What is itchiness?

Itchiness is a subjective, irritating sensation arising from the superficial layers of skin that provokes an urge to scratch. Scratching is a reflex response to an itch. The command to start scratching comes directly from the spine. We know this because researchers recently discovered itch specific receptors in a localized area of the spine.
 
 
 

Heroin itching

Heroin related itching typically occurs around the nose and upper part of the face. However, higher doses may affect more generalized areas, such as arms, legs and genitalia. Itchy skin is one of the most prevalent adverse effects of heroin use.  Many scientists believe that itchiness is an unavoidable after effect of opiate use.
 
 
 

The cause of the heroin itch?

After heroin enters the bloodstream, it enters into the brain and spinal cord. There it attaches to proteins atop nerve cells called opioid receptors. The most common type of opioid receptor is the mu-opioid receptor (MOR). Each MOR has several variants, which are called isoforms. Isoforms are like your hands. Maybe you use your left hand to stir things and your right hand to open things. In this way, each hand or isoform does something different. There is one MOR isoform in particular, called the MOR1D, which is the hand that opens the door to itchiness.

heroin-GRPR-itchyWhen heroin bumps into and activates a MOR1D receptor, the neuron sends out messages, called neurotransmitters, out to other receptors atop other neurons. Some of those neurotransmitters bump into and activate GRPR receptors (Gastrin Releasing Peptide Receptor). Scientific research, led by Zhou-Feng Chen, Ph.D., has found that GRPR receptors are itch specific receptors. GRPR receptors are found in a very small population of spinal cord nerve cells.

When a person uses heroin, or any other opioid for that matter, it sets off a cascade of events. The first of which, is that heroin binds to and activates MOR1D receptors, which subsequently sends out neurotransmitters that activate GRPR receptors, and this results in an itch sensation, which leads to scratching.

 

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