Effects of Nanosilver Exposure on Cholinesterase Activities, CD41, and CDF/LIF-Like Expression in ZebraFish (Danio rerio) Larvae

Abstract

Metal nanosolicoparticles are suspected to cause diseases in a number of organisms, including man. In this paper, we report the effects of nanosilver (Ag, 1–20 nm particles) on the early development of the zebrafish, a well-established vertebrate model. Embryos at the midgastrula stage were exposed to concentrations ranging from 100 to 0.001 mg/L to verify the effects on different endpoints: lethality, morphology, expression of cholinergic molecules, and development of the immune system. (1) Relative risk of mortality was exponential in the range between 0.001 and 10 mg/L. Exposure to 100 mg/L caused 100% death of embryos before reaching the tail-bud stage. (2) Developmental anomalies were present in the 72 h larvae obtained from embryos exposed to nanosilver: whole body length, decreased eye dimension, and slow response to solicitation by gentle touch with a needle tip, with a significant threshold at 0.1 mg/L. (3) Dose-dependent inhibition of acetylcholinesterase activity was significant among the exposures, except between 1 mg/L and 10 mg/L. (4) The distribution of CD41+ cells and of CDF/LIF-like immunoreactivity was altered according to the Ag concentration. The possible effect of nanosilver in impairing immune system differentiation through the inhibition of molecules related to the cholinergic system is discussed.

Immunomodulatory properties of silver nanoparticles contribute to anticancer strategy for murine fibrosarcoma

“…12 AgNPs have also been shown to inhibit molecules related to the cholinergic system and consequently impair the immune system differentiation in zebrafish. 13 AgNPs behave as allergens in mice, as reported in a recent proteome-based study. 14 The intravenous administration of AgNPs also showed immunotoxicity in murine models.…”

Sulfidation of silver nanoparticle reduces its toxicity in zebrafish

“…Any inhibition in AChE activity would prolong motor neuron firing that could adversely modify animal responses and behaviour. Nanosilver has been shown to inhibit AChE activity in zebrafish larvae (Myrzakhanova et al, 2013). This also suggests that owing to their nano size, AgNPs can easily cross blood-brain barrier and affect vital neuronal functions.…”

“…By contrast, sulfidation of AgNPs resulted in a small but significant increment (p<0.05) in brain AChE activity (0.997±0.002 μM acetylthiocholine hydrolyzed/mg protein/min) when compared to fish exposed to non-sulfidated AgNPs. AChE is well recognized as a marker of xenobiotic stress in aquatic organisms and is important for normal neural function (Myrzakhanova et al, 2013). Any inhibition in AChE activity would prolong motor neuron firing that could adversely modify animal responses and behaviour.…”

“…Numerous studies have suggested that exposure to AgNPs reduces the development of zebrafish. Myrzakhanova et al (2013) reported that AgNPs inhibit the expression of molecules related to cholinergic system and impact early development of zebrafish. Exposure to AgNPs has also been shown to affect the development of zebrafish embryo by altering gene expression, especially of the genes responsible for oxidative phosphorylation and protein synthesis.…”

Environmental Cases and Nanoecotoxicology

“…It is not clear if this effect resulted from mechanical perturbation (thigmomorphogenesis) and/or lack of oxygen or mineral uptake (suffocation) due to external (i.e., on the epidermis) TiO 2 -nanoparticles deposition, or from genuine uptake of particles. The tests with aquatic models showed that the effects of exposure to silver nanoparticles induced a trend to the impairment of immune responses, possibly related to the degree of inhibition of the cholinesterases activities [17][18][19][20][21][22]. 4.…”