Music and methamphetamine: Conditioned cue-induced increases in locomotor activity and dopamine release in rats

Abstract

Associations between drugs of abuse and cues facilitate the acquisition and maintenance of addictive behaviors. Although significant research has been done to elucidate the role that simple discriminative or discrete conditioned stimuli (e.g., a tone or a light) play in addiction, less is known about complex environmental cues. The purpose of the present study was to examine the role of a musical conditioned stimulus by assessing locomotor activity and in vivo microdialysis. Two groups of rats were given non-contingent injections of methamphetamine (1.0 mg/kg) or vehicle and placed in standard conditioning chambers. During these conditioning sessions both groups were exposed to a continuous conditioned stimulus, in the form of a musical selection ("Four" by Miles Davis) played repeatedly for ninety minutes. After seven consecutive conditioning days subjects were given one day of rest, and subsequently tested for locomotor activity or dopamine release in the absence of drug while the musical conditioned stimulus was continually present. The brain regions examined included the basolateral amygdala, nucleus accumbens, and prefrontal cortex. The results show that music is an effective contextual conditioned stimulus, significantly increasing locomotor activity after repeated association with methamphetamine. Furthermore, this musical conditioned stimulus significantly increased extracellular dopamine levels in the basolateral amygdala and nucleus accumbens. These findings support other evidence showing the importance of these brain regions in conditioned learning paradigms, and demonstrate that music is an effective conditioned stimulus warranting further investigation.

Music-induced context preference following cocaine conditioning in rats.

“…While it is possible that four consecutive days of cocaine administration could account for our observed CCP and locomotor effects, it is highly unlikely. In previous experiments, using a similar classical conditioning procedure, we included explicitly non-paired and no-music controls and did not see a significant locomotor effect (Polston et al, 2011). …”

“…The Miles Davis selection was chosen because it had been used successfully in past conditioned learning paradigms in our laboratory (Polston et al, 2011). The Beethoven selection was used because it was distinctly different from the Miles Davis selection.…”

“…During baseline, conditioning, and test sessions, these compositions were played on a continuous loop, at a volume that allowed the auditory range to remain between 65 and 75 decibels. This decibel range was chosen because it had been used successfully in past investigations involving rats and music (Feduccia & Duvauchelle, 2008; Otsuka et al, 2009; Polston et al, 2011). …”

“…Both of these studies concluded that music evoked no primary reinforcing property by itself. Our laboratory has also recently shown that after repeated pairing between music and methamphetamine, the music alone is able to produce significant increases in locomotor activity and significant increases in extracellular dopamine in the basolateral amygdala and nucleus accumbens (Polston, Rubbinaccio, Morra, Sell, & Glick, 2011). Taken together, these reports indicate that music can serve as an effective contextual CS in rats.…”

Increased Levels of Extracellular Dopamine in the Nucleus Accumbens and Amygdala of Rats by Ingesting a Low Concentration of a Long-Chain Fatty Acid

“…27) However, some recent studies have reported the involvement of the amygdala in both negative emotions and in positive ones. For example, Polston et al have reported an increased DA level in the amygdala in response to a reward stimulus such as methamphetamine, 28) and See et al have shown that the administration of a D 1 -receptor antagonist to the amygdala inhibited the reinstatement of cocaine self-administration. 29) Food addiction scores have been reported to be correlated with activation of the amygdala in fMRI measurements on young women, 30) and the activity of the amygdala observed during food intake (also with fMRI) increased more in response to an increase in taste intensity than to taste affective valence.…”