Dose-Dependent Beneficial Effect of Ketone Supplement-Evoked Ketosis on Anxiety Level in Female WAG/Rij Rats: Sometimes Less Is More

Abstract

While one-third of the population can be affected by anxiety disorders during their lifetime, our knowledge of the pathophysiology of these disorders is far from complete. Previously, it has been demonstrated in male animals that exogenous ketone supplement-evoked ketosis can decrease anxiety levels in preclinical rodent models, such as Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. Thus, in this study, we investigated whether intragastric gavage of the exogenous ketone supplement KEMCT (mix of 1,3-butanediol-acetoacetate diester/ketone ester/KE and medium-chain triglyceride/MCT oil in 1:1 ratio) for 7 days can alter the anxiety levels of female WAG/Rij rats using the light-dark box (LDB) test. We demonstrated that a lower dose of KEMCT (3 g/kg/day) increased blood R-βHB (R-β-hydroxybutyrate) levels and significantly decreased anxiety levels (e.g., increased the time spent in the light compartment) in female WAG/Rij rats on the seventh day of administration. Although the higher KEMCT dose (5 g/kg/day) increased blood R-βHB levels more effectively, compared with the lower KEMCT dose, anxiety levels did not improve significantly. We conclude that ketone supplementation might be an effective strategy to induce anxiolytic effects not only in male but also in female WAG/Rij rats. However, these results suggest that the optimal level may be moderately, not highly, elevated blood R-βHB levels when the goal is to alleviate symptoms of anxiety. More studies are needed to understand the exact mechanism of action of ketone supplementation on anxiety levels and to investigate their use in other animal models and humans for the treatment of anxiety disorders and other mental health conditions.

Keywords: LDB test; anxiety; exogenous ketone supplement; female WAG/Rij rat; mental health.

Figure 1

Effect of low KEMCT dose (3 g/kg/day; group 2) and high KEMCT dose (5 g/kg/day; group 3) on anxiety levels (A,B), blood R-βHB (C) and glucose levels (D), as well as body weight (E) compared with baseline (E), water-gavaged animals (control, group 1) (A,B) or both of them (baseline and control; C,D). Abbreviations: Bas, baseline; co., compartment; KEMCT, mix of ketone ester (1,3-butanediol-acetoacetate diester/KE) and medium-chain triglyceride (MCT) oil in 1:1 ratio; R-βHB, R-beta-hydroxybutyrate; * p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001.