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Differences in selection pressure in nature and labs have profound effects on zebrafish strains. The widely used AB strain of zebrafish has been domesticated over several decades. Recently, there has been an upsurge in the availability of genetically modified lines, e.g., the spiegeldanio ( ), which has a mutation in the fibroblast growth factor receptor 1a ( ) gene. This mutant strain ( ) has previously been reported to be bolder than fish of the Tübingen strain, from which it was generated. Our knowledge on behavioral differences between different zebrafish strains, relative to wild-caught zebrafish, is limited. In the present study we compare behaviors related to interpretation of boldness in male and female offspring (F1) of wild-caught fish, AB and zebrafish. A second aim of the study was to compare the behavior of fish from these strains when tested in different behavioral assays, i.e., shelter seeking, novel tank diving and scototaxis tests. The results demonstrate that behavioral variation exists both within and between the strains, but interpretation of boldness reveals a complex pattern in which behavior differs between strains but is also related to sex and test. Therefore, a careful assessment of various strains of fish using both males and females is warranted in order to strengthen interpretation of results. This is especially important in studies where zebrafish are used as model organisms for human conditions as well as studies evaluating the effects of pharmacological or toxicological substances on behavior.

Background Bitter taste receptors (Tas2rs) are generally considered to sense various bitter compounds to escape the intake of toxic substances. Bitter taste receptors have been found to widely express in extraoral tissues and have important physiological functions outside the gustatory system in vivo. Methods To investigate the physiological functions of the bitter taste receptor cluster Tas2r106/Tas2r104/Tas2r105/Tas2r114 in lingual and extraoral tissues, multiple Tas2rs mutant mice and Gnat3 were produced using CRISPR/Cas9 gene‐editing technique. A mixture containing Cas9 and sgRNA mRNAs for Tas2rs and Gnat3 gene was microinjected into the cytoplasm of the zygotes. Then, T7EN1 assays and sequencing were used to screen genetic mutation at the target sites in founder mice. Quantitative real‐time polymerase chain reaction (qRT‐PCR) and immunostaining were used to study the expression level of taste signaling cascade and bitter taste receptor in taste buds. Perception to taste substance was also studied using two‐bottle preference tests. Results We successfully produced several Tas2rs and Gnat3 mutant mice using the CRISPR/Cas9 technique. Immunostaining results showed that the expression of GNAT3 and PLCB2 was not altered in Tas2rs mutant mice. But qRT‐PCR results revealed the changed expression profile of mTas2rs gene in taste buds of these mutant mice. With two‐bottle preference tests, these mutant mice eliminate responses to cycloheximide due to genetic mutation of Tas2r105. In addition, these mutant mice showed a loss of taste perception to quinine dihydrochloride, denatonium benzoate, and cucurbitacin B (CuB). Gnat3‐mediated taste receptor and its signal pathway contribute to CuB perception. Conclusions These findings implied that these mutant mice would be a valuable means to understand the biological functions of TAS2Rs in extraoral tissues and investigate bitter compound–induced responses mediated by these TAS2Rs in many extraoral tissues. Multiple Tas2rs mutant mice and Gnat3 were generated by Crispr/Cas9 gene‐editing technique. QPCR and immunofluorescence assay was employed to study the expression of bitter receptor in taste bud from these mutant mice. Furthermore, two‐bottle preference test revealed that these mutant mice showed a loss of taste perception to Quinine (QHCI), Denatonium Benzoate (DB), and Cucurbitacin B (CuB). Gnat3‐mediated taste receptor and its signal pathway contributes to CuB perception. These mutant mice would be a valuable means to understand the biological functions of TAS2Rs in extraoral tissues.

Six assays of low-fat venison salchichon were produced using varying proportions of olive oil to replace the traditional pork meat added. The control contained 75% lean venison and 25% pork meat; in the other assays, 15, 25, 35, 45 and 55% of the pork meat was replaced by olive oil. Samples were evaluated by quantitative descriptive sensory analysis and consumer testing. Descriptive sensory analysis revealed significant differences for most of the attributes studied. The replacement of 35% or more of pork meat by olive oil. prompted a decrease in odour intensity, spicy odour, hardness and an increase of fat mouthfeel, together with the olive oil perception. By contrast, the replacement of 25% of pork meat by olive oil yielded a salchichon not greatly different to the control. Consumers accepted all assays, but preferred those in which no more than 25% of the pork meat was replaced by olive oil. From a sensory standpoint, therefore, it is recommended that the replacement of pork meat by olive oil in this product should not exceed 25%. --Keywords: dry-ripened venison sausage, olive oil, acceptance test, preference test, quantitative descriptive sensory analysis

Despite numerous studies on the neurobiology of depression, the etiological and pathophysiological mechanisms of this disorder remain poorly understood. A large number of animal models and tests to evaluate depressive-like behavior have been developed. Chronic unpredictable mild stress (CUMS) is the most common and frequently used model of depression, and the sucrose preference test (SPT) is one of the most common tests for assessing anhedonia. However, not all laboratories can reproduce the main effects of CUMS, especially when this refers to a decrease in sucrose preference. It is also unknown how the state of anhedonia, assessed by the SPT, relates to the state of anhedonia in patients with depression. We analyzed the literature available in the PubMed database using keywords relevant to the topic of this narrative review. We hypothesize that the poor reproducibility of the CUMS model may be due to differences in sucrose consumption, which may be influenced by such factors as differences in sucrose preference concentration threshold, water and food deprivation, and differences in animals’ susceptibility to stress. We also believe that comparisons between animal and human states of anhedonia should be made with caution because there are many inconsistencies between the two, including in assessment methods. We also tried to offer some recommendations that should improve the reproducibility of the CUMS model and provide a framework for future research.

Depression affects women nearly twice as frequently as men. In contrast, rodent models of depression have shown inconsistent results regarding sex bias, often reporting more depression-like symptoms in males. This sex discrepancy in rodents modeling depression may rely on differences in the baseline activity of males and females in depression-related behavioral tests. We previously showed that the baseline despair and anhedonia behaviors, major endophenotypes of depression, are not sex biased in young adolescent mice of C57BL/6N, DBA/2 and FVB/N inbred wild-type strains. Since the prevalence of depression in women peaks in their reproductive years, we here investigated sex differences of the baseline depression-like behaviors in adult mice using these three strains. Similar to the results in young mice, no difference was found between adult male and female mice in behavioral tests measuring despair in both tail suspension and forced swim tests, and anhedonia in the sucrose preference test. We then extended our study and tested apathy, another endophenotype of depression, using the splash test. Adult male and female mice showed significantly different results in the baseline apathy-like behaviors depending on the investigated strain. This study dissects the complex sex effects of different depression endophenotypes, stresses the importance of considering strain, and puts forward a hypothesis of the inconsistency of results between different laboratories investigating rodent models of depression.

Rationale Unconditioned tasks in rodents have been the mainstay of behavioural assessment for decades, but their validity and sensitivity to detect the behavioural consequences of early life stress (ELS) remains contentious and highly variable. Objectives In the present study, we carried out a meta-analysis to investigate whether persistent behavioural effects, as assessed using unconditioned procedures in rats, are a reliable consequence of early repeated maternal separation, a commonly used procedure in rodents to study ELS. Methods A literature search identified 100 studies involving maternally separated rats and the following unconditioned procedures: the elevated plus maze (EPM); open field test (OFT); sucrose preference test (SPT) and forced swim task (FST). Studies were included for analysis if the separation of offspring from the dam was at least 60 min every day during the pre-weaning period prior to the start of adolescence. Results Our findings show that unconditioned tasks are generally poor at consistently demonstrating differences between control and separated groups with pooled effect sizes that were either small or non-existent (EPM: Hedge’s g =  − 0.35, p  = 0.01, OFT: Hedge’s g =  − 0.32, p  = 0.05, SPT: Hedge’s g =  − 0.33, p  = 0.21, FST: Hedge’s g = 0.99, p  = 0.0001). Despite considerable procedural variability between studies, heterogeneity statistics were low; indicating the lack of standardization in the maternal separation protocol was the not the cause of these inconsistent effects. Conclusions Our findings indicate that in general, unconditioned tests of depression and anxiety are not sufficient to reveal the full behavioural repertoire of maternal separation stress should not be relied upon in isolation. We argue that more objective tasks that sensitively detect specific cognitive processes are better suited for translational research on stress-related disorders such as depression.

The use of animal models in biology research continues to be necessary for the development of new technologies and medicines, and therefore crucial for enhancing human and animal health. In this context, the need to ensure the compliance of research with the principles Replacement, Reduction and Refinement (the 3 Rs), which underpin the ethical and human approach to husbandry and experimental design, has become a central issue. The zebrafish ( Danio rerio ) is becoming a widely used model in the field of behavioral neuroscience. In particular, studying zebrafish social preference, by observing how an individual fish interacts with conspecifics, may offer insights into several neuropsychiatric and neurodevelopmental disorders. The main aim of this review is to summarize principal factors affecting zebrafish behavior during social preference tests. We identified three categories of social research using zebrafish: studies carried out in untreated wild-type zebrafish, in pharmacologically treated wild-type zebrafish, and in genetically engineered fish. We suggest guidelines for standardizing social preference testing in the zebrafish model. The main advances gleaned from zebrafish social behavior testing are discussed, together with the relevance of this method to scientific research, including the study of behavioral disorders in humans. The authors stress the importance of adopting an ethical approach that considers the welfare of animals involved in experimental procedures. Ensuring a high standard of animal welfare is not only good for the animals, but also enhances the quality of our science.

This study aimed to examine the antidepressant properties of apigenin in an experimental mouse model of chronic mild stress (CMS). Three weeks following CMS, albino mice of either sex were tested for their antidepressant effects using the tail suspension test (TST) and the sucrose preference test. The percentage preference for sucrose solution and the amount of time spent immobile in the TST were calculated. The brain malondialdehyde (MDA) levels, catalase activity, and reduced glutathione levels were checked to determine the antioxidant potential of treatments. When compared to the control, animals treated with apigenin during the CMS periods showed significantly shorter TST immobility times. Apigenin administration raised the percentage preference for sucrose solution in a dose-dependent manner, which put it on par with the widely used antidepressant imipramine. Animals treated with apigenin displayed a significantly (p ˂ 0.05) greater spontaneous locomotor count (281) when compared to the vehicle-treated group (245). Apigenin was also highly effective in significantly (p ˂ 0.01) lowering plasma corticosterone levels (17 vs. 28 µg/mL) and nitrite (19 vs. 33 µg/mL) produced by CMS in comparison to the control group. During CMS, a high dose (50 mg/kg) of apigenin was given, which greatly increased the reduced glutathione level while significantly decreasing the brain’s MDA and catalase activity when compared to the control group. As a result, we infer that high doses of apigenin may have potential antidepressant effects in animal models via various mechanisms.

Background The chronic unpredictable mild stress (CUMS) model has long been considered the best model for exploring the pathophysiological mechanisms underlying depression. However, there are no widely recognised standards for strategies for modeling and for behavioral testing. The present study aimed to optimize the protocols for food deprivation and the sucrose preference test (SPT) for the CUMS model. Methods We first evaluated the effects of different long periods of food deprivation on the body weight of Sprague Dawley (SD) rats by testing food deprivation for 24 hours (8:00‐8:00+), food deprivation for 12 hours during the daytime (8:00‐20:00) and food deprivation for 12 hours at night (20:00‐8:00+). Next, we established a SD rat CUMS model with 15 different stimulations, and used body weight measurement, SPT, forced swim test (FST), open field test (OFT) and Morris water maze (MWM) test to verify the success of the modeling. In the SPT, consumption of sucrose and pure water within 1 and 12 hours was measured. Results Twelve hours of food deprivation during the daytime (8:00‐20:00) had no effect on body weight, while 12 hours of food deprivation at night (20:00‐8:00+) and 24 hours of food deprivation (8:00‐8:00+) significantly reduced the mean body weight of the SD rats. When SPT was used to verify the successful establishment of the CUMS rat model, sucrose consumption measured within 12 hours was less variable than that measured within 1 hour. Conclusions Twelve hours of food deprivation in the daytime (8:00‐20:00) may be considered a mild stimulus for the establishment of a CUMS rat model. Measuring sucrose consumption over 12 hours is recommended for SPT.

From the preference of one good over another, the strength of the preference cannot automatically be inferred. While money is the common denominator to assess the value of goods in humans, it appears difficult at first glance to put a price tag on the decisions of laboratory animals. Here we used consumer demand tests to measure how much work female mice expend to obtain access to different liquids. The mice could each choose between two liquids, one of which was free. The amount of work required to access the other liquid, by contrast, increased daily. In this way, the value of the liquid can be determined from a mouse's microeconomic perspective. The unique feature is that our test was carried out in a home-cage based setup. The mice lived in a group but could individually access the test-cage, which was connected to the home-cage via a gate. Thereby the mice were able to perform their task undisturbed by group members and on a self-chosen schedule with minimal influence by the experimenter. Our results show that the maximum number of nosepokes depends on the liquids presented. Mice worked incredibly hard for access to water while a bitter-tasting solution was offered for free whereas they made less nosepokes for sweetened liquids while water was offered for free. The results demonstrate that it is possible to perform automated and home-cage based consumer demand tests in order to ask the mice not only what they like best but also how strong their preference is.