Methamphetamine Induces Anhedonic-Like Behavior and Impairs Frontal Cortical Energetics in Mice

Abstract

Introduction: We recently showed that a single high dose of methamphetamine (METH) induces a persistent frontal cortical monoamine depletion that is accompanied by helpless-like behavior in mice. However, brain metabolic alterations underlying both neurochemical and mood alterations remain unknown.

Aims: Herein, we aimed at characterizing frontal cortical metabolic alterations associated with early negative mood behavior triggered by METH. Adult C57BL/6 mice were injected with METH (30 mg/kg, i.p.), and their frontal cortical metabolic status was characterized after probing their mood and anxiety-related phenotypes 3 days postinjection.

Results: Methamphetamine induced depressive-like behavior, as indicated by the decreased grooming time in the splash test and by a transient decrease in sucrose preference. At this time, METH did not alter anxiety-like behavior or motor functions. Depolarization-induced glucose uptake was reduced in frontocortical slices from METH-treated mice compared to controls. Consistently, astrocytic glucose transporter (GluT1) density was lower in the METH group. A proton high rotation magic angle spinning (HRMAS) spectroscopic approach revealed that METH induced a significant decrease in N-acetyl aspartate (NAA) and glutamate levels, suggesting that METH decreased neuronal glutamatergic function in frontal cortex.

Conclusions: We report, for the first time, that a single METH injection triggers early self-care and hedonic deficits and impairs frontal cortical energetics in mice.

Keywords: Depressive-like behavior; Frontal cortex; Glucose metabolism; Methamphetamine.

Figure 1

Methamphetamine (METH) decreases grooming time in the splash test and sucrose preference in the sucrose preference test but does not affect anxiety. Effects of a single dose of METH (30 mg/kg, i.p.) on the grooming behavior [splash test (A) and sucrose preference test (B, C)], and on the anxiety‐like behavior [elevated plus maze test (D, E, F)] in mice 3 days after injection. (A) The grooming time, including nose/face grooming (strokes along the snout), head washing (semicircular movements over the top of the head and behind the ears), and body grooming (body fur licking), was significantly decreased in METH mice; (B) sucrose preference was significantly decreased 1 day after METH treatment and returned to basal levels at day 2 post‐METH injection; (C) sucrose consumption was significantly decreased 1 day after METH treatment and significantly increased 2 days after treatment; (D) the percentage of entries in the open arms; (E) the percentage of time spent in open arms; and (F) the number of entries in the closed arms was not statistically different between groups. Animals were monitored during 5 min in the splash test and in the elevated plus maze test. The sucrose preference test was performed during 4 days. Results are mean ± SEM of 7–8 mice in SAL group and eight mice in METH group. *P < 0.05; **P < 0.01; ***P < 0.001 versus saline group using an unpaired Student's t‐test and one‐way ANOVA followed by the Bonferroni post hoc analysis (sucrose preference test) between the indicated experimental groups.

Figure 2

Methamphetamine (METH) does not affect motor function. Effects of a single dose of METH (30 mg/kg, i.p.) on motor function [open field test (A) and pole test (B)] in mice 3 days after injection. The total distance traveled on the open field (A) and the descent time on the pole test (B) were not significantly different between groups. Animals were monitored during 5 min. Results are mean ± SEM of seven mice in SAL group and eight mice in METH group. Statistical analysis was performed using an unpaired Student's t‐test between the indicated experimental groups.

Figure 3

Methamphetamine (METH) impairs ex vivo glucose uptake in depolarized frontocortical slices. (A) Whereas resting glucose uptake by frontocortical slices was not significantly different between groups (n = 8; P > 0.05), glucose uptake in response to lasting depolarization was lower in the METH group; (B) The density of the 45 kDa but not that of the 55 kDa GluT1 isoform was decreased in the frontal cortex of the METH group (n = 8). Inset B’ shows representative Western blot of the 45 and 55 kDa glucose transporter (GluT1) isoforms in frontocortical extracts from SAL and METH groups; (C) The density of GluT3 (45 kDa) in the frontal cortex was not significantly different between groups (n = 7, P > 0.05). Inset C’ shows representative Western blots of GluT3 (45 kDa) in frontocortical extracts from SAL and METH groups. **P < 0.01 versus saline group using an unpaired Student's t‐test between the indicated experimental groups.

Figure 4

METH changes the metabolic profile of the frontal cortex. A typical 500 MHz CPMG ¹H NMR spectrum of the frontal cortex from mice injected with saline (SAL) or a single dose of METH (30 mg/kg, i.p.) (A). The chemical shift range was from 0.80 to 4.70 ppm. Peak assignments: Ala, alanine; Cre, creatine; PCre, phospho‐creatine; Total‐Cre, tCr (total creatine), Cre+PCre; Cho, choline; PC, phosphocholine; GPC, glycerophosphocholine; GABA, γ‐aminobutyric acid; Glu, glutamate; Gln, glutamine; Lac, lactate; myo‐Ins, myo‐inositol; NAA, N‐acetyl‐aspartate; Tau, taurine; (B) ¹H HRMAS spectral integration for metabolite quantification showing a significant decrease of the Glu and NAA levels in the METH group. Alanine, lactate, taurine, myo‐inositol, glutamine, and GABA levels were not significantly different between groups (P _adj > 0.05). (C) The ratios Lac/Ala, GABA/Glu, and Glu/Gln were also not significantly different between groups (P _adj > 0.05). Total creatine was used as internal reference for integration. Results are mean ± SEM of six mice in SAL group and eight mice in METH group. HRMAS data was analyzed by unpaired Student's t‐test followed by Benjamini–Hochberg (Benjamini and Hochberg, 1995) correction for multiple comparisons; the false discovery rate (FDR) adopted was 5%. *P _adj < 0.05 versus saline group.