The Biochemistry of Heroin

Grant Hurt

What are the symptoms of heroine use?

When people use heroin, they feel a sense of Euphoria. This means that they don't experience stress or pain and are in a deep state of bliss.


Short-term symptoms of heroin use include itching, nausea, vomiting, difficulty breathing, fatigue and dry mouth.


Long-term effects of heroin use include heart damage, lung damage, kidney failure, collapsed veins, liver disease, and pneumonia.

What type of cell communication pathway is involved with heroin?

Heroin communicates through the neurons in the brain using synaptic signaling, a type of local signaling which uses neurotransmitters as a ligand.

How does heroin elicit a cellular response?

Inside the body, heroin is converted to morphine. Morphine binds to a G-coupled receptor called an opioid recepter, which is found in the parts of the brain that regulate pain and pleasure. Using a membrane-bound G-protein pathway, morphine is able to inhibit pain and stimulate pleasure. (See lower sections for an in-depth explanation)

What is the correct mechanism to communicate pain and pleasure?

In a normal human body, a neurotransmitter called gamma-aminobutyric acid (GABA) binds to opioid receptors to lower dopamine levels in the brain through a g-protein communication pathway. Endorphins, on the other hand, increase the amount of Dopamine. Dopamine is a neurotransmitter which causes a sense of pleasure. Thus, endorphins and GABA are natural on and off switches for pleasure. When GABA binds to the G-protein coupled receptor, pleasure is turned off. When endorphins bind to the G-protein coupled receptor, pleasure is turned on.

What is the faulty mechanism caused by heroin?

Morphine (formed from heroin) is extremely similar in shape to endorphins, and competes with GABA to bind with opioid receptors. When the brain is flooded with morphine, the morphine binds to opioid receptors more often than the GABA does. Morphine acts like an endorphin, allowing for the excess production of dopamine. Excess dopamine in the brain causes a sense of euphoria, lack of stress, lack of pain, etc. Dopamine also contributes to addiction and dependency on heroin. Disturbance of the natural pain-pleasure systems contributes to imbalances of other chemicals, for example cAMP. This can cause harmful symptoms and death.

Here's a graphic of how opiates, such as morphine and endorphins, elicit the production of dopamine.

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How is heroin used medically and what research is being done?

Medically, heroin acts as a strong painkiller because of its ability to eliminate feelings of pain and stress.


Research is looking into how we can prevent addiction to heroin and how we can prevent or remedy the imbalances of chemicals such as cAMP that heroin causes.