Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Feb 11;9(1):81.
doi: 10.1038/s41398-019-0387-8.

G protein βγ subunits play a critical role in the actions of amphetamine

J C Mauna  1 , S S Harris  2 , J A Pino  2 , C M Edwards  1 , M R DeChellis-Marks  1 , C D Bassi  1 , J Garcia-Olivares  3 , S G Amara  3 , F G Guajardo  2   4 , R Sotomayor-Zarate  4 , M Terminel  5 , E Castañeda  5 , M Vergara  2 , T Baust  1 , E Thiels  6 , G E Torres  7   8
Affiliations

G protein βγ subunits play a critical role in the actions of amphetamine

J C Mauna et al. Transl Psychiatry. .

Abstract

Abnormal levels of dopamine (DA) are thought to contribute to several neurological and psychiatric disorders including drug addiction. Extracellular DA levels are regulated primarily via reuptake by the DA transporter (DAT). Amphetamine, a potent psychostimulant, increases extracellular DA by inducing efflux through DAT. Recently, we discovered that G protein βγ subunits (Gβγ) interact with DAT, and that in vitro activation of Gβγ promotes DAT-mediated efflux. Here, we investigated the role of Gβγ in the actions of amphetamine in DA neurons in culture, ex vivo nucleus accumbens (NAc), and freely moving rats. Activation of Gβγ with the peptide myr-Ser-Ile-Arg-Lys-Ala-Leu-Asn-Ile-Leu-Gly-Tyr-Pro-Asp-Tyr-Asp (mSIRK) in the NAc potentiated amphetamine-induced hyperlocomotion, but not cocaine-induced hyperlocomotion, and systemic or intra-accumbal administration of the Gβγ inhibitor gallein attenuated amphetamine-induced, but not cocaine-induced hyperlocomotion. Infusion into the NAc of a TAT-fused peptide that targets the Gβγ-binding site on DAT (TAT-DATct1) also attenuated amphetamine-induced but not cocaine-induced hyperlocomotion. In DA neurons in culture, inhibition of Gβγ with gallein or blockade of the Gβγ-DAT interaction with the TAT-DATct1 peptide decreased amphetamine-induced DA efflux. Furthermore, activation of Gβγ with mSIRK potentiated and inhibition of Gβγ with gallein reduced amphetamine-induced increases of extracellular DA in the NAc in vitro and in freely moving rats. Finally, systemic or intra-accumbal inhibition of Gβγ with gallein blocked the development of amphetamine-induced, but not cocaine-induced place preference. Collectively, these results suggest that interaction between Gβγ and DAT plays a critical role in the actions of amphetamine and presents a novel target for modulating the actions of amphetamine in vivo.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1
Fig. 1. Activation of Gβγ subunits in the nucleus accumbens prolongs and inhibition of Gβγ subunits in the nucleus accumbens blunts amphetamine-induced hyperlocomotion.
a Means ± s.e.m. of distance traveled across the 2 h testing period, depicted per 10 min block, for the scr-mSIRK-saline (n = 6), mSIRK-saline (n = 6), scr-mSIRK-amphetamine (n = 6) and mSIRK-amphetamine (n = 6) groups. Scr-mSIRK or mSIRK was infused into the nucleus accumbens (NAc) 30 min before saline or amphetamine injection. b Means ± s.e.m. of distance traveled by experimental period for the same groups. NAc infusion is the period immediately after intra-NAc infusion of scr-mSIRK, and intraperitoneal (i.p.) drug is the period immediately after saline or amphetamine injection. Habituation was performed in drug-free conditions. c Means ± s.e.m. of distance traveled across the 2 h testing period, depicted per 10 min block, for the vehicle-saline (n = 6), gallein-saline (n = 6), vehicle-amphetamine (n = 6) and gallein-amphetamine (n = 6) groups. Vehicle or gallein was infused into the NAc 30 min before saline or amphetamine injection. d Means ± s.e.m. of distance traveled by experimental period for the same groups. NAc infusion is the period immediately after intra-NAc infusion of vehicle of gallein, and i.p. drug is the period immediately after saline or amphetamine injection. Habituation was performed in drug-free conditions. *P < 0.05 between saline-treated and amphetamine-treated groups; #p < 0.05 between scr-mSIRK-amphetamine and mSIRK-amphetamine groups b or between vehicle-amphetamine and gallein-amphetamine groups d
Fig. 2
Fig. 2. Activation or inhibition of Gβγ subunits in the nucleus accumbens has no effect on cocaine-induced hyperlocomotion, whereas interference of Gβγ subunit binding with dopamine transporter (DAT) in the nucleus accumbens attenuates amphetamine-induced locomotor activity.
a Means ± s.e.m. of distance traveled by experimental period for the scr-mSIRK-saline (n = 6), mSIRK-saline (n = 6), scr-mSIRK-cocaine (n = 6), and mSIRK-cocaine (n = 6) groups. Nucleus accumbens (NAc) infusion is the period immediately after intra-NAc infusion of scr-mSIRK, and intraperitoneal (i.p.) drug is the period immediately after saline or amphetamine injection. Habituation was performed in drug-free conditions. b Means ± s.e.m. of distance traveled by experimental period for the vehicle-saline (n = 6), gallein-saline (n = 6), vehicle-cocaine (n = 6), and gallein-cocaine (n = 6) groups. NAc infusion is the period immediately after intra-NAc infusion of vehicle of gallein, and i.p. drug is the period immediately after saline or cocaine injection. Habituation was performed in drug-free conditions. c Means ± s.e.m. of distance traveled by experimental period for the TAT-scr-DATct1-saline (n = 5), TAT-DATct1-saline (n = 5), TAT-scr-DATct1-amphetamine (n = 6), and TAT-DATct1-amphetamine (n = 5) groups. NAc infusion is the period immediately after intra-NAc infusion of TAT-scr-DATct1 or TAT-DATct1, and i.p. drug is the period immediately after saline or amphetamine injection. Habituation was performed in drug-free conditions. d Means ± s.e.m. of distance traveled by experimental period for the TAT-scr-DATct1-saline (n = 5), TAT-DATct1-saline (n = 5), TAT-scr-DATct1-cocaine (n = 5), and TAT-DATct1-cocaine (n = 5) groups. NAc infusion is the period immediately after intra-NAc infusion of TAT-scr-DATct1 or TAT-DATct1, and i.p. drug is the period immediately after saline or cocaine injection. Habituation was performed in drug-free conditions. *P < 0.05 between saline-treated and cocaine- or amphetamine-treated groups; #p < 0.05 between TAT-scr-DATct1-amphetamine and TAT-DATct1-amphetamine groups
Fig. 3
Fig. 3. Activation or inhibition of Gβγ subunits or Gβγ–DAT interaction alters amphetamine-induced dopamine (DA) efflux in DA neurons in culture and nucleus accumbens tissue.
a Inhibition of Gβγ subunits or Gβγ–DAT interaction blunts amphetamine-induced DA efflux in DA neurons preloaded with 20 nM3[H]-DA. Data represented as percent of control conditions for neurons treated with gallein (20 μM), TAT-scr-DATct1 (20 μM), TAT-DATct1 (20 μM), or TAT-DATct1 (20 μM) plus gallein (20 μM), ±amphetamine (10 μM) (n = 5/group). b Activation of Gβγ subunits increases amphetamine-induced DA efflux in nucleus accumbens (NAc) tissue. Mean ± s.e.m. of total DA efflux for tissue treated with vehicle (n = 8), scr-mSIRK (100 μM) (n = 10), or mSIRK (100 μM) (n = 10) before and after amphetamine (10 μM). c Inhibition of Gβγ subunits reduces amphetamine-induced DA efflux. Fractional release of the total DA of tissue perfused with amphetamine alone (10 μM) compared to gallein (20 μM)+amphetamine (10 μM) (n = 5/group). d Area under the curve (AUC) data for total DA efflux of tissue perfused with amphetamine alone compared to gallein+amphetamine.*P < 0.05 between amphetamine and gallein-amphetamine in NAc tissue. **p < 0.01 between mSIRK-amphetamine and vehicle-amphetamine in NAc tissue; ##p < 0.01 between amphetamine and gallein-amphetamine in DA neurons, ###p < 0.001 between amphetamine and TAT-DATct1-amphetamine in DA neurons, ****p < 0.0001 between control and amphetamine or scr-TAT-DATct1-amphetamine in DA neurons
Fig. 4
Fig. 4. Activation or inhibition of Gβγ subunits alters amphetamine-induced extracellular dopamine (DA) levels in the nucleus accumbens of freely moving rats.
a Activation of Gβγ subunits increases amphetamine-induced extracellular DA levels in the nucleus accumbens (NAc). Data represented as percent increase of baseline extracellular DA levels per 10 min for rats treated with scr-mSIRK (1 mM)–amphetamine (3 mg/kg) (n = 4) or mSIRK (1 mM)–amphetamine (3 mg/kg) (n = 5) over 210 min of testing. scr-mSIRK or mSIRK was perfused through the microdialysis probe by reverse dialysis for 1 h (pretreatment period) before an intraperitoneal (i.p.) injection of amphetamine (3 mg/kg) (treatment period) and continually perfused through the 2 h treatment period. b Area under the curve (AUC) of total extracellular DA levels during the baseline, pretreatment, and treatment periods. c Inhibition of Gβγ subunits reduces amphetamine-induced extracellular dopamine levels in the NAc of freely moving rats. Data represented as percent increase of baseline extracellular DA levels per 10 min for rats treated with gallein (4 mg/kg)–saline (1 ml/kg) (n = 4), vehicle (25% dimethyl sulfoxide (DMSO) in saline)–amphetamine (3 mg/kg) (n = 7) or gallein–amphetamine (n = 7) over the 180 min testing period. The i.p. injections of vehicle or gallein occurred during the pretreatment period followed by an i.p. injection of amphetamine or saline during the 2 h treatment period. d AUC analysis of total extracellular DA levels during the baseline, pretreatment, and treatment periods. ***P < 0.001 denotes AUC between scr-mSIRK-amphetamine and mSIRK-amphetamine during the treatment period, ****p < 0.0001 denotes AUC between gallein-saline and vehicle-amphetamine during the treatment period, ####p < 0.0001 denotes AUC between vehicle-amphetamine and gallein-amphetamine during the treatment period
Fig. 5
Fig. 5. Inhibition of Gβγ subunits in the nucleus accumbens blunts amphetamine-induced place preference but has no effect on cocaine-induced place preference.
a Means ± s.e.m. of conditioned place preference index for the gallein-saline (n = 9), vehicle-amphetamine (n = 10), and gallein-amphetamine (n = 10) groups. Vehicle or gallein was infused directly into the nucleus accumbens (NAc) 30 min before saline or amphetamine injection (intraperitoneally (i.p.)) on days 1, 3, and 5. b Similar data as shown in a, except that vehicle or gallein was administered i.p. 30 min before saline or amphetamine injection. The group sizes were identical to those in a. Animals that received gallein, whether by intra-NAc infusion (a) or i.p. injection (b), displayed neither a place preference nor an aversion, regardless of whether they underwent amphetamine conditioning or served as gallein-only controls. c Means ± s.e.m. of the conditioned preference index for cocaine-treated animals (N = 7 for both groups). Vehicle or gallein was administered i.p. 30 min before cocaine injection (i.p.) on days 1, 3, and 5. Animals displayed a place preference for the cocaine-paired compartment, regardless of whether they were pretreated with gallein or vehicle. *P < 0.05 between group average and 0.0 (no conditioning-induced shift in preference); #p < 0.05 between the vehicle-amphetamine-treated group and either of the two gallein-pretreated groups
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Wise RA. Dopamine, learning and motivation. Nat. Rev. Neurosci. 2004;5:483–494. - PubMed
    1. Iversen SD, Iversen LL. Dopamine: 50 years in perspective. Trends Neurosci. 2007;30:188–193. - PubMed
    1. Gowrishankar R, Hahn MK, Blakely RD. Good riddance to dopamine: roles for the dopamine transporter in synaptic function and dopamine-associated brain disorders. Neurochem. Int. 2014;73:42–48. - PubMed
    1. Lin Z, et al. Monoamine transporters: vulnerable and vital doorkeepers. Prog. Mol. Biol. Transl. Sci. 2011;98:1–46. - PMC - PubMed
    1. German CL, Baladi MG, McFadden LM, Hanson GR, Fleckenstein AE. Regulation of the dopamine transporter and vesicular monoamine transporters: pharmacological target and implications for disease. Pharmacol. Rev. 2015;67:1005–1024. - PMC - PubMed

Publication types

MeSH terms