New repeat polymorphism in the AKT1 gene predicts striatal dopamine D2/D3 receptor availability and stimulant-induced dopamine release in the healthy human brain

Elena Shumay, Corinde E. Wiers, Ehsan Shokri-Kojori, Sung Won Kim, Colin A. Hodgkinson, Hui Sun, Dardo Tomasi, Christopher T. Wong, Daniel Weinberger, Gene Jack Wang, Joanna S. Fowler, Nora D. Volkow

Research output: Contribution to journalArticle

Abstract

The role of the protein kinase Akt1 in dopamine neurotransmission is well recognized and has been implicated in schizophrenia and psychosis. However, the extent to which variants in the AKT1 gene influence dopamine neurotransmission is not well understood. Here we investigated the effect of a newly characterized variant number tandem repeat (VNTR) polymorphism in AKT1[major alleles: L-(eight repeats) and H-(nine repeats)] on striatal dopamine D2/D3 receptor (DRD2) availability and on dopamine release in healthy volunteers. We used PET and [11C]raclopride to assess baseline DRD2 availability in 91 participants. In 54 of these participants, we also measured intravenous methylphenidate-induced dopamine release to measure dopamine release. Dopamine release was quantified as the difference in specific binding of [11C]raclopride (nondisplaceable binding potential) between baseline values and values following methylphenidate injection. There was an effect of AKT1 genotype on DRD2 availability at baseline for the caudate (F(2,90)=8.2, p=0.001) and putamen (F(2,90) = 6.6, p = 0.002), but not the ventral striatum (p = 0.3). For the caudate and putamen, LL showed higher DRD2 availability than HH; HL were in between. There was also a significant effect of AKT1 genotype on dopamine increases in the ventral striatum (F(2,53)=5.3, p=0.009), with increases being stronger in HH>HL>LL. However, no dopamine increases were observed in the caudate (p=0.1) or putamen (p=0.8) following methylphenidate injection. Our results provide evidence that the AKT1 gene modulates both striatal DRD2 availability and dopamine release in the human brain, which could account for its association with schizophrenia and psychosis. The clinical relevance of the newly characterized AKT1 VNTR merits investigation.

Original languageEnglish (US)
Pages (from-to)4982-4991
Number of pages10
JournalJournal of Neuroscience
Volume37
Issue number19
DOIs
StatePublished - May 10 2017

Keywords

  • AKT1
  • Dopamine
  • Dopamine receptor
  • Methylphenidate
  • PET

ASJC Scopus subject areas

  • Neuroscience(all)

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    Shumay, E., Wiers, C. E., Shokri-Kojori, E., Kim, S. W., Hodgkinson, C. A., Sun, H., Tomasi, D., Wong, C. T., Weinberger, D., Wang, G. J., Fowler, J. S., & Volkow, N. D. (2017). New repeat polymorphism in the AKT1 gene predicts striatal dopamine D2/D3 receptor availability and stimulant-induced dopamine release in the healthy human brain. Journal of Neuroscience, 37(19), 4982-4991. https://doi.org/10.1523/JNEUROSCI.3155-16.2017