(P30-002-25) Impact of Dietary Zinc Levels on ASD-Related Behaviors and Body Weight in BTBR Mice: An 8-Week Intervention Study

Objectives: Zinc (Zn) is an essential trace element implicated in ASD etiopathogenesis. Zn imbalances are linked to ASD traits like repetitive behavior and anxiety. While the effects of Zn deficiency are well-documented, the impact of normal/excess Zn on ASD behaviors is unclear. This study investigated the influence of different dietary Zn concentrations on ASD-like behavior and weight trends in the BTBR T+ Itpr3tf/J (BT), a well-established mouse model of ASD, in comparison to control C57BL/6J (B6) mice.

Methods: Eight-week-old BT and B6 mice were assigned to deficient, normal and excessive Zn diets with 0, 30, or 150 ppm in 8 mice/group, namely BT-0, BT-30, BT-150, B6-0, B6-30, and B6-150. Behavioral tests, including hole-board dips (anxiety), repeat hole dips (repetitive behavior), and marble burying (compulsive-like behavior) were performed at weeks 0, 4, and 8 (W0, W4, and W8). Body weight was recorded weekly. Data were analyzed using SPSS 29.0 and GraphPad Prism 10.4. (significance threshold p< 0.05).

Results: Hole-board dips: At W0, BT groups exhibited higher hole dips than B6. By W8, BT-30 declined to B6 levels but BT-150 maintained the highest dips compared to BT-30 and all B6 groups, indicating an anxiogenic effect. B6 showed normal behavior across time and Zn concentrations. Repeat dips: Prolonged excess Zn intake (W8, BT-150) exacerbated repetitive behavior by significantly increasing repeat dips compared to W4, BT-30. Marble burying: BT mice buried more marbles at W0 across all Zn levels. BT-150 by W4 and BT-30 by W8 normalized this behavior. Weight: BT-0 experienced severe weight loss (W0: 28.7±2.8 g; W4: 20.1±3.2 g; p< 0.03), necessitating their compassionate euthanasia by W4. In contrast, B6-0 mice maintained stable body weight, highlighting their resilience to Zn deficiency. Zn facilitated significant weight gain in both strains at concentrations of 30 and 150 ppm.

Conclusions: Dietary Zn significantly impacts the behavior and weight of BT mice, as excessive prolonged dietary Zn exacerbates ASD-like behaviors, while Zn deficiency could be lethal. B6 mice were less affected, suggesting a strain-specific susceptibility. In summary, this study suggests that a balanced dietary intake of Zn may lead to optimal outcomes in ASD and encourages further research to explore the underlying mechanisms.

Funding Sources: ASPIRE and START-UP Grants, UAEU