Transgenerational transmission of aspartame-induced anxiety and changes in glutamate-GABA signaling and gene expression in the amygdala

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 119; no. 49; p. e2213120119
• Main Authors: Jones, Sara K, McCarthy, Deirdre M, Vied, Cynthia, Stanwood, Gregg D, Schatschneider, Chris, Bhide, Pradeep G
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 06-12-2022
• Subjects: Allosteric properties; Amygdala; Animals; Anxiety; Anxiety - chemically induced; Anxiety - genetics; Aspartame; Benzodiazepines; Biological Sciences; Consumption; Diazepam; Drinking behavior; Drinking Water; Excitation; Female; Females; Field tests; GABARAP protein; gamma-Aminobutyric Acid; Gene Expression; Gene sequencing; Glutamatergic transmission; Glutamic Acid; Glutamic acid receptors (ionotropic); Glutamic acid receptors (metabotropic); Human populations; Humans; Male; Males; Mental health; Mice; Mice, Inbred C57BL; N-Methyl-D-aspartic acid receptors; Neurotransmitters; Offspring; Open-field behavior; Receptors; Receptors, GABA-A; RNA, Messenger; Signal transduction; Signaling; γ-Aminobutyric acid; γ-Aminobutyric acid A receptors; emotional behavior; artificial sweetener; intergenerational transmission
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2213120119

We report the effects of aspartame on anxiety-like behavior, neurotransmitter signaling and gene expression in the amygdala, a brain region associated with the regulation of anxiety and fear responses. C57BL/6 mice consumed drinking water containing 0.015% or 0.03% aspartame, a dose equivalent of 8 to 15% of the FDA recommended maximum human daily intake, or plain drinking water. Robust anxiety-like behavior (evaluated using open field test and elevated zero maze) was observed in male and female mice consuming the aspartame-containing water. Diazepam, an allosteric modulator of the GABA-A receptor, alleviated the anxiety-like behavior. RNA sequencing of the amygdala followed by KEGG biological pathway analysis of differentially expressed genes showed glutamatergic and GABAergic synapse pathways as significantly enriched. Quantitative PCR showed upregulation of mRNA for the glutamate NMDA receptor subunit 2D (
) and metabotropic receptor 4 (
) and downregulation of the GABA-A receptor associated protein (
) mRNA. Thus, taken together, our diazepam and gene expression data show that aspartame consumption shifted the excitation-inhibition equilibrium in the amygdala toward excitation. Even more strikingly, the anxiety-like behavior, its response to diazepam, and changes in amygdala gene expression were transmitted to male and female offspring in two generations descending from the aspartame-exposed males. Extrapolation of the findings to humans suggests that aspartame consumption at doses below the FDA recommended maximum daily intake may produce neurobehavioral changes in aspartame-consuming individuals and their descendants. Thus, human population at risk of aspartame's potential mental health effects may be larger than current expectations, which only include aspartame-consuming individuals.