It's not uncommon to hear someone talk about getting an "endorphin rush." Sex, exercise, even hot peppers -- all sorts of things are credited for these euphoric highs. So what are endorphins, and are they really responsible for our feelings of excitement or satisfaction?
In the early 1970s, researchers were studying how the brain is affected by opiates, such as heroin or morphine. They found that opiates interact with specialized receptors in cells that are primarily massed in the brain and spinal cord.
When opiates enter these receptors, they hinder or block the cell's transmission of pain signals. But why, wondered the scientists studying this phenomenon, would these specialized receptors exist in the first place? The most plausible answer was that opioid receptors exist due to the presence of an opiatelike substance produced naturally in the body.
