Abstract To investigate the behavioral characteristics of HSF1 gene-deficient mice and explore the role of HSF1 gene in mouse behavior. 39 male HSF1 gene-deficient mice and 36 wild-type mice were selected from 6 to 7 months for emotional scoring, open field experiments, elevated plus maze experiments, simple maze experiments, T-CAT experiments, single-wood bridge experiments and suspension experiments. To observe its emotional arousal level, anxiety level, exploration behavior, working memory ability and exercise ability. The results showed that HSF1 gene-deficient mice had lower levels of emotional arousal and anxiety, decreased search behavior, and lower conversion rate in T-CAT , suggesting that mice
Emotion, motivation to explore, and working memory are regulated by the HSF1 gene.
Keywords HSF1, mouse , gene , behavior.
1 Introduction
In the 1970s , Tissieres discovered that Drosophila can synthesize a group of proteins under heat induction , named heat shock proteins (HSPs) . Subsequent studies have found that the body can synthesize HSPs under other stress conditions . HSPs are a class of evolutionarily highly conserved proteins that are widely found in the cells of prokaryotic and eukaryotic organisms. HSPs are involved in intracellular protein folding, assembly, degradation and repair processes . Under stress, they can protect cells from protein denaturation and degradation of denatured proteins , maintain protein self-stabilizing system , protect the body from stress damage , and maintain the body. Its own homeostasis plays an important role. HSPs are currently considered to be an important stress protein. There is a palindrome upstream of the TATA5 ' end of the HSP gene , known as the heat shock element (HSE) . HSE is regulated by heat shock factor (the HSF), including heat shock factor HSF1, HSF2, HSF3, HSF4 the like, wherein HSF1 is the most important regulatory factors regulating the expression of the main body of HSPs under stress. The body lacking HSF1 cannot synthesize HSPs under stress conditions . Xiaoxian Zhong et constructed HSF1 gene-deficient mouse model, a good animal model for the study of HSPs. San2tos et al found that the brain of HSF1 gene-deficient mice showed morphology
Learning changes , microscopic observation revealed cell vacuolation, intracellular appearance of non-structural aggregates, nuclear pyknosis in the periventricular tissue of the brain , this change is characterized by gene accumulation effects. But these changes in brain structure and its impact on whether or not the degree of influence on the nervous system in mice, is still unclear. Many studies show that there are some important physiological functions of individual genes are knocked out, the gene defect behavior of the animals will be a series of changes, such as Lahdesmaki found that α 2 adrenergic receptor gene deficient mice exhibit increased vertical hair behavior, Impaired exercise capacity , increased anxiety behavior, and changes in circadian rhythms. Burne found that the motor function of vitamin D receptor-deficient mice was significantly impaired , but did not affect the cognitive function of mice. The HSF1 gene has important physiological functions in the individual's stress response, and HSF1 gene defects may also lead to many behavioral changes in individuals. During the study of the role of HSF1 in stress , we observed a decrease in the spontaneous activity of HSF1 gene-deficient mice in cages . In addition to spontaneous activity changes , are there other behavioral changes ? These behavioral changes What reason? for the further understanding of these issues, this study used a variety of methods from emotional behavioral observation, exploratory behavior, working memory ability and athletic ability in four areas of HSF1 gene-deficient mice behavior is evaluated to To explore the effects of HSF1 on brain function in mice , and to provide a basis for further research.
2 Materials and methods
2. 1 experimental animals and grouping
24 to 28 week old male knockout mice HSF1 39 (HSF1- / -), 36 wild-type mice (HSF1 + / +). real
The animals were imported from the Southwestern Medical Center of the University of Texas , and were reproduced by the Experimental Animal Center of Xiangya School of Medicine , Central South University.
2. 3 behavioral observation indicators
All animals were sequentially following seven acts at 9am observation experiment, after the completion of an experiment back in its cage rest 20min. All experiments were evaluated by two experimenters who were proficient in behavioral testing methods.
2. 3. 1 Emotional level assessment According to Ader et al., according to the Chinese hamster emotional level rating scale compiled by Wu Daxing et al.
. Specific methods are as follows: open box cage, mouse tail forceps, to remove the difficulty to assess whether difficulties, 1 or 2 times to seize that easier, referred to as a 0; 3 to 4 times that difficulties, referred to as 1 point ; 5 times or more is considered to be extremely difficult to score 2 points. After clamping the tail , the head is facing down , the strength is based on the rat's ground , and then observe for 30s to assess the degree of struggle, vocalization, and bowel movements ; the degree of struggle is 0 points for the limbs or slight struggles ; the limbs are struggling , the back is bent , head up but did not reach the tail to score 1 point ; strenuous struggle , turn over to the tail or bite the dice to score 2 points ; the degree of vocalization is no sound after being clamped or 1 to 4 times , the interval is long 0 min; 5 to 10 times Score 1 screaming; greater than or equal to 10 times screaming, rapid, marked 2; spontaneous urination, urination in a non-0 points; Score 1 urination; spontaneous bowel movement, referred to no defecation 0 points ; 1 point for bowel movements , summing the five items to get the total score of the emotional level , ranging from 0 to 8 points.
2. 3. 2 elevated cross maze experiment with elevated cross maze test to determine the animal's emotional arousal. The experimental device is a wooden black elevated cross maze. The maze consists of two open arms (50 cm × 10 cm) and two closed arms (50 cm × 10 cm × 40 cm), which are joined by a central zone (10 × 10 cm) and the labyrinth is placed on a 50 cm elevated frame. At the beginning of the experiment, the animals were placed on the closed arms and observed for 5 minutes . Outcome measures: frequency and time into the open arms, the number of closed arm entries and time. Calculate the ratio of the number of input arms and the number of open arms to the total number of input arms.
2. 3. 3 Field Experiment The market experiment is a classic behavioral experiment that can well assess the emotional level of animals and the exploration behavior in an open and unfamiliar environment. Experimental device wooden open field (100cm × 100cm × 30cm), with a bottom 25 strokes into 20cm × 20cm square, along the wall surrounding grid cells called, the remainder of the central cell, the animals were placed in the center cell, was observed within 5min Activity situation. The observation indicators are : the number of crawling in the central grid , the number of crawling around the grid , and the total number of crawling grids.
2. 3. 4 Simple Maze Experiment This experiment reflects the spontaneous exploration behavior of animals in a relatively closed environment. The simple fascinating box is a 120cm × 20cm × 20cm wooden box , which is divided into 8 grids by wooden boards . There are small holes for the mice to pass under the partitions , and the left, middle and right are randomly arranged. The wooden box is divided into a starting end and a destination end. During the experiment, the mice were placed in the square at the beginning , and the animal activity was observed for 5 minutes . The observed indicators are : 5 min crawling total number of grids.
2. 3. 5 　 The T2CAT experiment Gerlai invented the T-CAT program based on the new instinct of animal exploration , which can well measure the animal's motivation for exploration and working memory. The T-CAT consists of two arms—the starting arm ( straight arm ) and the target arm ( cross arm ), both 75cm × 12cm × 20cm, the two arms cross T -shaped , and the end of the starting arm passes through the movable door 24cm Separate a starting area. There are also movable doors at the two entrances of the target arm. The entire experiment included 1 passive selection test and 14 active selection tests. For the first time, the passive selection test , the movable door at the entrance of the target arm is closed , the animal can only explore one end of the target arm . When the experimental animal explores the target arm and returns to the starting arm by itself , the active door of the starting arm is closed. animals at the start of the region to be 5s. From
The second time, 14 consecutive active selection tests were started . At the same time, the two movable doors are opened , and the animal begins to explore the target arm . When the animal enters one end , the movable door at the other end is closed. When the animals return to the starting arm after the completion of exploration, shut the door activities start arm, allowing the animals to be 5s in the start arm, completed an exploration. The subsequent 2 to 14 explorations were carried out according to the above procedure. Because mice have a new instinct , each exploration tends to enter the target arm that was not explored last time. Conversions recorded 14 active choice quiz, and the completion of 15 Select time spent. 2. 3. 6 The single-wood bridge was tested by experiments using a wooden bridge to assess the animal's ability to balance exercise. The experimental device is a wooden single-wood bridge (100cm × 1cm) divided into a starting end and a destination end , and the destination end has a small platform (10cm × 10cm) . The wooden bridge is placed at a height of 30cm . Let start of the experiment mice were acclimated to the platform after 5min Mice were placed in single starting end, the recording time of the animals to reach the destination platform, the experimental limit 1min, if not completed, or from falling onto the log, are considered failures, referred to as time 60s . Each mouse was tested three times in succession , and the average time for the mice to reach the platform three times was calculated , with each test interval of 1 min .
2. 3. 7 Suspension experiments Suspension tests were used to assess the muscle strength and motor balance of the animals. Suspension experimental equipment is a 1m long wire (diameter 2mm), placed parallel at 50cm from the ground, one end of the wire has an escape entry. During the experiment, the forelimbs of the mice were grasped at one end of the wire, and each experiment was carried out for 3 minutes for 3 times , with an interval of 30 s between each experiment . If mice are hanging on the wire 4 to discuss our findings HSF1 gene-deficient mice and wild-type mice there are significant differences in the behavior of multiple tests, the performance of 3min or emotional call can be moved to escape the entrance counted as a successful experiment, remember It is 1 point ; if it falls from the wire within 3 minutes , the experiment fails , and it is recorded as 0 . The total score of the three suspension experiments of the mice was calculated.
2. 4 data processing
All data were analyzed by independent sample t test , and the difference significance was set to p<0.05. All data statistics were completed on the SPSS11.5 software package.
3 results
In addition to the three HSF1 gene-deficient mice failed to complete the T- CAT test, all remaining mice were successfully completed all test items. As shown by the experimental results listed in Table 1 , HSF1 gene-deficient mice showed significant differences in multiple behavioral tests compared to wild-type mice.
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