Adolescent rats who experienced social rejection from unresponsive play partners developed reduced pain sensitivity, and blocking CB1 receptors prevented both the social stress and the pain changes.
Read this if you are interested in how social experiences during adolescence affect the endocannabinoid system and pain processing.
CB1 receptor blockade prevented both the social stress response and the altered pain sensitivity from peer rejection.
What the researchers found
Researchers modeled adolescent social rejection by pairing adolescent Wistar rats with Fischer 344 rats, a strain known for being unresponsive to play solicitations. The Wistar adolescents showed clear signs of social distress: increased ultrasonic vocalizations at 50 kHz (associated with positive/seeking states) and increased play attacks, suggesting they were trying harder to engage their unresponsive partners.
After these experiences, the socially rejected rats showed decreased pain sensitivity to thermal stimuli. A low dose of the CB1 receptor blocker SR141716 given before the social encounter prevented both the compensatory social behaviors and the subsequent pain changes.
This demonstrates that the endocannabinoid system mediates the link between social pain (rejection) and physical pain processing, providing a biological explanation for why social and physical pain overlap.
Why it matters
The overlap between social and physical pain is well documented in humans but poorly understood mechanistically. This study identifies the endocannabinoid system as a key mediator, suggesting that the same system activated by cannabis is involved in processing the pain of social rejection during the sensitive adolescent period.
The numbers in context
Wistar rats paired with Fischer 344 partners showed increased 50 kHz ultrasonic vocalizations and increased play attacks. Social rejection reduced thermal pain sensitivity. Sub-threshold CB1 blockade prevented both social and pain-related effects.
How the study worked
Female adolescent Wistar rats were paired with either same-strain partners (control) or Fischer 344 rats (social rejection model) for acute social interaction sessions. Behavioral analysis included play attacks, ultrasonic vocalizations, and pain sensitivity testing. The CB1 receptor antagonist SR141716 was administered at a sub-threshold dose before social encounters to test endocannabinoid involvement.
What this study cannot tell us
This was a rodent study, and social dynamics in rats may not fully model human adolescent rejection. Only female rats were tested. The CB1 blocker was given before the social encounter, so it is unclear whether it would reverse already-established changes. The Fischer 344 pairing is a model of social rejection but not identical to human peer rejection.
How to read the evidence
Preliminary evidence from a well-controlled animal study demonstrating a clear mechanism, though translation to human adolescent social experiences requires further research.
When this study was published
Published in 2016. The intersection of social neuroscience and the endocannabinoid system continues to be explored.
The bigger picture
Adolescence is a period of heightened sensitivity to both social rejection and the effects of cannabinoids. This study connects these two vulnerabilities through a common biological system. The finding that social pain modifies physical pain through endocannabinoid signaling may help explain why some adolescents turn to cannabis after social difficulties.
Questions still open
- Does chronic adolescent social rejection produce lasting endocannabinoid system changes? Could endocannabinoid system dysfunction explain the link between peer rejection and substance use in human adolescents? Would these findings differ in male rats?
Common questions
How are social pain and physical pain connected?
Could this explain why some teens use cannabis after social difficulties?
Read the original research
Adolescent social rejection alters pain processing in a CB1 receptor dependent manner.
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology, 26(7), 1201-12
Citation
Schneider, Peggy; Pätz, Monique; Spanagel, Rainer; Schneider, Miriam. (2016). Adolescent social rejection alters pain processing in a CB1 receptor dependent manner.. European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology, 26(7), 1201-12. https://doi.org/10.1016/j.euroneuro.2016.04.007
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