Anxiety & Depression Tests
New behavioral tests are continuously developed and validated.
Elevated Plus Maze
The Elevated Plus Maze (EPM) is currently one of the most frequently used tests to study anxiety in small rodents.
The test is based on the aversion of rodents to open spaces and height. The EPM apparatus is elevated from the floor. The equipment is a four arm maze with two opposing open arms (lighted arms, without walls) and two opposing closed arms (sheltered arms, with walls). On the test day, the animal is placed in the center area facing the open arm. The behavior during the test session is recorded, and behavioral parameters such as time spent in the open and in the closed arms, number of visits in the open and closed arms as well as latency to enter the open arm are measured automatically.
|Time spent in the open arms of the Elevated plus maze of 6 week old TDP-43 transgenic TAR6/6 mice compared to non-transgenic littermates (ntg). n = 5 – 6; Mean + SEM. Mann Whitney test. ***p<0.001.|
Forced Swim Test
The Forced Swim Test is based on the assumption that animals try to escape from an aversive stimulus. The test is used to measure the effect of antidepressant drugs or the genotype on the emotional status of animals.
Animals are placed in a transparent Plexiglas cylinder filled with water. The animal’s behavior is recorded and the duration of immobility as well as struggling and swimming is measured. Increased immobility (floating) is interpreted as a behavioral correlate of negative mood, representing depression-like behavior in the animal.
|Forced Swim Test in adult Sprague Dawley rats treated with 2 mg/kg Diazepam. Time spent floating compared to vehicle treated animals. Diazepam: n = 8; Vehicle: n = 9; mean + SEM; T-test, ***p<0.001.|
Marble Burying Test
Marble burying is commonly used to test anxiety, where burying positively correlates with anxiety. The test is also demonstrated to analyze repetitive behavior.
Two days prior to training, two glass marbles are placed into the animal`s home cage to prevent neophobia during testing. Training and testing is conducted in a new home cage (equal size, filled with 3 cm wood chip bedding, covered with a wired cage lid), under dimmed light. On the training day, animals are allowed to freely explore the testing cage without marbles for 30 min for habituation. On the testing day, approx. 24 hours after training, 15 marbles are evenly placed in the test cage to ensure equal and consistent positioning of marbles. Animals are exposed to the marbles for 30 min, while videotaped. The manually evaluated parameters are latency to start burying and number of buried marbles.
|Marble Burying Test of 9 month old TMHT (tau) transgenic mice. Number of buried marbles within 30 minutes. n = 15 per group; mean +SEM; t-test; ***p<0.001.|
Novelty-Induced Hypophagia (NIH) Test
The novelty-induced hypophagia test is a behavioral paradigm analyzing for anxiety and depression-like states.
The single-housed rat in its home cage is presented with a bottle of sweetened milk for 15 minutes. Habituation is performed on 4 consecutive days. On the 4th day, the latency to drink and the amount of milk consumed is measured in the home cage. On the 5th day, animals are tested in a novel cage of same dimensions without bedding and under bright light of approx. 1000 Lux, thus in an aversive environment. The latency to approach the bottle and to start drinking, as well as the amount of milk consumed within 15 minutes is measured. The performance of the animals at the 4th and 5th day is videotaped and manually analyzed.