Stress Reaction Basics

Stress reactions in the human body are heavily regulated by naturally occurring steroid hormones called glucocorticoids; these hormones come from specific areas inside the paired adrenal glands, one of which sits on top of each of the kidneys. The main glucocorticoid hormones are known as cortisol (hydrocortisone) and cortisone. When dangerous conditions occur in your surroundings, the adrenal gland releases these hormones into the bloodstream. In turn, glucocorticoids make their way to almost every cell in the brain and body, where they attach themselves to specialized sites on the cell surfaces called glucocorticoid receptors. Under the influence of attached glucocorticoids, the glucocorticoid receptors produce chemical changes in your internal environment that manifest as stress-related reactions such as fear and anxiety.

Effects of Early Stress Exposure

Exposure to traumatic stress makes glucocorticoid receptors alter the normal activity of literally thousands of the body’s genes, according to research findings reported by the National Institute on Drug Abuse in 2012. These genes (like all genes) play an essential role in the most basic aspects of human life by issuing the instructions required to power the body’s functions and produce the materials used to construct various cellular components. In fully formed adults, the effects of glucocorticoid-related gene alteration are relatively minor; however, during early childhood, this alteration can produce profound changes in the normal course of growth and development.

One of the major consequences of stress-based gene alteration during early childhood is an increased tendency to exhibit unusually high levels of fear and anxiety under stressful circumstances during adulthood, according to the results of a 2012 study conducted by researchers at the University of Michigan, Ann Arbor. This study used glucocorticoid-based genetic alterations in rats to mimic the effects of the same alterations in human beings. The levels of fear and anxiety exhibited by these animals were high enough to reduce their desire to explore new environments or novel situations.

Impact on Cocaine Addiction Risks

Using the same rat model, the researchers from the University of Michigan also concluded that stress-based changes in the glucocorticoid receptors during early growth and development also significantly increase the adult brain’s sensitivity to the effects of cocaine. As is true in human beings, cocaine exposure in rats alters brain function by increasing the presence of certain chemicals, known as neurotransmitters, which facilitate communication between vital nerve cells in the brain called neurons. The increased presence of one neurotransmitter in particular, called dopamine, accounts for the intense rush of pleasure that draws many cocaine users into repeated drug abuse and the onset of drug addiction.

In addition to heightened cocaine sensitivity, stress-related alteration of the glucocorticoid receptors during early childhood produces several other changes that can make the adult brain more susceptible to cocaine addiction. These changes include alteration of the way in which immature neurons grow inside the brain, alteration of the connection points between the brain’s neurons, alteration of the ways in which the neurons release and use a range of neurotransmitters, and alteration of the adult ability to properly activate the mental functions that form the basis of memory and learning.


Traumatic stress during the early stages of childhood can also alter an adult’s underlying reasons for using/abusing cocaine, the University of Michigan researchers report. While people without a history of early stress exposure often start using cocaine out of an impulsive desire to try new things, people with a history of early stress exposure likely start using cocaine (at least in part) as a way to cope with their unusually high levels of fear and anxiety. When devising treatments to counter cocaine abuse and addiction, doctors and therapists may face significantly different issues when dealing with these distinctively different motivations for cocaine use.



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