Summary: Drug or opioid addiction treatment is quite challenging, and even more challenging is preventing relapse. For decades researchers have focused on neurons and various brain centers to understand changes that occur with drug addiction and neuronal changes associated with heroin relapse. However, now researchers realize that what they have been considering as supportive brain cells, glial cells like astrocytes, appear to play a vital role in heroin relapse. 

Substance-related disorders or drug addiction is a significant problem. Among illicit drugs, heroin use remains the most significant problem. It is an illicit stimulant. Heroin overdose-related deaths among young adults are not rare in the US.

SUD is not merely a behavioral disorder; it is a neurological disorder. Some people are prone to SUD, which occurs due to some changes in the brain. However, what anatomical or neurochemical changes cause SUD is still poorly understood, though there are many theories. In addition, when treated for heroin addiction, some individuals are more likely to relapse.

In recent years, researchers have paid significant attention to understanding substance-related disorders. They also understand that though most addictions share common traits, some brain changes are unique to specific substances. That is why some are prone to alcohol addiction, others to heroin, and so on.

Researchers have paid much attention to changes in the neurons when it comes to studying addiction effects on the brain. Neurons are the primary brain cells responsible for various mental abilities. Researchers have identified multiple changes in various brain parts. For example, they now better understand the role of the reward pathway in addiction. They have also identified the role of neurotransmitters like dopamine in addiction and relapse.

However, health experts also realize that many things still need to be understood. For example, there are many drugs that can modulate the working of dopamine or reward pathways, but they fail to prevent heroin relapse in many.

Researchers think that one of the reasons why their efforts failed to find treatment for heroin addiction signs and many other brain disorders is due to too much focus on neurons. Since neurons are responsible for mental abilities, it is easy to conclude that neuronal dysfunction causes brain disorders.

However, there are other types of brain cells too. For example, the human brain has glial cells that are more than neurons in numbers. They were thought to be supportive brain cells that hold neurons in their place or play an important role in brain metabolism and immunity. 

However, now researchers have started realizing that glial cells also play a role in the brain’s working. It appears that they regulate neuronal activity. Astrocytes, a type of glial cells, produce neurotransmitters like glutamate to control neuronal activity levels. They seem to act as traffic lights in the brain. Thus, they may modulate the working of neurons significantly. Now studies suggest that astrocyte dysfunction has much to do with heroin relapse.

Researchers used a mice model to study heroin addiction in a new study. First, they used a typical addiction model in which mice get their dose of heroin by pressing a button. Then, they are given other clues like light and sound. The next time when cues are repeated, they know about the availability of the heroin or substance. 

Using this approach, they were able to induce signs of heroin addiction, withdrawal, craving, and relapse in mice. Furthermore, they found that there were significant changes in the astrocyte working in those with relapse. Astrocytes in these mice moved further away from neurons, and thus they were less likely to act as breaks. In addition, they were less likely to use glutamate to prevent drug-using behavior. Hence, the researchers concluded that this altered astrocyte plasticity plays a central role in heroin relapse. 

These are still early days into the research. However, it is clear that using drugs modulating glutamate activity is not enough. There is a need to find medications that can influence the working of astrocytes. If experts can find a way to modulate astrocytes, they can also alter the working of neurons, strengthening this breaking mechanism and hence preventing heroin relapse.