Behavior-associated changes in blood pressure during heroin self-administration.
Changes in arterial blood pressure (ABP) were studied in freely moving rats during the development and performance of operant IV heroin self-administration (SA) behavior (100 micrograms/kg/injection). Heroin SA was accompanied by bidirectional, phasic ABP fluctuations in the absence of significant alterations in long-term, basal ABP levels. In trained rats, ABP gradually increased starting 5 min before each lever-press for the drug, reached a peak at the moment of lever-press and abruptly decreased after heroin infusion. This biphasic pattern corresponded to a preresponding behavioral activation followed by a postheroin sedation. These ABP fluctuations were absent during the initial heroin self-injections in drug-naive rats and during the first self-injections of a session in trained rats. A slight hypo- and hypertension were seen in these cases, respectively. The postdrug ABP decrease became more pronounced after rats received a double dose of heroin. With training, nonreinforced lever-presses and sound stimulation previously associated with heroin self-injections also significantly decreased ABP. Thus, a gradual ABP increase appears to be an essential correlate of drug-seeking and -taking behavior, while a subsequent ABP decrease may be related to the alleviation of these behaviors by heroin and possibly correlate to its rewarding (euphorigenic) action.
Kiyatkin
E A
EA
Department of Psychiatry, Medical College of Wisconsin, Milwaukee 53226.
Stein
E A
EA
D000161:Acoustic Stimulation; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D004298:Dopamine / Q000378:metabolism; D006556:Heroin Dependence / Q000503:physiopathology* / Q000523:psychology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012054:Reinforcement, Psychology; D012646:Self Administration
D004298:Dopamine