Behavioral sensitization to cocaine, but not cocaine-conditioned behavior, is associated with increased dopamine occupation of its receptors in the nucleus accumbens.

Abstract

Rats had repeated treatments with cocaine associated with a specific context (paired group). Evidence for classical conditioning of cocaine's motor-activity effects and context-specific behavioral sensitization to cocaine was obtained, relative to vehicle-treated (control) and pseudoconditioned (unpaired) groups. Only the paired group exhibiting context-specific behavioral sensitization had more dopamine bound to both D1-like and D2-like receptors in the nucleus accumbens than did rats in the control group receiving cocaine on the test day. No effects on receptor occupation were found in rats showing a classical conditioned response to a context previously paired with cocaine. Thus, sensitization to cocaine, but not classical conditioning of cocaine's behavioral effects, was associated with greater dopaminergic neurotransmission selectively in the nucleus accumbens.

Early Neonatal Experience of Long-Evans Rats Results in Long-lasting Changes in Reactivity to a Novel Environment and Morphine-induced Sensitization and Tolerance

“…Increases in horizontal and vertical activity after an injection of saline can be attributed to associative learning (i.e., Pavlovian conditioning). The phenomenon of increased activity, conditioned to the presentation of specific environmental cues has been described also for the administration of amphetamine and cocaine (Beninger and Hahn 1983;Burechailo and Martin-Iverson 1996;Anagnostaras and Robinson 1996). Robust conditioning of MS animals compared with other groups may be indicative of powerful and long-lasting alterations in general learning and attention processes as the result of maternal separation.…”

Stimulation of adenosine receptors in the nucleus accumbens reverses the expression of cocaine sensitization and cross-sensitization to dopamine D2 receptors in rats

“…In this way, adenosine receptor stimulation can offset excessive dopamine receptor stimulation resulting from repeated psychostimulant treatments (Bailey et al, 2008, Burechailo and Martin-Iverson, 1996, Burger and Martin-Iverson, 1994, Henry and White, 1991, Ujike et al, 1990). Adenosine and dopamine receptors can alter signaling of medium spiny GABA neurons within the striatum through a variety of mechanisms.…”

Sensitivity to psychostimulants in mice bred for high and low stimulation to methamphetamine

“…1995; Badiani et al . 1997; Burechailo & Martin‐Iverson 1996) and amphetamine (Sutton et al . 2000) have shown this conditioned activation.…”

“…When vehicle treatment replaces drug, the locomotor behavior of these rats is elevated compared to that of rats that have always had vehicle paired with the test environment. Studies with cocaine (Badiani et al 1995;Badiani et al 1997;Burechailo & Martin-Iverson 1996) and amphetamine (Sutton…”