Exploratory Behavior Research Articles

Non-conventional endpoints show higher sulfoxaflor toxicity to Chironomus riparius than conventional endpoints in a multistress environment

Evidence grows that standard toxicity testing might underestimate the environmental risk of neurotoxic insecticides. Behavioural endpoints such as locomotion and mobility have been suggested as sensitive and ecologically relevant additions to the standard tested endpoints. Possible interactive effects of chemicals and additional stressors are typically overlooked in standardised testing. Therefore, we aimed to investigate how concurrent exposure to environmental stressors (increased temperature and predation cues) and a nicotinic acetylcholine receptor (nAChR)-modulating insecticide (‘sulfoxaflor’) impact Chironomus riparius across a range of conventional and non-conventional endpoints. We used a multifactorial experimental design encompassing three stressors, sulfoxaflor (2.0–110 µg/L), predation risk (presence/absence of predatory cues), and elevated temperature (20 °C and 23 °C), yielding a total of 24 distinct treatment conditions. Additional stressors did not change the sensitivity of C. riparius to sulfoxaflor. To assess potential additive effects, we applied an Independent Action (IA) model to predict the impact on eight endpoints, including conventional endpoints (growth, survival, total emergence, and emergence time) and less conventional endpoints (the size of the adults, swimming abilities and exploration behaviour). For the conventional endpoints, observed effects were either lower than expected or well-predicted by the IA model. In contrast, we found greater than predicted effects of predation cues and temperature in combination with sulfoxaflor on adult size, larval exploration, and swimming behaviour. However, in contrast to the non-conventional endpoints, no conventional endpoints detected interactive effects of the neurotoxic insecticide and the environmental stressors. Acknowledging these interactions, increasing ecological context of ecotoxicological test systems may, therefore, advance environmental risk analysis and interpretation as the safe environmental concentrations of neurotoxic insecticides depend on the context of both the test organism and its environment.

Low sucrose diets protect long-term memory and EPA & DHA enriched diets alter insulin resistance in a mouse model of chemotherapy

Chemotherapy-related cognitive impairment (CRCI) and affective symptoms negatively impact quality of life in breast cancer survivors. The aim of this study was to determine the efficacy of high eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA) and low sucrose diets to alleviate these symptoms in a mouse model of chemotherapy. Potential mechanisms involving insulin resistance were explored. We hypothesized that diets enriched in EPA+DHA and low amounts of sucrose would protect against the impact of chemotherapy on measures of CRCI. Female C57Bl/6 mice were randomized to 1 of 4 diets (2% kcal eicosapentaenoic acid + docosahexaenoic acid [EPA+DHA]/high or low sucrose, low omega-3/high or low sucrose) for 6 weeks and treated with two injections of doxorubicin-based chemotherapy or vehicle during week 2 and 4. Behavioral tests were performed 7 days after second injection. Chemotherapy increased serum insulin and decreased body weight, locomotion and exploratory behavior (all p < .05). Low sucrose consumption resulted in better long-term memory regardless of chemotherapy or vehicle injection (p < .05). 2% EPA+DHA consumption lessened insulin resistance (p < .05); however, controlling for body weight attenuated this effect (p = .08). There were no significant differences by diet or injection on liver lipid content; however, liver lipid content was positively correlated with insulin resistance scores (p < .05). Low sucrose diets may protect long-term memory during chemotherapy. The effect of EPA+DHA on insulin resistance and affective side effects during chemotherapy requires further investigation.

Gut microbiota and inflammation analyses reveal the protective effect of medium-chain triglycerides combined with docosahexaenoic acid on cognitive function in APP/PS1 and SAMP8 mice

Accumulating evidence has demonstrated that medium-chain triglycerides (MCTs) and docosahexaenoic acid (DHA) positively affect cognitive function. However, it remains unclear whether the improvement is related to the alterations of gut microbiota and inflammation and the impact of the combined intervention. In this study, we hypothesized that the supplementation of MCTs combined with DHA could modulate gut microbiota, inflammation, and improve cognitive function in APPswe/PS1De9 (APP/PS1) model mice and senescence-accelerated mouse prone-8 (SAMP8), which are two different mouse models used in neurodegeneration research. The mice were divided into four groups: Control group, MCTs group, DHA group and MCTs+DHA group. The study assessed cognitive function, inflammatory cytokines, and gut microbiota composition. The results showed that supplementation of MCTs+DHA improved spatial learning ability, memory capacity, exploratory behavior; decreased the relative abundance of Proteobacteria; reduced the ratio of Firmicutes/Bacteroidetes (F/B); decreased the concentrations of serum interleukin (IL)-2, IL-6, monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-alpha), while increasing the concentration of IL-10. Furthermore, supplementation with MCTs+DHA exhibited significantly superior effects compared to MCTs or DHA alone in reducing inflammation, optimizing gut microbiota composition, and improving cognitive function. In conclusion, supplementation with MCTs+DHA improved cognition function, accompanied with favorable alterations in gut microbiota and inflammation in APP/PS1 and SAMP8 mice.

A train trajectory optimization method based on the safety reinforcement learning with a relaxed dynamic reward

Train trajectory optimization (TTO) is an effective way to address energy consumption in rail transit. Reinforcement learning (RL), an excellent optimization method, has been used to solve TTO problems. Although traditional RL algorithms use penalty functions to restrict the random exploration behavior of agents, they cannot fully guarantee the safety of the process and results. This paper proposes a proximal policy optimization based safety reinforcement learning framework (S-PPO) for the train trajectory optimization, including a safe action rechoosing mechanism (SARM) and a relaxed dynamic reward mechanism (RDRM) combining a relaxed sparse reward and a dynamic dense reward. SARM guarantees that the new states generated by the agent consistently adhere to the environmental security constraints, thereby enhancing sampling efficiency and facilitating algorithm convergence. RDRM makes it easier for agents to obtain successful samples by relaxing time constraints, which also offers a better balance between exploration and exploitation. The experimental results show that S-PPO can significantly improve performance and obtain better train operation trajectories than soft constraint methods, and the convergence process is smoother. Finally, it was demonstrated that S-PPO exhibits good adaptability across various speed limit tracks.

Young adolescent boys' and girls' attitudes toward uncommitted sexual behaviors and the perception of interest in sexual exploration in opposite-gender relations

The aim of this study is to measure young adolescent boys' and girls' attitudes toward uncommitted sexual behaviors and gain insight into their perception of peers' sexual exploration interest in committed versus non-committed opposite-gender relations. We constructed a new 5-item measurement of young adolescents' attitudes toward uncommitted sexual behavior (sociosexuality) and report on the reliability and construct validity of the scale. Analyses were performed on a sample of 425 secondary school students (187 boys, 238 girls, Mean age = 14.8, Age range 13–16). Results suggest that the new sociosexual attitudes scale is unidimensional and internally consistent across these ages for both genders. Relative to girls and younger participants, boys and older participants reported higher acceptance of uncommitted sexual behaviors (ranging from French kissing to intercourse). Further, participants' scores on the sociosexual attitude scale were positively related to frequency of pornography use, and to how they perceived sexual interest in scenarios of a boy and a girl in an intimate situation. Those scoring higher on sociosexuality were more likely to believe that their peers would be more sexually exploring and be less reluctant. The results attest to the construct validity of the scale, and its applicability to studies of young adolescents' understanding of sexual exploration behavior in non-committed sexual relations.

The metaverse experience: A scale development study

AbstractUnderstanding the metaverse experience (MEX) is paramount to allow companies to exploit its potential and to align with consumers' expectations. Accordingly, this paper develops a scale to identify the main dimensions that define the MEX as well as investigate which constituent dimensions of the MEX are more suited to enhance consumers' attitude toward the metaverse, a key element to foster consumers' exploratory behavior. By drawing on a research design based on multiple stages including qualitative and quantitative data and analysis, this paper develops a measure of the MEX that includes six dimensions: sensory/affective, intellectual, behavioral, relational, interoperability, and safety. The dimensions of intellectual, behavioral, and relational experience were found non‐significant showing that the MEX is built on the experiential dimensions of sensory/emotional, interoperability, and safety. These dimensions were also found to directly affect consumers' attitude toward the metaverse. The paper contributes to current discussion of the metaverse by offering the first tested and reliable scale to measure the MEX.

Effects of Continuous Prenatal Low Dose Rate Irradiation on Neurobehavior, Hippocampal Cellularity, Messenger RNA and MicroRNA Expression on B6C3F1 Mice.

Epidemiological, experimental, and ecological data have indicated the controversial effect of in utero chronic low dose rate (<6 mGy/h) with accumulative low (≤100 mGy) or high (>100 mGy) dose radiation exposure. Our main goal of this study was to examine if different low dose rates of chronic pre- and/or post-natal radiation exposure with accumulative high doses could induce hippocampal cellular, mRNA, and miRNA changes leading to neuropsychiatric disorders. The comprehensive mouse phenotypic traits, organ weight, pathological, and blood mRNA and miRNA changes were also studied. Using different approaches including SmithKline, Harwell, Imperial College, Royal Hospital, Phenotype Assessment (SHIRPA), neurobehavioral tests, pathological examination, immunohistochemistry, mRNA and miRNA sequencing, and real-time quantitative polymerase chain reaction (qRT-PCR) validation, we found that in prenatally irradiated (100 mGy/d for 18 days with an accumulative dose of 1.8 Gy) 1-year-old mice, no cellular changes, including immature neurons in the subgranular zone, mature neurons and glial cells in the hilus of the dentate gyrus and development of cognitive impairment, neuropsychiatric disorders, occurred. However, a significant reduction in body weight and mass index (BMI) was indicated by the SHIRPA test. A reduced exploratory behavior was shown by an open field test. Organ weights showed significant reductions in the testes, kidneys, heart, liver and epididymides with no abnormal pathology. mRNA and miRNA sequencing and qRT-PCR validation revealed the upregulation of Rubcnl and Abhd14b, and downregulation of Hspa1b, P4ha1, and Banp genes in both the hippocampus and blood of mice prenatally irradiated with 100 mGy/d. Meanwhile, downregulation of miR-448-3p and miR1298-5p in the hippocampus, miR-320-3p, miR-423-5p, miR-486b-5p, miR-486b-3p, miR-423-3p, miR-652-3p, miR-324-3p, miR-181b-5p, miR-let-7b, and miR-6904-5p in the blood was induced. The target scan revealed that Rubcnl is one of the miR-181b-5p targets in the blood. We, therefore, concluded that prenatal chronic irradiation with a low dose rate of 100 mGy/d and accumulative dose of 1.8 Gy or below might not induce significant adverse health effects on the offspring. Further study of different low dose rate radiation exposures with accumulative high doses may provide threshold doses for authorities or regulators to set new radiation safety guidelines to replace those extrapolated from acute high dose/dose rate irradiation to reduce unnecessary emergency evacuation or spending once a nuclear accident or leakage occurs.

Dynamics of spontaneous thoughts: Exploration, attentional profile and the segmentation of the stream of thoughts

For a long time, clinical knowledge and first-person reports have pointed to individual differences in the dynamics of spontaneous thoughts, in particular in the extreme case of psychiatric conditions (e.g. racing thoughts in Attention Deficit / Hyperactivity Disorder, ADHD; rumination in depression). We used a novel procedure to investigate this individual variability by combining verbal fluency tasks and introspective reports of thought content. Our goal was twofold. First, we tested the hypothesis that a greater segmentation of the stream of thoughts would be associated with trait inattention, in line with subjective reports of ADHD patients. Second, we tested whether the segmentation of the stream of thoughts increased with an increased tendency for exploratory behavior, following recent theoretical claims on the mechanisms underpinning the generation of spontaneous thoughts. Our results support both hypotheses, shedding light on the factors contributing to the individual variability in the dynamics of the stream of thought.

Reflex-based open-vocabulary navigation without prior knowledge using omnidirectional camera and multiple vision-language models

Various robot navigation methods have been developed, but they are mainly based on Simultaneous Localization and Mapping (SLAM), reinforcement learning, etc., which require prior map construction or learning. In this study, we consider the simplest method that does not require any map construction or learning, and execute open-vocabulary navigation of robots without any prior knowledge to do this. We applied an omnidirectional camera and pre-trained vision-language models to the robot. The omnidirectional camera provides a uniform view of the surroundings, thus eliminating the need for complicated exploratory behaviors including trajectory generation. By applying multiple pre-trained vision-language models to this omnidirectional image and incorporating reflective behaviors, we show that navigation becomes simple and does not require any prior setup. Interesting properties and limitations of our method are discussed based on experiments with the mobile robot Fetch.

Personality matters – The interplay between consistent individual differences and mouse welfare in female C57BL6/J mice

To ensure good welfare of animals in human hands, it is essential to modify housing conditions according to the animals’ needs. Traditionally, the effects of such modifications are studied by means of group-level comparisons, thereby widely neglecting consistent inter-individual differences (i.e., so-called ‘animal personalities’). However, as animals with distinct personality types might differ in their environmental needs and hence react differently to the same environment, such systematic inter-individual differences might have important welfare consequences. This becomes particularly apparent under laboratory conditions, where animals are typically housed under highly standardized and barren environments. Against this background, we here aim to investigate personality-dependent welfare consequences in response to different housing conditions in laboratory mice. Female C57BL/6J mice were characterized for their personality type in exploration behavior and the most and the least explorative individuals were set up in either simple or in highly complex housing conditions that included constantly changing environmental enrichment items. We monitored individual welfare by studying behavioral, physiological, and immunological outcome measures. Besides personality-dependent differences in immune parameters and overall improved welfare under complex housing conditions, we indeed found hints that individual mice were differently affected in their welfare depending on the specific combination of personality type and housing condition. Specifically, highly explorative mice appeared to be more adversely affected by simple housing, but also profited more from complex housing compared to low explorative mice. These findings indicate that welfare promoting adjustments do not necessarily benefit all individuals equally and therefore, call for a shift of perspectives in the evaluation of animal welfare.

Development of the Checklist for Imitation, Exploration and Imagination Behaviour for Play Observation in Preschool Age

Development of the Checklist for Imitation, Exploration and Imagination Behaviour for Play Observation in Preschool Age

Mouse Exploratory Behaviour in the Open Field with and without NAT-1 EEG Device: Effects of MK801 and Scopolamine.

One aspect of reproducibility in preclinical research that is frequently overlooked is the physical condition in which physiological, pharmacological, or behavioural recordings are conducted. In this study, the physical conditions of mice were altered through the attachments of wireless electrophysiological recording devices (Neural Activity Tracker-1, NAT-1). NAT-1 devices are miniaturised multichannel devices with onboard memory for direct high-resolution recording of brain activity for >48 h. Such devices may limit the mobility of animals and affect their behavioural performance due to the added weight (total weight of approximately 3.4 g). The mice were additionally treated with saline (control), N-methyl-D-aspartate (NMDA) receptor antagonist MK801 (0.85 mg/kg), or the muscarinic acetylcholine receptor blocker scopolamine (0.65 mg/kg) to allow exploration of the effect of NAT-1 attachments in pharmacologically treated mice. We found only minimal differences in behavioural outcomes with NAT-1 attachments in standard parameters of locomotor activity widely reported for the open field test between the drug treatments. Hypoactivity was globally observed as a consistent outcome in the MK801-treated mice and hyperactivity in scopolamine groups regardless of NAT-1 attachments. These data collectively confirm the reproducibility for combined behavioural, pharmacological, and physiological endpoints even in the presence of lightweight wireless data loggers. The NAT-1 therefore constitutes a pertinent tool for investigating brain activity in, e.g., drug discovery and models of neuropsychiatric and/or neurodegenerative diseases with minimal effects on pharmacological and behavioural outcomes.

Exposure to thimerosal induces behavioral abnormality in the early life stages of zebrafish via altering amino acid homeostasis

Thimerosal (THI) has become a significant source of organic mercury pollutants in aquatic ecosystems, but there is limited information regarding its adverse effects on fish. In this study, zebrafish embryos were exposed to THI at 0 (control), 5.0, and 50 ng/L from 0–5 days post fertilization (dpf), and variations in their survival, development, behavior, free amino acid contents, and the biochemical responses involved in monoaminergic systems were examined. Although THI exposure did not significantly affect the survival, heart rate, or hatching time of zebrafish embryos, it substantially increased swimming velocity (136–154 % of the control) and reduced exploratory behavior (141–142 % of the control) in zebrafish larvae at 5 dpf. Exposure also significantly altered the amino acid contents (51–209 % of the control) and monoamine levels (70–154 % of the control) in zebrafish larvae, some of which displayed significant correlations with behavioral traits. THI significantly elevated dopamine receptor gene expression and monoamine oxidase activity in zebrafish larvae. Adding extra phenylalanine or tryptophan to the E3 medium facilitates the recovery of zebrafish larvae from the abnormal behaviors induced by THI. These findings reveal for the first time that THI exposure at the level of ng/L is sufficient to induce neurobehavioral toxic effects in the early life stages of zebrafish, and disrupting amino acid homeostasis is a critical underlying mechanism. This study provides valuable insights into the toxicity of THI to fish and highlights the importance of assessing its potential risks to aquatic ecosystems.

Can you dig it? The impact of a movable substrate "dig pit" on naked mole rat (Heterocephalus glaber) behavior and welfare.

Zoos are often limited by exhibit design in the opportunities they can provide animals to express natural behaviors; however, the opportunity to perform certain natural behaviors is key to supporting good animal welfare. Traditionally, in zoos, naked mole rats (Heterocephalus glaber) are housed in gunite-lined acrylic chambers that replicate the look of their tunnel systems in the wild but don't offer the opportunity for natural digging and tunnel construction behaviors. In this study, naked mole rat behavior was evaluated when providing two different presentations of movable substrate added on to the original exhibit-a tank with loose substrate and a dig pit with hard-packed clay. We recorded 299 5-min focal observations with 30-s intervals and 30 group scans to understand behavioral changes across treatments (10 days of observation per treatment). Results were analyzed using Bayesian mixed models. Digging behavior emerged in both presentations of moveable substrate. A potential indicator of negative welfare, barrier-directed behavior, decreased when the mole rats had access to the tank of loose substrate. A potential indicator of positive welfare, exploratory behavior, increased with access to the dig pit when the mole rats had the opportunity to build tunnels. Additionally, affiliative social interactions increased, and aggressive interactions decreased with access to either presentation of movable substrate. The observed changes in colony behavior demonstrate that captive naked mole rats readily exhibited the natural behaviors of digging and tunnel building when the opportunity was presented, and the habitat modification likely improved naked mole rat welfare.

Amelioration of behavioral and histological impairments in somatosensory cortex injury rats by limbal mesenchymal stem cell transplantation.

Cortical lesions can cause major sensory and motor impairments, representing a significant challenge in neuroscience and clinical medicine. Limbal mesenchymal stem cells (LMSCs), renowned for their remarkable ability to proliferate and distinct characteristics within the corneal epithelium, offer a promising opportunity for regenerative treatments. This study aimed to assess whether the transplantation of LMSCs could improve tactile ability in rats with lesions of the barrel cortex. In this experimental study, we divided 21 rats into three groups: a control group, a lesion group with cortical cold lesion induction but no stem cell treatment, and a group receiving LMSC transplantation following cold lesion induction. We conducted 3-week sensory assessments using a texture discrimination test and an open-field test. We also performed Nissl staining to assess changes on the cellular level. Rats in the LMSC transplantation group demonstrated significant improvements in their ability to discrimination textures during the second and third weeks compared to those in the lesion group. The open-field test results showed an increased exploratory behavior of rats in the LMSC transplantation group by the third week compared to the lesion group. Additionally, Nissl staining revealed cellular alterations in the damaged cortex, with a significant distinction observed between rats in the LMSCs and lesion group. The findings suggest that LMSC transplantation enhances sensory recovery in rats with cortical lesions, particularly their ability to discriminate textures. LMSC transplantation benefits brain tissue reparation after a cold lesion on the somatosensory cortex.

Chemical Profile and Potential Application of Agri-food Waste Products for Counteracting Diabetes Induced Neuropathy in Rats.

This study aimed to prepare defatted ethanol extract of Abelmoschus esculentus leaves, Morus nigra leaves and Punica granatum peel, to identify the chemical composition of these extracts and to explore their efficacy in counteracting diabetic neuropathy. LC-ESI-MS spectrometry was the hyphenated tool for component identification of these extracts. Behavioral, biochemical, and histopathological investigations were carried out after treatments of diabetic rats. The phenolic contents in the extracts are 16.38, 34.75 and 40.57 mg GAE/g extract regarding A. esculentus leaves, M. nigra leaves and P. granatum peel respectively. Chemodiversity of the phenolic contents was observed from the LC/Mass, where A. esculentus extract contained isoflavonoids and flavanones, M. nigra extract consisted of benzofurans, prenylated flavonoids, stilbenes, and xanthones, and P. granatum extract was rich in ellagitanins, condensed tannins, and anthocyanins. The extracts normalize of blood glucose levels, enhance the explorative behavior of the rats and their response time to thermal pain, restore the oxidant/antioxidant balance, attenuate inflammation, augment brain monoamines levels and modulate MAO-A and Ache enzyme activity. Furthermore, they recovered brain histopathological alterations. Conclusively, this study offers experimental evidence for the neuroprotective impact of studied defatted ethanol extracts against diabetic neuropathy via their hypoglycemic effect, antioxidant activity, and anti-inflammatory potential.

Distinct populations of lateral preoptic nucleus neurons jointly contribute to depressive-like behaviors through divergent projections in male mice

The lateral preoptic area (LPO) is a component of the hypothalamus involved in various physiological functions including sleep-wakefulness transition, thermoregulation, and water-salt balance. In this study, we discovered that distinct LPO excitatory neurons project separately to the aversive processing center lateral habenula (LHb) and the reward processing hub ventral tegmental area (VTA). Following chronic restraint stress (CRS), the LHb-projecting and VTA-projecting LPO neurons exhibited increased and decreased neuronal activities, respectively. Optogenetic activation of LHb-projecting LPO excitatory neurons and LPO excitatory neuronal terminals within LHb evoked aversion and avoidance behaviors, while activation of VTA-projecting LPO excitatory neurons and LPO excitatory neuronal terminals within VTA produced preference and exploratory behaviors in mice. Furthermore, either optogenetic inhibition of LHb-projecting LPO excitatory neurons or activation of VTA-projecting LPO excitatory neurons during CRS effectively prevented the development of depressive-like behaviors. Our study unveils, for the first-time, divergent pathways originating from LPO that regulate opposite affective states in mice and implicates that an imbalance of their activities could lead to depressive-like behaviors. These circuitries represent promising therapeutic targets to relieve emotional dysfunctions in neuropsychiatric disorders.

Fixed oil from the Caatinga palm Syagrus coronata with effect on Complete Freund's Adjuvant (CFA)-induced arthritis.

Syagrus coronata, a native palm tree in the Caatinga domain, produces fixed oil (ScFO) used therapeutically and dietary by Northeast Brazilian communities. This study evaluated its anti-inflammatory potential of CFA-induced arthritis and its effect on behavioral parameters. In the acute model, ScFO at 25, 50, and 100mg/kg showed edematogenic effects similar to indomethacin at 4mg/kg (p > 0.05). In the arthritis model, 100mg/kg ScFO treatment was comparable to indomethacin (4mg/kg) (p > 0.05). TNF-α and IL-1β levels were significantly reduced in ScFO-treated groups at 25, 50, and 100mg/kg, and the indomethacin group (4mg/kg) versus the positive control (p > 0.05). Radiographs showed severe soft-tissue swelling and bone deformities in the control group, while the 100mg/kg ScFO group had few alterations, similar to the indomethacin group. Histopathological analysis revealed intense lymphocytic infiltration in the control group, mild diffuse lymphocytic infiltration in the indomethacin group, and mild lymphoplasmacytic infiltration with focal polymorphonuclear infiltrates in the 100mg/kg ScFO group. Behavioral analysis showed improved exploratory stimuli in ScFO and indomethacin-treated mice compared to the positive control (p > 0.05). ScFO demonstrated anti-inflammatory effects in both acute and chronic arthritis models, reducing edema and pro-inflammatory cytokines, and improved exploratory behavior due to its analgesic properties.

Transitional photoperiod induces a mania-like behavior in male mice.

This study aimed to investigate the behavioral responses and circadian rhythms of mice to both rapid and gradual increases in photoperiod, mimicking the transition from winter to summer, which is associated with a heightened prevalence of hospitalizations for mania and suicidal behavior. Behavioral tests were performed in C57BL/6 male mice exposed to a transitional photoperiod, from short to long durations. To determine if circadian rhythms are affected, we measured spontaneous locomotor activity and body temperature. Mice exhibited heightened exploratory and risk-taking behaviors compared with equatorial and static long (16:8 h of light-dark cycle for several days) groups. These behaviors were prevented by lithium. Spontaneous locomotor activity and body temperature rhythms persisted and were effectively synchronized; however, the relative amplitude of activity and interdaily stability were diminished. Additionally, the animals displayed increased activity during the light phase. Photoperiodic transition modulates behavior and circadian rhythms, mirroring certain features observed in bipolar disorder patients. This study introduces an animal model for investigating mania-like behavior induced by photoperiodic changes, offering potential insights for suicide prevention strategies and the management of mood disorders.

Nitric oxide-signalling affects panic-like defensive behaviour and defensive antinociception neuromodulation in the prelimbic cerebral cortex

Rationale: The prelimbic division (PrL) of the medial prefrontal cortex (mPFC) is a key structure in panic. Objectives: To evaluate the role of nitric oxide (NO) in defensive behaviour and antinociception. Methods: Either Nω-propyl-L-arginine (NPLA) or Carboxy-PTIO was microinjected in the PrL cortex, followed by hypothalamic treatment with bicuculline. The exploratory behaviours, defensive reactions and defensive antinociception were recorded. Encephalic c-Fos protein was immunolabelled after escape behaviour. Results: NPLA (an inhibition of nNOs) decreased panic-like responses and innate fear-induced antinociception. The c-PTIO (a membrane-impermeable NO scavenger) decreased the escape behaviour. PrL cortex pre-treatment with c-PTIO at all doses decreased defensive antinociception. c-Fos protein was labelled in neocortical areas, limbic system, and mesencephalic structures. Conclusion: The NPLA and c-PTIO in the PrL/mPFC decreased the escape behaviour and defensive antinociception organised by medial hypothalamic nuclei. The oriented escape behaviour recruits neocortical areas, limbic system, and mesencephalic structures. These findings suggest that the organisation of defensive antinociception recruits NO-signalling mechanisms within the PrL cortex. Furthermore, the present findings also support the role of NO as a retrograde messenger in the PrL cortex during panic-like emotional reactions.