxiety as a state in comparison with patients who have Val/Ala and Ala/Ala genotypes. No similar correlations were found in healthy smokers.

Differential effects of nitric oxide synthase inhibitors on anxiety in unstressed and stressed mice

Effects of selective nitric oxide synthase (NOS) inhibitors, 7-nitroindazole (7-NI), a selective inhibitor of neuronal nitric oxide synthase (nNOS) and aminoguanidine (AG), a selective inhibitor of inducible nitric oxide synthase (iNOS) on anxiety in unstressed and stressed mice were investigated using elevated plus maze (EPM) test and light-dark test (LDT). 7-NI (20 and 40 mg/kg, ip) produced anti-anxiety effect in unstressed mice but not in stressed mice. AG (50 and 100 mg/kg, ip) produced anxiolytic effect in stressed mice and failed to produce the similar effect in unstressed mice. Nitrite levels were increased in stressed mice, but not in unstressed mice, exposed to EPM and LDT for 5 min. Increased nitrite levels in stressed mice were attenuated by AG, but not by 7-NI. The effects of AG were enhanced by pyrrolidine-dithio-carbamate (PDTC), an inhibitor of NF-kappaB induction, in stressed mice. The results suggest the possible role of inducible nitric oxide synthase in stress-induced anxiogenesis as compared to unstressed mice, where neuronal form of NOS may plays predominant role.

Phosphodiesterase 10A inhibition is associated with locomotor and cognitive deficits and increased anxiety in mice

Phosphodiesterase 10A (PDE10A) mRNA and protein levels decline in the striatum of R6/1 and R6/2 Huntington's disease (HD) mice prior to motor symptom development. In human HD, PDE10A protein levels are significantly decreased in the caudate-putamen of patients with grade 3 HD compared to age-matched controls. To test whether the loss of PDE10A activity in the striatum was detrimental to normal brain function, we treated wild-type (WT) mice with chronic administration of papaverine, which is a specific inhibitor of PDE10A. At 7 weeks of age, mice were introduced to a weekly battery of motor tests, including assessment of weight, locomotion, gait, and coordination. Beginning at 8 weeks of age, mice received 0, 5, 10 or 20 mg/kg papaverine once daily until the completion of behavioral testing. Following 14 days of papaverine injections, mice were assessed for deficits in cognitive performance as measured in the Morris water maze (MWM). All behavioral tests occurred either immediately prior to or 30 min following a subcutaneous papaverine challenge dose. Twenty-four hours following completion of the 2-3 week MWM protocol, mice were given a dose of papaverine and 30 min later psychological function assessed in the Light-Dark (LD) Test. Chronic administration of papaverine for 42 days was associated with distinct motor perturbations, mild cognitive disturbance and anxiety-like behaviors. Subsequently, we assessed the effect of 14 days papaverine (i.e. sub-chronic) treatment on psychological function of WT and R6/1 HD mice. While sub-chronic papaverine induced anxiety-like behavior in WT mice, it appeared to have little effect on the behavior of R6/1 HD mice. Finally, a separate group of 6-week old WT and R6/2 HD mice were treated for 21 days with saline or 10 mg/kg fluoxetine, an agent with anxiolytic and anti-depressant effects, in order to compare the effects of papaverine and fluoxetine on anxiety-like behavior in the LD test. CREB and PDE10A protein levels in striatum and hippocampus were determined by western blot. While papaverine treatment reduced CREB protein levels in the hippocampus and striatum, fluoxetine increased CREB in the hippocampus. These data suggest that papaverine and fluoxetine may produce quite different effects on behavior; these behaviors may be linked to CREB expression in brain regions associated with motor and cognitive functions. PDE10A protein levels were decreased by both papaverine and fluoxetine. Chronic PDE10A inhibition produced a variety of behavioral and central neurochemical deficits and these effects were exacerbated by stress. The unique localization of PDE10A and its apparent role in basal ganglia function may underlie its role in psychiatric and neurological disorders involving the basal ganglia.

The endogenous cannabinoid anandamide has effects on motivation and anxiety that are revealed by fatty acid amide hydrolase (FAAH) inhibition

Converging evidence suggests that the endocannabinoid system is an important constituent of neuronal substrates involved in brain reward processes and emotional responses to stress. Here, we evaluated motivational effects of intravenously administered anandamide, an endogenous ligand for cannabinoid CB1-receptors, in Sprague-Dawley rats, using a place-conditioning procedure in which drugs abused by humans generally produce conditioned place preferences (reward). Anandamide (0.03-3 mg/kg intravenous) produced neither conditioned place preferences nor aversions. However, when rats were pre-treated with the fatty acid amide hydrolase (FAAH) inhibitor URB597 (cyclohexyl carbamic acid 3'-carbamoyl-3-yl ester; 0.3 mg/kg intraperitoneal), which blocks anandamide's metabolic degradation, anandamide produced dose-related conditioned place aversions. In contrast, URB597 alone showed no motivational effects. Like URB597 plus anandamide, the synthetic CB1-receptor ligand WIN 55,212-2 (50-300 microg/kg, intravenous) produced dose-related conditioned place aversions. When anxiety-related effects of anandamide and URB597 were evaluated in a light/dark box, both a low anandamide dose (0.3 mg/kg) and URB597 (0.1 and 0.3 mg/kg) produced anxiolytic effects when given alone, but produced anxiogenic effects when combined. A higher dose of anandamide (3 mg/kg) produced anxiogenic effects and depressed locomotor activity when given alone and these effects were potentiated after URB597 treatment. Finally, anxiogenic effects of anandamide plus URB597 and development of place aversions with URB597 plus anandamide were prevented by the CB1-receptor antagonist AM251 (3 mg/kg intraperitoneal). Thus, additive interactions between the effects of anandamide on brain reward processes and on anxiety may account for its aversive effects when intravenously administered during FAAH inhibition with URB597.

Deficiency in Na,K-ATPase alpha isoform genes alters spatial learning, motor activity, and anxiety in mice

Several disorders have been associated with mutations in Na,K-ATPase alpha isoforms (rapid-onset dystonia parkinsonism, familial hemiplegic migraine type-2), as well as reduction in Na,K-ATPase content (depression and Alzheimer's disease), thereby raising the issue of whether haploinsufficiency or altered enzymatic function contribute to disease etiology. Three isoforms are expressed in the brain: the alpha1 isoform is found in many cell types, the alpha2 isoform is predominantly expressed in astrocytes, and the alpha3 isoform is exclusively expressed in neurons. Here we show that mice heterozygous for the alpha2 isoform display increased anxiety-related behavior, reduced locomotor activity, and impaired spatial learning in the Morris water maze. Mice heterozygous for the alpha3 isoform displayed spatial learning and memory deficits unrelated to differences in cued learning in the Morris maze, increased locomotor activity, an increased locomotor response to methamphetamine, and a 40% reduction in hippocampal NMDA receptor expression. In contrast, heterozygous alpha1 isoform mice showed increased locomotor response to methamphetamine and increased basal and stimulated corticosterone in plasma. The learning and memory deficits observed in the alpha2 and alpha3 heterozygous mice reveal the Na,K-ATPase to be an important factor in the functioning of pathways associated with spatial learning. The neurobehavioral changes seen in heterozygous mice suggest that these mouse models may be useful in future investigations of the associated human CNS disorders.

Salivary alpha-amylase levels after yohimbine challenge in healthy men

CONTEXT

We and others have previously shown that standardized psychosocial stress significantly increases salivary alpha-amylase (sAA), but it remains unclear whether sAA reflects autonomic nervous system activation.

OBJECTIVE

The aim of this study was to assess cardiovascular effects and sAA and catecholamine secretion after iv injection of yohimbine.

DESIGN AND SETTING

We conducted a randomized double-blind placebo-controlled study at an academic research unit.

PARTICIPANTS

Thirteen healthy males (aged 20-28 yr) were examined.

INTERVENTION

Participants received iv injection of yohimbine (0.4 microg/kg) or placebo (0.9% NaCl).

MAIN OUTCOME MEASURES

Eight saliva and blood samples were taken before and after injection for the assessment of salivary flow rate and sAA and catecholamine concentrations. In addition, blood pressure, mood, and anxiety were assessed repeatedly.

RESULTS

Yohimbine induced increases of sAA activity and output in comparison to placebo (P = 0.034). Blood pressure (P < 0.001), salivary flow rate (P = 0.007), and catecholamines (P < 0.001) were also significantly increased. No significant correlations between alpha-amylase parameters and catecholamines were observed.

CONCLUSIONS

The results indicate that yohimbine administration activates not only autonomic parameters but also sAA via adrenergic mechanisms, suggesting that sAA might be an indirect indicator of the central sympathetic system.

Over-expression of two different forms of the α-secretase ADAM10 affects learning and memory in mice

Members of the ADAM family (adisintegrin and metalloprotease) are the main candidates for physiologically relevant alpha-secretases. The alpha-secretase cleaves in the non-amyloidogenic pathway the amyloid precursor protein within the region of the Abeta peptides preventing their aggregation in the brain. The increase of alpha-secretase activity in the brain provides a plausible strategy to prevent Abeta formation. Concerning this possibility two transgenic mouse lines (FVB/N) have been created: mice over-expressing the bovine form of the alpha-secretase (ADAM10) and mice over-expressing an inactive form of the alpha-secretase (ADAM10-E348A-HA; ADAM10-dn). For behavioral examination a F1 generation of transgenic mice (C57Bl/6 x FVB/N (tg)) was generated and compared to wild type F1 generation (C57Bl/6 x FVB/N). Behavior was characterized in the following tasks: standard open field, enriched open field, elevated plus-maze, and the Morris water maze hidden platform task. Concerning basal activity, exploration, and anxiety, transgenic mice behaved similar to controls. With respect to learning and memory both transgenic lines showed a significant deficit compared to controls. ADAM10 mice however, showed thigmotaxis with passive floating behavior in the Morris water maze indicating differences in motivation, whereas, ADAM10-dn mice displayed an inconspicuous but limited goal-directed search pattern. Thus variation of the enzymatic activity of alpha-secretase ADAM10 alters learning and memory differentially. Nevertheless, it could be concluded that both, ADAM10 and ADAM10-dn mice are suitable control mice for the assessment of alpha-secretase-related effects in animal models of Alzheimer's disease.

Requirement of hippocampal phospholipase A2 activity for long-term memory retrieval in rats

In rats, the inhibition of phospholipase A(2) (PLA(2)) in hippocampus was reported to impair memory acquisition. In the present study we investigated in rats whether PLA(2) inhibition in hippocampus is also related to impairment of memory retrieval. Rats were bilaterally implanted with cannulae in hippocampal CA1 region. After recovery, animals were submitted to one-trial step-down inhibitory avoidance task and tested for long-term memory (LTM) 24 h later. Before test session, animals received infusions of vehicle or the PLA(2) inhibitor PACOCF(3). Inhibition of PLA(2) activity impaired LTM retrieval. Memory impairment was fully reversed once PLA(2) activity was recovered. Moreover, LTM retrieval per se increased PLA(2) activity. To our knowledge, we demonstrated for the first time that PLA(2) activity is required for memory retrieval. Because reduced PLA(2) activity has been found in Alzheimer's disease brains, the present results may be relevant to clarify at least part of the biology of this disorder.

The influence of catecholamines on pseudocholinesterase enzymatic activity. Results of a laboratory investigation

OBJECTIVE

Acceleratory and inhibitory receptors have been described on the pseudocholinesterase (PCHE) molecule. An increased PCHE activity has been reported in patients with chronic pain and anxiety, conditions known to be correlated with increased plasma catecholamine levels. Aim of this laboratory investigation was to determine whether catecholamines have an effect on PCHE activity, as this knowledge could help to define the role of PCHE in the assessment of stress.

METHODS

After Ethics committee approval and written informed consent, 3 ml of blood was collected from five healthy volunteers. Fourteen samples of 50 mul each were prepared from each of the volunteer's plasma. Epinephrine (25, 50, 100, 200, 400 and 1000 pg) and norepinephrine (50, 100, 200, 400, 800 and 2000 pg) were added to samples of each subject. Sodium-chloride solution was added to control samples. PCHE activity was photometrically assessed.

RESULTS

PCHE activity was significantly higher after the addition of epinephrine (median 8304 versus 7386 U/l). This effect was not dose-dependent. PCHE activity did not change after addition of norepinephine.

CONCLUSIONS

This mechanism might explain previous findings that showed higher levels of PCHE activity in the presence of chronic pain and anxiety. In the absence of a dose-response curve in the concentration range studied, PCHE activity does not appear to be suitable for the assessment of levels of stress.

Behavioral characterization of CD26 deficient mice in animal tests of anxiety and antidepressant-like activity

CD26 exhibits a dipeptidylpeptidase-IV function (DPPIV) which regulates neuropeptide activity by N-terminal processing. Because abnormal plasma DPPIV was associated in mammals with behavioral changes, we examined the behavior of CD26-/- mice resulting from targeted inactivation of the gene. These animals had a decreased immobility in the forced swim and tail suspension tests, indicating a reduced depression-like behavior. We addressed some factors that could affect these results. No major differences between mutants and controls were observed in the black/white box test that investigates anxiety. In the hole-board apparatus that explores both curiosity and anxiety, CD26-/- mice of both genders made significantly more head dips than controls. In a motor activity test, mutants displayed higher horizontal and vertical activities i.e. increased novelty-induced behavioral activation. We conclude that DPPIV inactivation in mice broadly leads to an antidepressant-like and hyperactive phenotype.

Behavioural alterations in male mice lacking the gene for d-aspartate oxidase

D-serine and D-aspartate are important regulators of mammalian physiology. D-aspartate is found in nervous and endocrine tissue, specifically in hypothalamic supraoptic and paraventricular nuclei, pituitary, and adrenal medullary cells. Endogenous D-aspartate is selectively degraded by D-aspartate oxidase. We previously reported that adult male mice lacking the gene for D-aspartate oxidase (Ddo(-/-) mice) display elevated concentrations of D-aspartate in several neuronal and neuroendocrine tissues as well as impaired sexual performance and altered autogrooming behaviour. In the present study, we analyzed behaviours relevant to affect, cognition, and motor control in Ddo(-/-) mice. Ddo(-/-) mice display deficits in sensorimotor gating and motor coordination as well as reduced immobility in the forced swim test. Basal corticosterone concentrations are elevated. The Ddo(-/-) mice have D-aspartate immunoreactive cells in the cerebellum and adrenal glands that are not observed in the wild-type mice. However, no differences in anxiety-like behaviour are detected in open field or light-dark preference tests. Also, Ddo(-/-) mice do not differ from wild-type mice in either passive avoidance or spontaneous alternation tasks. Although many of these behavioural deficits may be due to the lack of Ddo during development, our results are consistent with the widespread distribution of D-aspartate and the hypothesis that endogenous D-aspartate serves diverse behavioural functions.

The decreased cyclic-AMP dependent-protein kinase A function in the nucleus accumbens: a role in alcohol drinking but not in anxiety-like behaviors in rats

The nucleus accumbens (NAc) brain structures have been implicated in the reward and reinforcing properties of ethanol. The present study investigated the role of nucleus accumbal cyclic AMP (cAMP)-dependent protein kinase A (PKA) signaling in alcohol drinking and anxiety-like behaviors of rats. It was found that infusion of PKA inhibitor (Rp-cAMP) into the NAc shell significantly increased the alcohol but not the sucrose intake, without modulating the anxiety-like behaviors, as measured by elevated plus maze test in rats. PKA inhibitor infusion into the NAc shell significantly decreased the protein levels of alpha-catalytic subunit of PKA (PKA-Calpha) and phosphorylated cAMP response element-binding protein (p-CREB) as well as decreased the protein levels of neuropeptide Y (NPY) in the shell but not in the NAc core of rats. On the other hand, infusion of PKA activator (Sp-cAMP) or NPY alone into the NAc shell did not produce any changes in alcohol intake; however, when these agents were coinfused with PKA inhibitor, they significantly attenuated the increases in alcohol preference induced by pharmacological inhibition of PKA. Interestingly, PKA activator coinfusion with PKA inhibitor into the NAc shell significantly normalized the PKA inhibitor-induced decreases in the protein levels of PKA-Calpha and p-CREB as well as of NPY in the NAc shell of rats. Taken together, these results provide the first evidence that decreased PKA function in the NAc shell is involved in alcohol drinking but not in anxiety-like behaviors of rats. Furthermore, decreased function of PKA may regulate alcohol drinking behaviors via CREB-mediated decreased expression of NPY in the NAc shell of rats.

Glyoxalase 1 and glutathione reductase 1 regulate anxiety in mice

Anxiety and fear are normal emotional responses to threatening situations. In human anxiety disorders--such as panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, social phobia, specific phobias and generalized anxiety disorder--these responses are exaggerated. The molecular mechanisms involved in the regulation of normal and pathological anxiety are mostly unknown. However, the availability of different inbred strains of mice offers an excellent model system in which to study the genetics of certain behavioural phenotypes. Here we report, using a combination of behavioural analysis of six inbred mouse strains with quantitative gene expression profiling of several brain regions, the identification of 17 genes with expression patterns that correlate with anxiety-like behavioural phenotypes. To determine if two of the genes, glyoxalase 1 and glutathione reductase 1, have a causal role in the genesis of anxiety, we performed genetic manipulation using lentivirus-mediated gene transfer. Local overexpression of these genes in the mouse brain resulted in increased anxiety-like behaviour, while local inhibition of glyoxalase 1 expression by RNA interference decreased the anxiety-like behaviour. Both of these genes are involved in oxidative stress metabolism, linking this pathway with anxiety-related behaviour.

Involvement of cyclic GMP-dependent protein kinase in nitrous oxide-induced anxiolytic-like behavior in the mouse light/dark exploration test

The second messenger cyclic GMP (cGMP) plays a role in the anxiolytic-like behavioral response of mice to nitrous oxide (N2O). This study was conducted to determine whether this behavioral effect of N2O is affected by inhibition of cGMP-dependent protein kinase (PKG). N2O-induced behavior in the light/dark exploration test was significantly attenuated by the PKG inhibitors H-8 and Rp-8-pCPT-cGMPS but not Rp-8-pCPT-cAMPS, an inhibitor of cAMP-dependent protein kinase. These findings implicate PKG in the mediation or modulation of the anxiolytic-like behavioral response to N2O.

Genetic alteration of anxiety and stress-like behavior in mice lacking CaMKIV

Calcium-calmodulin-dependent protein kinase IV (CaMKIV) phosphorylates the major transcription factor cyclic AMP-response element binding protein (CREB), which plays a role in emotional behavior. Here, CaMKIV knockout mice (CaMKIV^-/-) were tested in a battery of stress and anxiety-related behavioral tests, to determine if CaMKIV plays a role in emotional behavior. CaMKIV^-/-exhibited a decrease in anxiety-like behavior in both the elevated plus maze and dark-light emergence tests when compared to wild-type mice. Both the acoustic startle response and prepulse inhibition of startle were decreased with the deletion of CaMKIV. In addition, CaMKIV^-/- mice displayed a lack of stress-induced analgesia following restraint or cold swim stress. Our results demonstrate a key role for CaMKIV in anxiety and stress-related behavior.

Pseudocholinesterase activity increases and heart rate variability decreases with preoperative anxiety

BACKGROUND AND OBJECTIVE

The objective of this study was to determine the influence of preoperative anxiety on the activity of plasma cholinesterase and heart rate (HR) variability.

METHODS

A total of 50 subjects were studied, 25 male patients one day preoperatively and 25 male volunteers without surgical intervention as a control group. Blood samples were taken to determine plasma cholinesterase activity. HR variability was recorded for a period of 256 beat-to-beat intervals and analysed by frequency domain analysis into very low frequency (VLF: 0.02-0.04 Hz), low frequency (LF: 0.04-0.15 Hz) and high frequency (HF: 0.15-0.4 Hz). LF/HF ratio and total power over the 0.02-0.4 Hz range were calculated. Anxiety levels were assessed using the hospital anxiety and depression scale, the self-rating anxiety scale and a visual analogue scale.

RESULTS

The patient group had significantly higher anxiety scores. Plasma cholinesterase activity was significantly higher in patients vs. controls (6646 vs. 5324 units L(-1)). Total power, LF and HF were significantly lower in the patients (1489 vs. 2581 ms2; 656 vs. 1186 ms2; 491 vs. 964 ms2, respectively).

CONCLUSIONS

Preoperative anxiety increases plasma cholinesterase activity and decreases HR variability.

Importance of NO/cGMP signalling via cGMP-dependent protein kinase II for controlling emotionality and neurobehavioural effects of alcohol

Cyclic GMP is a second messenger for nitric oxide (NO) that acts as a mediator for many different physiological functions. The cGMP-dependent protein kinases (cGKs) mediate cellular signalling induced by NO and cGMP. Here, we explored the localization of cGMP-dependent protein kinase type II (cGKII) in the mouse brain. In situ hybridization revealed high levels of cGKII mRNA in cerebral cortex, thalamic nuclei, hypothalamic nuclei, and in several basal forebrain regions including medial septum, striatum and amygdala. The close link to NO and the distribution pattern of cGKII suggested that this enzyme might be involved in emotional reactions and responses to drugs of abuse. Therefore, cGKII knockout animals (cGKII-/-) were compared with littermate controls in behavioural tests (i) for emotion-linked and (ii) for acute and chronic ethanol responses. Deletion of cGKII did not influence aggressive behaviour but led to enhanced anxiety-like behaviour. In terms of acute responses to ethanol, cGKII-/- mice were hyposensitive to hypnotic doses of ethanol as measured by the loss of righting reflex, without an alteration in their blood alcohol elimination. In a two-bottle free choice test, cGKII-/- mice showed elevated alcohol consumption. No taste differences to sweet solutions were observed compared to control animals. In summary, our data show that cGKII activity modulates anxiety-like behaviour and neurobehavioural effects of alcohol.

Predictors of high ethanol consumption in RIIbeta knock-out mice: assessment of anxiety and ethanol-induced sedation

BACKGROUND

Genetic and pharmacological evidence suggests that the cyclic adenosine monophosphate-dependent protein kinase A pathway modulates neurobiological responses to ethanol. Mutant mice lacking the RIIbeta subunit of protein kinase A (RIIbeta(-/-)) are resistant to ethanol-induced sedation and drink significantly more ethanol than littermate wild-type mice (RIIbeta(+/+)). We determined whether high ethanol intake by the RIIbeta(-/-) mice on alternate genetic backgrounds is reliably predicted by high basal levels of anxiety or resistance to the sedative effects of ethanol.

METHODS

Two-bottle choice procedures and a battery of behavioral tests (elevated plus maze, open-field activity, and zero maze) were used to assess voluntary ethanol consumption and basal levels of anxiety in RIIbeta(-/-) and RIIbeta(+/+) mice on either a C57BL/6J or a 129/SvEv x C57BL/6J genetic background. Additionally, ethanol-induced sedation and blood ethanol levels were determined in RIIbeta(-/-) and RIIbeta(+/+) mice after intraperitoneal injection of ethanol (3.8 g/kg).

RESULTS

RIIbeta(-/-) mice on both genetic backgrounds consumed more ethanol and had a greater preference for ethanol relative to RIIbeta(+/+) mice. However, RIIbeta(-/-) mice showed reduced basal levels of anxiety when maintained on the C57BL/6J background but showed increased anxiety when maintained on the 129/SvEv x C57BL/6J background. Consistent with prior research, RIIbeta(-/-) mice were resistant to the sedative effects of ethanol, regardless of the genetic background. Finally, RIIbeta(-/-) and RIIbeta(+/+) mice showed similar blood ethanol levels.

CONCLUSIONS

These results indicate that high ethanol consumption is associated with resistance to the sedative effects of ethanol but that basal levels of anxiety, as well as ethanol metabolism, do not reliably predict high ethanol drinking by RIIbeta(-/-) mice.

Progesterone enhances motor, anxiolytic, analgesic, and antidepressive behavior of wild-type mice, but not those deficient in type 1 5 alpha-reductase

The importance of progesterone's (P(4)) metabolism by the 5 alpha-reductase type I enzyme was examined in homozygous and heterozygous 5 alpha-reductase type I knockout mice and their wild-type siblings. P(4) (1.0 mg) or vehicle was administered and effects on motor, anxiety, nociceptive, and depression behavior were observed. After testing, whole-brain progesterone and 5 alpha-pregnan-3 alpha-ol-20-one (3 alpha,5 alpha-THP) levels were determined by radioimmunoassay. Motor behavior in the horizontal crossing and open field tasks of 5 alpha-reductase-deficient mice administered P(4) was similar to vehicle control mice and significantly reduced compared to wild-type mice administered P(4). In the open field, 5 alpha-reductase-deficient mice administered P(4) had a similar number of central entries as did vehicle control mice, both were lower than central entries of P(4)-administered wild-type mice. However, in the plus maze, P(4) to 5 alpha-reductase-deficient or wild-type mice significantly increased open arm activity compared to vehicle-administered control mice. P(4) to wild-type, but not 5 alpha-reductase-deficient mice, significantly increased latencies to lick front and back paws in response to radiant heat stimuli compared to vehicle administration to control mice. In the forced swim test, 5 alpha-reductase-deficient mice administered P(4) were similar to vehicle control mice and the latency to immobility was significantly decreased, and the duration of immobility was significantly increased, compared to wild-type mice administered P(4). Thus, these data suggest metabolism by the 5 alpha-reductase type I enzyme may mitigate P(4)'s effects on some tasks of motor, anxiety, nociception, and depression behavior.

Possible interaction of alcohol dehydrogenase and aldehyde dehydrogenase genes with the dopamine D2 receptor gene in anxiety-depressive alcohol dependence

BACKGROUND

The role of the dopamine D2 receptor (DRD2) gene in the development of alcohol abuse or dependence is controversial. The controversy is due in part to the disparate definitions pertaining to the control groups used and to the definitions of subtypes in alcohol dependence. In the Han Chinese population, the alcohol dehydrogenase 1B*2/*2 (ADH1B*2/*2) genotype and the aldehyde dehydrogenase 2*2 (ALDH2*2) allele have been considered as protective factors against alcohol abuse or dependence. Moreover, the ADH1B and ALDH2 genes might be involved in dopamine metabolism. We hypothesized that the ADH1B and ALDH2 genes might interact with the DRD2 gene and that the association between the DRD2 gene and alcohol dependence might be affected by different ADH1B and ALDH2 genotypes. This study examined whether the DRD2 gene is associated with specific subtypes of alcohol dependence and evaluated the relationship between the DRD2 gene and alcohol-metabolizing genes in a specific subtype of alcohol dependence.

METHODS

Of the 465 Han Chinese subjects who were recruited for the study, 71 were classified with pure alcohol dependence, 113 with both alcohol dependence and anxiety-depression (ANX/DEP ALC), and 129 with anxiety-depression but without alcohol dependence (ANX/DEP). The remaining 152 subjects were supernormal controls. All subjects were interviewed with the Chinese version of the modified Schedule of Affective Disorders and Schizophrenia-Lifetime; all alcohol dependence, anxiety, and major depressive diagnoses were made according to DSM-IV criteria.

RESULTS

The DRD2 gene was not found to be associated with pure alcohol dependence or ANX/DEP, but was found to be associated with ANX/DEP ALC. Furthermore, the association between the DRD2 gene and ANX/DEP ALC was shown to be under the control of the ALDH2*1/*1 and ADH1B*1/*2 genotypes.

CONCLUSIONS

ANX/DEP ALC is a specific subtype of alcohol dependence. Because ANX/DEP ALC was associated with the DRD2 gene only under the stratification of ADH1B*1/*2 or ALDH2*1/*1, the DRD2 gene might interact with the ADH1B gene and the ALDH2 gene, respectively, in the development of ANX/DEP ALC in the Taiwan Han Chinese population.

Acetylcholinesterase/paraoxonase genotype and expression predict anxiety scores in Health, Risk Factors, Exercise Training, and Genetics study

Anxiety involves complex, incompletely understood interactions of genomic, environmental, and experience-derived factors, and is currently being measured by psychological criteria. Here, we report previously nonperceived interrelationships between expression variations and nucleotide polymorphisms of the chromosome 7q21-22 acetylcholinesterase-paraoxonase 1 (ACHE-PON1) locus with the trait- and state-anxiety measures of 461 healthy subjects from the Health, Risk Factors, Exercise Training, and Genetics Family Study. The AChE protein controls the termination of the stress-enhanced acetylcholine signaling, whereas the PON protein displays peroxidase-like activity, thus protecting blood proteins from oxidative stress damages. Serum AChE and PON enzyme activities were both found to be affected by demographic parameters, and showed inverse, reciprocal associations with anxiety measures. Moreover, the transient scores of state anxiety and the susceptibility score of trait anxiety both appeared to be linked to enzyme activities. This finding supported the notion of corresponding gene expression relationships. Parallel polymorphisms in the ACHE and PON1 genes displayed apparent associations with both trait- and state-anxiety scores. Our findings indicate that a significant source of anxiety feelings involves inherited and acquired parameters of acetylcholine regulation that can be readily quantified, which can help explaining part of the human variance for state and trait anxiety.

Protein tyrosine phosphatase alpha (PTP alpha) knockout mice show deficits in Morris water maze learning, decreased locomotor activity, and decreases in anxiety

Receptor PTPalpha is a widely expressed transmembrane enzyme enriched in brain. PTPalpha knockout (PTPalpha(-/-)) mice are viable and display no gross abnormalities. Brain and embryo derived fibroblast src and fyn activity is reduced to <50% in PTPalpha(-/-) mice. These protein kinases are implicated in multiple aspects of neuronal development and function. However, the effect of the loss of function of the PTPalpha gene on behavior has yet to be investigated. PTPalpha(-/-) and WT mice were tested for anxiety, swimming ability, spatial learning, cued learning, locomotor activity, and novel object recognition (NOR). PTPalpha(-/-) mice were indistinguishable from WT in swimming ability, cued learning and novel object recognition. Knockout mice showed decreased anxiety without an increase in head dips and stretch-attend movements. During Morris water maze (MWM) learning, PTPalpha(-/-) mice had increased latencies to reach the goal compared to WT on acquisition, but no memory deficit on probe trials. On reversal learning, knockout mice showed no significant effects. PTPalpha(-/-) mice showed decreased exploratory locomotor activity, but responded normally to a challenge dose of D-methamphetamine. The data suggest that PTPalpha serves a regulatory function in learning and other forms of neuroplasticity.

Putative anxiety-linked effects of the nitric oxide synthase inhibitor L-NAME in three murine exploratory behavior models

The aim of the current study was to extend investigation into possible linkage between nitric oxide (NO) and anxiety-linked behavior using a battery of tests. Effects of the NO synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) were investigated in three murine models of anxiety-the light-dark, hole-board and elevated plus-maze-in between-groups designs. Treatment groups included L-NAME (0 [vehicle, or Veh], 10, 25, and 50 mg/kg) and 50 mg/kg of the inactive isomer N(G)-nitro-D-arginine methyl ester (D-NAME) injected subcutaneously. Mice exhibited a robust anxiogenic-like response profile reflected by dose-related decreases in both light-dark (transitions and time in lighted area) and hole-board (head dips and time spent head dipping) test measures, reaching statistical significance at 25 and 50 mg/kg L-NAME when compared to Veh controls (P<.05 or.01; Dunnett's t test), while distance traveled and rearing showed no significant differential pattern in either model. In both models, there was a strong dissociation between nonspecific locomotion and putative exploratory behaviors. D-NAME was not significantly different from Veh condition in either model, indicating a stereospecific action and supporting NO involvement. A dose-related decrease was also observed for several traditional and ethological measures in the plus-maze; however, the effect was limited and relatively weak or absent; with the exception of open-arm and percent open-arm entries, putative anxiety-sensitive measures reached statistical significance only at the highest dose. Reductions in motor activity compromised ability to dissociate an anxiety linkage from a nonspecific motor effect in most measures. It is concluded that the hole-board and light-dark tests provide indication of anxiogenic-like action of NOS inhibition, suggesting that NO has an anxiolytic action. Data from the plus-maze are unclear, owing to a confounding motor influence in most measures.