ISSN:
1432-2072
Keywords:
Intracranial self-stimulation
;
Brain stimulation reward
;
Rate-free index
;
Nicotine
;
Mecamylamine
;
Chronic administration
;
Tolerance
;
Abstinence
;
Rat
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Rats were trained to shuttle between two selected (“ON”) arms of a Y maze, to obtain electrical stimulation of the medial forebrain bundle. Each shuttle response was rewarded with a brief pulse train. Repetitive entries into the same “ON” arm were not rewarded, nor were entries made into the third (“OFF”) arm. Every 67s, stimulation was made available from a different pair of arms. Test sessions lasted for 80 min, beginning immediately after SC injection. Undrugged subjects responded faster, and with a greater proportion of rewarded responses, the higher the stimulation current. In non-tolerant rats, nicotine (0–0.4 mg/kg) depressed responding and induced ataxia shortly after injection; from 40 min, nicotine increased low rates of responding but decreased high rates. All these effects were dose-dependent. Mecamylamine (2.0 mg/kg) prevented the initial depressant action. With repeated daily injections of nicotine (0.4 mg/kg), a marked stimulant action emerged which replaced the initial depressant action, and this was dose-dependent. However, responding was increased by nicotine even when brain stimulation was not available (“time-out”). In contrast, an additional “rate-free” index based on discrimination showed that nicotine did not augment the rewarding properties of the brain stimulation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00427826
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