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PubMed1990

Acrylamide exposure induces a delayed unscheduled DNA synthesis in germ cells of male mice that is correlated with the temporal pattern of adduct formation in testis DNA.

A study of meiotic and postmeiotic germ-cell-stage sensitivity of male mice to induction of unscheduled DNA synthesis (UDS) by acrylamide showed that DNA repair could be detected in early spermatocytes (after the last scheduled DNA synthesis) through about mid-spermatid stages. No DNA repair could be detected in later stages. The maximum UDS response was observed 6 hr after i.p. exposure and was about 5 times greater than the response measured immediately after treatment. This is the longest delay between chemical treatment and maximum UDS response yet observed in mouse germ cells. There was a linear relationship between the UDS response and acrylamide exposure from 7.8 to 125 mg/kg. By using 14C-labeled acrylamide it was determined that the temporal pattern of adduct formation in testes DNA paralleled that of the UDS response, with maximum binding occurring 4 to 6 hr after exposure. In contrast, the temporal pattern of adduct formation in liver DNA showed maximum binding within 1 to 2 hr after exposure and was an order of magnitude greater than that found for the testis DNA.

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PubMed1992

Acrylamide exposure preferentially impairs axonal transport of glycoproteins in myelinated axons.

The right L5 dorsal root ganglion of adult rats exposed to acrylamide (40 mg/kg body weight/day for nine consecutive days) was injected with either [3H]methionine or [3H]glucosamine. After allowing incorporation into macromolecules and axonal transport to proceed for 5 hr, the distribution of radioactivity in cross sections and longitudinal sections of sciatic nerve was determined by autoradiography. Control and treated animals showed no difference in distribution of label within the sciatic nerve with respect to rapidly transported proteins labelled with [3H]methionine. In control animals the distribution of rapidly transported glycoproteins labelled with [3H]glucosamine was similar to that found for [3H]methionine-labelled proteins. In contrast, acrylamide-exposed rats had a very different distribution of labelled glycoproteins; there was a marked paucity of label in the myelinated axons. We interpret this result as indicating that acrylamide preferentially inhibits glycosylation or axonal transport of glycoproteins in neurons bearing myelinated axons.

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PubMed1984

Effects of acrylamide and other sulfhydryl compounds in vivo and in vitro on staining of motor nerve terminals by the zinc iodide-osmium technique.

The zinc iodide-osmium technique blackens motor nerve terminals by selectively staining synaptic vesicles. Intraperitoneal injections of acrylamide (30 mg/kg/day, 5 times each week) cause inhibition of staining by this technique so that approximately one third of the end-plates in rat sternocostalis muscle are unstained after 24 hours, and by 17 days more than 70% are unstained. This is not associated with nerve fiber degeneration. A similar inhibition of staining can also be shown after prior incubation of the sternocostalis muscle in 4 mM acrylamide in oxygenated Ringer's solution. Intraperitoneal injection of the thiol group blocker N-ethylmaleimide also causes marked inhibition of staining of motor end-plates by this method. Dithiothreitol, which prevents the oxidation of thiol groups, will partly prevent the inhibition of staining by both acrylamide and N-ethylmaleimide, when given in vivo.

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PubMed1994

Acrylamide in polyacrylamide gels can modify proteins during electrophoresis.

Many notable discoveries have resulted from the characterization or purification of compounds by electrophoresis. The results reported here show that when polyacrylamide gels are used as the support matrix for electrophoresis, proteins can be modified by reaction with unpolymerized monomers of acrylamide, forming covalent acrylamide adduction products. This was demonstrated by electrophoresis of human and rat hemoglobins and subsequent analysis by electrospray ionization mass spectrometry. The degree of covalent acrylamide binding can be appreciable. The degree of adduction is dependent upon the condition of the gel matrix, the amount of material applied, and the reactivity of the material under investigation.

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PubMed1997

Simple neurobehavioral functional observational battery and objective gait analysis validation by the use of acrylamide and methanol with a built-in recovery period.

A functional observational battery (FOB) with modified objective gait analysis was validated using the neurotoxicants acrylamide and methanol. The FOB consisted of side cage observation (30 sec); open field observation (2 min); evaluation of handling, reflexes, and gait scoring; and grip strength of the fore limbs and hind limbs. Temperature and body weight were measured. Gait analysis was based on measurements of the distances and angles between sequential foot strides after walking in a corridor (90 x 10 x 10 cm). Landing foot splay was the distance between the inner surfaces of the fourth digits of each foot after the animals were dropped from a 30-cm height. Acrylamide was given at doses of 0 (saline), 20, and 40 mg/kg intraperitoneally. Days of dosing were 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19. Evaluations were done before dosing on Days 0, 2, 5, 11, 17, and 27 (for recovery). Methanol was given to another group at doses of 0 (distilled water), 3.25 (escalated to 8.5 before end of evaluation), and 6.5 ml/kg. Days of dosing were 3, 5, 7, and 10; evaluations were conducted at 0, 6, 8, and 12 days. Acrylamide at 40 mg/kg demonstrated a biologically significant increase in foot splay in males on Days 3 and 17 and was not recovered by Day 27. A significant decrease in the hind limb grip strength was seen in high-dose females, but with incomplete recovery on Day 27. Methanol (3.25/8.5 ml/kg) induced a biological decrease of activity postdosing on Days 6, 8, and 12. A significant increase in gait length was seen in females only at the 6.5 ml/kg dose at Day 12. Selected doses and schedule of observation validated the battery for screening and better quantification of acute and chronic neurotoxicity.

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PubMed1996

Alterations in the neutral proteinase activities of central and peripheral nervous systems of acrylamide-, carbon disulfide-, or 2,5-hexanedione-treated rats.

Proteinases are widespread in neuronal or nonneuronal eukaryotic cells. They are suggested to play an important role in the turnover of proteins in neuronal perikaryon and axon, and digestion of the transported cytoskeletal proteins in synaptic terminals. We examined the effect of acrylamide (50 mg/kg, ip), carbon disulfide (700 ppm, 9 h, 7 d a week), and 2,5-hexanedione (2,5-HD) (1% in drinking water) treatment of rats on mCANP (2 mM Ca2+), microCANP (0.1 mM Ca2+), and CINP (Ca(2+)-independent) activity in telencephalon + diencephalon (FB), rhombencephalon + mesencephalon (LB), spinal cord (SC), and sciatic nerve (SN). The proteinase activity was determined in the 30,000g supernatant fraction of tissues using 14C-methylated casein as the substrate. mCANP activity in FB, LB, and SC was inhibited only by acrylamide. Acrylamide or 2,5-HD treatment had no effect on microCANP and CINP activities of SN, whereas carbon disulfide enhanced microCANP after 15 d and CINP activity after 10 d. It is suggested that alteration in in vitro calpain activity shown by these chemicals may not be directly related to their neurotoxic effect. However, calpain may still be playing a role in this polyneuropathy by alteration in activity through inflow of Ca2+, release of Ca2+ from intracellular organelles, or other factors. Modification of cytoskeletal proteins making them more susceptible to proteases and the role of some other proteinase is also possible.

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PubMed1981

Interactions between handling and acrylamide on the striatal dopamine receptor.

Rats were either handled for one week or were left undisturbed in their home cages. Twenty-four hours after exposure to 100 mg/kg acrylamide, rats were sacrificed and spiroperidol binding investigated in the striatum. In handling-gentled rats, spiroperidol binding was reduced by acrylamide. In non-handled animals, no overall drug effects were seen, but the effect of acrylamide varied with the time of sacrifice. These results demonstrate the importance of environmental factors in the response to neurotoxicants.

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PubMed1989

In vitro binding of [14C]acrylamide to neurofilament and microtubule proteins of rats.

Acrylamide produces a dying back type of neuropathy in which there is an accumulation of neurofilaments in the axons. The in vitro binding of [14C]acrylamide to neurofilament and microtubule proteins obtained from rat spinal cord and brain was investigated. The relative binding to the high and middle molecular weight neurofilament was greater than to the low molecular weight neurofilament, while the rate of binding to MAP-1 (microtubule associated protein-1) and -2 was much greater than to tubulin. The binding rate to a 53 kDa protein which co-purified with the neurofilaments was between those of the middle and high molecular weight neurofilaments while the lowest rate of binding was to glial fibrillary acidic protein. These data indicate that there is a direct binding of acrylamide to cytoskeletal proteins.

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PubMed1990

The effect of acrylamide on the induction of ornithine decarboxylase in the dorsal root ganglion of the rat.

Injury of the rat sciatic nerve is accompanied by an increased activity of the enzyme ornithine decarboxylase (ODC) in dorsal root ganglia. This increase is impaired in streptozotocin-induced diabetes, in which retrograde axonal transport of proteins is reduced. In order to confirm the relationship between altered axonal transport and ODC induction we treated rats with acrylamide i.p. to cumulative doses of 150 and 350 mg/kg. One sciatic nerve was crushed under anaesthesia and 24 h later dorsal root ganglia were removed and assayed for ODC activity by a dual-label radioenzymatic method. The ratio of activity of 2.41 +/- 0.57 (crushed side over control side) was reduced to 1.66 +/- 0.9 and 1.7 +/- 0.65 after acrylamide treatment at 150 and 350 mg/kg, respectively. The results are consistent with the postulated role of retrograde axonal transport in the cell body responses to nerve injury and may explain the effect of acrylamide on nerve regeneration.

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PubMed1991

Peripheral pain fiber function is relatively insensitive to the neurotoxic actions of acrylamide in the rat.

Acrylamide causes degeneration of sensory nerve axons in a range of experimental animals and in humans. Evidence of selective vulnerability of large diameter fibers has been derived largely from histological and electrophysiological measurements. We have examined the effect of repeated doses of acrylamide on the function of small diameter peripheral pain fibers in rats by measuring the intensity of neurogenic edema initiated by chemosensitive nerve endings and assessing the sensitivity of the hind paws to a noxious stimulus. These effects have been compared to the impaired sensorimotor performance (landing foot spread) resulting from acrylamide treatment and the change in functional integrity of the pain fibers following surgical lesioning of the sciatic nerves. Our results show that the selective vulnerability of large over small diameter sensory fibers previously reported in the literature is reflected in the differential impairment of proprioceptive and pain-related functions in the rat.

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PubMed1991

Acrylamide is genotoxic to the somatic and germ cells of Drosophila melanogaster.

The genotoxic effects of acrylamide, a recently detected carcinogen, have been studied in the somatic (wing primordia) and germ cells of Drosophila melanogaster by the wing mosaic assay and the sex-linked recessive lethal test respectively. Larvae, 72 +/- 4 h old, were exposed to 6 different concentrations of acrylamide ranging between 0.25 mM and 5.0 mM in instant medium for 48 h. It is observed that acrylamide is both mutagenic and recombinogenic in the wing disc cells and induces sex-linked recessive lethals.

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PubMed1990

Involvement of capsaicin-sensitive nerves of the rat urinary bladder in acrylamide neuropathy.

Acrylamide monomer is neurotoxic in man and experimental animals, producing a sensorimotor distal axonopathy. In spite of remarkable effect of acrylamide on micturition, resulting in urine retention in both man and rat, bladder autonomic innervation has been little studied. This study focused on the effect of acrylamide on capsaicin-sensitive nerves of the rat bladder, because of the role played by these fibres in regulating the afferent arm of reflex micturition.

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PubMed1988

Inhibition of activity and quenching of intrinsic fluorescence of transglutaminase by acrylamide are independent events.

Addition of low concentrations of acrylamide to the assay mixture of erythrocyte transglutaminase leads to a strong inhibition of the enzyme with a mechanism consistent with a non-competitive inhibition against both substrates. For the quenching of the intrinsic fluorescence of the protein, much higher concentrations of acrylamide are required so that both phenomena appear independent of each other. In this particular case, therefore, acrylamide can be employed to obtain information on ligand-triggered conformational changes.

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PubMed1992

Viscosity dependence of acrylamide quenching of ribonuclease T1 fluorescence. The gating mechanism.

The structural regulation of the access of acrylamide molecules, as quenchers, to the buried tryptophans of a protein can be modelled by a simple gate concept. Such a gate, when open, allows transient exposure of the fluorophore to the quencher molecule in solution. We have previously shown that the observed viscosity dependence of acrylamide quenching process in ribonuclease T1 (RNAse T1) is not reconcilable with the gating mechanism. However, on that occasion, we neglected the effect of changes in the activity of the quencher molecule and the possible presence of static quenching. The experimental observation of a considerable contribution by static quenching and the realization that static quenching might produce dramatic effects in steady state measurements led us to reexamine the question. It is shown that in a gating model the static component can also influence the apparent dynamic quenching. In this paper, we present derived equations for the gated quenching mechanism including possible contributions from the static component. We also carefully remeasured the acrylamide quenching of RNAase T1 as a function of increasing glycerol concentration. Computer simulations were carried out to compare the experimental data set to the generalized model. We reach the conclusion that even the new, quite complex equations fail to predict the qualitative and quantitative features of the observed quenching experiments. We arrived at the conclusion that the fluorophore is never the target of the quencher molecules in solution.

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PubMed1988

Acrylamide quenching of Yt-base fluorescence in aqueous solution.

Acrylamide was found to be an effective quencher of Yt-base (Y-4,9-dihydro-4,6-dimethyl-9-oxo-1H-imidazo-1,2a-purine) in water. In the absence of collisional quenching the decay of Yt-base in water is predominantly a single exponential. The intensity decays become increasingly heterogeneous when quenched by acrylamide. The frequency-domain data were analyzed using the radiation model, which provides estimates of molecular parameters characteristic of the system. The mutual diffusion coefficient at 20 degrees C was found to be 0.5 x 10(5) cm2/s, the Yt-base acrylamide interaction radius was 8 A, and the rate constant for quenching was 100 cm/s. These values indicate that quenching is diffusion-limited, i.e., the encounter complex is deactivated at least 2-fold faster than the rate of diffusive encounters.

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PubMed1984

Carcinogenic activity of acrylamide in the skin and lung of Swiss-ICR mice.

Doses of acrylamide ranging from 12.5 to 50 mg/kg were administered orally to female ICR-Swiss mice over 3 days for each of 2 weeks (total doses of 75, 150 and 300 mg/kg). Two weeks later some of the animals were started on a promotion schedule involving the application of 2.5 micrograms TPA/mouse 3 times weekly. Development of tumors was observed weekly in the skin, and in the lungs at 1 year. Acrylamide was found to initiate squamous cell adenoma and carcinomas in the skin and increased the yield of adenomas and carcinomas in the lung. Skin tumor development was dependent upon 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion whereas lung tumor induction was not. These data extend previous observations of carcinogenic activity of acrylamide in the skin of SENCAR mice and lungs of strain A/J mice to a third strain of mouse, the ICR-Swiss.

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PubMed1984

Interaction of acrylamide with glutathione in rat erythrocytes.

Evidence is presented for an enzyme-catalyzed conjugation of acrylamide (ACR) in rat erythrocytes. Daily exposure of rats to ACR for a period of 7, 14 and 21 days resulted in a time-dependent decrease in glutathione content. In vitro incubation of ACR with rat erythrocytes suspension caused a concentration-dependent decrease in glutathione levels. Red blood cell (RBC) enzyme-catalyzed conjugation of ACR with glutathione increased with protein concentration and was dependent on pH and time of incubation. Glutathione-S-transferase (GST) activity using acrylamide and 1-chloro 2,4-dinitrobenzene (CDNB) as substrates followed the order: liver greater than kidney greater than brain greater than erythrocytes. Glutathione peroxidase activity of RBC's was inhibited by the in vitro addition of ACR to erythrocytes. These results suggest that rat erythrocytes are equipped with the mechanism which can inactivate toxic electrophilic chemicals, such as acrylamide.

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PubMed1985

Acrylamide alters oxidative enzyme activity in rat motoneurons.

Acrylamide (ACR) produces a central-peripheral distal axonopathy, via an unknown mechanism. We have investigated the effects of ACR on the activity of enzymes responsible for the oxidation of NADH (NADH-tetrazolium reductase activity, NADH-TR) with quantitative histochemical techniques. Chronic (5- or 10-day) injection of ACR (50 mg/kg/day) resulted in a significant decrease in enzyme activity in soleus motoneurons, which normally have high NADH-TR activity. The NADH-TR activity in motoneurons with low oxidative metabolism was not significantly affected. Retrograde labeling of motoneurons with horseradish peroxidase was diminished by the acrylamide treatment. These data demonstrate an acrylamide-induced change in the oxidative metabolism of certain motoneurons; further study will determine whether oxidative metabolism is the primary site of action of ACR in producing the distal axonopathy.

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