The tetrad test is a series of behavioral paradigms in which rodents treated with cannabinoids

Cannabinoids

Cannabinoids are a class of chemical compounds that include the phytocannabinoids , and chemical compounds that mimic the actions of phytocannabinoids or have a similar structure...

 such as THC

THC

THC commonly refers to tetrahydrocannabinol, the main active chemical compound in Cannabis.THC may also refer to:* Tan Holdings Corporation...

 show effects. It is widely used for screening drugs that induce cannabinoid receptor

Cannabinoid receptor

The cannabinoid receptors are a class of cell membrane receptors under the G protein-coupled receptor superfamily. As is typical of G protein-coupled receptors, the cannabinoid receptors contain seven transmembrane spanning domains...

-mediated effects in rodents. The four behavioral components of the tetrad are spontaneous activity, catalepsy, hypothermia, and analgesia. Common assays for these behavioral paradigms are as follows:

• Spontaneous activity (or hypomotility) is determined by an open field test, in which a mouse is placed in a cage with perpendicular grid lines, usually spaced by approx. 1 inch. An experimenter counts the number of line crossings by the mouse in a given amount of time.
• Catalepsy
  Catalepsy
  Catalepsy is also a term used by hypnotists to refer to the state of making a hypnotised subject's arm, leg or back rigid. "Arm catalepsy" is often a pre-hypnotic test performed prior to an induction into a full trance.-Causes:...
  
   is determined by the bar test. The mouse is placed on a bar oriented parallel to and approximately 1 inch off of the ground. If the mouse remains immobile on the bar for typically more than 20 seconds, it is considered cataleptic.
• Hypothermia
  Hypothermia
  Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
  
   is determined by using a rectal probe to measure the rectal temperature.
• Analgesia is usually determined by the hot plate or tail immersion test. In the hot plate test, the mouse is placed on a heated plate, typically between 54 and 58°C. An experimenter measures the time it takes for the mouse to jump off of the hot plate. In the tail immersion test, the mouse is immobilized and its tail is placed into a warm water bath, typically also between 54 and 58°C. An experimenter measures the time it takes for the mouse to remove its tail from the water bath.

Direct CB1 agonists, such as THC

THC

THC commonly refers to tetrahydrocannabinol, the main active chemical compound in Cannabis.THC may also refer to:* Tan Holdings Corporation...

 (the psychoactive component of marijuana), or WIN 55,212-2

WIN 55,212-2

WIN 55,212-2 is a chemical described as an aminoalkylindole derivative, that produces effects similar to those of cannabinoid derivatives such as THC but has an entirely different chemical structure....

, have effects in all components of the tetrad and induce hypomotility, catalepsy, hypothermia, and analgesia in rodents. Accordingly, all true "tetrad effects" are not observed following treatment with antagonists

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

 of CB1 such as rimonabant

Rimonabant

Rimonabant is an anorectic antiobesity drug that has been withdrawn from the market. It is an inverse agonist for the cannabinoid receptor CB1...

.