Impairment of the Organization of Locomotor and Exploratory Behaviors in Bile Duct-Ligated Rats

Hepatic encephalopathy (HE) arises from acute or chronic liver diseases and leads to several problems, including motor impairment. Animal models of chronic liver disease have extensively investigated the mechanisms of this disease. Impairment of locomotor activity has been described in different rat models. However, these studies are controversial and the majority has primarily analyzed activity parameters. Therefore, the aim of the present study was to evaluate locomotor and exploratory behavior in bile duct-ligated (BDL) rats to explore the spatial and temporal structure of behavior. Adult female Wistar rats underwent common bile duct ligation (BDL rats) or the manipulation of common bile duct without ligation (control rats). Six weeks after surgery, control and BDL rats underwent open-field, plus-maze and foot-fault behavioral tasks. The BDL rats developed chronic liver failure and exhibited a decrease in total distance traveled, increased total immobility time, smaller number of rearings, longer periods in the home base area and decreased percentage of time in the center zone of the arena, when compared to the control rats. Moreover, the performance of the BDL rats was not different from the control rats for the elevated plus-maze and foot-fault tasks. Therefore, the BDL rats demonstrated disturbed spontaneous locomotor and exploratory activities as a consequence of altered spatio-temporal organization of behavior

Evaluation of zinc effect on cadmium action in lipid peroxidation and metallothionein levels in the brain

Cadmium (Cd) is a known hepato- and nephrotoxic pollutant and zinc (Zn) metalloproteins are important targets of Cd. Hence, the administration of Zn may mitigate Cd toxic effects. However, the interaction of Cd and Zn has been little investigated in the brain. Previously, we reported a protective effect of Zn on mortality caused by Cd in rats. Here, we tested whether the protective effect of Zn could be related to changes in brain Zn-proteins, metallothionein (MT) and δ-aminolevulinate dehydratse (δ-ALA-D). Male adult rats were daily administered for 10 days with Zn (2 mg kg−1), Cd (0.25 and 1 mg kg−1) and 0.25 mg kg−1 of Cd plus Zn and 1 mg kg−1 of Cd plus Zn. The body weight loss, food intake deprivation, and mortality occurred in 1 mg kg−1 of Cd, but Zn co-administration did mitigate these effects. The brain Zn content was not modified by treatment with Cd, whereas cerebral Cd levels increased in animals exposed to Cd. The administration of 0.25 mg kg−1 of Cd (with or without Zn) induced lipid peroxidation and decreased MT concentration, but 2 mg kg−1 of Zn and 1 mg kg−1 of Cd did not change these parameters. Brain δ-ALA-D was not modified by Cd and/or Zn treatments. Since the co-administration of Zn did not attenuate the changes induced by Cd in the brain, our results suggest that the protective effect of Zn on impairments caused by Cd in animal status is weakly related to a cerebral interaction of these metals

Differences in spatio-temporal behavior of zebrafish in the open tank paradigm after a short-period confinement into dark and bright environments.

The open tank paradigm, also known as novel tank diving test, is a protocol used to evaluate the zebrafish behavior. Several characteristics have been described for this species, including scototaxis, which is the natural preference for dark environments in detriment of bright ones. However, there is no evidence regarding the influence of "natural stimuli" in zebrafish subjected to novelty-based paradigms. In this report, we evaluated the spatio-temporal exploratory activity of the short-fin zebrafish phenotype in the open tank after a short-period confinement into dark/bright environments. A total of 44 animals were individually confined during a 10-min single session into one of three environments: black-painted, white-painted, and transparent cylinders (dark, bright, and transparent groups). Fish were further subjected to the novel tank test and their exploratory profile was recorded during a 15-min trial. The results demonstrated that zebrafish increased their vertical exploratory activity during the first 6-min, where the bright group spent more time and travelled a higher distance in the top area. Interestingly, all behavioral parameters measured for the dark group were similar to the transparent one. These data were confirmed by automated analysis of track and occupancy plots and also demonstrated that zebrafish display a classical homebase formation in the bottom area of the tank. A detailed spatio-temporal study of zebrafish exploratory behavior and the construction of representative ethograms showed that the experimental groups presented significant differences in the first 3-min vs. last 3-min of test. Although the main factors involved in these behavioral responses still remain ambiguous and require further investigation, the current report describes an alternative methodological approach for assessing the zebrafish behavior after a forced exposure to different environments. Additionally, the analysis of ethologically-relevant patterns across time could be a potential phenotyping tool to evaluate the zebrafish exploratory profile in the open tank task

Seizures Induced by Pentylenetetrazole in the Adult Zebrafish: A Detailed Behavioral Characterization

<div><p>Pentylenetetrazole (PTZ) is a common convulsant agent used in animal models to investigate the mechanisms of seizures. Although adult zebrafish have been recently used to study epileptic seizures, a thorough characterization of the PTZ-induced seizures in this animal model is missing. The goal of this study was to perform a detailed temporal behavior profile characterization of PTZ-induced seizure in adult zebrafish. The behavioral profile during 20 min of PTZ immersion (5, 7.5, 10, and 15 mM) was characterized by stages defined as scores: (0) short swim, (1) increased swimming activity and high frequency of opercular movement, (2) erratic movements, (3) circular movements, (4) clonic seizure-like behavior, (5) fall to the bottom of the tank and tonic seizure-like behavior, (6) death. Animals exposed to distinct PTZ concentrations presented different seizure profiles, intensities and latencies to reach all scores. Only animals immersed into 15 mM PTZ showed an increased time to return to the normal behavior (score 0), after exposure. Total mortality rate at 10 and 15 mM were 33% and 50%, respectively. Considering all behavioral parameters, 5, 7.5, 10, and 15 mM PTZ, induced seizures with low, intermediate, and high severity, respectively. Pretreatment with diazepam (DZP) significantly attenuated seizure severity. Finally, the brain PTZ levels in adult zebrafish immersed into the chemoconvulsant solution at 5 and 10 mM were comparable to those described for the rodent model, with a peak after a 20-min of exposure. The PTZ brain levels observed after 2.5-min PTZ exposure and after 60-min removal from exposure were similar. Altogether, our results showed a detailed temporal behavioral characterization of a PTZ epileptic seizure model in adult zebrafish. These behavioral analyses and the simple method for PTZ quantification could be considered as important tools for future investigations and translational research.</p></div

Survival evaluation.

<p>Kaplan–Meier plot representing the animal index (%) that survived in 3 distinct periods: I – PTZ exposure; II – Washout period; III – survival evaluation in each 24 h after behavioral experiment procedures. Data are analyzed using the log-rank test for trend to compare groups. *Indicate significant differences from 100% survival, whereas the symbol (#) represents statistical difference profile between 10 and 15 mM PTZ groups.</p

Experimental protocol schematic representation.

<p>The methodological approach used to evaluate the epileptic seizure-like behavior (experimental conditions, exposure periods, washout period, and survival evaluation after behavioral tests).</p

Latency to score 0 during the washout period.

<p>Data are represented as mean ± S.E.M and analyzed by one-way ANOVA followed by Bonferroni’s test as post-hoc. Distinct letters indicate statistical differences among PTZ-treated groups (gray bars). The DZP/10 mM PTZ is represented as black bars and compared to 10 mM PTZ group by Student’s <i>t</i> test with no statistical difference.</p

Behavioral profile of PTZ-induced seizures in adult zebrafish.

<p>The main characteristic seizure behavior induced by 5–15 mM PTZ and DZP/10 mM PTZ treatments during 20 min (<i>n</i> = 12). (A) Seizure score (only the highest score reached was consider in each interval) and cumulative frequency (B). Data are represented as median ± interquartile range and as the animal index (%) that reached the scores across time, respectively. (C) Seizure intensity during distinct moment tests (0–150, 150–300, and 300–1200 s) evaluated by the area under curve observed for each treatment. (D) Latency to score 4 onset. Data from seizure intensity and latency are represented as mean ± S.E.M and analyzed by one-way ANOVA followed by Bonferroni’s test as post-hoc. Distinct letters indicate statistical differences among PTZ-treated groups (gray bars). The DZP/10 mM PTZ is represented as black bars and compared to 10 mM PTZ group by the Student’s <i>t</i> test. *indicates significant difference between groups.</p

Score phenotype of the PTZ seizure model in adult zebrafish.

<p>Score phenotype of the PTZ seizure model in adult zebrafish.</p

Quantification of the PTZ levels in the brain.

<p>The concentration of PTZ in the brain was determined as μg PTZ/mL sample at 5 mM (gray bars) with values of 1.885, 3.175, 1.612, and 10 mM (blue bars) with values of 3.222, 7.905, and 2.870, after 2.5 and 20-min of PTZ exposure, and after 60-min washout. Data are expressed as mean ± S.E.M and analyzed by two-way ANOVA followed by Bonferroni’s test as post-hoc. Distinct letters indicate statistical difference within the same group at different periods, (lower case letter for 5 mM and capital letters for 10 mM) whereas the asterisks (*) indicates significant difference between both PTZ groups for each time.</p