Social stress does not alter the expression of sensitization to cocaine.
The effects of chronic social stress on behavioral sensitization to cocaine were investigated in the Syrian hamster. Adolescent animals received either 15 mg/kg i.p. of cocaine or saline twice per day for 7 consecutive days. Two weeks following the last injection (young adulthood), they were given a challenge dose of 5 mg/kg i.p. of cocaine and scored for locomotion. Motor activity was significantly greater in cocaine-treated animals, demonstrating sensitization to this psychostimulant. Following the results of the first study, another group of adolescent animals was exposed to either a novel clean cage (control) or an aggressive resident male hamster (social stress) for 15 min following an injection of cocaine (20 mg/kg i.p. once daily) or saline for 7 consecutive days. The groups were as follows: Social Stress/Cocaine (SSC), No Social Stress/Cocaine (NSSC), Social Stress/Saline (SSS) and No Social Stress/Saline (NSSS). Two weeks following the last injection (Day 21), all animals were given a challenge dose of cocaine (5 mg/kg i.p.) and were rescored for locomotion. At that time, the suppressive effect of stress on locomotion was no longer detectable, as the expression of sensitization was observed in the NSSC but not in the SSC group. These results suggest that chronic social stress administered during adolescence does not cross-sensitize with cocaine in young adult hamsters.
Department of Psychology, 125 Nightingale Hall, Northeastern University, 107 Forsyth Street, Boston, MA 02115, USA.
Monika
M
Trzcińska
Jennifer
J
Bergh
Katrina
K
DeLeon
James R
JR
Stellar
Richard H
RH
Melloni
D000818:Animals; D002908:Chronic Disease; D003042:Cocaine / Q000494:pharmacology*; D006224:Cricetinae; D008297:Male; D008647:Mesocricetus; D009043:Motor Activity / Q000187:drug effects; D012930:Social Dominance; D012931:Social Environment; D013315:Stress, Psychological / Q000523:psychology*
D003042:Cocaine