Differential responses to anticipation of reward after an acute dose of the designer drugs benzylpiperazine (BZP) and tr
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ORIGINAL INVESTIGATION
Differential responses to anticipation of reward after an acute dose of the designer drugs benzylpiperazine (BZP) and trifluoromethylphenylpiperazine (TFMPP) alone and in combination using functional magnetic resonance imaging (fMRI) Louise E. Curley & Robert R. Kydd & Ian J. Kirk & Bruce R. Russell
Received: 12 January 2013 / Accepted: 17 April 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Rationale Functional magnetic resonance imaging (fMRI) studies have reported increased activation of the mesolimbic system in response to anticipation of rewarding stimuli. The anticipation of uncertain outcomes evokes activation in the amygdala, orbitofrontal cortex, inferior frontal gyrus and insula. Drugs known to effect dopaminergic and serotonergic neurons also alter regional activation. Objectives Benzylpiperazine (BZP) and/or trifluoromethylphenylpiperazine (TFMPP) have been recreationally used worldwide for more than a decade. BZP affects mainly dopaminergic neurons, while TFMPP has serotonergic effects. L. E. Curley (*) : B. R. Russell School of Pharmacy and Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand e-mail: [email protected] B. R. Russell e-mail: [email protected] R. R. Kydd Department of Psychological Medicine and Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand e-mail: [email protected]
Methods We investigated the effects of an acute dose of BZP, TFMPP or a combination of BZP and TFMPP on the anticipation of reward in a double-blind, placebo-controlled, crossover study using fMRI. An event-related gambling paradigm was completed by healthy controls 90 min after taking an oral dose of either BZP (200 mg), TFMPP (either 50 or 60 mg), BZP + TFMPP (100+30 mg) or placebo. Results After giving BZP, the anticipation of a $4 reward decreased the activation of the inferior frontal gyrus, insula and occipital regions in comparison to placebo. TFMPP increased the activation of the putamen but decreased the activity in the insula relative to placebo. When BZP and TFMPP were given in combination, activation of the rolandic operculum occurred. The magnitude of reward also affected neural correlates. Conclusion We propose that the effects of BZP and TFMPP on dopaminergic and serotonergic circuitry, respectively, reflect regional changes. The dopaminergic effects of BZP appear to increase positive arousal and subsequently reduce the response to uncertainty, while TFMPP appears to alter the response to uncertainty by increasing emotional responses. Keywords BZP . TFMPP . Designer drugs . Reward anticipation . fMRI
Introduction I. J. Kirk Department of Psychology and Centre for Brain Research, Faculty of Science, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand e-mail: [email protected]
A relatively new group of designer drugs, which includes benzylpiperazine (BZP) and trifluor
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