Effort-based decision making in response to high-dose androgens: role of dopamine receptors.
Level 5 - mechanism / opinion, no new human data
Controlled animal study in rats
PubMed 36148834 · doi:10.1097/FBP.0000000000000687
What was done
Rats received chronic high-dose testosterone (7.5 mg/kg; n = 9) or vehicle (n = 9) and were tested in an effort discounting task. In the task, animals chose between a small easy reward (1 lever press for 1 sugar pellet) and a large difficult reward (2, 5, 10, or 15 presses for 3 pellets). Preference for the large reward was evaluated at baseline and after administration of a D1-like receptor antagonist (SCH23390, 0.01 mg/kg) or a D2-like receptor antagonist (eticlopride, 0.06 mg/kg).
What was found
At baseline, preference for the large reward lever at fixed ratio 5 (FR5) did not differ significantly between testosterone-treated (68.6 ± 9.7%) and vehicle-treated rats (85.7 ± 2.5%). SCH23390 reduced large reward preference significantly in both groups (FR5: testosterone 41.3 ± 9.2%, vehicle 49.1 ± 8.2%; F(1,16) = 17.7, P < 0.05). Eticlopride decreased large reward preference in both groups, but the reduction was significantly stronger in testosterone-treated rats (FR5: testosterone 37.0 ± 9.7%, vehicle 56.3 ± 7.8%; F(1,16) = 35.3, P < 0.05).
Why it matters
This study demonstrates that chronic exposure to high-dose androgens alters effort-based decision making through heightened sensitivity to dopamine D2-like receptor signaling. This provides a potential neurochemical mechanism for the altered cost-benefit calculations and reward-seeking behaviors associated with anabolic steroid abuse.
Limits
The study was conducted in a small sample of male rats (n = 18 total), precluding direct translation to human steroid users. Only single doses of the dopamine antagonists were reported in the abstract, and direct neurochemical or accumbens receptor-binding measurements were not reported alongside the behavioral testing.