The most commonly used experimental animals are mammals

It is generally required to select more than two different species of animals, one is rodent and the other is non-rodent.

Selection principles: Try to choose animals whose toxicity of test chemicals is similar to humans; animals that are easy to operate and easy to raise and manage; animals that are low-priced and easy to obtain.

Sensitive strains should be selected

inbreeding

outcross

random reproduction

common animals

cleaning animals

specific pathogen free animals

germ-free animals

Usually in the same experiment, the average body weight of animals in each dose group differs by no more than 5%, and the difference in body weight within the group should be less than 10%.

P209

Oral administration

Feeding method

capsule swallowing method

Acute toxicity refers to the rapid and severe poisoning reaction, including fatal effects, that occurs in a short period of time after humans or animals are exposed to an exogenous chemical in a single or multiple large doses within 24 hours.

Understanding the role of acute toxicity of exogenous chemicals

Understand the nature of the toxic effects of exogenous chemicals, characteristics of toxic effects and possible target organs, and preliminarily evaluate the dangers of exogenous chemicals

Exploring dose-response relationships for exogenous chemicals

Preliminarily understand the causes of animal death and provide clues for studying the mechanism of toxic effects.

Provide basis for risk assessment of test substances

function accumulation

Can use chemical methods to detect the presence of the parent or metabolite of the chemical in the body

fixed dose method

ascending dose method

20d accumulation test method

Subchronic toxicity refers to the toxic effects caused by continuous exposure of experimental animals to larger doses of exogenous chemicals over a longer period of time.

"Large dose" is relative and there is no clear lower limit, but the upper limit of the dose should be less than the dose of LD 50 of acute toxicity, which requires equal doses per day or each time of exposure during the experiment. "Longer time" refers to a time approximately equivalent to 1/30 to 1/10 of the life span of the experimental animal.

Further explore the toxicological properties of the tested chemicals, the types of toxic effects and target organs

Preliminarily determine the threshold dose, maximum no-effect dose and maximum tolerated dose of toxic effects of exogenous chemicals

Estimate the risk of chronic exposure based on the chemical's subchronic toxic dose and maximum no-effect dose

There are three main routes of exposure: oral, respiratory tract and skin.

The exposure dose in the high-dose group should cause obvious poisoning effects or typical damage to target organs in experimental animals, but should not cause death of experimental animals.

The medium-dose group has produced mild toxic effects, which is equivalent to the threshold dose for subchronic toxicity.

The low-dose group did not produce any toxic effects and was equivalent to the subchronic maximum no-effect level.

General indicators

Biochemical test indicators

autopsy examination

specificity index

Chronic toxicity refers to the toxic effects caused by long-term and repeated exposure of humans or experimental animals to low-dose chemical poisons, also known as long-term toxicity

Determine the chronic toxic effects that occur after repeated administration of test substances to experimental animals, especially progressive and irreversible toxic effects and tumorigenic effects

Determine the lower limit of toxicity of long-term exposure of experimental animals to exogenous chemicals, that is, the minimum dose that causes damage to the body or the expected amount of chronic toxicity, and the maximum no-effect dose that is harmless to the body, that is, the maximum dose and dose at which no harm is observed. -Reaction relationship

Studying the reversibility of chronic toxic damage from exogenous chemicals

Elucidate the nature, target organs, and mechanisms of toxic effects of exogenous chemicals