Dose-Effect Analysis
Objective: Determine whether naltrexone's attenuation of dopamine elevation is due to reduced ethanol intake or direct interference with ethanol's efficacy through simultaneous measurement of dialysate dopamine levels and operant responding for ethanol
Protocol Steps
Training phase
Male Wistar rats trained to self-administer ethanol solution
Note: Training continued until reliable self-administration was established
View evidence from paper
“Male Wistar rats were trained to self-administer ethanol (10–15%, w/v) in 0.2% (w/v) saccharin during daily 30 min sessions”
Surgical preparation
Rats surgically prepared for intracranial microdialysis
Note: Performed after training phase
View evidence from paper
“were surgically prepared for intracranial microdialysis”
Injection
Rats injected subcutaneously with either naltrexone or saline control
Note: Naltrexone dose 0.25 mg/kg; saline used as control
View evidence from paper
“Rats were injected with naltrexone (0.25 mg/kg, s.c.) or saline”
Waiting period
Rats placed in operant chamber with no ethanol available
Note: Begins 10 min after injection
View evidence from paper
“10 min later were placed inside the operant chamber for a 20 min waiting period with no ethanol available”
Ethanol access period
Rats given access to ethanol for self-administration while dopamine levels measured
Note: Follows immediately after waiting period
View evidence from paper
“followed by 30 min of access to ethanol”
Dose-effect analysis
Subsequent dose-effect analyses to determine whether naltrexone's effect on dopamine is due to reduced intake or direct interference with ethanol efficacy
Note: Establishes that naltrexone attenuates efficacy of ethanol to elevate dopamine, not merely a function of reduced intake
View evidence from paper
“Subsequent dose–effect analyses established that the latter effect was not merely a function of reduced ethanol intake but that naltrexone attenuated the efficacy of ethanol to elevate dialysate dopamine levels”