Deltamethrin exposure inhibits adult hippocampal neurogenesis and causes deficits in learning and memory in mice.

Deltamethrin exposure inhibits adult hippocampal neurogenesis and causes deficits in learning and memory in mice.

Hossain MM;Belkadi A;Al-Haddad S;Richardson JR

Toxicological Sciences

2020

2020-09-25

Deficits in learning and memory are often associated with disruption of hippocampal neurogenesis, which is regulated by numerous processes, including precursor cell proliferation, survival, migration, and differentiation to mature neurons. Recent studies demonstrate that adult born neurons in the dentate gyrus (DG) in the hippocampus can functionally integrate into the existing neuronal circuitry and contribute to hippocampal-dependent learning and memory. Here, we demonstrate that relatively short-term deltamethrin exposure (3 mg/kg every 3 days for 1 month) inhibits adult hippocampal neurogenesis and causes deficits in learning and memory in mice. Hippocampal-dependent cognitive functions were evaluated using two independent hippocampal-dependent behavioural tests, the novel object recognition task and Morris water maze. We found that deltamethrin-treated mice exhibited profound deficits in novel object recognition and learning and memory in water maze. Deltamethrin exposure significantly decreased bromodeoxyuridine (BrdU)-positive cells (39%) and Ki67+ cells (47%) in the dentate gyrus (DG) of the hippocampus, indicating decreased cellular proliferation. In addition, deltamethrin-treated mice exhibited a 44% decrease in nestin-expressing neural progenitor cells and a 38% reduction in the expression of doublecortin (DCX), an early neuronal differentiation marker. Furthermore, deltamethrin exposed mice exhibited a 25% reduction in total number of granule cells in the DG. These findings indicate that relatively short-term exposure to deltamethrin causes significant deficits in hippocampal neurogenesis that is associated with impaired learning and memory. (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

mice; pyrethroid; cognition; adult neurogenesis

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1096-0929

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