Histological and immunohistochemical study of the effect of gold nanoparticles on the brain of adult male albino rat

Gold nanoparticles (GNPs) have numerous medical applications as in biological imaging, cancer treatment and in implants (pacemakers and stents). Many conflicting results about GNPs safety and its accumulation in liver, kidney and brain were recorded. This work was carried out to study the histological effect of long period exposure to gold nanoparticle on the brain of adult male albino rat. Twenty adult male albino rats were divided into two equal groups: The first one served as a control group and the second one received 400 μg/kg/day GNPs by gastric tube once daily for eight weeks. Brain specimens were collected at the end of the experiment for histological and immunohistochemical studies using caspase-3 and glial fibrillary acidic protein (GFAP). GNPs treated group revealed wide spread histological alterations and deposition of gold nanoparticle aggregates in the neurons of cerebral cortex and hippocampus and also in the epithelium of choroid plexus with hyalinization of the wall of some blood vessels and disruption of the capillaries. All these changes were associated with localized positive caspase 3 reaction. Various degrees of astrogliosis were evidenced by astrocytic proliferation and increase size of their cell body with increase number and length of their processes. It could be concluded that repeated exposure of adult male albino rats to gold nanoparticles induced its deposition in the brain in association with histological alterations and various degrees of astrogliosis.