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Effects of early life stress on stimulant self‐administration in rhesus monkeys
Author(s) -
Ewing Sarah B.,
Howell Leonard L.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.713.8
Subject(s) - stimulant , self administration , medicine , psychology , anesthesia , physiology , pharmacology
Early life stress can have effects on behavior and stress reactivity which are linked to sensitivity to stimulants in rodents. The present study investigated whether rhesus monkeys that experienced early life stress (n=4) would show altered sensitivity to the reinforcing effects of stimulants as compared to controls (n=3). Experimental monkeys experienced periodic maternal separations between 3–6 months of age and exhibited a phenotype of altered HPA axis function and hyper‐responsivity to stress, predictive of enhanced propensity to stimulant use. Monkeys were trained initially to self‐administer cocaine (0.1mg/kg/inj) under a fixed ratio (FR) 1 schedule and parameters were increased once all 10 injections were taken for 3 consecutive sessions. Ultimately the schedule was a second order schedule of FR 20 components with drug injection following the first ratio completed after 10 min elapsed (FI 600). Dose‐effect curves were determined for cocaine (0.01–1.0 mg/kg/inj) and amphetamine (0.003–0.3 mg/kg/inj) with each dose tested until response rates were stable over 5 consecutive sessions. As compared to control animals, experimental animals showed reduced behavioral output during the acquisition of self‐administration and in the dose‐response curves for both stimulants. The results do not provide support for early life stress leading to enhanced vulnerability to stimulant use. (Supported by USPHS grants MH58922, DA10344, DA00517 and RR00165.)