The Endocrine Effects of Nicotine and Cigarette Smoke

Introduction

Tobacco is an important cause of mortality and morbidity in developed countries, and the prevalence is increasing in developing countries and the developed world as well. There is no single organ in the body in which cigarette smoking is less harmful. Atherosclerosis (formation of fibrofatty deposits in the inner wall of the blood vessel) due to smoking is the major cause of death in cardiovascular diseases. Tobacco contains numerous compounds that contain carcinogens, such as carbon monoxide, nicotine, and other gases. It increases the physical stress on the body. Nicotine is a psychoactive ingredient of tobacco that affects various metabolic processes of the body. The effects of nicotine are increased release and synthesis of hormones and neurotransmitters. It has important psychological consequences and a huge impact on endocrine hormones such as thyroid hormones, sex hormones, adrenal hormones, pituitary hormones, and parathyroid hormones.

What Is the Link Between Smoking and Hormones?

The link is explained as follows:

• The endocrine system comprises organs and glands that produce hormones throughout the body.

• They are involved in crucial processes of the body, like growth, metabolism, reproduction, and sleep.

• Tobacco chemicals, such as nicotine, influence the secretion, production, and hormone levels throughout the body, affecting the thyroid, hypothalamus, and ovarian and adrenal glands functions.

• The nicotine from smoking increases cortisol, prolactin, and growth hormone levels in the blood.

How High Nicotine in Cigarettes Influences the Body?

The actions of nicotine on the body are:

• Nicotine is the main psychoactive chemical in tobacco. Nicotine creates a feeling of relaxation, increases the amount of oxygen supplied to the heart, and increases heart rate. It causes a surge of endorphins that relieve stress and pain and improve mood.

• The body quickly absorbs nicotine and sends it to the brain, and their levels peak quickly after, and the feelings of pleasure are short-lived. This short-lived feeling creates a cycle of people continuing to smoke to sustain pleasurable sensations.

• Nicotine increases dopamine (neurotransmitter) levels and improves the feelings of reward and pleasure. The dopamine release reinforces the behavior of taking tobacco over and over again.

How Does Smoking Increase the Adrenocortical Hormones Secretion?

The effects of smoking on adrenocortical secretion include:

• Cigarette smoking increases the release of anterior and posterior pituitary hormones.

• Cortisol is a glucocorticoid hormone essential for normal blood pressure in the body and, in excess, produces hypertension (high blood pressure). It is produced from the zona fasciculate layer of the adrenal cortex.

• It is a corticosteroid produced in small amounts by the adrenal cortex.

• The adrenal cortex secretes cortisol, aldosterone, and androgens during a stress response.

• Cortisol is released in our body in response to stress. Smoking causes increased levels of cortisol. Chronic levels of high cortisol levels cause decreased fertility and high blood pressure.

• Nicotine stimulates the release of ACTH (adrenocorticotropic hormone) hormone from the anterior pituitary gland, increasing blood cortisol production.

• High cortisol levels inhibit insulin production and trigger a flood of glucose in the bloodstream that supplies energy in response to stress.

• It increases the body's sympathetic activity, narrowing the blood vessels and eventually increasing blood pressure.

• Smoking stimulates the formation of fibrofatty plaques in the inner wall of the blood vessels. The most prevalent cause of plaque buildup in the blood vessels is low-density lipoprotein (LDL). Smoking increases the levels of LDL (bad cholesterol). Smoking lowers the HDL (high-density cholesterol) in the body, making the blood stickier and forming clots.

• Fibrofatty plaque is made up of cholesterol, fat, and other substances that block normal blood flow. High cholesterol levels lead to cardiovascular diseases.

• The chemicals of the cigarette increase the clot formation inside the veins and arteries. It causes the blood to thicken. This disrupts the blood flow, eventually resulting in cardiovascular diseases.

How Does Nicotine Influence the Secretion of the Adrenal Medulla?

The nicotine effects on the adrenal medulla are:

• The adrenal medulla is the inner part of the adrenal gland that secretes epinephrine and norepinephrine, which regulates the body's autonomic nervous system. It is involved in the regulation of the heart rate.

• These hormones are released in response to stress.

• Norepinephrine responds to stress by increasing blood sugar levels and narrowing the blood vessels. This narrowing leads to a rise in blood pressure.

• Nicotine in cigarettes stimulates the adrenal release of norepinephrine.

• Smoking increases the catecholamine release. They have direct effects on sympathetic nerve endings that increase blood pressure. During smoking, the plasma levels of epinephrine and norepinephrine increase markedly.

How Does Smoking Impact Thyroid Hormone Secretion?

Cigarette smoking has multiple effects on thyroid function, such as stimulatory and inhibitory actions. Smoking worsens the symptoms of Hashimoto's disease and hypothyroidism. The cyanide present in cigarette smoke is converted into the chemical thiocyanate. The thiocyanate interferes with thyroid functions in three ways:

• It inhibits the uptake of iodine by the thyroid gland, which reduces the release of thyroid hormones like thyroxine and triiodothyronine.

• It increases the excretion of iodine from thyroid glands. This increases the inflammation of the thyroid gland.

• The inflammation caused by smoking results in further inflammation in Grave's disease (an autoimmune condition characterized by thyroid enlargement) and Hashimoto's disease (an autoimmune disease linked with hypothyroidism).

How Does Smoking Affect Women’s Sex Hormones?

The following hormone changes occur in women:

• Women smokers have more circulating testosterone and low estrogen levels than non-smokers. Smoking has increased the risk of high testosterone levels in women.

• Estrogen in women helps to build strong skeletons and bones in women. Smoking lowers the circulating estrogen in the body.

• Low estrogen causes more belly fat, reduced sex drive, and bone loss in women.

The signs of low estrogen are:

• Hot flashes.

• Weak or brittle bones.

• Irritability and mood swings.

• Weight gain.

• Decreased sex drive.

• Tender breasts.

Conclusion

Smoking can increase the risk of heart disease affecting the whole body functioning. The only solution to all these problems is to quit smoking. There are many structured programs that help guide individuals to quit smoking, like smoking cessation programs. Nicotine causes hormonal imbalances in the body that causes various side effects. Smoking cessation programs have information on how to stop smoking and undergo therapies.