Long term exposure of nanoparticles e.g., silica dust (SiO2) from desert environments, or engineered nanoparticles from metals viz., Cu, Al or Ag from industry, ammunition, military equipment and related products may lead to adverse effects on mental health. However, it is unclear whether these nanoparticles may further adversely affect human health in cardiovascular or metabolic diseases e.g., hypertension or diabetes. It is quite likely that in diabetes or hypertension where the body immune system is already compromised there will be greater adverse effects following nanoparticles exposure on human health as compared to their exposure to healthy individuals. Previous experiments from our laboratory showed that diabetic or hypertensive animals are more susceptible to heat stress-induced neurotoxicity. Furthermore, traumatic injury to the spinal cord in SiO2 exposed rats resulted in exacerbation of cord pathology. However, whether nanoparticles such as Cu, Ag or SiO2 exposure will lead to enhanced neurotoxicity in diabetic animals are still not well investigated. Previous data from our laboratory showed that Cu or Ag intoxication (50 mg/kg, i.p. per day for 7 days) in streptozotocine induced diabetic rats exhibited enhanced neurotoxicity and exacerbation of sensory, motor and cognitive function as compared to normal animals under identical conditions. Thus the diabetic animals showed exacerbation of regional blood-brain barrier (BBB) disruption, edema formation and cell injuries along with greater reduction in the local cerebral blood flow (CBF) as compared to normal rats. These observations suggest that diabetic animals are more vulnerable to nanoparticles induced brain damage than healthy rats. The possible mechanisms and functional significance of these findings are discussed in this review largely based on our own investigations.
Keywords: Nanoparticles, SiO2, Cu, Ag, Blood-brain barrier, brain edema, neuronal injury, myelin damage, diabetes, streptozotocine, electron microscopy, cerebral blood flow, neurotoxicity, sensory-motor function, cognitive disturbances, hyperglycemia
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