Morphine and Its Relationship to Endorphins in the Human Body

MORPHINE 1

Morphine and Its Relationship to Endorphins in the Human Body

Tammi McDaniel

South Gibson County High School Honors Chemistry

Revised 12/13/15

Abstract

This paper explores the opiate compound morphine. The paper will cover a brief history of morphine and its chemical structure before moving into a description of how morphine interacts with the human body and nervous system via opioid receptors. The opioid peptide endorphin and its natural production and interaction with the nervous system will be discussed for comparison. The paper will describe the positive use of morphine for pain relief within the clinical setting, but will also reveal the effects and dangers of morphine addiction.This paper will conclude that in many ways the discovery of morphine has been positive and that although morphine and endorphins act similarly, morphine is more powerful and dangerous.

Keywords: addiction, benzylisoquinoline alkaliod, endorphins, morphine, neurotransmitters

Morphine and Its Relationship to Endorphins in the Human Body

Morphine is a drug commonly used in the medical industry. It relieves pain, but it is also addictive. In addition to relieving pain, morphine can induce a feeling of euphoria, produce sleepiness, and impair cognition(Busse, 2006). Endorphins occur naturally in the human body and modify communication in the brain. Endorphins act as the body’s natural painkiller and also produce the effects of sleepiness and sense of well-being without the additional side effect of impaired cognition(Advameg, Inc., 2015). This paper seeks to examine morphine, its effects on the human body, and its relationship to naturally produced endorphins.

Morphine is one of the principal ingredients of opium, a naturally occurring drug that is cultivated directly from the poppy plant. Morphine and opium are in a category of substances called opiates. Opiates are used for pain reduction in hospitals. The effects of opiates result from their interaction with biological processes inside the human body. For example, opiates alter the functioning of specialized cells called neurons that are found in the nervous system. Neurons help people to sense and perceive light and sound, express emotions, and think. Thus, opiates can affect feelings, cognition, and behavior(Busse, 2006).

Physicians have used opiates for over a thousandsyears to reduce pain. Ancient texts indicate that even the Sumerians and Greeks had poppy-based medicines. These cultures were also aware of the addictiveness of these chemicals. Greek scholars Hippocrates and Galen stressed control when using opiates. They wrote that although the poppy eases pain and brings sleep, large quantities could cause dependence or death(Busse, 2006). In the early 5th Century, opium was advertised as a cure for quite a number of ailments from dropsy and gout to hysteria and insanity. The peddling of opium in this manner continued into the 18th and 19th Centuries where it was used in elixirs because it gave the illusion of a cure. The added benefit to those producing these elixirs was the frequent return of addicted customers(Hodgson, 2001).

Although it is unknown when the opiate morphine was exactly discovered, it is usually accepted by medical historians that it was discovered between 1805 and 1816 by Fredrich Wilhelm Serturner. Serturner was able to isolate a yellowish-white, crystalline compound from raw opium by immersing it in hot water. He then tested the drug on dogs, three boys, and himself. He discovered that the drug relieved pain, but it also produced a dysphoric feeling and nausea(Busse, 2006).He named the drug morphine after Morpheus, the Greek god of sleep (Mandal, 2013).

Commercial production of morphine began in the mid-19th century; however, its acceptance by the public was resisted. The primary reason for this resistance was that the drug was administered orally.People believed that the drug would be digested by the body and then expelled rather than distributed through the body to produce the desired effects.Morphine gained wider acceptance in 1853 when the hypodermic needle was invented and morphine began to be administered intravenously(Busse, 2006). Morphine was approved by the Food and Drug Administration (FDA) in 1941 (Cerner Multum, Inc., 2015).

The chemical formula for morphine is C17H19NO3. It is a benzylisoquinoline alkaloid (BIA) with a five-ring structure(Mandal, 2013). BIAs are a group of plant-based metabolites. Despite sharing a common biosynthetic origin, BIAs are very structurally diverse (Hagel & Facchini, 2013). Three of morphine’s five rings lie in the same plane,while the other two rings are at right angles to the first three. Like other opioids, morphine has an aromatic ring and a quaternary carbon atom linked to a tertiary amine group by two other carbon atoms. The nitrogen atom is attached to a methyl group (see appendix)(Mandal, 2013).

It is the interaction of morphine with the biological processes of the body that is responsible for its ability to produce effects. This interaction closely resembles the interaction of human endorphins(Busse, 2006). This interaction takes place within the brain with billions of nerve cells called neurons. Neurons are in both the central and peripheral nervous systems. The central nervous system is made up of the brain and spinal cord; the peripheral nervous system is comprised of nerve cells in the tissues and organs. In order for the human body to correctly process sensations (such as pain, light, and sound), the neurons must communicate with each other.Nerve cells accomplish this by secreting neurotransmitters that carry messages from one neuron to another. Neurotransmitters are secreted from synaptic knobs at the end of one cell and picked up by receptor sites on the dendrite (branch-like protrusion) of another neuron. (Advameg, Inc., 2015).

Morphine affects neurons that have certain types of receptors, called opioid receptors. There are three types of opioid receptors: The mu (found in the brain and spinal cord), the kappa (found in the brain), and the delta (found in the spine)(Busse, 2006). These receptors are found in different regions of the brain as well as the limbic system (amygdala, hypothalamus, and thalamus)(Petrizzo, Mohr, Mantione, & Goldstein, 2014).Morphine acts as an opioid agonist at these receptors, evoking a neuronal response. An opioid agonist is a drug that imitates the effects of opioid peptides. Opioid peptides include enkephalin, endorphin, and dynorphin. Once opioid receptors are activated by morphine, neurotransmitters shut down other neurons' ability to talk with one another. Without communication, sensations and perception are altered. Persons may not feel or care about pain, may seem confused or unsure about where they are, and/or may be especially euphoric(Busse, 2006).

However, the human body is capable of altering the perception of pain by itself, though its effectiveness is limited. This phenomenon is due to the release of opioid peptides, their activity on opioid receptors, and the subsequent inhibition of neuronal communication (Cerner Multum, Inc., 2015).Endorphin is an abbreviation of endogenous morphine andis amember of this opioid peptide family. Endorphins were discovered in 1972 when scientists at Johns Hopkins University were studying drug addictions andfound the receptor sites where morphine binds to nerve cells. Researchers reasoned that the body must use these sites to bind compounds. Experiments showed that the compounds were small peptides(Cowell, 1997).

Endorphins are not actual neurotransmitters. Instead they are classified as neuromodulatory,that is, they modify the action of neurotransmitters(Sullivan, 2015).This is the same method by which morphine alters the brain’s communication. Like morphine, endorphin will shut down neuronal communication when it attaches to an opioid receptor on a neuron(Busse, 2006).

Endorphins are produced and released by the brain through a variety of ways. One method of endorphin production is by exercise, stretching, or meditation. Laughter and listening to music also produce endorphins. The production of endorphins may also be enhanced through other methods such as aromatic candles, acupuncture, taking ginseng, and eating a chili pepper or chocolate(Reader's Digest, 2015).Endorphins can also block processing pain during traumatic events, childbirth, and sports competitions(Petrizzo, Mohr, Mantione, & Goldstein, 2014).

Endorphins are released via a descending corticospinal tract, a pathway that runs from the brain to the spine, allowing the body to mediate its own analgesia. Endorphins binding to the opioid receptors on y-aminobutyric acid (GABA) B interneurons stimulates release of nitric oxide. This blocks the stress response of inhibiting the production of dopamine within the reward center of the brain and the hypothalamus, the emotional center of the brain. The resulting increase of dopamineis responsible for a sense of wellbeing and satisfaction.(Petrizzo, Mohr, Mantione, & Goldstein, 2014).

The two key differences in morphine and endorphin lie in their strength and side effects. Morphine is more powerful than endorphin. The power of morphine is due to its exogenous nature. Since morphine is a substance that originates outside the human body, it can be introduced into the body at adesired concentration.The production of endorphins is controlled by the body itself and is less generously mediated by the brain (Cowell, 1997). Additionally, should pain persist, more morphine can be injected into the body. Endorphins, by contrast, decrease if the sensation of pain continues. This suggests the idea that the body’s production of endorphin is a short-term measure, giving a person the ability to manage or flee what is causing the pain before being rendered immobile by the sensation(Michelle, 2015).

Since endorphins are produced by the body, their job is very specific and they carry no negative side effects. Morphine, however, carries the risk of dangerous side effects and dependence. Morphine can attach to other neuronal receptors throughout the body, giving it the ability to alter other functions including emotional stability, changes in respiration, blood pressure, body temperature, and digestion(Busse, 2006). Prolonged use can lead to respiratory depression, vomiting, dizziness, constipation, itching, dysphoria, diarrhea, change of physiological structure of the body, and insomnia(Petrizzo, Mohr, Mantione, & Goldstein, 2014).

Another negative side effect of morphine use is neuronal tolerance. Neuronal tolerance occurs at the dendritic receptor where neurotransmitters attach. Neurons respond to repetitive morphine-induced activation by reducing the number of dendritic mu receptors to which morphine or opioid peptides can attach. Therefore, the endorphins lose their ability to mediate analgesia. Even the production of endorphin itself is reduced through excessive use of morphine. The body loses its ability to create a sense of well-being and manage stress and pain, and the patient becomes dependent upon the morphine compound (Busse, 2006).

When people become addicted to morphine, they will avoid morphine withdrawal(Busse, 2006). Morphine withdrawal symptoms are the polar opposite of morphine's effects. Symptoms include teary eyes, a runny nose, muscle pain, loss of appetite, and rapid heartbeat(Narconon International, 2015). Another symptom of morphine withdrawal is hyperalgesia, or increased pain sensitivity(Sprouse-Blum, Smith, Sugai, & Parsa, 2010).

The discovery of morphine in many ways has been positive. It is an integral part of clinical medicine and pain relief and even led to the additional discovery of opioid peptides like endorphin. Although the two interact very similarly within the brain, morphine is more powerful as a result of its exogenous nature and is far more dangerous due to its side effects. Perhaps through the study of this drug and its side-effect-free twin, endorphin, scientists may develop new drugs that carry the same positive analgesic effects of morphine without the resulting addiction and negative effects.

References

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Appendix

The Chemical Structure of Morphine

(NEUROtiker, 2007)