Dangers of Belladonna, the Deadly Nightshade and Uses of Atropine

The deadly nightshade plant, also known as belladonna, is so poisonous that eating as few as two berries can kill a child. The plant contains atropine and other dangerous alkaloid chemicals, including scopolamine and hyoscyamine. Despite its toxicity, when used in small quantities atropine has important medical applications.

The scientific name of the deadly nightshade is Atropa belladonna. All parts of the plant are poisonous. Deadly nightshade is native to Europe, Africa and Asia but grows in North America too. It has bell-shaped, purple flowers and produces shiny black berries. The deadly nightshade is sometimes called black cherry or devil’s cherries.

Not only is eating any part of the deadly nightshade dangerous, but simply touching the plant can be harmful if the skin has cuts. Symptoms of deadly nightshade poisoning include rapid heartbeat, dry mouth, slurred speech, light sensitivity, blurred vision, inability to urinate, loss of balance, flushed skin, a rash, memory loss, seizures, confusion and unpleasant hallucinations. Severe poisoning can cause paralysis, a coma and respiratory failure. Deadly nightshade is definitely a plant that should be admired from a distance.

Eating atropine inside a part of the deadly nightshade plant is very dangerous, but small amounts of atropine used in medications can be helpful. Atropine affects the activity of our parasympathetic nervous system.

The sympathetic division of the nervous system prepares our bodies for emergencies. It’s often said to stimulate the “flight or fight” response. The sympathetic system causes the heart to beat faster, the breathing rate to increase and the pupils to dilate. It also inhibits digestion. The parasympathetic division of the nervous system causes the opposite effects, and is sometimes called the “rest and digest” system. It relaxes the body, slows the heartbeat and breathing rate, constricts the pupils and stimulates digestion.

Atropine interferes with the action of the parasympathetic nervous system. Nerves of the parasympathetic system release a chemical called acetylcholine, which is a type of neurotransmitter – a chemical released from the end of a stimulated nerve cell in order to stimulate the next nerve cell. The acetylcholine must bind to a receptor on the second nerve cell in order to transmit the nerve impulse. Atropine blocks acetylcholine receptors, preventing the acetylcholine from doing its job.

The Heart

Atropine injections are given to speed up a very slow heartbeat. The atropine blocks the action of the vagus nerve. This nerve is part of the parasympathetic nervous system and slows down the heartbeat. When the action of the vagus nerve is inhibited by atropine the heart will beat faster.

The Eyes

Atropine is also used in eye drops to make the pupils dilate so that a doctor can examine the inside of the eyes properly. The pupils stay dilated for several days. It’s been reported that in earlier times some Italian women would use belladonna to dilate their pupils, making them look more attractive. The name “belladonna” means “beautiful lady” and supposedly comes from this use. The women’s vision would also have become blurred, since atropine inhibits accommodation – the process in which the lens changes shape to focus on objects at different distances from the eye.

The Digestive Tract

Food is passed along the digestive tract by wave-like contractions in the intestinal wall called peristalsis. Atropine calms the stomach and intestinal muscles and slows the frequency and strength of muscle contractions. It’s therefore been used to treat conditions such as irritable bowel syndrome.

Urination

The parasympathetic nervous system triggers urination by two methods. It stimulates the muscle in the urinary bladder wall to contract, which causes urine to be pushed out of the bladder. In addition, the parasympathetic system affects the sphincter muscle that surrounds the passageway which transports urine out of the bladder. When the sphincter muscle contracts, the passageway is closed and the bladder is able to fill with urine. The parasympathetic nervous system causes the sphincter muscle to relax, allowing urination to occur. Since atropine inhibits the activity of the parasympathetic nervous system it reduces urination. Atropine also inhibits spasms of the urinary bladder. These abilities help some urinary system problems.

Body Secretions

Atropine also decreases body secretions, including saliva, mucus and sweat. It's been used in cough syrups to help clear the airways.

Sedation

Atropine is sometimes used as a sedative. It’s known that acetylcholine is used as a neurotransmitter in the brain as well as in the parasympathetic nervous system, which is why atropine can affect brain functions when it interferes with the action of acetylcholine.

Inhibiting Chemical Weapons

Most chemical weapons that act on nerves belong to a group of chemicals known as organophosphates. These chemicals prevent acetylcholine from being broken down once it has done its job, so the acetylcholine continues to stimulate nerves. Atropine is used as an antidote to these nerve agents, since it blocks acetylcholine receptors, preventing the acetylcholine from reaching the nerves. Military personnel may carry an atropine auto-injector to protect themselves from chemical weapons.

The bittersweet nightshade, Solanum dulcamara, is sometimes known as the deadly nightshade. It's poisonous and can be deadly, but is not quite as toxic as the true deadly nightshade. The attractive flowers have blue petals, which are curved backwards to display a yellow or orange center, and the berries are bright red. The leaf has one large lobe and a pair of small lobes at the base. An alternate name for the plant is woody nightshade. It's a perennial vine which is native to Europe and Asia but is widespread in North America.

All parts of the bittersweet nightshade are poisonous. Like the deadly nightshade, the bittersweet nightshade contains toxic alkaloids. In a way the plant is more dangerous than deadly nightshade, because it's much more common and children, pets and livestock are more likely to encounter it. Eating bittersweet nightshade can kill children and animals. People should wear protective gloves when removing the plant.

The deadly and bittersweet nightshades are attractive and interesting plants to look at, but need to be treated with a great deal of respect. Even toxic plants can have benefits, such as the the production of atropine, but It's very important that children, pets and livestock (and adult humans!) avoid touching the plants or eating any part of them.