Researchers have discovered that the body deals with physical rejection in the same manner as physical pain by releasing natural painkillers, the UK's Daily Telegraph reported.
The study from the University of California in Los Angeles found that a variation in the mu-opioid receptor gene (OPRM1), often associated with physical pain, is related to how much social pain a person feels in response to heartbreak.
In the study, researchers collected saliva samples from 122 participants to assess which form of the OPRM1 pain gene they had, then they measured their sensitivity to social rejection.
First, participants completed a survey, which asked a series of questions such as: "I am very sensitive to any signs that a person might not want to talk to me."
Next, a subset of the group was tested to see the level of rejection they felt when they were excluded during a virtual ball-tossing computer game.
"What we found is that individuals with the rare form of the OPRM1 gene, who were shown in previous work to be more sensitive to physical pain, also reported higher levels of rejection sensitivity and showed greater activity in social pain-related regions of the brain … in response to being excluded," study co-author Professor Noami Eisenberger said in a media statement.
This is the first time that it has been proved in human studies that genes involved in physical pain are linked to mentally stressful situations such as the breaking up of a relationship, Professor Eisenberger said.
See Sexologist Dr Gabrielle Morrissey's tips for dealing with rejection