Reduced Anxiety Behavior Research Articles

Effect of Ajwain Extract and Carvone on Behavioral Disorders Induced by Chronic Immobilization in Adult Male Rats

Introduction: In this study, we examined the impact of a hydroethanolic extract derived from ajwain and carvone (a compound present in ajwain), on learning, spatial memory, and anxiety levels in adult male rats that were chronically immobilized.
 Methods: There were 60 rats used in this study, divided into six groups of 10 rats each. To expose stress, 30 rats (in 3 groups including Stress, Stress-Carvone, and Stress-Ajwain groups) were placed in a restrainer for 6 hours every day for 21 consecutive days. Stress-Carvone and Stress-Ajwain groups received carvone (20 mg/kg) and ajwain extract (500 mg/kg) by gavage respectively. Thirty rats were also used in three groups (Control, Carvone, and Ajwain groups). Spatial learning and memory were studied using the Morris water maze, and anxiety was assessed by the elevated-plus maze.
 Results: Compared to the control group, chronic immobilization caused the rats to swim a longer time (P < 0.01) and distance (P < 0.05) to reach the hidden platform, and a shorter time and distance to swim in the target quarter (P < 0.05) in the Morris water maze. The percentage of entering the open arm in the elevated plus maze (P < 0.001) and the percentage of time staying in this arm (P < 0.01) were lower than the control group. The carvone improved the performance of stressed animals in the Morris maze, but the ajwain extract had no effect on the memory deficit of stressed animals. Furthermore, treating ajwain extract and carvone increased the percentage of entry into the open arm and the percentage of time spent in the open arm in animals exposed to stress.
 Conclusion: Ajwain extract and carvone reduce anxiety behavior in rats exposed to chronic immobility stress; carvone treatment prevents memory impairment in these animals. It is possible that the extract of ajwain (partially through carvone) is effective in reducing damage caused by stress in the nervous system.

Prenatal Di-methoxyethyl phthalate exposure impairs cortical neurogenesis and synaptic activity in the mice.

Di-methoxyethyl phthalate (DMEP) is a well-known environmentally prevalent endocrine disruptor and may be associated with neurodevelopmental disorders including attention deficit/hyperactivity disorder and intellectual disability. However, the regulatory mechanisms leading to these neurodevelopmental disorders are still poorly understood. Here, we demonstrate that prenatal DMEP exposure causes abnormal brain morphology and function in the mice. DMEP (50 mg/kg) was chronically administered to pregnant mice orally once a day starting on embryonic day 0 (E0) to breast-feeding cessation for the fetus. We found that prenatal DMEP exposure significantly reduced the number of neurons in the parietal cortex by impairing neurogenesis and gliogenesis during the developing cortex. Moreover, we found that prenatal DMEP exposure impaired dendritic spine architectures and synaptic activity in the parietal cortex. Finally, prenatal DMEP exposure in mice induces hyperactivity and reduces anxiety behaviors. Altogether, our study demonstrates that prenatal DMEP exposure leads to abnormal behaviors via impairment of neurogenesis and synaptic activity.

Rapamycin improves social and stereotypic behavior abnormalities induced by pre-mitotic neuronal subset specific Pten deletion.

The mechanistic target of rapamycin (mTOR) pathway is a signaling system integral to neural growth and migration. In both patients and rodent models, mutations to the phosphatase and tensin homolog gene (PTEN) on chromosome 10 results in hyperactivation of the mTOR pathway, as well as seizures, intellectual disabilities and autistic behaviors. Rapamycin, an inhibitor of mTOR, can reverse the epileptic phenotype of neural subset specific Pten knockout (NS-Pten KO) mice, but its impact on behavior is not known. To determine the behavioral effects of rapamycin, male and female NS-Pten KO and wildtype (WT) mice were assigned as controls or administered 10 mg/kg of rapamycin for 2 weeks followed by behavioral testing. Rapamycin improved social behavior in both genotypes and stereotypic behaviors in NS-Pten KO mice. Rapamycin treatment resulted in a reduction of several measures of activity in the open field test in both genotypes. Rapamycin did not reverse the reduced anxiety behavior in KO mice. These data show the potential clinical use of mTOR inhibitors by showing its administration can reduce the production of autistic-like behaviors in NS-Pten KO mice.

Explicit memory, anxiety and depressive like behavior in mice exposed to chronic intermittent hypoxia, sleep fragmentation, or both during the daylight period

Obstructive sleep apnea (OSA) is a chronic and highly prevalent condition characterized by chronic intermittent hypoxia (IH) and sleep fragmentation (SF), and can lead to a vast array of end-organ morbidities, particularly affecting cardiovascular, metabolic and neurobehavioral functioning. OSA can induce cognitive and behavioral and mood deficits.Male C57Bl/6J 8-week-old mice were housed in custom-designed cages with a silent motorized mechanical sweeper traversing the cage floor at 2-min intervals (SF) during daylight for four weeks. Sleep control (SC) consisted of keeping sweeper immobile. IH consisted of cycling FiO2 21% 90 seconds-6.3% 90s or room air (RA; FiO2 21%) for sixteen weeks and combined SF-IH was conducted for nine weeks. Open field novel object recognition (NOR) testing, elevated-plus maze test (EPMT), and forced swimming test (FST) were performed.SF induced cognitive NOR performance impairments in mice along with reduced anxiety behaviors while IH induced deficits in NOR performance, but increased anxiety behaviors. SF-IH induced impaired performance in NOR test of similar magnitude to IH or SF alone. Combined SF-IH exposures did not affect anxiety behaviors.Thus, both SF an IH altered cognitive function while imposing opposite effects on anxiety behaviors. SF-IH did not magnify the detrimental effects of isolated SF or IH and canceled out the effects on anxiety. Based on these findings, the underlying pathophysiologic processes underlying IH and SF adverse effects on cognitive function appear to differ, while those affecting anxiety counteract each other.

Sphingosine 1‐phosphate (S1P) analogue FTY720 decreases ceramide levels and ameliorates memory performance in AD mice model

AbstractBackgroundNo effective therapeutic drugs were found for Alzheimer’s disease (AD), which focuses on amyloid plaques and neurofibrillary tangles in the past decades. Sphingolipid changes in AD patients and animals are getting more attention, especially the shift between ceramide and S1P in the brain, proposing an essential role in the amyloid‐β formation, neuroinflammation, and neuronal apoptosis in AD pathophysiology. Fingolimod (FTY720) is a drug that resembles sphingosine‐1‐phosphate (S1P) chemical structure and bioactivity. Therefore, we hypothesized that by increasing S1P signaling by means of FTY720, sphingolipid disbalance could be restored in the brain, and memory impairment observed in AD transgenic mouse models would be prevented.MethodTwo doses of FTY720 (0.1 mg/kg and 0.5 mg/kg daily) were given by oral gavage for 3 months to transgenic mouse models of AD on human apolipoprotein (APOE) APOE4 or APOE3 genetic background. During the drug administration, blood was withdrawn at different time points, and animals were challenged with behavioral tests for memory locomotion and anxiety. Brain was then collected for sphingolipids analysis by mass spectrometry and Aβ quantification.ResultSphingolipid analysis in the cortex showed that ceramide subsets elevated in AD mice. In the plasma, ceramides and sphingomyelins overall diminish in concentration over time. The behavioral tests analysis suggested that especially the low dose of FTY720 mildly prevented memory impairment in E4FAD and reduced anxiety behavior in APOE4 mice.ConclusionOn cerebral sphingolipids, Fingolimod shifted the pathway towards reducing ceramide, especially in the cortex. Our data are supportive of targeting the sphingolipid metabolism as a valid pathway for developing new therapeutic drugs for AD.

Pharmacological Investigation of Serial Anxiety Tests in the Mouse: A Pilot Study

The use of test batteries has been suggested as a means to enhance throughput, to broaden the spectrum of anxiety parameters detectable and to minimise the numbers of experimental animals required in behavioural studies. This study was undertaken to determine the sensitivity of test batteries each of open field, zero mazes and staircase tests to anxiety behaviours in randomised mouse groups. Mice (n = 8) were exposed to these apparatuses serially in that order, thirty minutes following intraperitoneal administration of distilled water, 0.5 and 1.0 mg/kg diazepam. Each mouse was allowed to spend 5 minutes to freely explore each test apparatus. The results showed diazepam-treated mice exhibited significantly (p<0.05) reduced anxiety behaviours compared to the placebo group on most rodent anxiety parameters evaluated. The findings of this study suggest these behavioural test apparatuses, when used in serial combination, are sensitive and reliable to measure murine anxiety-related behaviours and the anxiolytic effects of standard/putative agents.

Effectiveness of Video-Feedback with Cognitive Preparation in Improving Social Performance and Anxiety through Super Skills for Life Programme Implemented in a School Setting.

Effectiveness of video-feedback with cognitive preparation to treat anxiety problems (especially social anxiety) has been scarcely explored on children. Super Skills for Life (SSL) is a CBT-based intervention to reduce anxiety and comorbid problems that, apart from social skills training and behavioural activation, integrates video-feedback with cognitive preparation. This study aimed to evaluate SSL effects, implemented in a school setting, on social performance and to test self-concept and social skills as potential mediators of pre- and post-test changes in social anxiety and generalized anxiety. Sample comprised 57 children aged 8–11 years with emotional symptoms. Children were video recorded in the first and last session to assess social performance. Anxiety and self-concept measures were completed by children pre-test and post-test. Participants reduced anxiety behaviours and improved social and communication skills after treatment. In general, girls showed better social performance than boys, but SSL impact was greater in males. Social self-concept was the only mediator of change in pre- to post-treatment social anxiety. This study provides evidence of SSL to improve children’s social performance and reduce anxiety through video-feedback with cognitive preparation. Improving social concept seems essential to reduce social anxiety. An SSL programme is an ideal prevention protocol for anxious children.

Fluoxetine Attenuated Anxiety-Like Behaviors in Streptozotocin-Induced Diabetic Mice by Mitigating the Inflammation.

Patients with diabetes mellitus (DM) showed an increased risk of anxiety. High anxiety levels are also shown to increase stress of diabetic patients, which may contribute to poor clinical outcomes. The mechanisms underlying the development of anxiety disorders in diabetic patients remain unknown. As a result, there are no available treatments yet. Here, we tested the hypothesis that glial cells in the hippocampal area of DM mice might be responsible for their anxiety-like behaviors. Furthermore, we postulated that treatment with antidepressant, fluoxetine, could reduce anxiety behaviors and prevent the dysregulation of glial cells (oligodendrocyte and astrocyte) in DM mice. Diabetic mice were administered a single injection of streptozotocin (STZ), followed by treatment with fluoxetine. Mice were then tested on Y maze, open field, dark and light transition, and elevated plus maze tests to measure the status of anxiety and cognition. After completing these behavioral tests, mice were sacrificed and western blot was used to detect the oligodendrocyte and astrocyte maker proteins in hippocampal tissues. Emphasis was directed towards adult oligodendrocyte precursor cells (OPCs) and their marker protein to measure their proliferation and differentiation. We found that fluoxetine could effectively mitigate the level of anxiety and attenuate the cognitive dysfunction in diabetic mice. Meanwhile, fluoxetine inhibited astrocyte activation in mice exposed to STZ, prevented the loss of myelin basic protein (MBP), and affected the function of OPCs in these diabetic mice. The results suggested that the changes of these glial cells in the brains of diabetic mice might be related to the high anxiety levels and cognitive deficit in DM mice. Fluoxetine could ameliorate the high anxiety level and prevent cognitive deficit via inhibiting astrocyte activation and repairing the oligodendrocyte damage.

Increased seizure sensitivity, emotional defects and cognitive impairment in PHD finger protein 24 (Phf24)-null rats

Phf24 is known as Gαi-interacting protein (GINIP) and is associated with the GABAB receptor. To study the function of Phf24 protein in the central nervous system (CNS), we have newly developed Phf24-null rats and investigated their behavioral phenotypes, especially changes in seizure sensitivity, emotional responses and cognitive functions. Phf24-null rats did not exhibit any spontaneous seizures. However, they showed a higher sensitivity to pentylenetetrazol (PTZ)- or pilocarpine-induced convulsive seizures. Phf24-null rats also showed an elevated susceptibility to kindling development with repeated PTZ treatments, suggesting that Phf24 acts as an inhibitory modulator in epileptogenesis. Although young Phf24-null rats showed normal gross behaviors, elevated spontaneous locomotor activity, especially in terms of the circadian dark period, emotional hyper-reactivity, reduced anxiety behaviors in the elevated plus-maze (EPM) test, and cognitive deficits in the Morris water maze test were explicitly observed at older age (20-week-old). The present results suggest that Phf24 is essential for proper functioning of the CNS, especially in preventing epileptogenesis and controlling emotional and cognitive functions.

Interleukin-4 signalling pathway underlies the anxiolytic effect induced by 3-deoxyadenosine.

Converging evidence suggests that neuroimmunity plays an important role in the pathophysiology of anxiety. Interleukin (IL)-4 is a key cytokine regulating neuroimmune functions in the central nervous system. More efficient anxiolytics with neuro-immune mechanisms are urgently needed. To determine whether 3'-deoxyadenosine (3'-dA) exerts an anxiolytic effect and to examine the role of IL-4 in the anxiolytic effect of 3'-dA in mice. We investigated the effects of 3'-dA on anxiety-like behaviors using elevated plus maze (EPM) or light-dark box (LDB) tests after 45min or 5days of treatment. Expression of IL-4, IL-10, IL-1β, TNF-α, and IL-6 in the prefrontal cortex (PFC) was detected by Western blot and/or double immunostaining. Intracerebroventricular injection of RIL-4Rα (an IL-4-specific inhibitor) and intraperitoneal injection of 3'-dA or imipramine were co-administered, followed by EPM test. 3'-dA exhibited a stronger and faster anxiolytic effect than imipramine in behavioral tests. Furthermore, 3'-dA enhanced IL-4 expression after 45min or 5days, TNF-α and IL-1β expression decreased significantly after a 5-day treatment with 3'-dA, and IL-10 expression increased after a 5-day treatment with 3'-dA or imipramine in the PFC. IL-4 was expressed in neurons and in some astrocytes and microglia. IL-4 expression showed a strong positive correlation with reduced anxiety behaviors. RIL-4Rα completely blocked the anxiolytic effects induced by 3'-dA and imipramine. This study identifies a novel and common anxiolytic IL-4 signaling pathway and provides an innovative drug with a novel neuro-immune mechanism for treating anxiety disorder.

Effects of prenatal maternal cold stress on spontaneous, exploratory and anxious behaviors in offspring

To study the effects of prenatal cold stress on the behavior and mood of offspring in pregnant rats. Six SPF-class Wister pregnant rats were randomly divided into normal temperature control group and cold stress group with 3 rats in each group. The pregnant female rats in the normal temperature control group were kept in the environment of (22 ±2)℃, and the pregnant female rats in the cold stress group were placed in the artificial intelligence climate chamber at(4 ±0.1)℃ for 7 days before the birth, and the young rats were divided into normal temperature after the young rats were born. After the young rats were born, they were divided into normal temperature control group of male rats (MR, 22), normal temperature control group of mother rats (FR, 15), cold stress group of male rats (MC, 15), and cold stress group of female rats (FC, 15) .In the fourth generation of the offspring, the open field experiment and the elevated cross maze test were carried out. In the open field experiment, there was no significant difference in spontaneous activity and exploration behavior between the normal temperature control group and the cold stress group (P＞0.05). In the elevated plus maze experiment, the retention time of the open arms, the number of open arms and the distance of the male and female rats in the cold stress group were significantly higher than those in the normal temperature control group (P＜0.05). Prenatal maternal cold stress has no significant effect on spontaneous activity, exploration behavior and activity level of offspring, but the offspring have obvious abnormal behaviors with reduced anxiety behavior.

Prefrontal cortex-dependent innate behaviors are altered by selective knockdown of Gad1 in neuropeptide Y interneurons.

GABAergic dysfunction has been implicated in a variety of neurological and psychiatric disorders, including anxiety disorders. Anxiety disorders are the most common type of psychiatric disorder during adolescence. There is a deficiency of GABAergic transmission in anxiety, and enhancement of GABA transmission through pharmacological means reduces anxiety behaviors. GAD67—the enzyme responsible for GABA production–has been linked to anxiety disorders. One class of GABAergic interneurons, Neuropeptide Y (NPY) expressing cells, is abundantly found in brain regions associated with anxiety and fear learning, including prefrontal cortex, hippocampus and amygdala. Additionally, NPY itself has been shown to have anxiolytic effects, and loss of NPY+ interneurons enhances anxiety behaviors. A previous study showed that knockdown of Gad1 from NPY+ cells led to reduced anxiety behaviors in adult mice. However, the role of GABA release from NPY+ interneurons in adolescent anxiety is unclear. Here we used a transgenic mouse that reduces GAD67 in NPY+ cells (NPYGAD1-TG) through Gad1 knockdown and tested for effects on behavior in adolescent mice. Adolescent NPYGAD1-TG mice showed enhanced anxiety-like behavior and sex-dependent changes in locomotor activity. We also found enhancement in two other innate behavioral tasks, nesting construction and social dominance. In contrast, fear learning was unchanged. Because we saw changes in behavioral tasks dependent upon prefrontal cortex and hippocampus, we investigated the extent of GAD67 knockdown in these regions. Immunohistochemistry revealed a 40% decrease in GAD67 in NPY+ cells in prefrontal cortex, indicating a significant but incomplete knockdown of GAD67. In contrast, there was no decrease in GAD67 in NPY+ cells in hippocampus. Consistent with this, there was no change in inhibitory synaptic transmission in hippocampus. Our results show the behavioral impact of cell-specific interneuron dysfunction and suggest that GABA release by NPY+ cells is important for regulating innate prefrontal cortex-dependent behavior in adolescents.

Aqueous extract of saffron administration along with amygdala deep brain stimulation promoted alleviation of symptoms in post-traumatic stress disorder (PTSD) in rats

Post-traumatic stress disorder (PTSD) as one of the most devastating kinds of anxiety disorders, is the consequence of a traumatic event. Crocus sativus L., commonly known as saffron have been traditionally used for treatment of stress and anxiety. In this study, we evaluated the effects of peripheral administration of saffron, along with deep brain stimulation (DBS) in a post-traumatic stress disorder (PTSD) model caused by contextual fear conditioning (electrical foot shock chamber) in male Wistar rats. rats (220-250 g) were divided into 7 groups (n=8) and underwent stereotactic surgery for implantation of the electrodes in the right-baso lateral of the amygdala (BLA). After 7 days, some animals received the foot shock, followed by another 7-day treatment (DBS treatment or combination treatment by saffron 5 mg/kg (i.p)) then freezing behavior as a predicted response in the absence of the foot shock (re-exposure time) and general anxiety were measured using elevated plus maze test. Serum corticosterone level and amygdala c-Fos protein expression were assessed using ELISA and Western blot analysis, respectively. DBS treatment and the combination therapy of saffron (5 mg/kg (I.P)) with DBS significantly (p<0.001) increased serum corticosterone levels. Also both treatments could significantly (p<0.001) reduce c-Fos protein expression and freezing behaviors time. However, DBS treatment had no effect on the general anxiety in rats with PTSD. On the other hand, combination therapy significantly (p<0.001) reduced anxiety behavior in rats with PTSD. These results might show the potential of this combination therapy for treatment of treatment-resistant PTSD patients.

Long term treadmill exercise performed to chronic social isolated rats regulate anxiety behavior without improving learning

AimThe type and duration of exposure to stress is an important influence on emotional and cognitive functions. Learning is the adaptive response of the central nervous system that occurs in hippocampus which affects from environmental factors like exercise. In this study, we investigated effects of long term treadmill exercise on learning and behavior on chronic social isolated rat. Main methodsMale Wistar rats (n = 32) randomly assigned into four groups: control, exercised, social isolation, social isolation + exercise during postnatal days (PNDs) 21–34. Social isolation protocol was applied during 14 days by placing rat in a cage one by one. Rats were exercised during 5 days, days were chosen randomly for overall 4 weeks (20, 30, 50, 60 min respectively). Finally, learning performance was evaluated by Morris water maze (MWM). Anxiety behavior was evaluated by Open field and elevated plus maze test. At the end of learning and behavior tests, the rats were decapitated to collect blood samples via intracardiac puncture and corticosterone analysis was performed with ELISA method. Key findingsAnimal weights and water consumption did not change significantly but food intake differed among groups. Corticosterone level did not change between groups. The frequency of entering to the target quadrant increased in exercised rat significantly. However, there was no difference in learning and memory in rats. Treadmill exercise reduced anxiety behavior significantly. SignificanceTaken together these findings may point out that, long term treadmill exercise did not change learning and memory but reduced anxiety level of rat without changing corticosterone level.

S.02.02 - Adult hippocampal neurogenesis and cognitive flexibility - linking memory and mood

S.02.02 - Adult hippocampal neurogenesis and cognitive flexibility - linking memory and mood

New Botanical Anxiolytics for Use in Companion Animals and Humans.

As part of our ongoing research into botanical therapies for anxiety disorders, the neotropical vine Souroubea sympetala was chosen for study as a phytochemical discovery strategy focusing on rare Central American plant families. When orally administered to male Sprague-Dawley rats, the crude plant extract, its ethyl acetate fraction, supercritical carbon dioxide fraction, or its isolated triterpenes reduced anxiety and/or fear-related behavior in standardized behavioral models. Pharmacological studies showed that the extracts acted at the benzodiazepine GABAA receptor and reduced corticosterone levels. A preparation containing Souroubea fortified with a second triterpene containing plant, Platanus occidentalis, was shown to be safe in a 28-day feeding trial with beagles at 5 times the intended dose. Subsequent trials with beagles in a thunderstorm model of noise aversion showed that the material reduced anxiety behaviors and cortisol levels in dogs. The formulation has been released for the companion animal market in Canada and the USA under the Trademark "Zentrol." Ongoing research is exploring the use of the material in treatment of anxiety and post-traumatic stress in humans.

Endogenously Released Neuropeptide Y Suppresses Hippocampal Short-Term Facilitation and Is Impaired by Stress-Induced Anxiety

Neuropeptide Y (NPY) has robust anxiolytic properties and is reduced in patients with anxiety disorders. However, the mechanisms by which NPY modulates circuit function to reduce anxiety behavior are not known. Anxiolytic effects of NPY are mediated in the CA1 region of hippocampus, and NPY injection into hippocampus alleviates anxiety symptoms in the predator scent stress model of stress-induced anxiety. The mechanisms that regulate NPY release, and its effects on CA1 synaptic function, are not fully understood. Here we show in acute hippocampal slices from mice that endogenous NPY, released in response to optogenetic stimulation or synaptically evoked spiking of NPY+ cells, suppresses both of the feedforward pathways to CA1. Stimulation of temporoammonic synapses with a physiologically derived spike train causes NPY release that reduces short-term facilitation, whereas the release of NPY that modulates Schaffer collateral synapses requires integration of both the Schaffer collateral and temporoammonic pathways. Pathway specificity of NPY release is conferred by three functionally distinct NPY+ cell types, with differences in intrinsic excitability and short-term plasticity of their inputs. Predator scent stress abolishes the release of endogenous NPY onto temporoammonic synapses, a stress-sensitive pathway, thereby causing enhanced short-term facilitation. Our results demonstrate how stress alters CA1 circuit function through the impairment of endogenous NPY release, potentially contributing to heightened anxiety. <b>SIGNIFICANCE STATEMENT</b> Neuropeptide Y (NPY) has robust anxiolytic properties, and its levels are reduced in patients with post-traumatic stress disorder. The effects of endogenously released NPY during physiologically relevant stimulation, and the impact of stress-induced reductions in NPY on circuit function, are unknown. By demonstrating that NPY release modulates hippocampal synaptic plasticity and is impaired by predator scent stress, our results provide a novel mechanism by which stress-induced anxiety alters circuit function. These studies fill an important gap in knowledge between the molecular and behavioral effects of NPY. This article also advances the understanding of NPY+ cells and the factors that regulate their spiking, which could pave the way for new therapeutic targets to increase endogenous NPY release in patients in a spatially and temporally appropriate manner.

Endogenously Released Neuropeptide Y Suppresses Hippocampal Short-Term Facilitation and Is Impaired by Stress-Induced Anxiety.

Neuropeptide Y (NPY) has robust anxiolytic properties, and its levels are reduced in patients with post-traumatic stress disorder. The effects of endogenously released NPY during physiologically relevant stimulation, and the impact of stress-induced reductions in NPY on circuit function, are unknown. By demonstrating that NPY release modulates hippocampal synaptic plasticity and is impaired by predator scent stress, our results provide a novel mechanism by which stress-induced anxiety alters circuit function. These studies fill an important gap in knowledge between the molecular and behavioral effects of NPY. This article also advances the understanding of NPY+ cells and the factors that regulate their spiking, which could pave the way for new therapeutic targets to increase endogenous NPY release in patients in a spatially and temporally appropriate manner.

Loss of hypothalamic corticotropin-releasing hormone markedly reduces anxiety behaviors in mice.

A long-standing paradigm posits that hypothalamic corticotropin-releasing hormone (CRH) regulates neuroendocrine functions such as adrenal glucocorticoid release, while extra-hypothalamic CRH plays a key role in stressor-triggered behaviors. Here we report that hypothalamus-specific Crh knockout mice (Sim1CrhKO mice, created by crossing Crhflox with Sim1Cre mice) have absent Crh mRNA and peptide mainly in the paraventricular nucleus of the hypothalamus (PVH) but preserved Crh expression in other brain regions including amygdala and cerebral cortex. As expected, Sim1CrhKO mice exhibit adrenal atrophy as well as decreased basal, diurnal and stressor-stimulated plasma corticosterone secretion and basal plasma ACTH, but surprisingly, have a profound anxiolytic phenotype when evaluated using multiple stressors including open field, elevated plus maze, holeboard, light-dark box, and novel object recognition task. Restoring plasma corticosterone did not reverse the anxiolytic phenotype of Sim1CrhKO mice. Crh-Cre driver mice revealed that PVHCrh fibers project abundantly to cingulate cortex and the nucleus accumbens shell, and moderately to medial amygdala, locus coeruleus, and solitary tract, consistent with the existence of PVHCrh-dependent behavioral pathways. Although previous, nonselective attenuation of CRH production or action, genetically in mice and pharmacologically in humans, respectively, has not produced the anticipated anxiolytic effects, our data show that targeted interference specifically with hypothalamic Crh expression results in anxiolysis. Our data identify neurons that express both Sim1 and Crh as a cellular entry point into the study of CRH-mediated, anxiety-like behaviors and their therapeutic attenuation.

β-Endorphin neuronal transplantation into the hypothalamus alters anxiety-like behaviors in prenatal alcohol-exposed rats and alcohol-non-preferring and alcohol-preferring rats.

Alcohol exposure has adverse effects on stress physiology and behavioral reactivity. This is suggested to be due, in part, to the effect of alcohol on β-endorphin (β-EP)-producing neurons in the hypothalamus. In response to stress, β-EP normally provides negative feedback to the hypothalamic-pituitary-adrenal axis and interacts with other neurotransmitter systems in the amygdala to regulate behavior. We examined whether β-EP neuronal function in the hypothalamus reduces the corticosterone response to acute stress, attenuates anxiety-like behaviors, and modulates alcohol drinking in rats. To determine whether β-EP neuronal transplants modulate the stress response, anxiety behavior, and alcohol drinking, we implanted differentiated β-EP neurons into the paraventricular nucleus (PVN) of the hypothalamus of normal, prenatal alcohol-exposed, and alcohol-preferring (P) and alcohol-non-preferring (NP) rats. We then assessed corticosterone levels in response to acute restraint stress and other markers of stress response in the brain and anxiety-like behaviors in the elevated plus maze and open-field assays. We showed that β-EP neuronal transplants into the PVN reduced the peripheral corticosterone response to acute stress and attenuated anxiety-like behaviors. Similar transplants completely reduced the hypercorticosterone response and elevated anxiety behaviors in prenatal alcohol-exposed adult rats. Moreover, we showed that β-EP reduced anxiety behavior in P rats with minimal effects on alcohol drinking during and following restraint stress. These data further establish a role of β-EP neurons in the hypothalamus for regulating physiological stress response and anxiety behavior and resemble a potential novel therapy for treating stress-related psychiatric disorders in prenatal alcohol-exposed children and those genetically predisposed to increased alcohol consumption.