Exercise reinforcement, stress, and β-endorphins: an initial examination of exercise in anabolic-androgenic steroid
Tom Hildebrandt1, Sydney Shope1, Eleanna Varangis1
1Department of Psychiatry, Ichan School of School of Medicine at Mount Sinai, New York, NY, USA.
Background:
Anabolic-androgenic steroids (AASs) are abused primarily in the context of intense exercise and for the purposes of increasing muscle mass as opposed to drug-induced euphoria. AASs also modulate the HPA axis and may increase the reinforcing value of exercise through changes to stress hormone and endorphin release. To test this hypothesis, 26 adult males drawn from a larger study on AAS use completed a progressive ratio task designed to examine the reinforcing value of exercise relative to financial reinforcer.
Method:
Sixteen experienced and current users (8 on-cycle, 8 off-cycle) and 10 controls matched on quantity×frequency of exercise, age, and education abstained from exercise for 24 h prior to testing and provided 24-h cortisol, plasma cortisol, ACTH, β-endorphin samples, and measures of mood, compulsive exercise, and body image.
Results:
Between group differences indicated that on-cycle AAS users had the highest β-endorphin levels, lowest cortisol levels, higher ACTH levels than controls. Conversely, off-cycle AAS users had the highest cortisol and ACTH levels, but the lowest β-endorphin levels. Exercise value was positively correlated with β-endorphin and symptoms of AAS dependence.
Conclusion:
The HPA response to AASs may explain why AASs are reinforcing in humans and exercise may play a key role in the development of AAS dependence.
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