Shocked conditioning experiment method
1. Basic principle: Shock reflex is a simple behavioral response of mammals to external stimuli and a sensitive indicator for evaluating animal reactivity. It consists of a series of rapid movements starting from the head and tail: as the sound stimuli are generated and enhanced, the main muscle groups of the animal contract and relax. Anxiolytic drugs reduce this response and decrease the amplitude, and the anxiety agent is the opposite.
2. PPI (pre-pulse suppression): A transient and intense (generally greater than 80 dB) auditory stimulus can cause shock reflexes. By applying a sound stimulus to the experimental animal that does not cause shocking reflexes within 20 to 500 ms before the emergence of a strong shock reflex stimulus, the magnitude of the shock can be reduced by 80%. This inhibition of shocking reflexes that occurs during a period of time before the appearance of a strong shock reflex stimulus is called PPI.
3, PPI test usually uses auditory stimulation mode, usually using blasting white noise, the common stimulation sequence is as follows: each round of stimulation initially adapts the subject to a certain intensity of background noise, and continues throughout the experiment, first given only A small experiment with strong stimuli, then give a series of small experiments with weak stimuli and strong stimuli at different time intervals. The small experimental sequence is given in a random manner. The interval between each small experiment is 8~30s or more. Long (usually 15~20s), so that the subsequent stimulus appears as a novel stimulus, avoiding the effect of the refractory period generated by the previous stimulus on the subsequent stimulus, and the experimental interval of random variation is less than the fixed interval. The adaptability of reflection.
4. In order to ensure the sound stimulation and the accuracy of the experimental data, the equipment should be equipped with standard instruments, and the equipment should be calibrated with standard instruments before each experiment.
Example 1:
Introduction: Male Wistar rats weighing approximately 200 g were used in a special device, including:
(1) Several open cages (8cm*8cm*16cm);
(2) A soundproof box with four platforms and a row of fans that provide 50dB (SPL) of noise inside the box. There is a speaker at the top of the box 14cm from the animal to produce white noise;
(3) strain gauge;
(4) Computer (loading Xeye shock conditioning system analysis processing software);
experiment process:
1. The rats were individually placed in cages, which restricted the movement of the rats but did not fix the rats. The cage was then placed on a soundproof box platform and the rats were quietly acclimated for 5 min.
2. The sound stimulation consists of burst noise of 98dB and 120dB (for 20ms). At the same time as each stimulus was generated, the response of the rat within 200 ms was measured.
3. The body movement of the rat in the cage is measured by a strain gauge, expressed as a voltage change, and converted into a weight (g) by digital simulation, and the computer automatically records the data. The maximum weight change at 200 ms after stimulation was the shock peak, and the same stimulus was repeated 12 times to give an average peak. An experimental interval consisted of randomly repeating each stimulus intensity 12 times with a stimulation interval of 20 to 40 s (random appearance). The test was taken as a control value before the experiment, and the result was expressed as a percentage of the measured value after administration as a percentage of the value before administration.
Example 2: Spontaneous Nicotine Withdrawal Potentiates the Effects of Stress in Rats
Process: divided into two separate phases (session)
1. The rat was placed in a shocked cage and quietly adapted to 5 min in dim conditions.
2. The rats then performed 30 shock stimuli, 90, 95, and 105 dB, respectively, 10 times (?), with an average stimulation interval of 30 s, a pseudorandom sequence (pseudorandom), and a dark environment, the first phase of the shock test.
3. The rats were then removed from the experimental cage and placed in the cage, which was also quietly adapted to 5 min or 15 min in a dark environment.
4. The rat is then placed in the shocked cage to prepare for the second phase of the experiment.
5. The second phase of the experiment is exactly the same as the first phase, except that one is in a dark environment and the other is in a bright environment.
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