Reduced Efficacy of d-Amphetamine and 3,4-Methylenedioxymethamphetamine in Inducing Hyperactivity in Mice Lacking the Postsynaptic Scaffolding Protein SHANK1

Abstract

Genetic defects in the three SH3 and multiple ankyrin repeat domains (SHANK) genes (SHANK1, SHANK2, and SHANK3) are associated with multiple major neuropsychiatric disorders, including autism spectrum disorder (ASD), schizophrenia (SCZ), and bipolar disorder (BPD). Psychostimulant-induced hyperactivity is a commonly applied paradigm to assess behavioral phenotypes related to BPD and considered to be the gold standard for modeling mania-like elevated drive in mouse models. Therefore, the goal of our present study was to test whether Shank1 plays a role in the behavioral effects of psychostimulants and whether this is associated with genotype-dependent neurochemical alterations. To this aim, male and female null mutant Shank1^-/- mice were treated with d-amphetamine (AMPH; 2.5 mg/kg) and 3,4-methylenedioxymethamphetamine (MDMA, commonly known as ecstasy; 20 mg/kg), and psychostimulant-induced hyperactivity was compared to heterozygous Shank1^+/- and wildtype Shank1^+/+ littermate controls. Results show that Shank1^-/- mice display reduced psychostimulant-induced hyperactivity, although psychostimulants robustly stimulated locomotor activity in littermate controls. Shank1 deletion effects emerged throughout development, were particularly prominent in adulthood, and seen in response to both psychostimulants, i.e., AMPH and MDMA. Specifically, while AMPH-induced hyperactivity was reduced but still detectable in Shank1^-/- mice, MDMA-induced hyperactivity was robustly blocked and completely absent in Shank1^-/- mice. Reduced efficacy of psychostimulants to stimulate hyperactivity in Shank1^-/- mice might be associated with alterations in the neurochemical architecture in prefrontal cortex, nucleus accumbens, and hypothalamus. Our observation that psychostimulant-induced hyperactivity is reduced rather than enhanced in Shank1^-/- mice clearly speaks against a behavioral phenotype with relevance to BPD. Lack of BPD-like phenotype is consistent with currently available human data linking mutations in SHANK2 and SHANK3 but not SHANK1 to BPD.

Keywords: MDMA; dopamine; ecstasy; noradrenaline; norepinephrine; serotonin.

FIGURE 1

AMPH-induced hyperactivity in juvenile Shank1 mice. (A) Exemplary figure depicting the locomotor activity pattern of individual juvenile Shank1^+/+, Shank1^+/-, and Shank1^-/- mice injected with saline (NaCl) on day 2 (upper panel) and with AMPH on day 3 (lower panel); measured over 45 min. (B) Bar graph depicting the distance traveled by all genotypes during baseline testing (white bar), following saline administration (blue bar), and after AMPH treatment (green bar). (B′) Line graph depicting the distance traveled by Shank1^+/+ (black circle), Shank1^+/- (white circle), and Shank1^-/- (black triangle) over the three consecutive test days. Data are presented as means + SEM or means ± SEM. ^##p < 0.001 (B), ^#p < 0.05 vs. day 2 (B′).

FIGURE 2

AMPH-induced hyperactivity in juvenile Shank1 mice. (A–C) Bar graphs and (A′–C′) line graphs depicting the distance traveled by Shank1^+/+ (black bar/black circle), Shank1^+/- (striped bar/white circle), and Shank1^-/- (white bar/black triangle). Locomotor activity was compared during baseline testing (A,A′), following saline administration (B,B′), and after AMPH treatment (C,C′). Data are presented as means + SEM or means ± SEM. ^∗p < 0.05, ^∗∗p < 0.001.

FIGURE 3

(A) AMPH-induced hyperactivity in adult Shank1 mice. Exemplary figure depicting the locomotor activity pattern of individual adult Shank1^+/+, Shank1^+/-, and Shank1^-/- mice injected with saline (NaCl) on day 2 (upper panel) and with AMPH on day 3 (lower panel); measured over 45 min. (B) Bar graph depicting the distance traveled by all genotypes during baseline testing (white bar), following saline administration (blue bar), and after AMPH treatment (green bar). (B′) Line graph depicting the distance traveled by Shank1^+/+ (black circle), Shank1^+/- (white circle), and Shank1^-/- (black triangle) over the three consecutive test days. Data are presented as means + SEM or means ± SEM. ^##p < 0.001 (B), ^##p < 0.001 vs. day 2 (B′).

FIGURE 4

AMPH-induced hyperactivity in adult Shank1 mice. (A–C) Bar graphs and (A′–C′) line graphs depicting the distance traveled by Shank1^+/+ (black bar/black circle), Shank1^+/- (striped bar/white circle), and Shank1^-/- (white bar/black triangle). Locomotor activity was compared during baseline testing (A,A′), following saline administration (B,B′), and after AMPH treatment (C,C′). Data are presented as means + SEM or means ± SEM. ^∗∗p < 0.001.

FIGURE 5

MDMA-induced hyperactivity in adult Shank1 mice. (A) Exemplary figure depicting the locomotor activity pattern of individual adult Shank1^+/+, Shank1^+/-, and Shank1^-/- mice injected with saline (NaCl) on day 2 (upper panel) and with MDMA on day 3 (lower panel); measured over 45 min. (B) Bar graph depicting the distance traveled by all genotypes during baseline testing (white bar), following saline administration (blue bar), and after MDMA treatment (orange bar). (B′) Line graph depicting the distance traveled by Shank1^+/+ (black circle), Shank1^+/- (white circle), and Shank1^-/- (black triangle) over the three consecutive test days. Data are presented as means + SEM or means ± SEM. ^#p < 0.05, ^##p < 0.001 (B), ^#p < 0.05 vs. day 2 (B′).

FIGURE 6

MDMA-induced hyperactivity in adult Shank1 mice. (A–C) Bar graphs and (A′–C′) line graphs depicting the distance traveled by Shank1^+/+ (black bar/black circle), Shank1^+/- (striped bar/white circle), and Shank1^-/- (white bar/black triangle). Locomotor activity was compared during baseline testing (A,A′), following saline administration (B,B′), and after MDMA treatment (C,C′). Data are presented as means + SEM or means ± SEM. ^∗p < 0.05, ^∗∗p < 0.001.

FIGURE 7

Catecholamine/indolamine, precursor, and metabolite concentrations in the prefrontal cortex of Shank1 mice. Basal levels of (A) Tyrosine (Tyr), (B) Tryptophan (Trp), (C) Dopamine (DA), (D) DA-metabolite dehydroxyphenylacetic acid (DOPAC), (E) DOPAC/DA ratio, (F) Noradrenaline (NA), (G) NA-metabolite 4-hydroxy-3-methoxy-phenylglycol (MHPG), (H) MHPG/NA ratio, (I) 5-hydroxytryptamine (5-HT; serotonin), (J) 5-HT-metabolite 5-hydroxy-indol-acetic acid (5-HIAA), and (K) 5-HIAA/5-HT ratio in Shank1^+/+ (black bar), Shank1^+/- (striped bar), and Shank1^-/- mice (white bar). N = 10–16 per genotype. Data are presented as means + SEM. ^∗p < 0.05. Schematic representation of the prefrontal cortex was adapted from Paxinos and Franklin (2001).

FIGURE 8

Catecholamine/indolamine, precursor, and metabolite concentrations in the nucleus accumbens of Shank1 mice. Basal levels of (A) Tyrosine (Tyr), (B) Tryptophan (Trp), (C) Dopamine (DA), (D) DA-metabolite dehydroxyphenylacetic acid (DOPAC), (E) DOPAC/DA ratio, (F) Noradrenaline (NA), (G) NA-metabolite 4-hydroxy-3-methoxy-phenylglycol (MHPG), (H) MHPG/NA ratio, (I) 5-hydroxytryptamine (5-HT; serotonin), (J) 5-HT-metabolite 5-hydroxy-indol-acetic acid (5-HIAA), and (K) 5-HIAA/5-HT ratio in Shank1^+/+ (black bar), Shank1^+/- (striped bar), and Shank1^-/- mice (white bar). N = 13–16 per genotype. Data are presented as means + SEM. ^∗p < 0.05. Schematic representation of the nucleus accumbens was adapted from Paxinos and Franklin (2001).

FIGURE 9

Catecholamine/indolamine, precursor, and metabolite concentrations in the hypothalamus of Shank1 mice. Basal levels of (A) Tyrosine (Tyr), (B) Tryptophan (Trp), (C) Dopamine (DA), (D) DA-metabolite dehydroxyphenylacetic acid (DOPAC), (E) DOPAC/DA ratio, (F) Noradrenaline (NA), (G) NA-metabolite 4-hydroxy-3-methoxy-phenylglycol (MHPG), (H) MHPG/NA ratio, (I) 5-hydroxytryptamine (5-HT; serotonin), (J) 5-HT-metabolite 5-hydroxy-indol-acetic acid (5-HIAA), and (K) 5-HIAA/5-HT ratio in Shank1^+/+ (black bar), Shank1^+/- (striped bar), and Shank1^-/- mice (white bar). N = 12–15 per genotype. Data are presented as means + SEM. ^∗p < 0.05. Schematic representation of the hypothalamus was adapted from Paxinos and Franklin (2001).