Silver nanoparticle exposure in pregnant rats increases gene expression of tyrosine hydroxylase and monoamine oxidase in offspring brain

Abstract

Context: Maternal exposure to silver nanoparticles (AgNPs) affects neurobehavioral reflexes and spatial memory formation in offspring. Although the transmission of AgNPs into the brain has been reported, its toxic effect on dopamine metabolism in the brain of offspring has not been studied so far.

Objective: The aim of the present study was to investigate the expression levels of tyrosine hydroxylase (TH) and monoamine oxidase A (MAO-A) genes in the brain of offspring exposed in utero to various concentrations of AgNPs.

Materials and methods: Time mated pregnant adult rats were assigned into three groups including control, low dose of AgNPs (0.2 mg/kg) and high dose of AgNPs (2 mg/kg). AgNPs were subcutaneously (SC) injected at days of 1, 4, 7, 10, 13, 16 and 19 of pregnancy. Gene expression of TH and MAO-A was analyzed in the brain of offspring (male and female) at days of 1, 7, 14 and 21 after birth.

Results: Administration of AgNPs to pregnant rats in a time- and dose-dependent manner increased the expression levels of TH in the brain of male and female pups at all tested days after birth (p < 0.05). AgNPs had stimulatory effect on MAO-A mRNA expression in pups only at the age of 7 and 14. Female pups showed the higher level of TH and MAO-A compared to that in male pups (p < 0.001).

Discussion and conclusions: Results obtained here demonstrated that the exposure of pregnant rats to AgNPs increases the expression of genes involved in dopamine metabolism in the brain of offspring.

Keywords: Nanosilver; brain; dopamine metabolism; maternal exposure; offspring.