Testosterone enhances risk tolerance without altering motor impulsivity in male rats.
Anabolic-androgenic steroids (AAS) increase impulsive and uncontrolled aggressive ('roid rage) in humans and enhance agonistic behavior in animals. However, the underlying mechanisms for AAS-induced aggression remain unclear. Potential contributing elements include an increase risk-taking and/or motor impulsivity due to AAS. This study addressed the effects of chronic high-dose testosterone on risk tolerance using a risky decision-making task (RDT) and motor impulsivity with a go/no-go task in operant chambers. Male Long-Evans rats were treated for at least 4 weeks with testosterone (7.5mg/kg) or vehicle beginning in late adolescence. Testosterone was used because it is popular among human AAS users. In RDT testing, one lever was paired with delivery of a small "safe" food reward, while the other was paired with a large "risky" reward associated with an increasing risk of footshock (0%, 25%, 50%, 75%, 100%) in successive test blocks. Three shock intensities were used: 1.0, 1.2, and 1.4mA/kg. As shock intensity and risk of shock increased, preference for the lever signifying a large reward significantly declined for both vehicle- and testosterone-treated rats (p<0.05). There was also a significant effect of drug (p<0.05), where testosterone-treated rats showed greater preference for the large reward, compared to vehicle-treated controls. Increased preference for the large reward, despite risk of footshock, is consistent with increased risk tolerance. In go/no-go testing, rats were trained to press a single lever if the go cue was presented (stimulus light) or to refrain from pressing during the no-go cue (tone). There was no effect of testosterone on pre-cue responses, or performance in go and no-go trials. These results suggest that AAS may increase risk-tolerance without altering motor impulsivity.
Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033, USA.
Sarah E
SE
Cooper
Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033, USA; Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90033, USA.
Sydney P
SP
Goings
Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033, USA.
Jessica Y
JY
Kim
Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033, USA. Electronic address: riw@usc.edu.
Ruth I
RI
Wood
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects; D003657:Decision Making / Q000187:drug effects; D007175:Impulsive Behavior / Q000097:blood; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D020318:Rats, Long-Evans; D012309:Risk-Taking; D012741:Sexual Maturation / Q000187:drug effects / Q000502:physiology; D013739:Testosterone / Q000494:pharmacology*
D013739:Testosterone
Anabolic agents; Go/no-go; Punishment; Response inhibition; Reward; Risk