Passive Avoidance Behavior Research Articles

Role of the Nucleus Accumbens in Signaled Avoidance Actions.

Animals, humans included, navigate their environments guided by sensory cues, responding adaptively to potential dangers and rewards. Avoidance behaviors serve as adaptive strategies in the face of signaled threats, but the neural mechanisms orchestrating these behaviors remain elusive. Current circuit models of avoidance behaviors indicate that the nucleus accumbens (NAc) in the ventral striatum plays a key role in signaled avoidance behaviors, but the nature of this engagement is unclear. Evolving perspectives propose the NAc as a pivotal hub for action selection, integrating cognitive and affective information to heighten the efficiency of both appetitive and aversive motivated behaviors. To unravel the engagement of the NAc during active and passive avoidance, we used calcium imaging fiber photometry to examine NAc GABAergic neuron activity in ad libitum moving mice performing avoidance behaviors. We then probed the functional significance of NAc neurons using optogenetics and genetically targeted or electrolytic lesions. We found that NAc neurons code contraversive orienting movements and avoidance actions. However, direct optogenetic inhibition or lesions of NAc neurons did not impair active or passive avoidance behaviors, challenging the notion of their purported pivotal role in adaptive avoidance. The findings emphasize that while the NAc encodes avoidance movements, it is not required for avoidance behaviors, highlighting the distinction between behavior encoding or representation and mediation or generation.

Exploring the Link Between Cyber Victimization and Depression.

Cyber victimization is strongly and positively associated with depressive symptoms in adolescence. Identifying mechanisms of this association is imperative to benefit adolescents' mental health. Applying the General Aggression Model in a theoretically novel way, this study examined a complex mediational pathway between cyber victimization and depressive symptoms. Two hundred seventy-seven adolescent participants (M age = 15.84; 65.7% females) reported their own cyber victimization experiences, depressive symptoms, and cognitive, emotional, and behavioral attributions in response to a hypothetical cyber victimization scenario. Path analysis within structural equation modeling was used to test a model where cyber victimization predicted depressive symptoms through characterological self-blame cognitions, sadness emotions, and passive avoidance behaviors. Characterological self-blame was found to partially mediate the positive and significant association between cyber victimization and depressive symptoms. Sadness emotions and passive avoidance behaviors did not emerge as significant mediators. The findings implicate the importance of cognitions in explaining the association between cyber victimization and depression and suggest incorporating cognitive re-framing education into anti-cyberbullying prevention programs.

Effects of Soy Protein Isolate on Fragile X Phenotypes in Mice.

Obesity is a pediatric epidemic that is more prevalent in children with developmental disabilities. We hypothesize that soy protein-based diets increase weight gain and alter neurobehavioral outcomes. Our objective herein was to test matched casein- and soy protein-based purified ingredient diets in a mouse model of fragile X syndrome, Fmr1KO mice. The experimental methods included assessment of growth; 24-7 activity levels; motor coordination; learning and memory; blood-based amino acid, phytoestrogen and glucose levels; and organ weights. The primary outcome measure was body weight. We find increased body weight in male Fmr1KO from postnatal day 6 (P6) to P224, male wild type (WT) from P32-P39, female Fmr1KO from P6-P18 and P168-P224, and female Fmr1HET from P9-P18 as a function of soy. Activity at the beginning of the light and dark cycles increased in female Fmr1HET and Fmr1KO mice fed soy. We did not find significant differences in rotarod or passive avoidance behavior as a function of genotype or diet. Several blood-based amino acids and phytoestrogens were significantly altered in response to soy. Liver weight was increased in WT and adipose tissue in Fmr1KO mice fed soy. Activity levels at the beginning of the light cycle and testes weight were greater in Fmr1KO versus WT males irrespective of diet. DEXA analysis at 8-months-old indicated increased fat mass and total body area in Fmr1KO females and lean mass and bone mineral density in Fmr1KO males fed soy. Overall, dietary consumption of soy protein isolate by C57BL/6J mice caused increased growth, which could be attributed to increased lean mass in males and fat mass in females. There were sex-specific differences with more pronounced effects in Fmr1KO versus WT and in males versus females.

Dual Modulator of ASIC Channels and GABAA Receptors from Thyme Alters Fear-Related Hippocampal Activity.

Acid-sensing ion channels (ASICs) are proton-gated ion channels that mediate nociception in the peripheral nervous system and contribute to fear and learning in the central nervous system. Sevanol was reported previously as a naturally-occurring ASIC inhibitor from thyme with favorable analgesic and anti-inflammatory activity. Using electrophysiological methods, we found that in the high micromolar range, the compound effectively inhibited homomeric ASIC1a and, in sub- and low-micromolar ranges, positively modulated the currents of α1β2γ2 GABAA receptors. Next, we tested the compound in anxiety-related behavior models using a targeted delivery into the hippocampus with parallel electroencephalographic measurements. In the open field, 6 µM sevanol reduced both locomotor and θ-rhythmic activity similar to GABA, suggesting a primary action on the GABAergic system. At 300 μM, sevanol markedly suppressed passive avoidance behavior, implying alterations in conditioned fear memory. The observed effects could be linked to distinct mechanisms involving GABAAR and ASIC1a. These results elaborate the preclinical profile of sevanol as a candidate for drug development and support the role of ASIC channels in fear-related functions of the hippocampus.

Blockade of Ghrelin Receptor Signaling Enhances Conditioned Passive Avoidance and Context-Associated cFos Activation in Fasted Male Rats

Introduction: Interoceptive feedback to the brain regarding the body’s physiological state plays an important role in guiding motivated behaviors. For example, a state of negative energy balance tends to increase exploratory/food-seeking behaviors while reducing avoidance behaviors. We recently reported that overnight food deprivation reduces conditioned passive avoidance behavior in male (but not female) rats. Since fasting increases circulating levels of ghrelin, we hypothesized that ghrelin signaling contributes to the ability of fasting to reduce conditioned avoidance. Methods: Ad libitum-fed male rats were trained in a passive avoidance procedure using mild footshock. Later, following overnight food deprivation, the same rats were pretreated with ghrelin receptor antagonist (GRA) or saline vehicle 30 min before avoidance testing. Results: GRA restored passive avoidance in fasted rats as measured by both latency to enter and time spent in the shock-paired context. In addition, compared to vehicle-injected fasted rats, fasted rats that received GRA before reexposure to the shock-paired context displayed more cFos activation of prolactin-releasing peptide (PrRP)-positive noradrenergic (NA) neurons in the caudal nucleus of the solitary tract, accompanied by more cFos activation in downstream target sites of PrRP neurons (i.e., bed nucleus of the stria terminalis and paraventricular nucleus of the hypothalamus). Discussion: These results support the view that ghrelin signaling contributes to the inhibitory effect of fasting on learned passive avoidance behavior, perhaps by suppressing recruitment of PrRP-positive NA neurons and their downstream hypothalamic and limbic forebrain targets.

The effects of stress on avoidance in rodents: An unresolved matter.

In the face of a possible threat, a range of physiological (e.g., increased heart rate) and behavioral (e.g., avoidance or escape) responses are recruited. Here, we will focus on avoidance, in its persistent form one of the core symptoms of anxiety disorders and obsessive-compulsive disorder. The initial goal of fear and avoidance responses is to increase survival, but if they become persistent or overgeneralize, they can disrupt normal daily functioning, and ultimately even result in anxiety-related disorders. Relatedly, acute stress responses promote adaptation and survival, while chronic stress has been found to aggravate pathophysiology. Thus, stress might trigger the transition from adaptive to maladaptive responses, e.g., from goal-directed to persistent avoidance. Animal models are prime tools to unravel if and how stress influences avoidance. This is typically done by performing stress inductions prior to the assessment of (passive or active) avoidance behavior. Despite its clinical relevance, the current literature on this topic is fragmented, and an overall conclusion is lacking. In this Review, we first recapitulate the state of the art regarding stress and active as well as passive avoidance procedures. We then summarize the behavioral effects of acute and chronic stress on active and passive avoidance, and discuss the main neurobiological findings of the field. Finally, we highlight possible reasons for the largely contradictory findings in the literature and we propose strategies to further unravel the effect of stress on avoidance behavior. A deeper understanding of this currently unresolved matter may provide further insights in the etiology and treatment of anxiety-related disorders.

Influence of Faradarmani Consciousness Field (CF) on Spatial Memory and Passive Avoidance Behavior of Scopolamine Model of Alzheimer Disease in Male Wistar Rats

In another study titled “Influence of Faradarmani Consciousness Field (CF) on Spatial Memory and Passive Avoidance Behavior of Scopolamine Model of Alzheimer Disease in Male Wistar Rats,” (Authors: Mohammad Ali Taheri, Sara Torabi, Noushin Nabavi, Farid Semsarha), we evaluated the influence of Faradarmani CF on scopolamine-induced memory impairments in male Wistar rats. The passive avoidance and Morris water maze (MWM) tests were conducted to evaluate memory function in scopolamine-induced rats. The results of passive avoidance and MWM tests showed a significant decrease in spatial memory and cognitive function in scopolamine groups, whereas Faradarmani CF improved scopolamine-induced cognitive impairment. In conclusion, this experiment suggests that Faradarmani CF, as a non-material/non-energetic Field, can be a safe and suitable way to treat or prevent learning and memory disorders. *Corresponding Author: Farid Semsarha Ph.D., Institute of Biochemistry and Biophysics (IBB), University of Tehran, P.O. Box: 13145-1384, Tehran, Iran. Email: Semsarha@alumni.ut.ac.ir. Pending Review.

Oxytocin modulation in the medial prefrontal cortex of pair-exposed rats during fear conditioning

IntroductionSocial buffering is the phenomenon, in which stress and fear reactions caused by exposure to stressful stimuli when animals are exposed to homogeneous relationships are attenuated. Social buffering reduces fear memory behavior such as escape, avoidance, and freezing behavior in rodents due to social existence. Here, we aimed to determine alterations of fear behavior and neural activity in the medial prefrontal cortex (mPFC) in response to the presence of another rat in fear-exposed conditions and to confirm the role of oxytocin in mPFC in regulating social buffering. MethodsWe performed a passive avoidance test and determined positive c-Fos expression in single- and pair-exposed rats. Anisomycin (a protein synthesis inhibitor) and oxytocin receptor regulators (carbetocin; agonist and atosiban; antagonist) were microinjected into the mPFC to clarify the role of oxytocin in the mPFC. ResultsWhile single-exposed rats showed a significant increase in both freezing and passive avoidance behaviors compared to control rats, pair-exposed rats showed significantly less fear behavior compared to single-exposed rats. The c-Fos expression in the prelimbic (PL) mPFC was significantly increased in pair-exposed rats compared to that in control and single-exposed rats. The pair-exposed effect was blocked by anisomycin injections into the PL mPFC of pair-exposed rats. Furthermore, when a carbetocin was injected into the PL mPFC in single-exposed rats, fear behavior was decreased, and these changes were blocked by atosiban. DiscussionOur findings suggest that reduction of fear-related behavior induced by acute pair-exposure is mediated by oxytocin receptors in the PL mPFC. Pair exposure with conspecifics during fear-inducing situations helps coping with fear by significantly increasing the role of oxytocin in the PL mPFC.

Erratum: Drosophila Passive Avoidance Behavior as a New Paradigm to Study Associative Aversive Learning.

An erratum was issued for:Drosophila Passive Avoidance Behavior as a New Paradigm to Study Associative Aversive Learning. The Representative Results and Discussionsections wereupdated. In the Representative Results, the legend for Figure 5 was updated from: Figure 5: Comparison of passive avoidance and grooming behavior in D. simulans males and females. (A)Average latency (s) per trial. The graph shows no statistically significant differences between males and females in the latencies. (B) An average number of received shocks per trial. The graph shows no statistically significant differences between males and females in the number of received shocks. (C) The total duration of grooming bouts in trials 1-3. While there were no statistically significant differences between males and females, the female flies showed a considerable increase in grooming behavior during trials 2 and 3 compared to trial 1. Abbreviations: *- P<0.05. One-way ANOVA with Tukey's multiple comparisons test. to: Figure 5: Comparison of passive avoidance and grooming behavior in D. simulans males and females. (A)Average latency (s) per trial. The graph shows no statistically significant differences between males and females in the latencies. (B) An average number of received shocks per trial. The graph shows no statistically significant differences between males and females in the number of received shocks. (C) The total duration of grooming bouts in trials 1-3. While there were no statistically significant differences between males and females, the female flies showed a considerable decrease in grooming behavior during trials 2 and 3 compared to trial 1. Abbreviations: *- P<0.05. One-way ANOVA with Tukey's multiple comparisons test. In the Discussion, the third paragraphwas updated from: The assay worked equally well in D. melanogaster and D. simulans male and female flies, demonstrating that the paradigm could be adapted to different D. species. The changes in fly behavior characterized by increased latencies and decreased number of shocks were statistically significant in the second trial and would strengthen with subsequent trials. Interestingly, if naïve flies were habituated to the apparatus without electric shock, they would enter the upper compartment a little faster on the second and the third trials. However, the decrease in latencies was not statistically significant (data not shown). No statistically significant differences were observed between sexes, although female flies had somewhat longer latencies and received slightly more shocks. This difference could be due to a combination of factors, including females' failure to associate the shock with the upper compartment, a stronger geotaxis, or possibly because females are slightly larger and slower than males. The total duration of grooming bouts was significantly higher in the second and third trials in female flies, which draws a parallel between D. and rodent anxiety-like behaviors26. to: The assay worked equally well in D. melanogaster and D. simulans male and female flies, demonstrating that the paradigm could be adapted to different D. species. The changes in fly behavior characterized by increased latencies and decreased number of shocks were statistically significant in the second trial and would strengthen with subsequent trials. Interestingly, if naïve flies were habituated to the apparatus without electric shock, they would enter the upper compartment a little faster on the second and the third trials. However, the decrease in latencies was not statistically significant (data not shown). No statistically significant differences were observed between sexes, although female flies had somewhat longer latencies and received slightly more shocks. This difference could be due to a combination of factors, including females' failure to associate the shock with the upper compartment, a stronger geotaxis, or possibly because females are slightly larger and slower than males. The total duration of grooming bouts was significantly lowerin the second and third trials in female flies, which draws a parallel between D. and rodent anxiety-like behaviors26.

Repeated ethanol exposure following avoidance conditioning impairs avoidance extinction and modifies conditioning-associated prefrontal dendritic changes in a mouse model of post-traumatic stress disorder.

Treatment of post-traumatic stress disorder is complicated by the presence of alcohol use disorder comorbidity. Little is known about the underlying brain mechanisms. We have recently shown, in mice, that the post-traumatic stress disorder-like phenotype is characterised by the increase and decrease in total dendritic number and length in the prelimbic and infralimbic areas of the medial prefrontal cortex, respectively. Here, we examined whether repeated ethanol exposure would exacerbate these changes and whether this would be associated with difficulty to extinguish passive avoidance behaviour, as an indicator of treatment resistance. We also analysed whether other known trauma-associated changes, like increased or decreased corticosterone and decreased brain-derived neurotrophic factor levels, would also be exacerbated. Male mice underwent trauma exposure (1.5-mA footshock), followed, 8 days later, by a conditioned place preference training with ethanol. Tests for fear sensitization, passive avoidance, anxiety-like behaviour, extinction acquisition and relapse susceptibility were used to assess behaviour changes. Plasma corticosterone and brain-derived neurotrophic factor levels and prefrontal dendritic changes were subsequently measured. Trauma-susceptible mice exposed to ethanol acquired a strong place preference and behaved differently from those not exposed to ethanol, with delayed avoidance extinction and higher avoidance relapse vulnerability. Ethanol potentiated trauma-associated dendritic changes in the prelimbic area and suppressed trauma-associated dendritic changes in the infralimbic area. However, ethanol had no effect on trauma-induced increased corticosterone and decreased brain-derived neurotrophic factor levels. These data suggest that the modification of prefrontal trauma-related changes, due to alcohol use, can characterise, and probably support, treatment-resistant post-traumatic stress disorder.

Drosophila Passive Avoidance Behavior as a New Paradigm to Study Associative Aversive Learning.

This protocol describes a new paradigm for analyzing aversive associative learning in adult flies (Drosophila melanogaster). The paradigm is analogous to passive avoidance behavior in laboratory rodents in which animals learn to avoid a compartment where they have previously received an electric shock. The assay takes advantage of negative geotaxis in flies, which manifests as an urge to climb up when they are placed on a vertical surface. The setup consists of vertically oriented upper and lower compartments. On the first trial, a fly is placed into a lower compartment from where it usually exitswithin 3-15 s, and steps into the upper compartment where it receives an electric shock. During the second trial, 24 h later, the latency is significantly increased. At the same time, the number of shocks is decreased compared to the first trial, indicating that flies formed long-term memory about the upper compartment. The recordings of latencies and number of shocks could be performed with a tally counter and a stopwatch or with an Arduino-based simple device. To illustrate how the assay can be used, the passive avoidance behavior of D. melanogaster and D. simulans male and female were characterized here. Comparison of latencies and number of shocks revealed that both D. melanogaster and D. simulans flies efficiently learned the passive avoidance behavior. No statistical differences were observed between male and female flies. However, males were a little faster while entering the upper compartment on the first trial, while females received a slightly higher number of shocks in every retention trial. The Western diet (WD) significantly impaired learning and memory in male flies while flight exercise counterbalanced this effect. Taken together, the passive avoidance behavior in flies offers a simple and reproducible assay that could be used for studying basic mechanisms of learning and memory.

Sex and metabolic state interact to influence expression of passive avoidance memory in rats: Potential contribution of A2 noradrenergic neurons

Competing motivational drives coordinate behaviors essential for survival. For example, interoceptive feedback from the body during a state of negative energy balance serves to suppress anxiety-like behaviors and promote exploratory behaviors in rats. Results from past research suggest that this shift in motivated behavior is linked to reduced activation of specific neural populations within the caudal nucleus of the solitary tract (cNTS). However, the potential impact of metabolic state and the potential role of cNTS neurons on conditioned avoidance behaviors has not been examined. The present study investigated these questions in male and female rats, using a task in which rats learn to avoid a context (i.e., a darkened chamber) after it is paired with a single mild footshock. When rats later were tested for passive avoidance of the shock-paired chamber, male rats tested in an overnight food-deprived state and female rats (regardless of feeding status) displayed significantly less avoidance compared to male rats that were fed ad libitum prior to testing. Based on prior evidence that prolactin-releasing peptide (PrRP)-positive noradrenergic neurons and glucagon-like peptide 1 (GLP1)-positive neurons within the cNTS are particularly sensitive to metabolic state, we examined whether these neural populations are activated in conditioned rats after re-exposure to the shock-paired chamber, and whether neural activation is modulated by metabolic state. Compared to the control condition, chamber re-exposure activated PrRP+ noradrenergic neurons and also activated neurons within the anterior ventrolateral bed nucleus of the stria terminalis (vlBNST), which receives dense input from PrRP+ terminals, in both male and female rats when fed ad libitum. In parallel with sex differences in passive avoidance behavior, PrRP+ neurons were less activated in female vs. male rats after chamber exposure. GLP1+ neurons were not activated in either sex. In both sexes, overnight food deprivation before chamber re-exposure reduced activation of PrRP+ neurons, and also reduced vlBNST activation. Our results support the view that PrRP+ noradrenergic neurons and their inputs to the vlBNST contribute to the expression of passive avoidance memory, and that this contribution is modulated by metabolic state.

Role of Medial Prefrontal Cortical Neurons and Oxytocin Modulation in the Establishment of Social Buffering.

Fear-related behaviors are rigidly controlled by the medial prefrontal cortex (mPFC). The mPFC is activated by the prosocial hormone oxytocin, which plays an important role in social buffering. We used a slice patch current-clamp recording in single- and pair-exposed rats who were subjected to electric shocks, to determine the cellular mechanism of the action of oxytocin in the mPFC under social buffering conditions. Pair-exposed rats showed a significant reduction in both freezing and passive avoidance behaviors compared to single-exposed rats. It was observed that input resistance in pyramidal neurons decreased in both single- and pair-exposed rats than na?ve rats, but input resistance in interneurons increased in pair-exposed rats than single-exposed rats. We found that the number of action potential (AP) spikes in the mPFC pyramidal neurons decreased significantly in pair-exposed rats than in single-exposed rats. The pyramidal neurons in the mPFC were similarly regulated by oxytocin in singleand pair-exposed rats, while the number of AP spikes in interneurons by oxytocin decreased in single-exposed rats, but there was no significant change in pair-exposed rats. Therefore, our findings reveal that a decrease in mPFC pyramidal neuronal activity in pair-exposed rats through social interaction induces a reduction in fear-related behavior via obstruction of fear-memory formation; however, no such reduction was observed in single-exposed rats. Moreover, we suggest that the oxytocin-mediated decrease in neuronal activity in the mPFC could facilitate social buffering.

Influence of Faradarmani Consciousness Field (FCF) on Spatial Memory and Passive Avoidance Behavior of Scopolamine Model of Alzheimer Disease in Male Wistar Rats

Alzheimer's disease (AD) is a growing public health concern affecting millions of patients worldwide and costing billions of dollars annually. With regards to the pathophysiology of AD and associated memory loss in AD patients, one of the most relevant defects is the degeneration of cholinergic neurons in the nucleus basalis of Meynert, a group of neurons located in the basal forebrain. Well-known conventional and complementary drugs and treatments are involved in reducing the symptoms of the disease and delaying its progression. Achieving the most optimum treatment strategy for AD, with its growing numbers annually, is a concern of clinical researchers. The use of the Faradarmani Consciousness Fields introduced by Taheri treat biological cells, modifying and optimizing their structures and functions has been reported in recent studies. In our study, we study the influence of Faradarmani Consciousness Field on the spatial memory and avoidance behavior of a rat model of AD. The rats in our study have an inhibited acetylcholine response due to use of the scopolamine, a medication used to treat motion sickness and postoperative nausea and vomiting. According to the results of this study, the Faradarmani Consciousness Field shows a remarkable restorative and restorative-enhancing effect on distorted spatial memory and passive avoidance behavior of AD rat models, respectively.

Ultrasound Stimulation of Periaqueductal Gray Induces Defensive Behaviors.

Low-intensity focused ultrasound stimulation (LIFUS) has the potential to noninvasively penetrate the intact skull and to modulate neural activity in the cortex and deep brain nuclei. The midbrain periaqueductal gray (PAG) is associated with the generation of defensive behaviors. The aim of this study was to examine whether LIFUS of the PAG induced defensive behaviors in mice. A 3.8-MHz head-mounted ultrasound transducer with a small focus size (0.5 mm × 0.5 mm) was fabricated in house to precisely stimulate the free-moving mice. The corresponding behaviors were recorded in real time. Avoidance, flight, and freezing were used to assess ultrasound-induced defensive responses. The safety of LIFUS was examined via hematoxylin and eosin (H&E) staining and Nissl staining. Ultrasound stimulation of the PAG induced multiple defensive behaviors, including location-specific passive avoidance behavior, flight, and freezing. In addition, H&E and Nissl staining verified that LIFUS did not cause any injury to the brain tissue. These findings demonstrate that LIFUS may have neuromodulatory effects on the innate defensive behaviors in mice. LIFUS may be used as a novel neuromodulatory tool for the treatment of psychological diseases associated with defensive behaviors.

Will Corporate Tax Avoidance Lead to Forced Executives Turnover?

Based on the data of A-share listed companies in 2004-2018, this paper discusses the possible economic consequences of corporate tax avoidance from the individual level of executives. In this paper, the degree of corporate tax avoidance is divided into aggressive tax avoidance behavior and passive tax avoidance behavior, respectively, to study the impact of different degrees of tax avoidance on executives forced to be replaced by listed companies. It is found that both aggressive tax avoidance and passive tax avoidance will lead to forced executives turnover. In addition, this paper also examines the moderation effects of the nature of property rights, the performance of corporate social responsibility and market concentration on the above-mentioned research, and finds that private companies, companies that perform social responsibility well and companies in areas with fierce market competition, the passive tax avoidance behavior has a greater impact on executives forced turnover.

Verification of a UAV swarm flight simulating the passive inertial emergency obstacle avoidance behavior of a pigeon flock

In this paper, the passive inertial emergency obstacle avoidance behavior of pigeons is studied and applied to the coordinated flight verification of an unmanned aerial vehicle (UAV) swarm. Pigeons in nature dynamically adjust their routes during flight. When they encounter obstacles, emergency behaviors are generated; i.e., they change the current direction passively, get cross obstacles toward the largest gap between obstacles, and thus complete obstacle avoidance. Prior to the flight verification, the design of the UAV swarm system architecture is explained. Further, two scenarios of static emergency obstacle avoidance on the ground and with moving obstacles in the air are set up. The corresponding timing sequence diagrams and flight path diagrams are also given.

Deletion of Glucocorticoid Receptors in Forebrain GABAergic Neurons Alters Acute Stress Responding and Passive Avoidance Behavior in Female Mice.

The glucocorticoid receptor (GR) is critically involved in regulation of stress responses [inhibition of the hypothalamic-pituitary-adrenal (HPA) axis], emotional behavior and cognition via interactions with forebrain corticolimbic circuity. Work to date has largely focused on GR actions in forebrain excitatory neurons; however, recent studies suggest a potential role mediated by interneurons. Here, we targeted GR deletion in forebrain GABAergic neurons, including the cortical interneurons, using a Dlx5/6-Cre driver line to test the role of forebrain interneuronal GR in HPA axis regulation and behavior. Our data indicate that GR deletion in GABAergic neurons causes elevated corticosterone stress responsiveness and decreased cross-over latencies in a passive avoidance task in females, but not males. Dlx5/6-Cre driven gene deletion caused loss of GR in interneurons in the prefrontal cortex (PFC) and hippocampus, but also in select diencephalic GABAergic neurons (including the reticular thalamic nucleus and dorsomedial hypothalamus). Our data suggest that GR signaling in interneurons is differentially important in females, which may have implications for GR-directed therapies for stress-related affective disease states.

Vitamin C Improves Passive Avoidance Learning and Memory in Rats Exposed to Radiofrequency Waves Generated by a Base Transceiver Station (BTS) Antenna Model

Background: Hazardous health effects of the exposure to radiofrequency waves (RFWs) have become of great public concern and impaired memory has been reported following the exposure to electromagnetic radiations. Objectives: As the deleterious effects of the RFW on passive avoidance learning and memory had already been reported, the aim of this study was to evaluate the prophylactic effect of vitamin C on this activity. Methods: 20 male Sprague-Dawley rats (230 ± 20 g) were divided randomly into four groups as: control, control-exposed (exposed to 900 MHz RFW), control treatment (without exposure to RFW receiving 250 mg/kg of body weight/day L-ascorbic acid by gavage), and treatment (exposed to 900MHz RFW receiving the abovementioned dose of vitamin C) groups. The exposure was performed for 30 consecutive days (4 h/day). Learning and memory were evaluated in the last day by the shuttle box and expressed as the period of remaining within the light area; this time was called “light time”. Results: The exposure to RFW significantly decreased the duration of light time in the control-exposed group compared to the other three groups (P < 0.05). In the fourth group, vitamin C significantly increased the light time compared to the control-exposed group (P < 0.05). No significant difference was observed between control, control treatment, and treatment groups. Conclusions: Exposure to RFW significantly altered the passive avoidance behavior. Vitamin C probably due to its antioxidant effects has facilitative results on the acquisition and retrieval activities of passive avoidance learning and memory in rats.

Candesartan, angiotensin II type 1 receptor blocker is able to relieve age-related cognitive impairment.

Candesartan is one of the standard antihypertensive drug belonging to AT1R angiotensin receptor blockers (ARBs) group. Beneficial effects of this drug in the treatment of hypertension are well recognized. In this study we tested a hypothesis that candesartan could alleviate age-related memory decline. Aged and young rats have been treated with candesartan (0.1mg kg-1) for 21days and then underwent a battery of behavioral tests: for assessment of long-term memory (Passive avoidance test - PA), recognition memory (Object recognition test - OR), locomotor functions (Open field - OF) and anxiety behavior (Elevated plus maze - EPM). Aged rats (2-years-old) displayed clear declining tendency in the retrieval of passive avoidance behavior showing thus increased forgetting. Prolonged administration of candesartan significantly (p<0.01) reversed this phenomenon causing recall measured as the avoidance latency, and surprisingly also showed the tendency to recall deterioration observed in the young rats. More optimistic results were achieved in the OR, where candesartan significantly improved recognition memory (p<0.001) of aged rats who performed even better than the young ones (p<0.05). It appears that candesartan potently abolishes some kinds of aging-induced memory impairments and cognitive declines in aged rats, but in some circumstances it may even could increase the damage of memory. It seems that the use of sartans in the treatment of hypertension for patients with associated cognitive impairment, or for people in risk groups for such disorders can be an interesting alternative.