Acrylamide-Induced Changes in the Neurofilament Protein of Rat Cerebrum Fractions

Abstract

Acrylamide (ACR) is known to produce central-peripheral distal axonopathy, which is characterized by distal swellings and secondary degeneration both in experimental animals and human. Ultrastructurally, excessive accumulation of neurofilaments (NFs) in the distal swollen axon is a major pathological hallmark. However, the mechanisms of ACR axonopathy remain unknown. Twenty seven male Wistar rats were randomly divided into three groups. Lower and higher ACR groups were received 20 and 40 mg/kg ACR by i.p. injection respectively. The control group received physiological saline. All rats were sacrificed after 8 weeks of treatment and their cerebrums were dissected, homogenized and used for the determination of the NF proteins. In general, the levels of light NF (NF-L) and medium NF (NF-M) subunits increased consistently in the supernatant, whereas they decreased consistently in the pellet from rats treated with ACR. Compared to that of the control group, the levels of NF-L increased respectively by 104% and 45% (P<0.01) in the supernatant and decreased by 16% and 11% (P<0.01) in the pellet of rat cerebrums in lower and higher groups. The enhancement of NF-M was 76% and 147% (P<0.05, P<0.01) in supernatant, and the reduction was 26% and 36% (P<0.01) in pellet in lower and higher group respectively. The heavy NF (NF-H) level changed slightly. The present results suggested that the change of NF-L and NF-M levels in cerebrum might be relevant to the mechanisms of the neurofilamentous axonopathies induced by ACR.

The Changes of Cytoskeletal Proteins in Plasma of Acrylamide-Induced Rats

“…1). Gait scores from an initial 1 ± 0 (a normal gait) increased to 4 ± 0 (a severely abnormal gait) in high ACR group and relatively slowly increased to just 2 ± 0 (a slightly abnormal gait) in low ACR group [14].…”

“…the high ACR dosage caused a significant retardation of normal weekly weight gain [14]. Both groups of ACR-treated rats showed abnormal neurobehavioral function, i.e.…”

“…Gait scores of ACR-treated groups and control group were compared using the Mann-Whitney U test [13]. Body weight and integrated optical densities (IOD) of the blots of all these proteins contents were analyzed with one-way analysis of variance (ANOVA) respectively and followed by LSD's or Dunnett's (equal variances not assumed) post hoc tests which were provided by SPSS 11.0 statistical software (Chicago, USA) [14,17]. For all comparisons described above, the differences were considered statistically significant at P < 0.05.…”

“…To measure gait abnormalities, rats were placed in a clear plexiglass box (90 · 90 cm) and were observed for 3 min, and a gait score was assigned from 1 to 4 according to the criteria of numerical gait score for ACR, i.e. 1 (unaffected) = a normal gait; 2 (slightly affected) = a slightly abnormal gait (slight ataxia, hopping gait and foot splay); 3 (moderately affected) = moderately abnormal gait (obvious ataxia and foot splay with limb abduction during ambulation); 4 (severely affected) = severely abnormal gait (inability to support body weight and foot splay) [13,14]. Neurotoxicity was assessed weekly in rats after initiation of ACR i.p.…”

“…All the tubes were stored at 4°C 60 min and then centrifuged at 3,000 · g for 20 min. The plasma was separated carefully and mixed with homogenizing buffer containing 10 mM Hepes, pH 6.8,50 mM NaF, 1 mM EGTA, 1 mM, 2 mM levamisol, and 1 mM EDTA phenylmethylsulfonyl fluoride (PMSF) and then stored at -80°C [14]. All the process of the control and ACRinduced groups were completely parallel.…”