A<unk> , referred to in slang as a "downer," is a chemical agent that diminishes the function or activity of a specific part of the body (see also sedative). The term is especially used with regard to the central nervous system (CNS). Alcohol (consumed in alcoholic beverages) is the most obvious example of a<unk> . Although some drugs act on the CNS by targeting or involving receptors such as the NMDA receptor, the mu-opioid receptor, and the CB1 cannabinoid receptor, many<unk> s impact the CNS by increasing the activity of a particular neurotransmitter known as gamma-aminobutyric acid (GABA),
GABA's role is to calm the CNS and promote sleep. Drugs that stimulate the activity of this amino acid slow brain function and result in a drowsy or calm feeling. These characteristics account for the prescription of<unk> s to relieve symptoms of anxiety or insomnia. Internal systems regulate the body's production of GABA, but when substances that stimulate GABA action are ingested, it is possible to induce hazardously high levels of the amino acid, which can slow breathing and heart rates dangerously, and may result in death.
CNS<unk> s require a period of adaptation. Typically, initial side effects include slurred speech, dizziness, and loss of coordination, effects commonly associated with alcohol consumption.
Depressant
Mood stabilizer
Stimulant
Heroic
Tricyclic antidepressant
Antidepressants
Dioptrics
Antipsychotics