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Narcotic drugs

Explanations > Brains > Brain Chemistry > Narcotic drugs

Alcohol | Amphetamine | Benzodiazepines | Cocaine | Cannabis | Nicotine | Opiates | LSD | PCP | See also

There are many narcotics and other chemicals that are commonly used in recreational drug-taking. Strictly speaking, 'narcotics' are only those that suppress the central nervous system and only opiates here have this effect, while others are stimulants. In everyday practice, however, the term 'narcotics' is loosely used to indicate all drugs that are taken for the effect on the mind, are often illegal, and which often have harmful effects.

Alcohol

Action

Significant use of of alcohol leads to increases in inhibitory transmission at GABA-A channels, increased seratonin function, dopamine release and transmission at opiate receptors, and a reduction of excitatory transmission at glutamate receptors.

Effect

Positive effects include anxiety reduction, inebriation sedation and relaxation.

Negative 'hangover' effects include headaches, trembling, memory loss and sickness. Withdrawal effects include autonomic hyperreactivity, nausea, hand tremor, anxiety, hallucinations and memory loss.

Amphetatmine

Action

Amphetamine increases monoamine release, particularly dopamine. Secondary effects appear in the inhibition of dopamine reuptake. The enhanced release and inhibited re-uptake of dopamine is important for its reinforcing effects.

Effect

Negative withdrawal effects include anxiety, depression, tiredness, sleeping, increased appetite, psychosis and suicidal thoughts.

Benzodiazepines

Action

Benzodiazepines binding at the GABA-A/benzodiazepine receptor. This leads to an increase in chloride passing through chloride ion channels, enhancing inhibitory transmission. Increased dopamine transmission can occur from the Ventral tegmental area with significant benzodiazepine use, although decreased dopamine levels occur in the nucleus accumbens.

Effect

Positive effects include euphoria, sedation, relaxation and memory depression.

Negative effects include drowsiness, headaches, amnesia and stomach upsets.

Cocaine

Action

Cocaine binds to dopamine, noradrenaline, and serotonin transporters, though prevention of dopamine re-uptake is particularly significant in its reinforcing and psychomotor stimulant effects.

Cocaine has been linked with depression of the orbito-frontal cortex, where thoughtful decisions are made. It has also been suggested that it depletes natural opiods to the extent that the body tries to compensate by creating more opiod receptors or increasing existing receptor readiness to bind with with opiod molecules.

Effect

Positive effects include euphoria. Negative withdrawal effects include dysphoria, fatigue, sleep disturbance, increased appetite and anxiety.

Cannabis

Action

The main active ingredient in cannabis is delta-tetrahydrocannabinol (delta-THC), which is an agonist at the cannabinoid receptor. This prevents reuptake of dopamine, seratonin, GABA, and norepinephrine. The CB1 cannabinoid (receptor is most common in the hippocampus, basal ganglia, and cerebellum.

Effect

Positive effects include relaxation and a sense of well-being.

Nictotine

Action

Nicotine is an agonist at the nicotinic receptor, leading to increased transmission of a number of neurotransmitters including acetylcholine, norepinephrine, dopamine, seratonin, glutamate, and endorphin.

Effect

Positive effects include mild euphoria and relaxation.

Withdrawal effects include dysphoria, insomnia, anxiety, restlessness, decreased heart rate and weight gain.

Opiates

Endogenous opioids are peptide that include endorphins and enkephalins. Exogenous opiates include morphine and heroin (diacetylated morphine).

Action

Opioids are as agonist at three major opiate receptors. The mu receptor is important for the reinforcing effects and are largely located on cell bodies of dopamine neurons in the ventral tegmental area and on neurons in the nucleus accumbens. Delta opiate receptors may be important for the control of behavioral reinforcers. Kappa opiate receptors are involved in withdrawal symptoms of opiates.

Effect

Positive effects include a sense of well being and euphoria.

Negative withdrawal effects include dysphoria, nausea, muscle cramps, tear production, diarrhoea, sweating, anxiety and fever.

LSD (Lysergic acid diethylamide)

Interestingly, this is a drug that animals do not reliably self-administer.

Effect

Vivid hallucinations.

Phencyclidine (PCP)

Action

High levels of the PCP receptor are found in the hippocampus and neocortex, with intermediate levels in the amygdala, nucleus accumbens and caudate nucleus.

Effects

Positive effects include ehuphoria and inebriation.

Altered body image, feelings of isolation, disorganization, drowsiness, hostility.

See also

Neurotransmitters