59 Fun Facts About Dopamine

The enzyme that turns L-DOPA into dopamine also makes which other famous mood chemical?

Serotonin comes off the same production line: one enzyme clips a carboxyl group from L-DOPA to give dopamine and from 5-HTP to give serotonin. Children born without it run short of both.

Rather than pleasure itself, mainstream pharmacology holds that dopamine signals what?

Motivational salience is how strongly an outcome grabs you, good or bad. One group of dopamine neurons fires for unpleasant events as well as for treats.

Dopamine belongs to which chemical family, along with the stress hormones epinephrine and norepinephrine?

Catecholamines are built in sequence: the body turns dopamine into norepinephrine and then into epinephrine, so the so-called reward chemical is also the raw material for fight or flight.

Dopamine synthesis starts with which essential amino acid, named in the warning on diet-soda cans?

Phenylalanine is a building block of the sweetener aspartame. The label protects people with the inherited disorder PKU, who cannot break it down, which is why newborns are routinely screened for it.

Which enzyme carries out the rate-limiting step of dopamine synthesis, turning an amino acid into L-DOPA?

Tyrosine hydroxylase sets the pace for the whole pathway. When dopamine builds up it latches onto the enzyme and slows it down, a built-in brake against overproduction.

Turning dopamine into norepinephrine needs which vitamin, also used to build collagen?

Vitamin C is used up in the reaction: each time the copper-containing enzyme adds an oxygen to dopamine, a molecule of the vitamin gives up electrons to make it happen.

What is the main inactive end product of dopamine breakdown, excreted in urine?

Homovanillic acid leaves the body in urine, which makes it a handy clue for doctors: a raised level helps reveal neuroblastoma, a childhood tumour that churns out dopamine-family chemicals.

Which two enzymes, along with aldehyde dehydrogenase, break dopamine down?

Monoamine oxidase and COMT are both drug targets: Parkinson's medicines that block either enzyme slow the breakdown of dopamine, so each dose of treatment lasts longer.

Which Back to the Future star was diagnosed with Parkinson's, a disease of dying dopamine cells?

Michael J. Fox noticed a twitching little finger while filming Doc Hollywood. He kept the diagnosis private until 1998, then launched the research foundation that bears his name.

Dopamine blockers such as haloperidol are used to calm the involuntary movements of which condition?

Tourette syndrome tics respond most reliably to dopamine blockers, yet many people with the condition never need medication, and the tics usually ease by the early twenties.

Anthropologist Helen Fisher found dopamine-rich reward areas lit up when her brain-scan volunteers gazed at photos of whom?

Their new sweetheart lit up the same dopamine circuitry that drives cravings. Fisher went on to argue that early romantic love is a natural addiction, complete with tolerance, withdrawal and relapse.

Tetrabenazine, which blocks dopamine storage, calms which disease's jerky movements?

Huntington's disease causes chorea, sudden movements a person cannot control. The drug blocks VMAT2, the transporter that loads dopamine into vesicles, so less is released and the movements settle.

A McGill University study found the brain releases dopamine at the moment a favourite piece of music produces what?

Chills marked the peak, but the scans held a second surprise: a different dopamine region fired during the build-up, while listeners were still only anticipating their favourite passage.

The substantia nigra, whose dopamine neurons die in Parkinson's, sits in which part of the brain?

The midbrain houses this structure, whose Latin name means black substance. By the time Parkinson's symptoms appear, a large share of its dopamine cells have already died.

What gives the substantia nigra its dark colour?

Neuromelanin is a dark pigment that builds up in dopamine cells as we age. In Parkinson's those pigmented cells die off, and the pigment is lost with them.

Brain scans showed Parkinson's patients releasing a substantial burst of their own dopamine after being given what?

A placebo was enough: simply expecting relief made the patients' damaged dopamine system release a substantial burst, showing the placebo effect is real brain chemistry rather than imagination.

Which 'reward' projection carries dopamine from the ventral tegmental area to the nucleus accumbens?

The mesolimbic pathway sits at the heart of addiction research: cocaine, alcohol and nicotine can all leave its dopamine system over-responsive long after the drug has worn off.

Dopamine from the hypothalamus is the main inhibitor of which pituitary hormone?

Prolactin is the milk-making hormone, held in check by a steady supply of dopamine. That is why dopamine-blocking drugs can trigger breast-milk production, even in men.

Bright daylight makes the retina release dopamine, a leading explanation for why outdoor play protects children against what?

Short-sightedness develops when the eyeball grows too long, and dopamine released by the retina in bright light appears to act as a stop signal for that growth.

In Olds and Milner's famous experiment, rats kept pressing a lever again and again to get what?

A jolt to the brain, delivered through an implanted electrode, beat every natural reward: the rats pressed on and on, forgetting to eat and drink.

Robinson and Berridge's addiction theory split reward into which two parts, only one driven by dopamine?

Wanting and liking turned out to be separate systems: dopamine fuels the craving, not the pleasure. That is why people with addictions can want a drug more and more while enjoying it less.

Cambridge neuroscientist Wolfram Schultz discovered that dopamine neurons signal what?

Errors in reward prediction drive the cells: a better-than-expected reward makes them fire, a fully expected one draws no response, and a reward that fails to arrive makes their firing dip.

Why is L-DOPA given to Parkinson's patients instead of dopamine itself?

It cannot cross the blood-brain barrier, whereas L-DOPA slips through and is turned into dopamine inside the brain. A partner drug, carbidopa, stops the body converting it too early, so a smaller dose does the job.

L-DOPA was first isolated in 1913 from the seeds of which plant?

The broad bean, or fava bean, holds enough L-DOPA to act like the drug: in a small trial, Parkinson's patients who ate a large plate of cooked beans moved markedly better for the next few hours.

Which Vienna-based scientist found that Parkinson's disease stems from a dopamine deficiency?

Oleh Hornykiewicz found dopamine badly depleted in the brains of Parkinson's patients who had died. A year later he and a Vienna neurologist injected L-DOPA, and bedridden patients stood up and walked.

Oliver Sacks's memoir Awakenings, filmed in 1990, describes giving L-DOPA to survivors of which epidemic?

Encephalitis lethargica swept the world in the 1910s and 1920s, leaving survivors frozen in hospital wards for decades. In 1969 L-DOPA had some of them up and dancing, though for many the benefits proved erratic or short-lived.

Which misfolded protein clumps into Lewy bodies in Parkinson's disease?

Alpha-synuclein clumps turned up throughout Robin Williams's brain at autopsy. The actor had been told he had Parkinson's a few months before he died; the Lewy bodies pointed to a related dementia.

Dopamine-mimicking Parkinson's drugs such as pramipexole carry a warning about which unexpected side effect?

Compulsive gambling, along with sudden urges to shop, overeat or have sex, has been reported in patients with no history of it. The drugs switch on the brain's reward circuits as well as its movement circuits.

Cocaine raises dopamine levels in the synapse mainly by doing what?

Blocking the dopamine transporter jams the pump that recycles dopamine, so it piles up between nerve cells. With repeated use the brain adapts, and everyday rewards such as food start to register less.

The founding president of which company admitted in 2017 that it was built to give users 'a little dopamine hit'?

Facebook's Sean Parker, who earlier co-founded Napster, called its likes a social-validation feedback loop that exploits a weakness in human psychology. God only knows, he added, what it is doing to children's brains.

In the early 1980s, Californian drug users developed Parkinson's symptoms almost overnight from a tainted lab-made copy of which drug?

Heroin substitutes from an illegal lab carried a by-product, MPTP, that wipes out the brain's dopamine-making cells. The same poison went on to give researchers a powerful animal model of Parkinson's.

Chlorpromazine's blocking of dopamine receptors inspired the dopamine hypothesis of which illness?

Schizophrenia was what chlorpromazine turned out to calm, though it began as a French military surgeon's aid to anaesthesia. He noticed it left patients strangely indifferent and urged psychiatrists to try it.

Dopamine-blocking drugs such as metoclopramide are given to chemotherapy patients to control which side effect?

Nausea starts in a brainstem patch that samples the blood for poisons and is studded with dopamine receptors. That is also why Parkinson's drugs that mimic dopamine so often make patients feel sick.

Which fruit is unusually rich in dopamine, in both its flesh and its peel?

In bananas, dopamine is a strong antioxidant rather than a mood chemical. The peel holds far more of it than the flesh, even when the fruit is ripe and ready to eat.

Squid ink is laced with dopamine that other squid can smell, which helps the ink cloud work as what?

An alarm signal is the ink's second job. Besides blinding a predator, the cloud carries L-DOPA and dopamine that a squid's smell organs pick up, warning others nearby that danger is close.

Why does the seaweed Ulvaria obscura pack itself with dopamine?

To deter grazers: dopamine makes up about 4% of the seaweed's dry weight, and sea urchins and snails eat less of it as a result. That may help it pile up in 'green tide' blooms.

Dopamine was first synthesised in 1910 at Wellcome Laboratories in which city?

London chemists made it during a survey of adrenaline-like compounds. For the next four decades it was written off as a mere stepping stone in the body's production of noradrenaline.

In a 1998 study, brain scans first caught dopamine being released during human behaviour while volunteers were doing what?

Playing a video game, steering a tank around a battlefield to collect flags for cash, drove dopamine up in the volunteers' reward centre. The better they played, the bigger the release.

Dopamine Nobel laureate Arvid Carlsson also helped create the first of which drug family, later made famous by Prozac?

SSRIs began with zimelidine, which Carlsson's group developed with the Swedish drug firm Astra. It was soon withdrawn over rare cases of a paralysing nerve disorder, leaving Prozac to make the family famous.

What happened to rabbits that Arvid Carlsson drained of dopamine?

They stopped moving until a dose of L-DOPA, the raw material for dopamine, had them up and about again. Carlsson saw the likeness to Parkinson's, and the drug became its standard treatment.

Manufactured dopamine, sold as Intropin, is given intravenously mainly to treat what?

Severe low blood pressure, as in shock, is its main use: moderate doses make the heart pump harder and higher doses tighten the blood vessels. The body clears it within minutes, so it runs as a continuous drip.

Bupropion, an antidepressant that acts on dopamine, has also been sold as Zyban to help people give up what?

Smoking is easier to quit on bupropion because it blunts nicotine cravings and withdrawal symptoms such as low mood and irritability. It is thought to work by slowing the brain's reuptake of dopamine and noradrenaline.

In the kidneys, locally made dopamine has what effect?

It increases sodium excretion, so more salt and water leave in the urine. When the kidney's own dopamine system falters, the body hangs on to salt, which is one recognised route to high blood pressure.

What does dopamine do to the hormone-producing beta cells of the pancreatic islets?

Reduces their insulin release: beta cells carry dopamine receptors and let out dopamine along with their insulin, as a built-in brake. That may help explain why dopamine-blocking antipsychotics can upset blood sugar.

In her bestseller Dopamine Nation, psychiatrist Anna Lembke calls which everyday object 'the modern-day hypodermic needle'?

The smartphone, she writes, delivers digital dopamine around the clock, and we reach for it for quick hits with every swipe. Lembke, a Stanford addiction doctor, argues that leaves almost everyone a little hooked.

Which two ADHD medications work by raising both dopamine and noradrenaline in the brain?

Methylphenidate and amphetamine are both stimulants, which sounds backwards for a condition marked by hyperactivity. Raising the two chemicals in the prefrontal cortex sharpens attention and self-control.

Polydopamine, a coating that sticks to almost any surface, was inspired by the glue of which sea creature?

Mussels anchor themselves to wet rock with sticky proteins. Copying that chemistry in 2007, researchers found a shortcut: dip almost any object in a dopamine solution and it comes out wearing a thin, clingy film.

According to Cameron Sepah, who popularised it, what is 'dopamine fasting' really meant to achieve?

Reducing impulsive behaviours such as emotional eating and excessive internet use was the aim, using methods from behavioural therapy. The name is only a catchy title: nobody can fast from a chemical the brain makes itself.

Where in the human body, besides neurons, is dopamine mainly synthesised?

Dopamine there is a stepping stone toward adrenaline.

Loss of dopamine with age is thought to explain which common change in older people?

Decreased arm swing when walking is a faint echo of Parkinson's disease, where the dopamine loss is far steeper. An arm that swings less on one side is often noticed early in the course of the disease.

Drugs that mimic dopamine, developed for Parkinson's disease, are also prescribed to calm which night-time condition?

Restless legs syndrome eases on these drugs, but there is a catch: with long use the urge to move can come back worse and start earlier in the day.

Toxoplasma, a parasite with genes for a dopamine-building enzyme, makes infected rats lose their fear of which animal?

Cats are the only animals in which the parasite can breed, so a rat that wanders towards the smell of one suits it nicely. Whether its dopamine genes do the steering is still in dispute.

In what salt form is dopamine supplied for chemical and pharmaceutical use?

Hydrochloride is the ending on countless medicine labels for the same reason: pairing a drug with hydrochloric acid gives a stable salt that dissolves in water. Dopamine's free form reacts readily and spoils.

In leeches, dopamine inhibits swimming and promotes which behaviour instead?

Crawling starts up even in a single cluster of leech nerve cells cut out and bathed in dopamine: its motor cells fire in the slow stretch-and-squeeze rhythm for minutes on end, with no brain attached.

The tiny lab worm C. elegans releases dopamine to slow itself down when it senses what?

A patch of food, which for this worm means a lawn of bacteria, is sensed by touch: dopamine nerve cells feel the microbes brush against its body. Slowing down keeps it where the eating is good.

The L-DOPA-rich velvet bean has pod hairs sold as which prank product?

Itching powder is one fate of the pods' needle-like hairs, which carry an enzyme that makes skin itch fiercely. Itch researchers now routinely use the same hairs on volunteers to study how itch works.

In insects, which noradrenaline-like chemical was long thought to carry reward signals instead of dopamine?

Octopamine, named after the octopus in whose salivary glands it turned up, does teach fruit flies that sugar is good. But it works by switching on a set of dopamine neurons, so dopamine was the messenger after all.

In 2013, psychologist Vaughan Bell mocked dopamine's tabloid fame by calling it which celebrity 'of neurotransmitters'?

Kim Kardashian, he wrote, because dropping the name lends instant appeal to listless reporting. One of his favourite examples was a tabloid claim that cupcakes could be as addictive as cocaine.

Which former Fifth Harmony singer released her long-awaited debut solo album, Dopamine, in 2024?

Normani had told fans she had the title back in 2018. After years of them asking where the record was, she announced it on a website called wheresthedamnalbum.com.