Experiments on the analgesic effect of drugs
Experiments on the analgesic effect of drugs
Experiments on the analgesic effects of drugs can be used to: screen for drugs that can selectively inhibit and alleviate a variety of pain and reduce pain resulting in fear tension and uneasy emotional pain.
Operation method
Experiments on the analgesic effect of drugs
Principle
Mice have smooth, bare, hairless soles, which are suitable for thermal stimulation pain modeling. If the mice are placed on a metal hot plate at a temperature of 55℃±0.5℃, the phenomenon of "licking the hindfoot" can be used as an indicator of the emergence of a pain response. The efficacy of analgesic drugs can be reflected by examining the time of pain response (pain threshold). However, the hot plate model is mainly used to screen narcotic analgesics, and is not suitable for screening antipyretic analgesics, which can be evaluated using the chemical analgesic model. Morphine is a central analgesic and belongs to the opioid class, acting mainly on u-opioid receptors. Sodium salicylate is a peripheral antipyretic analgesic, and its analgesic effect is closely related to its anti-inflammatory effect. In this experiment, we compared the differences in the analgesic mechanism of morphine and sodium salicylate through the thermal stimulation analgesic model.
Materials and Instruments
Mice (Kunming breed) Half and half of each sex Move 1. Screening of mice The mice were placed on a metal hot plate at a temperature of 55℃±0.5℃, and the appearance time of the pain response (the phenomenon of licking the hind foot) was measured twice, each time with an interval of 5 min. If the time of the appearance time of the pain response was between 10s and 30s, the mice were regarded as qualified. A total of 9 mice were screened. Caveat 1. Mouse gender selection: Since male mice have a prolapsed scrotum, scrotal skin can contact the hot plate and are more sensitive to pain, which may affect the results of the experiment, female mice were selected for this experiment. 2. If the mice do not show pain response within 60s on the hot plate, they should be removed from the hot plate to avoid burns. 3. The hot plate method is a commonly used method for evaluating the analgesic effect of drugs, with the advantages of simple device, little damage to mice, and repeated use of experimental animals. In addition to the thermal stimulation model of analgesia, other screening models of analgesics also include: mechanical stimulation, electrical stimulation, chemical stimulation and other methods. Thermal, mechanical and electrical stimulation models are suitable for screening narcotic analgesics, while the chemical stimulation model (torsion method) is suitable for screening antipyretic analgesics. Common Problems Analgesic mechanism: In the process of nociceptive transmission to the center, nociception stimulates the sensory nerve endings and releases Glu and SP, which act on the corresponding receptors and complete the transmission of nociceptive impulses to the center causing pain. Endogenous opioid peptides released from specific neurons can agonize opioid receptors on the presynaptic and postsynaptic membranes of sensory nerves, inhibit adenylate cyclase, promote K+ efflux, reduce Ca2+ efflux by G-protein coupling mechanism, reduce the release of transmitters from the presynaptic membrane, hyperpolarize the postsynaptic membrane, and ultimately attenuate or block nociceptive signaling and produce analgesic effects. Morphine analogs exert analgesic effects by agonizing gray matter μ-receptors in the glial region of the spinal cord, medial thalamus, ventricles, and periaqueductal gray matter, mimicking endogenous opioid peptides, and by acting on the opioid receptors in the limbic system and the bluish pallidum, they slow down the unpleasantness, anxiety, and other moods and euphoria induced by pain. For more product details, please visit Aladdin Scientific website.
Hydrochloric acid Morphine solution 4% sodium salicylate hydrochloride (acetylsalicylic acid) solution Picric acid Physiological saline
Hot plate Syringe Balance
2. Grouping The mice were first weighed one by one, and then sorted according to body weight from small to large (or from large to small). They were divided into 3 groups (A, B, C) according to the principle of simplified randomization, with 3 mice in each group.
3. Intraperitoneal administration of mice (15 ml/kg) Group A was 0.1% morphine hydrochloride solution, group B was 4% sodium salicylate hydrochloride (acetylsalicylic acid) solution, and group C was saline. The time of administration was recorded.
4. Observation The time of emergence of pain response (pain threshold) was measured using the hot plate method after 15, 30, 45, and 60 min of administration, respectively, and all were considered to be 60 s if the pain response did not occur within 60 s of placing on the hot plate.
5. Calculation of the percentage of improvement of the pain threshold