"医学論文訳"
"医学論文訳"
Male Wistar rats (Charles River Laboratories) weighing 300?320 g were surgically
prepared with silastic catheters in the jugular vein and trained to respond on an
‘active’ lever for food pellets (45 mg; 60 min sessions) under a fixed ratio 5 timeout 20 s (FR5TO20) schedule of reinforcement. Rats then responded for cocaine on the FR5TO20 reinforcement schedule during 1-h daily testing sessions for at least
seven consecutive days. Cocaine hydrochloride was dissolved in sterile saline
solution (0.9% w/v). Each cocaine infusion earned resulted in the delivery of
0.5 mgkg21 per infusion cocaine (0.1 ml injection volume delivered over 4 s),
and initiated a 20-s timeout period signalled by a light cue located above the
active lever during which responding on the lever was without consequence. In
all cases, a control group of rats were surgically prepared with jugular catheters
and trained to respond for food reinforcement as described above, but remained
cocaine-naive for the duration of the experiment. To determine the cocaine dose?
response curve, the unit dose of cocaine available for self-administration was
adjusted upward or downward during 3-h testing sessions every other day
between regular 6-h self-administration sessions; for detailed description see
ref. 7. Doses of cocaine were tested once, and in the following order: 0.5,
0.0625, 0.25, 0.125 and 0 mgkg21 per infusion.
