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Colored enrichment devices used in this experiment were (from left to right) translucent amber, clear, red (polycarbonate) and opaque (polyvinyl chloride) and had identical internal diameters and lengths.
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Environmental enrichment (EE) gives laboratory animals opportunities to engage in species-specific behaviors. However, the effects of EE devices on normal physiology and scientific outcomes must be evaluated. We hypothesized that the spectral transmittance (color) of light to which rats are exposed when inside colored enrichment devices (CED) affec...
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Context 1
... the current study, we explored the effect of spectral trans- mittance exposure from commonly used CED (amber, clear, red, and opaque; Figure 1) during the light period in male albino Sprague-Dawley rats. We chose this rat stock because it is among the most widely used in laboratory research, comprising approxi- mately 53% of EE studies. ...
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... in the inside front of the cages were averaged for all cage positions and had little variance (57.6 ± 10.5 lx, n = 84 [7 wk, 12 cages]). Laboratory CED used in this experiment are shown in Figure 1. Measurements of radiometric irradiance (lx) from inside the CED positioned in the middle of the 2 ventilated rack rows to ensure that there were no significant differences in lighting intensity inside the cages (at rodent eye level). ...
Citations
... These cells can respond to different wavelengths of light compared to other photoreceptors. Considering these effects, few studies have investigated the effects of various color lighting treatments Dedeke et al., 2017), colorful rat cages (Wren et al., 2014;LaFollettea et al., 2019 ), and colorful objects used in the cages (Wren-Dail et al., 2016) on several performance parameters of rats and their physiological and metabolic properties. However, since many factors such as pigmentation, body temperature, hormonal state, age, species, and sex are effective in meeting the light needs of rats, further studies are required to identify their needs. ...
... Indeed, Davidyan et al., (2021) found that the testosterone hormone was very important for the development of muscle mass in rats, especially during puberty, and its critical importance disappeared with advancing age. In their study, Wren-Dail et al., (2016) augmented standard rat cages with amber, transparent, red, and opaque igloos and found that rats preferred red, amber, and opaque tunnels more than transparent color tunnels. Feed consumption, water consumption, live weight gain, and plasma melatonin levels were higher in the red group. ...
The study aimed to determine how the complete visible light spectrum and white light affected the growth characteristics of rat puppies, oxidative stress measures, and mother fertility. For the purposes of the study, a total of 56 female and 28 male breeding rats (Sprague Dawley) were mated, with 8 female and 4 male rats per group. Growth characteristics were followed until the 63rd day. At the end of the research, 4 female and 4 male rats from each group were euthanized under anesthesia. Oxidative stress parameters were determined in their blood samples. The group that received green lighting had the highest puppy yield and weaning rate. The blue lighting group had the highest live weight and live weight gain during the suckling period. The groups that were red and green had the highest pubertal weights. The highest feed consumption was obtained in the green lighting group. Feed utilization and water consumption were found to be similar among the lighting groups. The white lighting group had the highest total antioxidant level (TAS), while the red lighting group had the lowest. The highest total oxidant (TOS) and oxidative stress index (OSI) were found in the red group. These results suggest that rats were affected differently by the light spectrum at varying physiological periods.
... 24 Several examples in the literature show that rats prefer red-tinted enrichments that filter out light in their visible spectrum and also decrease overall light intensity. 23,35 Rats housed in red cages and under reduced light intensity (25 lx) seem to have more positive affect. 10 While most of our knowledge of rodent light preferences comes from rat research, a recent study found that female CD-1 mice generally prefer to gather nesting material and spend more time inactive in red tinted cages (108 ± 21 lx) compared with clear cages (342 ± 85 lx). 3 The only time mice showed equal preference between the 2 cage types was the combination of 32 °C (a temperature near thermoneutrality and considered preferred) and a clear cage. ...
... Both rats and mice prefer environments that are darker than typical cage conditions. 3,23,35 Mice also naturally build nests, and if nests are complex enough to form an enclosed dome, light will certainly be blocked by the material. 6,11 Nonetheless, further measurements across cage Vol 61, No 6 Journal of the American Association for Laboratory Animal Science November 2022 locations within a rack would document the true extent of light variability. ...
... While evidence in mice is lacking, research in rats shows that changes in light wave frequency can alter various hormone pathways. 35,36 However, to the best of our knowledge, the physiologic consequences of exposure to different light intensities (for example 10 lx compared with 100 lx compared with 500 lx) during the light cycle is unknown. ...
Excessive sound, vibration, and light are detrimental to rodent welfare, yet these parameters are rarely recorded in vivaria. Whether housing environments exceed the suggested thresholds and which specific factors may alter these parameters is generally unknown. The goal of this study was to determine how environmental factors may alter sound, vibration, and light at the room and cage levels. Measurements were made using an ultrasonic microphone, accelerometer, and light sensor. Measurement sites were 1) in open air at a central location in 64 rooms located in 9 buildings, and 2) inside an empty mouse or rat cage containing chow, water, and bedding and located on an animal transfer station ( n = 51) or housing rack ( n = 102). Information collected for each transfer station and rack measurement included the year of manufacture, the species on the rack, and the number of cages on the rack. For each location, a baseline measurement was taken with the transfer station turned off, followed by another measurement after the transfer station was turned on. In general, many factors influenced ambient sound, vibration, and light, indicating that values are not uniform across rodent rooms in the same institution or across cages in a single room. Sound peaks capable of startling rodents were measured in association with hallway ultrasonic motion sensors and during cage change. Vibration and light intensity were generally low when cages were located on the rack. In contrast, active transfer stations had more vibration and light intensity, reaching levels that were potentially stressful for rodents. These data reflect the ambient sound, vibration, and light that rodents experience during normal facility operations. These patterns may extend to other locations, but given the variability in all parameters, the data highlight the need for institutions to conduct their own monitoring.
... While our study did not find physiologic effects indicative of stress based on the acute use of a red-tinted chamber, some evidence suggests that chronic use of red light and red-tinted products has both physiologic and behavioral effects in rodents. 17,18,24,34,43,48,52,55,66,67 Some of these studies have documented significant effects in albino strains despite their visual limitations. For example, albino Sprague-Dawley (SD) rats have disruptions in sleep patterns, locomotor activity, and ovulatory timing after exposure to red light during the dark cycle. ...
... 24,34,48 In addition, the use of redtinted enrichment devices and caging in SD rats significantly alters other circadian parameters, including food and water intake, plasma melatonin, and corticosterone. 18,66,67 Our findings here add to a growing body of evidence suggesting that red light and red-tinted products can have wide-ranging (and strain specific) effects on rodents and research. ...
Isoflurane has been characterized as a distressing agent for rodents, causing both physiologic and behavioral effects. Using a “darkened home cage” has been recommended during CO2 administration for rodent euthanasia; this is arguably a similar animal experience to anesthetic induction with isoflurane. Based on the premise that rodents perceive red light as darkness via the primary optic tract, we compared physiologic and behavioral markers of stress in 2 inbred strains of mice (C57BL/6J and BALB/cJ) anesthetized with isoflurane in either a red-tinted (dark) induction chamber or a traditional translucent induction chamber. Physiologic stress was assessed based on plasma levels of norepinephrine, epinephrine, and corticosterone. Stress-related behaviors (rearing, face wiping, and jumping) were recorded on video and scored from initiation of induction to loss of consciousness. No significant correlations were found between chamber type and physiologic stress hormones. As compared with the translucent chamber, stress-related behaviors were more frequent in the red-tinted chamber, including: 1) significantly higher rearing frequencies in BALB/cJ mice; 2) higher behavioral stress scores in BALB/cJ and male C57BL/6J mice; and 3) more face wiping behavior when considering all mice combined. These findings suggest that mice do not experience significant alleviation of physiologic indices of stress when anesthetized in a red-tinted induction chamber. Furthermore, isoflurane induction in the red tinted chamber appeared to increase the expression of stress related behaviors, particularly in BALB/cJ mice. Based on our findings and a growing body of literature on the unintended effects of red light, we do not recommend using red-tinted chambers for induction of anesthesia in mice.
... TThe light intensity per se in the laboratory and housing tanks may also impact behavioral and endocrine responses in zebrafish, as demonstrated in the LDT under different illumination conditions (Facciol et al., 2019;Facciol et al., 2017) and in housing tanks of different colors . Furthermore, colors can also provide important physiological and emotional benefits to laboratory animals (Dauchy et al., 2013;LaFollette et al., 2019;Wren-Dail et al., 2016), as rats emit more 50-kHz ultrasonic vocalizations in red 200-lux vs. clear cages (LaFollette et al., 2019). Likewise, rats housed with opaque colored EE objects display disrupted night-time melatonin concentrations compared to clear colored EE objects (Wren-Dail et al., 2016). ...
... Furthermore, colors can also provide important physiological and emotional benefits to laboratory animals (Dauchy et al., 2013;LaFollette et al., 2019;Wren-Dail et al., 2016), as rats emit more 50-kHz ultrasonic vocalizations in red 200-lux vs. clear cages (LaFollette et al., 2019). Likewise, rats housed with opaque colored EE objects display disrupted night-time melatonin concentrations compared to clear colored EE objects (Wren-Dail et al., 2016). It is therefore possible that similar benefits can be provided by color-based EE is zebrafish. ...
Color is an important environmental factor that in multiple ways affects human and animal behavior and physiology. Widely used in neuroscience research, various experimental (animal) models may also improve our understanding of how different colors impact brain and behavioral processes. The zebrafish (Danio rerio) is rapidly emerging as an important novel model species to explore complex neurobehavioral processes. The growing utility of zebrafish in biomedicine makes it timely to consider the role of colors in their behavioral and physiological responses. Here, we summarize mounting evidence implicating colors as a critical variable in zebrafish models and neurobehavioral traits, with a particular relevance to CNS disease modeling, genetic and pharmacological modulation, as well as environmental enrichment and animal welfare. We also discuss the growing value of zebrafish models to study color neurobiology and neurobehavioral phenomics, and outline future directions of research in this field.
... Likewise, findings in rats demonstrated the importance of taking opacity into account. An experiment performed by Wren-Dail et al. aimed to examine the impact of different colored tunnels (amber, red, clear, or opaque) on the metabolism of pair-housed male Crl:SD rats (Wren-Dail et al., 2016). The colored devices, which were placed for 25 days into the animals' cages, altered the circadian rhythms of plasma measures of metabolism and physiology. ...
... The colored devices, which were placed for 25 days into the animals' cages, altered the circadian rhythms of plasma measures of metabolism and physiology. Thus, all mentioned opacity-investigating studies, including ours, assumed opacity to affect experimental outcomes (Wren-Dail et al., 2016). Nevertheless, future studies are necessary in mice to investigate opacity related differences to validate the presumption. ...
Group-housing is highly important for social animals. Group-housing of male mice in captivity though often leads to aggression with partially disastrous consequences for the animals as well as for the quality of experimental data. In this study we investigated the effect of a novel “cross-enrichment”, i.e. a colored partial cage divider, which is provided in transparent or black and which is partly separating the cage in four small areas. Group-housed male C57BL/6NCrl mice (three per cage) were maintained under either standard conditions (nestlet group) or enriched conditions (nestlet + cage divider in black [EB-group] or in transparent [ET-group]) for eight weeks. Several physiological parameters (body weight, blood glucose, stress induced hyperthermia, fecal corticosterone metabolites and organ weights) and behavioral tests (Nest test, Openfield/social Novel-Object, Dark-Light-Box, Hotplate and Resident-Intruder test) were measured/performed to determine enrichment-induced effects. In comparison to nestlet- and ET-group animals, EB-mice showed significant increased stress-associated parameters, i.e. in the blood glucose concentration. Furthermore, EB animals seemed to have enhanced emotional stress with a poorer outcome in the nest test and a higher amount of fecal boli at the end of the social Novel-Object test. Additionally, EB-mice behaved more aggressively towards conspecifics after cleaning cages. We conclude that the opacity of the tested partial cage dividers has a huge impact on aggressive behavior and therefore may lead to significant changes in behavioral and physical measures potentially altering research outcomes.
... In addition to providing rats a place to hide, red tinted shelters also change the lighting environment including light intensity and spectral make up which could impact rat affect. Tinted shelters reduce overall light intensity (Wren-Dail et al., 2016) and those tinted red reduce the intensity of blue-green wavelengths of light (Wren et al., 2014). Rats find high light intensity aversive, which can increase rat stress and anxiety (Schlingmann et al., 1993a(Schlingmann et al., , 1993b. ...
Environmental enrichment provides physiological and emotional benefits to laboratory rodents. Red tinted shelters are a common enrichment found in laboratories that provide rodents with a hiding space shielded from bright light. Red tinting alters the light’s spectral make-up which reduces the amount of blue-green wavelengths while also reducing overall light intensity. However, it is unknown if red tinting has behavioral affects. Heterospecific play, or “rat tickling,” is a technique that mimics aspects of rat rough-and-tumble play and elicits 50-kHz ultrasonic vocalizations (USVs). These USVs are indicative of positive affect and reward in rats, which could be used to evaluate the impact of environmental enrichment. Our objective was to determine the effect of housing rats in different cage colors (red or clear) and light intensities (25 or 200 lx) on USV production during tickling.
Long Evans and CD rats (N = 48) were born, raised, and tickled in a randomly assigned caging treatment: red 200 lx, red 25 lx, clear 200 lx, or clear 25 lx. Rats were co-housed at weaning into same sex pairs (1 Long Evans, 1 CD). Rats were tickled for seven days and then once weekly for 10 weeks total. Recordings of USVs were made during each session and data were analyzed using general linear models.
Our results showed an interaction effect between cage color and light intensity. For our primary outcome of 50-kHz USVs during weekly tickling sessions, rats produced more 50-kHz USVs in red 200 lx cages than in either clear 200 lx cages or red 25 lx cages (p’s < 0.0001). Additionally, rats produced more 50-kHz USVs in clear 25 lx cages than either clear 200 lx cages or red 25 lx cages (p’s < 0.0001).
In conclusion, our results indicate that the environment rats are raised, housed, and tickled in – specifically light intensity and spectral make-up - as influenced by cage color – significantly impacts rat positive affect. This conclusion is based on increased 50-kHz USV production during tickling in red 200 lx cage and clear 25 lx caging. It appears that at high light intensity, red caging results in the most positive affect. Conversely, at low light intensity clear caging results in the most positive affect. Overall, our results support the importance of reporting and considering environmental variables on positive affect as assessed via tickling.
... It has been generally viewed that light is the principal synchronizer of the circadian clock (Contin et al., 2016). Thus, prolonged exposure to artificial light during animal experiments is suspected to be harmful in terms of their behavior and physiology Wren-Dail et al., 2016). An inappropriate light source can also cause cellular damage to animals in experiments, which can ultimately affect the outcomes of many valuable scientific investigations. ...
... It would be reasonable to replace conventional lighting with a more suitable light source that has fewer damaging effects on biological systems but is still capable of generating the specific wavelength requirements for the environment or species while also consuming less power (Pimputkar et al., 2009;Hasan et al., 2014;Seo et al., 2016). Since LEDs are considered such a light source, it would be advantageous if LED-generated spectral tunability could be more conscientiously used for animal care, maintenance, and experiments Wren-Dail et al., 2016). Therefore, it is necessary that we assess any unexpected LED-mediated consequences clearly and understand its mechanism precisely for taking effective measures against any unexpected damage prior to adopting this new light source for animal experiments. ...
Light is an indispensable part of routine laboratory works in which conventional light is generally used. Light‐emitting diodes (LEDs) have come to replace the conventional light thus could be a potent target in biomedical studies. Since blue light is a major component of visible light wavelength, in this study, using a somatic cell from African green monkey kidney, we assessed the possible consequences of blue spectra of LED light in future animal experiments and proposed a potent mitigation against light induced damages. COS‐7 cells were exposed to blue LED light (450 nm) and the growth and DNA damage were assessed at different exposure times. A higher suppression in cell growth and viability was observed under a longer period of blue LED light exposure. The number of apoptotic cells increased as light exposure time was prolonged. Reactive oxygen species generation was also elevated in accordance to the extension of light exposure times. A comparison to dark‐maintained cells revealed that the upregulation of ROS by blue LED light plays a significant role in causing cellular dysfunction in DNA in a time‐dependent manner. In turn, antioxidant treatment has shown to improve the cell growth and viability under blue LED light conditions. This indicates that antioxidants are potential against blue LED light‐induced somatic cell damage. It is expected that this study will contribute to the understanding of the basic mechanism of somatic cell death under visible light and to maximize the beneficial use of LED light in future animal experiments.
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Background: Drug treatment for Spatial memory impairment has a wide range of adverse effects. Objective: To assess the effects of climbing exercise (CE)on spatial memory performance and hippocampal oxidative stress in colchicine induced memory impaired rats. Methods: Thirty male Long-Evans rats (8±2weeks; 225±75 gm)were grouped (6 rats/group)into normal control, sham control, colchicine control, pre colchicine CE and post colchicine CE. In CE, each rat performed 08 to 12 climbs/hour in a climbing tool for consecutive 28 days. Then, reference memory (RM) [Mean escape latency (EL) in acquisition phase, average EL of 5th and 6thacquisition days; number of target crossing (TC) and time spent in target (TT) in probe trial] and working memory (WM) [Mean EL and savings in training and test phase] were assessed by Morris water maze (MWM) test. Then, after sacrifice, hippocampal malondialdehyde (MDA) and glutathione peroxidase (GPx) were estimated. Data were expressed as mean±SEM and analyzed by one way ANOVA followed by Bonferroni’s post hoc test where p£0.05 was considered as statistically significant. Results: This study indicate that intrahippocampal colchicine administration significantly impaired spatial memory, and elevated MDA, decreased GPx level in hippocampus of colchicine control rats. In contrast, both pre and post treatment of CE significantly improved spatial memory retention and attenuated the oxidative damage almost to normal. Conclusion:CE is equally effective in prevention as well as alleviation of colchicine induced spatial memory impairment along with hippocampal oxidative stress in male Long-Evans rats. J Bangladesh Soc Physiol 2024;19(1): 9-22
Background: Memory impairment is an important presentation of many diseases. Sidestream cigarette smoke (SCS), a form of passive smoke, causes neural complications such as impaired memory. The aim of this study was to assess the effect of sidestream cigarette smoke on memory of male Long-Evans rats. Methods: This experimental study was conducted in the Physiology Department of Bangabandhu Sheikh Mujib Medical University. Twelve male Long-Evans rats, having 150 to 200 grams body weight were collected from central animal house of this University. Rats were divided into fresh air group (control) and experimental group (exposer to SCS for 30 minutes twice daily) for 30 consecutive days. For memory evaluation, Morris water maze (MWM) test was performed. Working memory was measured as escape latency in training and four trial phases. Reference memory (escape latency in acquisition phase and target crossings in probe trial. For estimation of hippocampal antioxidant enzymes, catalase and glutathione peroxidase levels were measured by ELISA. Data were expressed as mean (standard error of mean) and t test was done to compare the two groups. P <0.05 was considered as statistically significant. Results: Two to five times higher escape latency (working memory) was observed in experimental rats compared to those of control rats (P<0.001). Moreover, significantly lower (3.8 versus 7.8) target crossings (P<0.001) were found in experimental rats compared to the control rats. In addition, hippocampal catalase (6.2 versus 17.6 U/mg protein) and glutathione peroxidase (1.9 versus 5.6 U/mg protein) levels were found significantly lower (P<0.001) in experimental rats when compared to control rats. Conclusion: The sidestream cigarette smoke caused memory impairment and decrement of hippocampal antioxidant enzymes level in male Long-Evans rats.
Light is an environmental factor that is extrinsic to animals themselves and that exerts a profound influence on the regulation of circadian, neurohormonal, metabolic, and neurobehavioral systems of all animals, including research animals. These widespread biologic effects of light are mediated by distinct photoreceptors—rods and cones that comprise the conventional visual system and melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) of the nonvisual system that interact with the rods and cones. The rods and cones of the visual system, along with the ipRGCs of the nonvisual system, are species distinct in terms of opsins and opsin concentrations and interact with one another to provide vision and regulate circadian rhythms of neurohormonal and neurobehavioral responses to light. Here, we review a brief history of lighting technologies, the nature of light and circadian rhythms, our present understanding of mammalian photoreception, and current industry practices and standards. We also consider the implications of light for vivarium measurement, production, and technological application and provide simple recommendations on artificial lighting for use by regulatory authorities, lighting manufacturers, designers, engineers, researchers, and research animal care staff that ensure best practices for optimizing animal health and well-being and, ultimately, improving scientific outcomes.
