Acrylamide disturbs the subcellular distribution of GABA_A receptor in brain neurons

Abstract

Mechanisms underlying the action of acrylamide on neurons were studied by monitoring the expression of GABA(A) receptor (R) in cultured brain neurons derived from chicken embryos. In situ trypsinization of the neurons and 3H-flunitrazepam binding assay were employed to examine the subcellular distribution of GABA(A)R. A 3-h exposure of the cultured neurons to 10 mM of acrylamide raised reversibly the proportion of intracellular (trypsin-resistant) 3H-flunitrazepam binding sites by about 48% and decreased cell surface binding 24% from respective control values, without altering total cellular binding and the affinity of the ligand. Moreover, the acrylamide treatment induced more intense perikaryal immunostaining of GABA(A)R alpha subunit proteins than that in control neurons but did not change the total level of cellular alpha immunostain, in accordance with the binding data. In the cell bodies of acrylamide-treated neurons, the level of neurofilament-200 kDa proteins was similar to control, whereas the tubulin protein content was significantly lowered approximately 51% from control, as revealed by quantifying the immunostained cytoskeletal elements. In addition, electron microscopic observations found reductions in the numbers of microtubules and neurofilaments in the perikarya of acrylamide-treated neurons. As exhibited by the 3H-leucine and 3H-monosaccharide incorporation experiments, the exposure to acrylamide inhibited the rate of general protein synthesis in the culture by 21%, while the rate of glycosylation remained unaltered. Furthermore, in situ hybridization analysis showed that acrylamide did not modify the expression of GABA(A)R alpha subunit mRNAs. Taken together, these data suggest that acrylamide may downregulate the microtubular system and disintegrate neurofilaments, and thereby block the intracellular transport of GABA(A)R, resulting in the accumulation of intracellular receptors.

The possible protective role of ginseng on the sciatic nerve neuropathy induced experimentally by acrylamide in adult male albino rat

“…This will lead to increased permeability of the membranes and disturbance of the ion concentration in the cytoplasm and cell organelles. The alterations and irregularity in shape that were found in the acrylamide-treated group could be coincided with the results of some previous studies [24]. Accumulation of sodium leads to an increase in water content in the cell leading to its swelling.…”

Acrylamide Alters Cytoskeletal Protein Level in Rat Sciatic Nerves

“…The increase in the rate of tubulin polymerization by ACR may alter the rate of transport of axonal constituents including NF and contribute toward their accumulation in the focal swellings observed in this neuropathy [41]. However, another study revealed that ACR down regulated the MT system as revealed both by immunostained and electron microscopic [38], which was similar to this tubulin result in pellet.…”

“…Previous studies showed that ACR induces collapse of NFs in human neuroblastoma cells to form perikaryal inclusion bodies [37] and reduction in the numbers of NFs in the perikarya [38]. ACR increased the expression of mRNA for NF-M NF (acute effect) and NF-L (chronic effect) protein sub-units in rat brain [39].…”

Effect of subchronic acrylamide exposure on the expression of neuronal and inducible nitric oxide synthase in rat brain

“…An in vitro study showed that ACR blocks the intracellular transport of the GABAa receptor, resulting in receptor distribution disturbance [11]. In addition, a recent study, using brain synaptosomes, showed that ACR impairs synaptic functions and subsequent decreases in neurotransmitter release [12].…”