Effects Of Environmental Enrichment Research Articles

Balancing welfare and habitat damage in pigs (Sus scrofa) under extensive farming: an ethological approach for determining the effects of group composition and environmental enrichment

Balancing welfare and habitat damage in pigs (Sus scrofa) under extensive farming: an ethological approach for determining the effects of group composition and environmental enrichment

Long‐lasting behavioral and neurochemical effects of early‐life environmental enrichment in rats submitted to neonatal morphine administration

AbstractThe present study examined the medium‐ and long‐term effects of early environmental enrichment (EE) on neuromotor, nociceptive, cognitive, behavioral, and neurochemical parameters in newborn rats repeatedly exposed to morphine. The study employed 90 Wistar rats: 10 adult nulliparous females and 80 male pups. Litter was split into standard and EE housing. Following, half of each litter received saline (S) or morphine (M) injections, resulting in four groups: SC + S, EE + S, SC + M, and EE + M. EE was applied from PND1 to PND21, while morphine or saline was given daily (5 μg/s.c.) from PND8 to PND14. Neuromotor development was similar between groups. In the OF test, morphine reduced outer and total crossings, whereas EE increased inner crossings and rearings. Adult rats showed a decrease in outer and total crossings and grooming and an increase in rearing. EE increased the number of protected and unprotected head dipping. Adult rats showed an increase in protected head dipping. Adult rats showed a lower recognition index, and, when exposed to EE, a lower anxiety index and analgesia. EE increased brainstem and hippocampal BDNF levels. Adult rats had increased hypothalamus, spinal cord, and brainstem BDNF levels, an increase in the spinal cord, and decreased hypothalamus TNF‐α levels. This study demonstrated that early‐life EE raises BDNF levels in the brainstem and hippocampus of rats and modifies their behaviors (such as nociception, exploration, and anxiety) in a state‐dependent manner (morphine and age).

PSII-3 Effect of environmental enrichment on pig average daily feed intake and average daily gain in the early nursery phase

Abstract Transition from the sow to nursery is a stressful time for pigs and commonly leads to negative impacts on pig health, welfare, and lifetime performance. The objective of this study was to determine if the addition of a biologically relevant enrichment device affected average daily gain (ADG) and average daily feed intake (ADFI) during the first 2 wk of nursery. A total of 160 mixed-sex pigs (Camborough 1050 X 337, PIC), 19 to 24 d of age [body weight (BW) = 5.77 SD 0.97 kg], were randomly allocated to pens at the Iowa State University Swine Nutrition Farm. Each pen contained 10 pigs (~0.29 m2/pig). Each pen was randomly assigned to one of two treatments: 1) enrichment device with no attractant (positive treatment; n = 8), or 2) no enrichment device (negative treatment; n = 8). Each positive treatment pen had two enrichment devices, consisting of one cotton rope and two biscuits, suspended from the feeder at pig height. The biscuits were replaced daily at about 0800 h throughout wk 1 in nursery (d 0 to d 6). In wk 2 (d 7 to d 13) no pens had an enrichment device. Each pen was equipped with a 4-hole, dry self-feeder measuring 0.61 m long and two affixed nipple drinkers. The feeder was weighed daily, and the pigs weighed weekly. Changes in daily feeder weight and weekly pig BW were used to calculate average daily feed intake (ADFI) and average daily gain (ADG). Pen was the experimental unit. Data were analyzed using the PROC Mixed procedure of SAS. The model included treatment, week, and treatment by week interaction. A P-value of ≤ 0.05 was considered significantly different. There was an observed difference in ADFI and ADG between wk (P ≤ 0.001, Table 1). However, there were no observed differences in ADFI or ADG for treatment (P ≤ 0.79) or treatment by week interaction (P ≤ 0.93). In conclusion, the addition of this biologically relevant enrichment did not improve or impair ADFI and ADG during the first 2 wk of the nursery phase.

Effects of Environmental Enrichment on the Growth, Gonadal Development, and Welfare of the Chinese Hooksnout Carp (Opsariichthys bidens)

To investigate the effects of environmental enrichment on the growth and welfare level of the Chinese hooksnout carp (Opsariichthys bidens), an experiment was carried out for 56 d with four types of enrichment environments: low-density physical enrichment, high-density physical enrichment, low-density social enrichment, and high-density social enrichment. The experimental results revealed that both physical and social enrichment treatments positively affected the growth and gonadal development of O. bidens. The physical enrichment treatment was found to increase the antioxidants’ content, such as CAT, SOD, and GSH, in the liver of O. bidens. Moreover, this treatment was able to lead to a reduction in MDA content and enhancement of the fish’s antioxidant capabilities. Behavioral observations, cortisol level analysis, and pcna gene expression analysis indicated that the physical enrichment treatment redused the clustering, aggression, and stress behaviors of O. bidens, maintaining them in a low-stress state. In most respects, the high-density physical enrichment has more positive effects than the low-density one. In contrast, the social enrichment treatments resulted in higher stress levels for O. bidens.

Adult neurogenesis improves spatial information encoding in the mouse hippocampus

Adult neurogenesis is a unique form of neuronal plasticity in which newly generated neurons are integrated into the adult dentate gyrus in a process that is modulated by environmental stimuli. Adult-born neurons can contribute to spatial memory, but it is unknown whether they alter neural representations of space in the hippocampus. Using in vivo two-photon calcium imaging, we find that male and female mice previously housed in an enriched environment, which triggers an increase in neurogenesis, have increased spatial information encoding in the dentate gyrus. Ablating adult neurogenesis blocks the effect of enrichment and lowers spatial information, as does the chemogenetic silencing of adult-born neurons. Both ablating neurogenesis and silencing adult-born neurons decreases the calcium activity of dentate gyrus neurons, resulting in a decreased amplitude of place-specific responses. These findings are in contrast with previous studies that suggested a predominantly inhibitory action for adult-born neurons. We propose that adult neurogenesis improves representations of space by increasing the gain of dentate gyrus neurons and thereby improving their ability to tune to spatial features. This mechanism may mediate the beneficial effects of environmental enrichment on spatial learning and memory.

Experience-dependent grooming microstructure alterations and gastrointestinal dysfunction in the SAPAP3 knockout mouse model of compulsive behaviour

BackgroundCompulsive- and anxiety-like behaviour can be efficiently modelled in SAPAP3 knockout (KO) mice, a preclinical model of relevance to obsessive-compulsive disorder (OCD). Although there is emerging evidence in the clinical literature of gastrointestinal dysfunction in OCD, no previous studies have investigated gut function in preclinical models of relevance to OCD. Similarly, the effects of voluntary exercise (EX) or environmental enrichment (EE) have not yet been explored in this context. MethodWe comprehensively phenotyped the SAPAP3 KO mouse model, including the assessment of grooming microstructure, anxiety- and depressive-like behaviour, and gastrointestinal function. Mice were exposed to either standard housing (SH), exercise (EX, provided by giving mice access to running wheels), or environmental enrichment (EE) for 4 weeks to investigate the effects of enriched housing conditions in this animal model relevant to OCD. FindingsOur study is the first to assess grooming microstructure, perseverative locomotor activity, and gastrointestinal function in SAPAP3 KO mice. We are also the first to report a sexually dimorphic effect of grooming in young-adult SAPAP3 KO mice; along with changes to grooming patterning and indicators of gut dysfunction, which occurred in the absence of gut dysbiosis in this model. Overall, we found no beneficial effects of voluntary exercise or environmental enrichment interventions in this mouse model; and unexpectedly, we revealed a deleterious effect of wheel-running exercise on grooming behaviour. We suspect that the detrimental effects of experimental housing in our study may be indicative of off-target effects of stress—a conclusion that warrants further investigation into the effects of chronic stress in this preclinical model of compulsive behaviour.

Virtual Reality Environmental Enrichment Effects on Craving for Cigarette in Smokers.

Background: Preclinical studies suggested the exposure to environmental enrichment (EE) as an intervention able to prevent or reduce nicotine-taking and nicotine-seeking behaviors. Virtual reality (VR) may help to test the effects of EE in smokers in a reproducible and feasible manner. Materials and Methods: In the present study, 31 smokers (14 women) were divided into two groups: (1) exposure to a virtual EE (VR-EE) and (2) exposure to a virtual neutral environment (VR-NoEE). Cigarette craving was assessed as basal and evoked, at different timepoints during the session. Behavior activity during VR exposure, mood, and subjective measures were also collected. Results: EE exposure in VR significantly reduced craving scores from basal timepoint. This was not observed in the VR-NoEE group, which significantly increased craving compared with values at neutral scenario. When both groups were exposed to smoking-related VR scenario, the VR-EE group showed an increased craving compared with previous timepoint up to score values not different from those in the VR-NoEE group. A significant positive correlation between basal craving scores and interactive behavior with virtual smoking cues was observed in the VR-NoEE but not in the VR-EE group. Conclusion: These findings suggest that virtual EE might have an inhibitory effect in smokers on basal, but not on evoked cigarette craving. Noteworthily, the interactive activity correlation to craving scores in the VR-NoEE participants was not observed in the VR-EE group, adding further evidence that the enrichment simulation was nonetheless able to modify behavior in the smoking-related scenario.

Effects of maternal age and environmental enrichment on learning ability and brain size.

It is well known that maternal age at reproduction affects offspring lifespan and some other fitness-related traits, but it remains understudied whether maternal senescence affects how offspring respond to their environments. Early environment often plays a significant role in the development of an animal's behavioral phenotype. For example, complex environments can promote changes in cognitive ability and brain morphology in young animals. Here, we study whether and how maternal effect senescence influences offspring plasticity in cognition, group behavior, and brain morphology in response to environmental complexity. For this, juvenile 3-spined sticklebacks from young and old mothers (i.e. 1-yr and 2-yr-old) were exposed to different levels of environmental enrichment and complexity (i.e. none, simple, and complex), and their behavior, cognitive ability, and brain size were measured. Exposing fish to enriched conditions improved individual learning ability assessed by a repeated detour-reaching task, increased the size of the whole brain, and decreased aggressive interactions in the shoal. Maternal age did not influence the inhibitory control, learning ability, and group behavioral responses of offspring to the experimental environmental change. However, maternal age affected how some brain regions of offspring changed in response to environmental complexity. In offspring from old mothers, those exposed to the complex environment had larger telencephalons and cerebellums than those who experienced simpler environments. Our results suggest that maternal effect senescence may influence how offspring invest in brain functions related to cognition in response to environmental complexity.

The effect of late-life environmental enrichment on stress and anxiety: The role of sex and age-related differences in coping with aversive stimuli

Anxiety significantly diminishes the quality of life in older adults, and the drugs used for its treatment often come with risky side effects. Non-pharmacological protocols could be valuable, but more research is needed in this area. Environmental enrichment induces positive effects on anxiety-like behavior in young and adult animals; whether the same happens in aged animals is still elusive. The aged brain undergoes changes that contribute to make it “fragile” and consequently even mild, potentially positive stimuli can trigger dyshomeostasis, worsening rather than ameliorating functioning. Here, by combining behavioral analysis and measurement of serum and brain corticosterone levels, we show that late-life environmental enrichment can induce eustress or distress, depending on sex and hypothalamic-pituitary-adrenal axis function. These findings pave the way for optimizing outcomes and minimizing undesired effects in the clinical setting, underscoring the need to overcome the limits of gender medicine and emphasizing the crucial role of individually tailored therapies.

Effects of Environmental Enrichment on Exposure to Human-Relevant Mixtures of Endocrine Disrupting Chemicals in Zebrafish.

Fish models used for chemical exposure in toxicological studies are normally kept in barren tanks without any structural environmental enrichment. Here, we tested the combined effects of environmental enrichment and exposure to two mixtures of endocrine disrupting chemicals (EDCs) in zebrafish. Firstly, we assessed whether developmental exposure to an EDC mixture (MIX G1) combined with rearing the fish in an enriched environment influenced behaviour later in life. This was evaluated using locomotion tracking one month after exposure, showing a significant interaction effect between enrichment and the MIX G1 exposure on the measured locomotion parameters. After three months, we assessed behaviour using custom-made behaviour tanks, and found that enrichment influenced swimming activity. Control fish from the enriched environment were more active than control fish from the barren environment. Secondly, we exposed adult zebrafish to a separate EDC mixture (MIX G0) after rearing them in a barren or enriched environment. Behaviour and hepatic mRNA expression for thyroid-related genes were assessed. There was a significant interaction effect between exposure and enrichment on swimming activity and an effect of environment on latency to approach the group of conspecifics, where enriched fish took more time to approach the group, possibly indicating that they were less anxious. Hepatic gene expression of a thyroid-related gene (thrb) was significantly affected by EDC exposure, while enrichment had no discernible impact on the expression of the measured genes. In conclusion, environmental enrichment is important to consider when studying the effects of EDCs in fish.

Naturalistic housing condition promotes behavioral flexibility and increases resilience to stress in rats.

Behavioral flexibility is an indispensable cognitive ability that allows the adjustment of behavioral responses to different situations, while resilience refers to the capability to deal effectively with stress. On one hand, standard laboratory housing provides impoverished cognitive, sensory, and physical stimulation compared to the conditions found in nature. Conversely, enriched and naturalistic housing conditions offer a broadening in the behavioral repertoire that can be depicted by the animals in their home cages, in addition to enabling a better management of possible stressors. Here, we investigated the effects of environmental enrichment and naturalistic housing compared to the standard laboratory housing on different behavioral tasks, including Morris water maze, open field, object location, and fear conditioning. This allowed us to evaluate how different housing conditions modulate behavioral flexibility and resilience to stress, in addition to spatial memory, in adult male rats. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Effects of environmental enrichment on GLUT expression in the visual cortex of amblyopic rats

ObjectiveTo investigate the potential changes of glucose metabolism and glucose transporter protein (GLUT) in the visual cortex of formally deprived amblyopic rats, as well as the effects of enriched environments on the levels of nerve conduction and glucose metabolism in the visual cortex of amblyopic rats. Methods36 rats were randomly divided into three groups: CON + SE (n = 12), MD + SE (n = 12) and MD + EE (n = 12). The right eyelids of both MD + SE and MD + EE groups were sutured. After successful modelling, the MD + EE group was maintained in an enriched environment, and the other two groups were kept in the same environment. Pattern visual evoked potentials (PVEP) was used to confirm models' effect, glucose metabolism was analyzed by Micro-PET/CT (18F-FDG), and the protein as well as mRNA expression levels of GLUT were detected by Western Blot and quantitative RT-PCR (quantitative Reverse Transcription-Polymerase Chain Reaction) analyses, site of GLUT expression by immunofluorescence (IF). ResultsAfter suture modelling, both the MD + EE and MD + SE groups objective visual nerve conduction function decreased, the glucose metabolism in the visual cortex was markedly lower. After the enriched environment intervention, it recovered in the MD + EE group. The expression levels of GLUT1 and GLUT3 were increased in the MD + EE group in comparison with the MD + SE group. GLUT1 was primarily expressed on astrocytes and endothelial cells, but GLUT3 was mainly expressed on neurons. ConclusionEnrichment of the environment exhibited a therapeutic effect on amblyopia, which could be related to the enhancement of glucose metabolism and GLUT expression in the visual cortex.

Effects of Environmental Enrichment on Stress and Welfare in Laboratory Animals

Purpose: The general purpose of this study was to examine the effects of environmental enrichment on stress and welfare in laboratory animals.
 Methodology: The study adopted a desktop research methodology. Desk research refers to secondary data or that which can be collected without fieldwork. Desk research is basically involved in collecting data from existing resources hence it is often considered a low cost technique as compared to field research, as the main cost is involved in executive’s time, telephone charges and directories. Thus, the study relied on already published studies, reports and statistics. This secondary data was easily accessed through the online journals and library.
 Findings: The findings reveal that there exists a contextual and methodological gap relating to the effects of environmental enrichment on stress and welfare in laboratory animals. Preliminary empirical review revealed that that enriching their living environments significantly improved their well-being. They found that interventions such as physical, social, cognitive, and sensory enrichment reduced stress levels, promoted natural behaviors, and enhanced cognitive function. Tailoring enrichment programs to specific species' needs and considering factors like environmental complexity and novelty proved crucial. Moreover, these interventions not only benefited animal welfare but also improved research outcomes by reducing stress and enhancing the validity of preclinical studies. Overall, the research underscored the importance of implementing evidence-based enrichment strategies to ensure the ethical treatment of laboratory animals and enhance the reliability of scientific research.
 Unique Contribution to Theory, Practice and Policy: The Biophilia Hypothesis, Optimal Stimulation theory and Stress Inoculation theory may be used to anchor future studies on stress and welfare in laboratory animals. The study made significant contributions to theory, practice, and policy in the field of laboratory animal welfare. It provided valuable insights into the underlying mechanisms of environmental enrichment's influence on animal well-being, contributing to existing theoretical frameworks such as the Biophilia Hypothesis, Optimal Stimulation Theory, and Stress Inoculation Theory. Additionally, the study offered practical recommendations for implementing evidence-based enrichment programs tailored to the needs of different animal species. These findings informed policy development by guiding the establishment of standards for enrichment in laboratory animal facilities, enhancing the protection and welfare of laboratory animals across institutional and national levels.
 Keywords: Environmental Enrichment, Laboratory Animals, Stress, Welfare, Mechanisms, Biophilia Hypothesis, Optimal Stimulation Theory, Stress Inoculation Theory, Implementation, Standards, Well-Being

Social isolation and post-weaning environmental enrichment effects on rat emotional behavior and serotonergic system.

Social isolation (SI) is related to adverse neurobehavioral effects and neurochemical changes when it occurs early in development. On the other hand, environmental enrichment (EE) is associated with a reduction in anxiety-like and depression-like behavior, as well as an increase in serotonin (5-HT) levels in the prefrontal cortex and hippocampus in rodents. This study systematically reviewed the effects of SI and EE on emotional behavior and serotonergic system components in rats after weaning. Primary experimental studies that used subgroups of rats subjected to SI, EE, and normal social conditions after weaning were considered eligible. Studies that used transgenic rodents, ex vivo studies, in vitro studies, human research, or in silico studies were ineligible. Two authors completed searches in Medline/PubMed, LILACS, Scopus, Web of Science, EMBASE, and Open Gray. The Kappa index was calculated to assess agreement between reviewers and assess study quality. The results showed that the animals exposed to EE showed better adaptation to a new environment. Furthermore, EE increased 5-HT levels in the hippocampus and prefrontal cortex of rodents. Thus, it appears that an EE during the critical period of development may reduce anxiety/depression-like behaviors, as well as increase long-term neurotransmitter response.

Environmental enrichment promotes adaptive responding during tests of behavioral regulation in male heterogeneous stock rats

Organisms must regulate their behavior flexibly in the face of environmental challenges. Failure can lead to a host of maladaptive behavioral traits associated with a range of neuropsychiatric disorders, including attention deficit hyperactivity disorder, autism, and substance use disorders. This maladaptive dysregulation of behavior is influenced by genetic and environmental factors. For example, environmental enrichment produces beneficial neurobehavioral effects in animal models of such disorders. The present study determined the effects of environmental enrichment on a range of measures related to behavioral regulation using a large cohort of male, outbred heterogeneous stock (HS) rats as subjects. Subjects were reared from late adolescence onwards either in pairs in standard housing with minimal enrichment (n = 200) or in groups of 16 in a highly enriched environment consisting of a large multi-level cage filled with toys, running wheels, and shelters (n = 64). Rats were subjected to a battery of tests, including: (i) locomotor response to novelty, (ii) light reinforcement, (iii) social reinforcement, (iv) reaction time, (v) a patch-depletion foraging test, (vi) Pavlovian conditioned approach, (vii) conditioned reinforcement, and (viii) cocaine conditioned cue preference. Results indicated that rats housed in the enriched environment were able to filter out irrelevant stimuli more effectively and thereby regulate their behavior more efficiently than standard-housing rats. The dramatic impact of environmental enrichment suggests that behavioral studies using standard housing conditions may not generalize to more complex environments that may be more ethologically relevant.

The Comparative Effect of Occupational and Musical Enrichment on Fecal Glucocorticoid Metabolite Levels in a Captive Colony of Stumptail Macaques (Macaca arctoides).

Environmental enrichment improves captive animal welfare by reducing stress-related behaviors. Previous studies in a captive colony of stumptail macaques (Macaca arctoides) reported a reduction of aggression, coprophilia, and stereotypic behaviors after an occupational enrichment program; however, the effect on stress hormones such as glucocorticoids has not been investigated yet. The goal of this study was to compare the effect of sex, age, and social rank on changes in fecal glucocorticoid metabolites (fGCM) after applying two kinds of enrichments (occupational vs. musical) in a captive colony of stumptail macaques. We collected 234 fecal samples from 25 stumptail macaques under the following conditions: (1) basal (no enrichment), (2) three weeks of occupational enrichment, and (3) three weeks of relaxing/classical music. The Generalized Estimated Equation Model showed an increase in fGCM levels after the occupational enrichment only in adult subjects (p = 0.003 compared to basal). The fGCM levels reached by the adults after the occupational enrichment was higher than that of juveniles (p = 0.002) and subadults (p = 0.02). Occupational and musical enrichment decreased fGCM levels only in middle-ranking individuals (p < 0.001 and p = 0.013, respectively). No sex differences were found. In conclusion, there were age and rank differences in individuals' physiological reactivity to the effects of environmental enrichment which need to be considered when planning enrichment programs.

Effects of Environmental Enrichments on Welfare and Hepatic Metabolic Regulation of Broiler Chickens.

The aims of this study were to find suitable environmental enrichment (EE) and evaluate the combined effect of two EEs, variable light intensity (VL) lighting program and EH, on mental health and hepatic metabolic regulation in commercial broilers. To find the advantageous EEs for broilers, three different EEs (board, hut, and ramp) were tested in trial 1. EEs were placed and the engagement of birds to EEs, dustbathing behavior, and daily physical activity were observed. Birds treated with huts showed higher engagement than the board- or ramp-treated birds (p < 0.05). The results of dustbathing behavior and daily physical activity indicated that the environmental hut (EH) is the most favorable enrichment for broilers. In the second trial, to test the effect of EHs on mental health and hepatic metabolic conditions, the brain and liver were sampled from the four treatment birds (20 lx_Con, 20 lx_Hut, VL_Con and VL_Hut) on day 42. The lower expression of TPH2 (tryptophan hydroxylase 2) of VL_Hut birds than those of VL_Con and 20 lx_Hut treated birds suggests the combining effect of EHs with the VL lighting program on the central serotonergic homeostasis of broilers. Reduced expressions of TH (tyrosine hydroxylase), GR (glucocorticoid receptor), BDNF (brain-derived neurotrophic factor) of VL_Hut treated birds compared to those of VL_Con and 20 lx_Hut birds suggest lower stress, stress susceptibility, and chronic social stress in VL_Hut treated birds. The expression of CPT1A (carnitine palmitoyl transferase 1) increased over three-fold in the liver of VL_Con birds compared to 20 lx_Con birds (p < 0.05). EHs treatment in VL birds (VL_Hut) significantly decreased CPT1A but not in 20 lx birds (20 lx_Hut). The expression of ACCα (acetyl-CoA carboxylase alpha) was significantly decreased in VL_Con birds compared to 20 lx_Con birds. There was no significant difference in the hepatic FBPase (fructose-1,6-bisphosphatase), GR, and 11β-HSD1 (11 β-hydroxysteroid dehydrogenease-1) expression between 20 lx_Con and VL_Con birds, but EHs significantly stimulated GR in 20 lx_Hut birds, and stimulated FBPase and 11β-HSD1 expression in the VL_Hut birds compared to 20 lx_Con birds, suggesting that the VL lighting program reduced fatty acid synthesis and increased fatty acid β-oxidation in the broilers' liver and VL_Hut improved the hepatic de novo glucose production. Taken together, the results suggest that the stimulated voluntary activity by EHs in the light-enriched broiler house improved mental health and hepatic metabolic function of broilers and may indicate that the improved hepatic metabolic function contributes to efficient nutritional support for broilers.

Maternal environmental enrichment protects neonatal brains from hypoxic-ischemic challenge by mitigating brain energetic dysfunction and modulating glial cell responses

There is evidence that maternal milieu and changes in environmental factors during the prenatal period may exert a lasting impact on the brain health of the newborn, even in case of neonatal brain hypoxia-ischemia (HI). The present study aimed to investigate the effects of maternal environmental enrichment (EE) on HI-induced energetic and metabolic failure, along with subsequent neural cell responses in the early postnatal period. Male Wistar pups born to dams exposed to maternal EE or standard conditions (SC) were randomly divided into Sham-SC, HI-SC, Sham-EE, and HI-EE groups. Neonatal HI was induced on postnatal day (PND) 3. The Na+,K+-ATPase activity, mitochondrial function and neuroinflammatory related-proteins were assessed at 24 h and 48 h after HI. MicroPET-FDG scans were used to measure glucose uptake at three time points: 24 h post-HI, PND18, and PND24. Moreover, neuronal preservation and glial cell responses were evaluated at PND18. After HI, animals exposed to maternal EE showed an increase in Na+,K+-ATPase activity, preservation of mitochondrial potential/mass ratio, and a reduction in mitochondrial swelling. Glucose uptake was preserved in HI-EE animals from PND18 onwards. Maternal EE attenuated HI-induced cell degeneration, white matter injury, and reduced astrocyte immunofluorescence. Moreover, the HI-EE group exhibited elevated levels of IL-10 and a reduction in Iba-1 positive cells. Data suggested that the regulation of AKT/ERK1/2 signaling pathways could be involved in the effects of maternal EE. This study evidenced that antenatal environmental stimuli could promote bioenergetic and neural resilience in the offspring against early HI damage, supporting the translational value of pregnancy-focused environmental treatments.

New insights into the physiological effects of structural environmental enrichment on black sea bream (Acanthopagrus schlegelii) based on a combined analysis of transcriptomics and metabolomics

Environmental enrichment (EE) has been generally accepted as an effective and promising way to enhance the performance and improve the welfare of animals kept in captivity. Evidence for the effects of EE on fish has accumulated rapidly, but little is known about its underlying mechanisms. In this study, black sea bream (Acanthopagrus schlegelii) were reared under enriched and enrichment-free conditions for 30 (post-larval) and 60 (juvenile) days. Physiological, transcriptome, and metabolome data were compared to investigate potential rearing improvements, physiological responses to acute stress, and the underlying mechanisms. The results showed that fish reared under enriched conditions had significantly better growth performance, a higher survival rate, and lower basal cortisol levels. Meanwhile, the cortisol, lactic acid, malondialdehyde (MDA), and total antioxidant capacity (T-AOC) levels in fish subjected to acute stress suggested that EE-reared individuals presented greater stress resistance. However, the effect of EE may decrease with the extension of treatment time for larger fish. The transcriptome analysis showed that energy-related pathways (including oxidative phosphorylation, the citrate cycle, and glycolysis/gluconeogenesis) as well as protein folding, sorting, and degradation-related pathways (protein processing in the endoplasmic reticulum and proteasome pathways); replication and repair related pathways (including pathways involved in nucleotide excision repair, base excision repair, mismatch repair, and homologous recombination); and immune-related pathways (complement and coagulation cascades pathway and the IL-17 signaling pathway) were significantly altered in the EE-reared individuals. In addition, integrated analysis of metabolome and transcriptome data revealed marked enrichment of transcription-associated metabolites involved in cortisol synthesis and secretion, taste transduction, olfactory transduction, and protein digestion and absorption pathways. Our results suggested that EE may influence the growth, fitness, and stress resistance of A. schlegelii by regulating a series of biological processes including energy metabolism, cortisol synthesis, antioxidant enzyme activities, protein folding, DNA replication and repair, and complement and coagulation cascades.

Sex difference in the effect of environmental enrichment on food restriction-induced persistence of cocaine conditioned place preference and mechanistic underpinnings

Psychosocial and environmental factors, including loss of natural reward, contribute to the risk of drug abuse. Reward loss has been modeled in animals by removal from social or sexual contact, transfer from enriched to impoverished housing, or restriction of food. We previously showed that food restriction increases the unconditioned rewarding effects of abused drugs and the conditioned incentive effects of drug-paired environments. Mechanistic studies provided evidence of decreased basal dopamine (DA) transmission, adaptive upregulation of signaling downstream of D1 DA receptor stimulation, synaptic upscaling and incorporation of calcium-permeable AMPA receptors (CP-AMPARs) in medium spiny neurons (MSNs) of nucleus accumbens (NAc). These findings align with the still evolving ‘reward deficiency’ hypothesis of drug abuse. The present study tested whether a compound natural reward that is known to increase DA utilization, environmental enrichment, would prevent the persistent expression of cocaine conditioned place preference (CPP) otherwise observed in food restricted rats, along with the mechanistic underpinnings. Because nearly all prior investigations of both food restriction and environmental enrichment effects on cocaine CPP were conducted in male rodents, both sexes were included in the present study. Results indicate that environmental enrichment curtailed the persistence of CPP expression, decreased signaling downstream of the D1R, and decreased the amplitude and frequency of spontaneous excitatory postsynaptic currents (EPSCs) in NAc MSNs of food restricted male, but not female, rats. The failure of environmental enrichment to significantly decrease food restriction-induced synaptic insertion of CP-AMPARs, and how this may accord with previous pharmacological findings that blockade of CP-AMPARs reverses behavioral effects of food restriction is discussed. In addition, it is speculated that estrous cycle-dependent fluctuations in DA release, receptor density and MSN excitability may obscure the effect of increased DA signaling during environmental enrichment, thereby interfering with development of the cellular and behavioral effects that enrichment produced in males.