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Safety learning allows the identification of non-threatening situations, a learning process instrumental for survival and psychic health. In contrast to fear learning, in which a sensory cue (conditioned stimulus, CS) is temporally linked to a mildly aversive stimulus (US), safety learning is studied by presenting the CS and US in an explicitly unpaired fashion. This leads to conditioned inhibition of fear responses, in which sensory cues can acquire a safety meaning (CS-). In one variant of safety learning, an auditory CS- was shown to reduce contextual fear responses during recall, as measured by freezing of mice. Here, we performed control experiments to test whether auditory stimuli might interfere with freezing by mechanisms other than safety learning, a phenomenon also called external inhibition. Surprisingly, when auditory stimulation was omitted during training (US-only controls), such stimuli still significantly suppressed contextual freezing during recall, indistinguishable from the reduction of freezing after regular safety training. The degree of this external inhibition was positively correlated with the levels of contextual freezing preceding the auditory stimulation. Correspondingly, in fear learning protocols which employ a new context during recall and therefore induce lower contextual freezing, auditory stimuli did not induce significant external inhibition. These experiments show that in safety learning protocols that employ contextual freezing, the freezing reduction caused by auditory stimuli during recall is dominated by external inhibition, rather than by learned safety. Thus, in safety learning experiments extensive controls should be performed to rule out possible intrinsic effects of sensory cues on freezing behavior. [ABSTRACT FROM AUTHOR]

BACKGROUND: Halyomorpha halys is one of the most damaging invasive agricultural pests in North America and southern Europe. It is commonly monitored using pheromone traps, which are not very effective because few bugs are caught and some escape and/or remain outside the trap on surrounding plants where they feed, increasing the damage. Other monitoring techniques are based on visual sampling, sweep‐netting and tree‐beating. However, all these methods require several hours of human labor and are difficult to apply to large areas. The aim of this work is to develop an automated monitoring system that integrates image acquisition through the use of drones with H. halys detection through the use of artificial intelligence (AI). RESULTS: The study results allowed the development of an automated flight protocol using a mobile app to capture high‐resolution images. The drone caused only low levels of disturbance in both adult and intermediate instars, inducing freezing behavior in adults. Each of the AI models used achieved very good performance, with a detection accuracy of up to 97% and recall of up to 87% for the X‐TL model. CONCLUSION: The first application of this novel monitoring system demonstrated the potential of drones and AI to detect and quantify the presence of H. halys. The ability to capture high‐altitude, high‐resolution images makes this method potentially suitable for use with a range of crops and pests. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Safety learning allows the identification of non-threatening situations, a learning process instrumental for survival and psychic health. In contrast to fear learning, in which a sensory cue (conditioned stimulus, CS) is temporally linked to a mildly aversive stimulus (US), safety learning is studied by presenting the CS and US in an explicitly unpaired fashion. This leads to conditioned inhibition of fear responses, in which sensory cues can acquire a safety meaning (CS-). In one variant of safety learning, an auditory CS- was shown to reduce contextual fear responses during recall, as measured by freezing of mice. Here, we performed control experiments to test whether auditory stimuli might interfere with freezing by mechanisms other than safety learning, a phenomenon also called external inhibition. Surprisingly, when auditory stimulation was omitted during training (US-only controls), such stimuli still significantly suppressed contextual freezing during recall, indistinguishable from the reduction of freezing after regular safety training. The degree of this external inhibition was positively correlated with the levels of contextual freezing preceding the auditory stimulation. Correspondingly, in fear learning protocols which employ a new context during recall and therefore induce lower contextual freezing, auditory stimuli did not induce significant external inhibition. These experiments show that in safety learning protocols that employ contextual freezing, the freezing reduction caused by auditory stimuli during recall is dominated by external inhibition, rather than by learned safety. Thus, in safety learning experiments extensive controls should be performed to rule out possible intrinsic effects of sensory cues on freezing behavior.

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A micromechanics‐based thermo‐hydro‐mechanical model for capturing the freezing behavior of porous media is devised, where a microstructure‐dependent constitutive relation, thermo‐hydro‐mechanical conditions, and the origin of freezing deformation are comprehensively considered. A micromechanical upscaling approach is proposed to improve the physical understanding of the freezing behavior of porous media. Comparisons against experimental and theoretical results suggest that the present model is a reliable means to predict the freezing deformation of saturated and air‐entrained porous media. The results show that the freezing deformation induced by the hydraulic pressure strongly depends on the boundary and air‐entrained conditions, and the undercooling phenomenon can be captured well. Moreover, the magnitude of surface energy (0–8 MPa) is in the ascending order of saturated undrained, drained, and air‐entrained conditions. The proposed model sheds light on the quantitative effects of freezing rate, liquid water transfer, and pore shape on the freezing deformation of porous media, which can provide insights into the freezing resistance mechanism of porous media. Key Points: A coupled thermo‐hydro‐mechanical model is presented for the freezing behavior of porous mediaThe origin of the freezing deformation of porous media is analyzedEffects of freezing rate, water transfer, and pore shape on the freezing deformation are characterized [ABSTRACT FROM AUTHOR]

Upon visually detecting a moving predator, animals often freeze, i.e. stop moving, to minimize being uncovered and to gather detailed information of the object's movements and properties. In certain conditions, the freezing behavior can be enough to avoid a predatory menace but, when the risk is high or increases to a higher level, animals switch strategy and engage in an escape response. The neural bases underlying escape responses to visual stimuli have been extensively investigated both in vertebrates and arthropods. However, those involved in freezing behaviors are much less studied. Here, we investigated the freezing behavior displayed by the crab Neohelice granulata when confronted with a variety of looming stimuli simulating objects of distinct sizes approaching on a collision course at different speeds. The experiments were performed in a treadmill-like device. Animals engaged in exploratory walks responded to the looming stimulus with freezing followed by escaping. The analysis of the stimulus optical variables shows that regardless of the looming dynamic, the freezing decision is made when the angular size of the object increases by 1.4 deg. In vivo intracellular recording responses of monostratified lobula giant neurons (MLG1) to the same looming stimuli show that the freezing times correlate with the times predicted by a hypothetical spike counter of this neuron., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

During fear learning, defensive behaviors like freezing need to be finely balanced in the presence or absence of threat-predicting cues (conditioned stimulus, CS). Nevertheless, the circuits underlying such balancing are largely unknown. Here, we investigate the role of the ventral tail striatum (vTS) in auditory-cued fear learning of male mice. In vivo Ca2+ imaging showed that sizable sub-populations of direct (D1R+) and indirect pathway neurons (Adora+) in the vTS responded to footshocks, and to the initiation of movements after freezing; moreover, a sub-population of D1R+ neurons increased its responsiveness to an auditory CS during fear learning. In-vivo optogenetic silencing shows that footshock-driven activity of D1R+ neurons contributes to fear memory formation, whereas Adora+ neurons modulate freezing in the absence of a learned CS. Circuit tracing identified the posterior insular cortex (pInsCx) as an important cortical input to the vTS, and recording of optogenetically evoked EPSCs revealed long-term plasticity with opposite outcomes at the pInsCx synapses onto D1R+ - and Adora+ neurons. Thus, direct- and indirect pathways neurons of the vTS show differential signs of plasticity after fear learning, and balance defensive behaviors in the presence and absence of learned sensory cues.

Objective(s): Post-traumatic stress disorder (PTSD), one of the most devastating kinds of anxiety disorders, is the consequence of a traumatic event followed by intense fear. In rats with contextual fear conditioning (CFC), a model of PTSD caused by CFC (electrical foot shock chamber), deep brain stimulation (DBS) alleviates CFC abnormalities.Materials and Methods: Forty Male Wistar rats (220–250 g) were divided into 5 groups (n=8) and underwent stereotactic surgery to implant electrodes in the right basolateral nucleus of the amygdala (BLn). After 7 days, some animals received a foot shock, followed by another 7-day treatment schedule (DBS treatment). Next, freezing behavior was measured as a predicted response in the absence of the foot shock (re-exposure time). Blood serum corticosterone levels and amygdala c-Fos protein expression were assessed using Enzyme-linked immunosorbent assay (ELISA) and Western blot, respectively. Furthermore, freezing behaviors by re-exposure time test and general anxiety by elevated plus-maze (EPM) were evaluated. Results: PTSD decreased serum corticosterone levels and increased both amygdala c-Fos expression and freezing behaviors. Therefore, DBS treatment significantly (P

In this work, a kind of superhydrophobic aluminum surface (treated-Al-SA) is fabricated by chemical etching using hydrochloric acid and hydrogen peroxide, and then treated by stearic acid. The surface of treated-Al-SA has typical hierarchical structure, which hold its durable superhydrophobicity under water droplet impact test, bending test, temperature test, humidity test and corrosive liquids test. Moreover, treated-Al-SA show excellent self-cleaning property at the different tilt angle under room temperature. Results on the dynamic behavior of water droplet is indicated the good anti-adhesion and superhydrophobicity of the treated-Al-SA. The whole freezing process of the water droplets on the surface of untreated-Al and treated-Al-SA is observed. The freezing time of treated-Al-SA is 59 s, which is longer than that of untreated-Al. It is estimated that the different anti-freezing behavior is caused by the thermal conductivity between the water droplet and plate, which is provided an insight into freezing characteristics of water droplet. This study is offered the novel opinion of the superhydrophobic aluminum surface produced by chemical etching, which may help the application of structured aluminum surface. [ABSTRACT FROM AUTHOR]

Freezing of extracellular spaces is the first event when plants are exposed to freezing temperatures, but mechanisms of ice nucleation and propagation remain poorly understood. Japanese cold hardy dwarf bamboos grow in one of the northernmost areas of bamboo distribution and are known to employ deep supercooling in most living tissues as the freeze survival strategy. Studies have been performed on mechanisms of their deep supercooling capability. However, little is known about the ice nucleating factors which may initiate freezing at the apoplast of the vascular and epidermal tissues. This study focused on ice nucleation activity (INA) in aploplast extracts from cold hardy bamboo species, Sasa kurilensis, S. nipponica and Sasamorpha borealis. We obtained apoplast extracts from leaf blades and culms and determined their INA following size fractionation using membrane filters. The apoplast extracts from leaf blades and culms had highly extractable and particulate INA (size: 10 kDa<<0.2 μm). INA of substances larger than 300 kDa (<<0.2 μm) were similar to the freeze initiation temperatures of the vascular and epidermal tissues. Results of heat and protease treatments indicated that the major substance(s) responsible for ice nucleation in the apoplast extracts is proteinaceous, irrespective of the seasons, tissues or species. [ABSTRACT FROM AUTHOR]

Significant changes in concrete's internal structure profoundly affect its performance across varied environmental conditions. Concrete behaves differently in low-temperature environments compared to room temperature due to phase transitions and the freezing of pore water within its matrix. However, understanding the microstructure within cementitious material's gel pores under low-temperature conditions, especially the ice-water-matrix connection mode, has remained elusive. Our molecular dynamics simulations have unveiled that pore size and temperature wield a considerable influence on the connection mode within these gel pores. We have delved deeply into the melting process of ice crystals and the intricate nature of unfrozen water films (UWFs) across different temperatures and pore sizes. The results elucidate that pore size's impact on the connection mode largely hinges on whether gel pores of specific sizes can retain an intact ice layer. At lower temperatures, thinner UWFs emerge, revealing at the nanoscale a reduction in the layers of water molecules within the connection structure. Additionally, we have observed the pivotal role played by calcium ions and water-like molecules in substituting within the matrix's connection structure. These findings offer theoretical insights for construction practices in cold regions, enhancing our ability to predict concrete behavior under low-temperature conditions. • The connection modes of unfrozen water films within CSH gel pores have been elucidated. • The microstructure of unfrozen water films is influenced by pore size and temperature. • Surface calcium ions and water-like molecules serve as substitutes in the connectivity structure. [ABSTRACT FROM AUTHOR]

Freezing behavior is commonly used as a measure of associative fear memory. It can be measured by a trained observer, but this task is time-consuming and subject to variation. Commercially available software packages can also be used to quantify freezing; however, they can be expensive and usually require various parameters to be adjusted by the researcher, leading to additional work and variability in results. With this in mind, we developed Phobos, a freely available, self-calibrating software that measures freezing in a set of videos using a brief manual quantification performed by the user to automatically adjust parameters. To optimize the software, we used four different video sets with different features in order to determine the most relevant parameters, the amount of videos needed for calibration and the minimum criteria to consider it reliable. The results of four different users were compared in order to test intra- and interobserver variability in manual and automated freezing scores. Our results suggest that Phobos can be an inexpensive, simple and reliable tool for measurement of fear-related behavior, with intra- and interuser variability similar to that obtained with manual scoring.

Increased experience of aversive stimuli/events is a psychological-neurobiological state of major importance in psychiatry. It occurs commonly in generalized anxiety disorder, post-traumatic stress disorder, and major depression. A sustained period of exposure to threat (chronic stressor) is a common risk factor, and a major symptom is generalized excessive perception of, and reactivity to, aversive stimuli. In rodents, Pavlovian aversion learning and memory (PAL, PAM), quantified in terms of the conditioned defensive behavior freezing, is an extensively studied behavioral paradigm, and well understood in terms of underlying neural circuitry. In mice, chronic social stress (CSS) is a 15-day resident-intruder paradigm in which C57BL/6 adult males are exposed continuously and distally to dominant-aggressive CD-1 male mice (sustained threat) interspersed with a brief daily period of proximal attack (acute threat). To ensure that physical wounding is minimized, proximal attacks are limited to 30 to 60 s/day and lower incisor teeth of CD-1 mice are blunted. Control (comparison) mice are maintained in littermate pairs. The CSS and CD-1 mice are maintained in distal contact during subsequent behavioral testing. For PAL, CSS and control (CON) mice are placed in a conditioning chamber (context) and exposed to a tone [conditioned stimulus (CS)] and mild, brief foot shock [unconditioned stimulus (US)]. For PAM, mice are placed in the same context and presented with CS repetitions. The CSS mice acquire (learn) and express (memory) a higher level of freezing than CON mice, indicating that CSS leads to generalized hypersensitivity to aversion, i.e., chronic social aversion leads to increased aversion salience of foot shock. Distinctive features of the model include the following: high reproducibility; rare, mild wounding only; male specificity; absence of "susceptible" vs "resilient" subgroups; behavioral effects dependent on continued presence of CD-1 mice; and preclinical validation of novel compounds for normalizing aversion hypersensitivity with accurate feedforward prediction of efficacy in human patients. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Chronic social stress (CSS) Basic Protocol 2: Pavlovian aversion learning and memory (PALM)., (© 2024 The Authors. Current Protocols published by Wiley Periodicals LLC.)

• As in mammals, hippocampus of pigeon is required for the formation and retrieval of context-aversive stimulation. • Zenk protein might be a molecular substrate of retrieval of conditioned fear memory in pigeons. • Differential activation in different parts of the avian hippocampus is associated with retrieval of fearful memories. The hippocampus has a fundamental role in many learning and memory processes, which include the formation and retrieval of context-fear associations, as evidenced by studies in rodents and birds. The present paper has analyzed contextual memory and Zenk expression in the hippocampus of the pigeon after fear conditioning. Pigeons were trained under four conditions: with 3 tone-shock associations (Paired), with shock and tone presented randomly (Unpaired), with exposure to the experimental chamber without stimulation (Control) and with only daily handling (Naive). The testing was conducted 24 h after training. All sessions were digitally recorded. The level of freezing expressed by the Paired and Unpaired groups differed significantly from that of the control group during both training and test sessions. Pigeons from the Paired group revealed a significantly greater density of Zenk positive nuclei in the ventromedial region of the hippocampus than did the Unpaired, Control and Naive groups. These data suggest that Zenk-mediated processes of synaptic plasticity in the hippocampus are induced during the retrieval of conditioned fear memory in the pigeon. [ABSTRACT FROM AUTHOR]

Freezing behavior is commonly used as a measure of associative fear memory. It can be measured by a trained observer, but this task is time-consuming and subject to variation. Commercially available software packages can also be used to quantify freezing; however, they can be expensive and usually require various parameters to be adjusted by the researcher, leading to additional work and variability in results. With this in mind, we developed Phobos, a freely available, self-calibrating software that measures freezing in a set of videos using a brief manual quantification performed by the user to automatically adjust parameters. To optimize the software, we used four different video sets with different features in order to determine the most relevant parameters, the amount of videos needed for calibration and the minimum criteria to consider it reliable. The results of four different users were compared in order to test intra- and interobserver variability in manual and automated freezing scores. Our results suggest that Phobos can be an inexpensive, simple and reliable tool for measurement of fear-related behavior, with intra- and interuser variability similar to that obtained with manual scoring. [ABSTRACT FROM AUTHOR]

Objective(s): Post-traumatic stress disorder (PTSD), one of the most devastating kinds of anxiety disorders, is the consequence of a traumatic event followed by intense fear. In rats with contextual fear conditioning (CFC), a model of PTSD caused by CFC (electrical foot shock chamber), deep brain stimulation (DBS) alleviates CFC abnormalities. Materials andMethods: Forty Male Wistar rats (220-250 g) were divided into 5 groups (n=8) and underwent stereotactic surgery to implant electrodes in the right basolateral nucleus of the amygdala (BLn). After 7 days, some animals received a foot shock, followed by another 7-day treatment schedule (DBS treatment). Next, freezing behavior was measured as a predicted response in the absence of the foot shock (re-exposure time). Blood serum corticosterone levels and amygdala c-Fos protein expression were assessed using Enzyme-linked immunosorbent assay (ELISA) and Western blot, respectively. Furthermore, freezing behaviors by re-exposure time test and general anxiety by elevated plus-maze (EPM) were evaluated. Results: PTSD decreased serum corticosterone levels and increased both amygdala c-Fos expression and freezing behaviors. Therefore, DBS treatment significantly (P<0.001) enhanced serum corticosterone levels and could significantly (P<0.001) reduce both c-Fos protein expression and freezing behaviors' duration. However, DBS treatment has no effect on the general anxiety in PTSD rats. Conclusion: We argue that these outcomes might demonstrate the mechanism of DBS treatment, a complete therapeutic strategy, in PTSD patients [ABSTRACT FROM AUTHOR]

Shorebird populations face increasing challenges as rising sea levels and growing human populations constrain their breeding habitats. On recreational beaches, the nesting season often coincides with a season of high visitor use, increasing the potential for conflict, which may negatively influence beach-nesting shorebird species. We designed a field experiment to study the responses of nesting American Oystercatchers (Haematopus palliatus) to off-road passenger vehicles (ORVs) at Cape Hatteras and Cape Lookout National Seashores in North Carolina, USA. We used continuous video and heart rate recordings to assess changes in the behavior and physiology of incubating oystercatchers. We conducted driving experiments affecting 7 nesting pairs in 2014 and 19 nesting pairs in 2015, between April and July of each year. Experimental treatments were repeated throughout the incubation period for each nest. Although responses were highly variable within and among pairs, paired randomized permutation tests indicated that, overall, oystercatcher pairs spent a greater proportion of time with their heads up and exhibited slower heart rates during driving treatments. Pairs also left their nests more frequently and attended their nests for a lower proportion of time during driving treatments, although these responses diminished over time. Higher nest attendance and lower departure rates late in incubation may have reflected a stronger attachment to nests closer to hatching or habituation to the driving treatment, although individuals continued to exhibit physiological responses to passing vehicles throughout incubation. Beach-nesting birds may benefit from reduced vehicle traffic at their nesting sites, allowing parents to spend more time attending the nest and less time on defensive behaviors. [ABSTRACT FROM AUTHOR]

TMT (2,5-dihydro-2,4,5-trimethylthiazoline) is known as a component of fox feces inducing fear in rodents. However, no recent chemical analyses of fox feces are available, and few studies make direct comparisons between TMT and fox feces. Fox feces from 3 individuals were used to prepare 24 samples to be analyzed for the presence of TMT using gas chromatography-mass spectrometry (GC-MS). When TMT was added in low amounts (50–2000 nmol/g), TMT was detected in 10 out of 11 samples. When no TMT was added, TMT was detected in only 1 out of 13 samples. In a second experiment, we tested the behavioral response of male Brown Norway (BN) and Wistar rats to either fox feces, a low amount of TMT (0.6 nmol) or 1-hexanol. TMT induced freezing in the rats, but fox feces induced significantly more freezing episodes and longer total duration of freezing in both rat strains. In experiment 3, male BN rats were exposed over several days to fox feces, rat feces, 1-hexanol, cadaverine, 2-phenylethylamine, and TMT, one odor at a time. Fox feces induced significantly more freezing episodes of a longer total duration than any of the other odors, with rat feces and 1-hexanol giving rise to the lowest amount of freezing. This finding, together with our inability to verify the presence of TMT in fox feces, indicates that the concentration of TMT in our fox feces samples was below 50 nmol/g. It may also be that other compounds in fox feces play a role in its fear-inducing properties. [ABSTRACT FROM AUTHOR]

This study investigated the effects of a high-voltage electrostatic field (HVEF) on the freezing behavior and quality maintenance of pork tenderloin. Based on the freezing behavior of deionized water (DW) under both AC and DC conditions, the freezing of pork samples using DC treatment was examined. It was found that the freezing point ( T m ) and phase-transition time (crystallization time, t c ) of the meat varied with increasing voltage. The water-holding capacity of samples treated by 10 kV exceeded that of the control group, which was proven using low-field nuclear calorimetry (LF-NMR) and differential scanning calorimetry (DSC). The total area of ice crystal for the cross sections of pork tenderloin treated with 10 kV HVEF was much smaller than that without HVEF. Microstructural observations indicated that freezing assisted by 10 kV HVEF was superior to freezing without HVEF in maintaining the quality of frozen pork. [ABSTRACT FROM AUTHOR]

The fuel support piece in a boiling water reactor (BWR) is used to brace fuel assemblies. The channel within the fuel support piece is determined to be a potential corium relocation path from the core region to the lower head during the severe accident of BWR. In the present study, the improved ∗∗∗Moving Particle Semi-implicit (MPS) method was adopted to simulate the flow and solidification behavior of the melt in a fuel support piece. The MPS method was first validated against the Pb-Bi plate ablation test that was performed by CRIEPI. The predicted ablation mass of the plate agreed well with the experimental results. Then the flowing and freezing behaviors of molten stainless steel (SS) and zircaloy in the fuel support piece were simulated by MPS method with a three dimensional particle configuration, respectively. In this study, the flow and solidification behavior of SS was simulated first. After all the SS passed through the channel, the flowing behavior of Zr in the fuel support piece was simulated. The simulation results indicated that the crust layer formed on the inner surface of the fuel support piece during the melt discharging process. The fuel support piece was plugged by the solidified zircaloy particles in the lower initial temperature case. The fuel support piece kept intact in all the calculation that were performed under the assumed order of melt injection. The present results could help to reveal the progression of a BWR severe accident. [ABSTRACT FROM AUTHOR]

The bed nucleus of the stria terminalis (BNST) modulates anxiety-like responses, including conditioned emotional responses. Evidence suggests that glutamatergic neurotransmission in the BNST plays a role in the modulation of defensive responses. However, little is known about the involvement of glutamate NMDA receptor activation within the BNST, and its resultant increase in nitric oxide (NO) levels, in the expression of contextual fear conditioning (CFC). We investigated whether the antagonism of NMDA receptors or the reduction of NO levels in the BNST would attenuate behavioral and autonomic responses (i.e. increase in arterial pressure and heart rate, and decrease in tail cutaneous temperature) of rats submitted to a CFC paradigm. Intra-BNST infusion of AP7, an NMDA receptor antagonist, attenuated both behavioral and autonomic changes induced by CFC. Similar results were observed with NPLA and c-PTIO, an nNOS inhibitor and an NO scavenger, respectively. A positive correlation between BNST NO levels and the time spent in freezing behavior was also observed for animals submitted to the CFC. These findings indicate that the expression of CFC involves a facilitation of BNST NMDA receptor-NO signaling. This article is part of the Special Issue entitled ‘Ionotropic glutamate receptors’. [ABSTRACT FROM AUTHOR]

Early maternal separation (MS) may produce lasting effects in the dorsal hippocampus (DH) that can change its response to chronic stress in adulthood. Chronic stress affects DH morphology and function, but tianeptine (an anti-depressant) can reverse the stress-induced morphological impairments. Morphologic alterations of hippocampus can affect contextual memory. Therefore, we evaluated the effect of tianeptine in MS and chronically stressed rats on: 1) volume of the DH and its areas using stereology and 2) hippocampal-dependent memory using a fear conditioning test. Male Wistar rats were subjected to daily MS for 4.5 h between postnatal days (PND) 1–21, or to animal facility rearing (AFR). Between (PND) days 50 and 74, rats were exposed to chronic unpredictable stress and were treated daily with tianeptine (10 mg/kg) or vehicle, providing eight groups: AFR-unstressed/vehicle (n = 5 for stereology,n = 18 for fear conditioning test); AFR unstressed/tianeptine (n = 6 andn = 10); AFR-chronic stress/vehicle (n = 6 andn = 14); AFR-chronic stress/tianeptine (n = 6 andn = 10), MS-unstressed/vehicle (n = 5 andn = 19), MS-unstressed/tianeptine (n = 6 andn = 10), MS-chronic stress/vehicle (n = 6 andn = 18), and MS-chronic stress/tianeptine (n = 6 andn = 10). MS-chronic stress/tianeptine rats showed a diminished CA1 area than the corresponding MS-unstressed/tianeptine rats. The combination of stressors produced a freezing response similar to those of the control group during postconditioning. During retrieval, MS led to a diminished freezing response compared to the AFR-unstressed groups. Tianeptine had no effect on freezing behavior. Our results show that tianeptine can affect the CA1 area volume differently depending on the nature and quantity of stressors but cannot alter freezing to context. [ABSTRACT FROM PUBLISHER]

The cannabinoid receptor type 1 (CB1) is highly expressed in the dorsal portion of hippocampus – a brain region that has been involved in the control of conditioned emotional response (CER) in the contextual fear conditioning (CFC) model. These responses are characterized by increased freezing behavior and autonomic parameters. Moreover, CB1 receptors activation negatively modulate the release of several neurotransmitters, including glutamate and GABA, which also have been related to modulation of CER. Therefore, our aim was to investigate the involvement of CB1 receptors in the dorsal hippocampus on CER expression. Independent groups of male Wistar rats submitted to the contextual fear conditioning received bilateral intra-hippocampal injections (500 nL/side) of the following drugs or vehicle before re-exposure to the aversive context: AM251 (CB1 antagonist; 0.1, 0.3 and 1 nmol); AP7 (NMDA antagonist; 1nmol)+AM251 (0.3 nmol); NPLA (0.01 nmol; nNOS inhibitor)+AM251 (0.3 nmol); Bicuculline (1.3 pmol; GABA A antagonist)+AM251 (0.1 and 1 nmol). In the present paper, AM251 (0.3 nmol) increased CER, while this response was prevented by both AP7 and NPLA pretreatment. After pretreatment with Bicuculline, the lower and higher ineffective doses of AM251 were able to increase the CER, supporting the balance between GABAergic and glutamatergic mechanisms controlling this response. Our results suggest that increased CER evoked by CB1 blockade in the dorsal hippocampus depends on NMDA receptor activation and NO formation. Moreover, a fine-tune control promoted by GABAergic and glutamatergic mechanisms in this brain area modulate the CER after CB1 blockade. [ABSTRACT FROM AUTHOR]

Wintering Sasa senanensis, dwarf bamboo, has been known to employ deep supercooling as the mechanism of cold hardiness in its most of the tissues from leaves to rhizomes. The unique cold hardiness mechanism of this plant was further characterized using current year leaf blades. Cold hardiness levels increased from August (LT20: –11 °C) to December (LT20: –20 °C), which coincided with the initiation temperature of low temperature exotherms (LTE) detected in differential thermal analyses. When leaf blades were stored at –5 °C for 1-14 days, there was no nucleation of the supercooled tissue units compartmentalized by the longitudinal and transverse veins either in summer or winter. However, only summer leaves suffered significant injury after prolonged supercooling of the tissue units. This may be a novel type of low temperature-induced injury in supercooled state at subfreezing temperatures. When winter leaf blades were maintained at the threshold temperature (-20 °C), a longer storage period (1-7 days) increased lethal freezing of the supercooled tissue units. Within a wintering shoot, the second or third leaf blade from the top was most cold hardy and leaf blades at lower positions tended to suffer more injury due to lethal freezing of the supercooled units, which was not correlated with the leaf water content. LTE were shifted to higher temperatures (2-5 °C) after a lethal freeze-thaw cycle. The results demonstrate that the tissue unit compartmentalized with longitudinal and transverse veins serves as the unit of supercooling and temperature- and time-dependent freezing of the units is lethal both in laboratory freeze tests and in the field. To establish such supercooling in the unit, structural ice barriers such as development of sclerenchyma and biochemical mechanisms to increase the stability of supercooling are considered important. We discussed these mechanisms in regard to ecological and physiological significance in winter survival.