Catecholamines: Say Hello to Your Built-in Stress Responders

WHAT ARE CATECHOLAMINES?

The adrenal glands are glands that sit on top of each kidney. They belong to the endocrine system, a highly specialised body system composed of glands that release hormones. Each adrenal gland has two distinct parts: the medulla (inner part) and the cortex (outer part), which have different functions. The adrenal cortex releases a group of hormones called corticosteroids, which include gonadocorticoids, glucocorticoids, and mineralocorticoids. On the other hand, the adrenal medulla releases its own group of hormones called catecholamines, namely epinephrine, norepinephrine, and dopamine. They’re designated as catecholamines because of a particular molecule called aromatic amine present in their structure.

EPINEPHRINE, NOREPINEPHRINE, AND DOPAMINE SHARE THE FOLLOWING CHARACTERISTICS:

1. All three catecholamines act as both neurotransmitters and hormones.
2. As neurotransmitters, they’re produced in the brain and function as chemical messengers, conveying messages from a sender nerve cell to a receiver cell (it can be another nerve cell, muscle cell or gland).
3. As hormones, they’re produced and released from the adrenal glands and stimulate several tissues and organs. They’re released in response to stress or sympathetic nervous system stimulation.
4. All three are made from the precursor (building block) tyrosine, an amino acid.
5. All three participate in the fight-or-flight response to varying degrees. Epinephrine contributes the most effects, followed by norepinephrine and then dopamine.

Epinephrine is also known as adrenaline. Its release from the adrenal gland is a vital part of the sympathetic nervous system, a system used by the body to respond to danger.

FIGHT-OR-FLIGHT RESPONSE

The fight-or-flight response, also called the sympathetic alarm reaction, refers to the body’s reaction to a stressful situation, like facing a fear or running away from your neighbour’s English Mastiff (a big and heavy dog). The term fight-or-flight originates from our ancestors who either fought or fled a dangerous situation during their time. Yes, it was that simple back then—no policemen, firefighters, or paramedics to call. The fight-or-flight response starts with your brain perceiving danger. Your brain then sends signals down to your spinal cord. The nerves from the spinal cord rapidly stimulate numerous tissues and organs to react to the situation. The neurotransmitter used to convey the signals from your brain to the organs is norepinephrine.

The fight-or-flight response includes the following reactions:

1. The pupils of your eyes dilate to allow more light for better vision of your environment.
2. Blood flow is rerouted to vital organs such as your brain, heart, and skeletal muscles. Your skin turns pale as a result of this diversion of blood flow. As a consequence, your muscles react with greater speed and strength.
3. Your heart beats faster and stronger to deliver more oxygen and nutrients to your muscles.
4. Your breathing becomes more rapid and deeper. The airways widen, so more oxygen is delivered to your blood.
5. Your liver releases more glucose to provide energy.

Let’s not forget about your adrenal glands, which are also activated during a fight-or-flight response. Norepinephrine stimulates them to release catecholamines from the adrenal glands. These hormones travel to the same target organs mentioned above. They inform the tissues and organs to continue reacting until your brain tells them that you’re out of danger. The epinephrine’s effects on your body when not in fight-or-flight response include the same reactions mentioned above but to lesser degrees.

EPINEPHRINE AS A DRUG FOR EMERGENCY MEDICAL CONDITIONS

Epinephrine produced pharmaceutically is used to treat patients with the following life-threatening conditions:

1. Patients in cardiac arrest, where epinephrine is utilised to activate your heart.
2. Patients who have severe allergies, for example, a nut allergy. Epinephrine is the drug of choice for anaphylaxis, a severe form of allergic reaction. This is because epinephrine relaxes the muscles in the airways to allow oxygen to come in.
3. Patients with a severe asthma attack not responding to first-line treatment are also given epinephrine to decrease spasms and open the lung airways.
4. Epinephrine also increases the blood pressure of patients with septic shock, a condition wherein the blood pressure is very low after an infection.

EPINEPHRINE IMBALANCE: HIGH LEVELS VS LOW LEVELS

1. High levels of epinephrine can lead to hypertension (high blood pressure), too much sweating, headache, irregular or fast heart rate, pale or cold skin, and feeling nervous most of the time.
2. Pheochromocytoma is a tumour that grows in the adrenal gland. It can release too much epinephrine (and norepinephrine) into the bloodstream and result in the signs and symptoms mentioned above.
3. Low epinephrine levels can lead to anxiety, depression, irregular sleep, headaches, lack of energy secondary to low blood sugar, irregular heart rate, and unstable blood pressure.

This catecholamine also goes by the name noradrenaline. Epinephrine comes from norepinephrine, which comes from dopamine. If there’s an imbalance of dopamine, there will be an imbalance of epinephrine and norepinephrine. Norepinephrine is also a part of the fight-or-flight response.

As a neurotransmitter in the brain and spinal cord, it does the following:

1. Improve focus, arousal, attention, and alertness.
2. Narrows blood vessels to maintain adequate blood pressure under stressful conditions.
3. It plays an essential role in regulating mood, processing of memory, and helps control the sleep-wake cycle together with two other hormones, melatonin and cortisol.

As a hormone, any type of stress may trigger the release of norepinephrine from the adrenal glands. This process triggers several changes similar to the effects of epinephrine, including the fight-or-flight response.

NOREPINEPHRINE AS A DRUG FOR PARTICULAR MEDICAL CONDITIONS

Pharmaceutically produced norepinephrine, together with other medicines, is used in the treatment of:

1. Neurogenic shock. This condition happens when the spinal cord is severely injured.
2. Septic shock.
3. Pericardial tamponade. A condition resulting in excess fluid building up in the space around the heart. The excess fluid squeezes the heart and prevents it from pumping adequate blood to the tissues and organs.

NOREPINEPHRINE IMBALANCE: HIGH LEVELS VS LOW LEVELS

Excess and deficient levels of norepinephrine can lead to the same signs and symptoms seen in people with high and low epinephrine levels (see above). Attention deficit hyperactivity disorder (ADHD) and norepinephrine. Both dopamine and norepinephrine help us concentrate, focus, and pay attention better. It has been observed that people with ADHD have low levels of these chemicals. As a result, people with ADHD have difficulty focusing, have short attention spans, have impulse control issues, and never seem to stay put in one place (always moving).

Like the other two members of this group, dopamine acts as a hormone and neurotransmitter.

Dopamine has the following additional functions:

1. Dopamine slows down motility in the gastrointestinal tract.
2. It decreases insulin production in the pancreas.
3. It promotes salt removal from the body through increased urine output.
4. Dopamine widens and narrows blood vessels at low and high doses, respectively.

Dopamine is known as the feel-good hormone because it provides you with a sense of pleasure. It’s part of the reward system in your brain. This particular system is designed to reward you with a feeling of elation (happiness) when you’ve accomplished things you need to do to sustain yourself or, more primitively, to survive. Simple pleasures like drinking water, eating, and taking a bath will get a release of dopamine. As a result, you feel good and want more of it. Processed foods and junk foods stimulate the release of huge amounts of dopamine in the brain, giving the person a sense of pleasure that they intend to repeat. This is the reason why these types of foods are addicting.

DOPAMINE IMBALANCE

The table below is a rough guide to gauge whether you may have a dopamine imbalance:

Note: Please remember that the table is simply a rough guide. Several other conditions, neurotransmitters, and hormones can contribute to the symptoms mentioned.

There are several diseases linked with decreased and increased dopamine levels. Experts are still trying to determine the relationships between dopamine levels and particular illnesses. Also adding confusion to the mix is that the role of one neurotransmitter or hormone like dopamine can’t be analysed in isolation, separate from the other neurotransmitters or biochemicals in the body. The processes are complex and challenging to understand. Experts know that some specific diseases are associated with high or low dopamine levels.

DOPAMINE AS A MEDICATION

Levodopa is a type of drug used to treat Parkinson’s disease. People diagnosed with Parkinson’s disease have low dopamine levels, which lead to movement symptoms such as muscle spasms, twitching, and tremors. The problem with levodopa is that it has a hard time reaching the brain. To circumvent this problem, it’s combined with another drug called carbidopa. Once levodopa reaches the brain, it’s converted to dopamine.

Catecholamines both function as hormones and neurotransmitters. They play roles in several essential body functions, including the body’s fight-or-flight response, movement, memory, and other everyday processes. An imbalance in any of these catecholamines is connected to various diseases and mental health disorders. When used as medications, they treat an array of life-threatening medical conditions. Surprisingly, there’s still a lot to unravel regarding their interactions with other chemicals in the body and their applications in medicine.