Effects of acrylamide exposure during pregnancy and lactation on the development of myelin sheath of corpus callosum in offspring rats

Abstract

Acrylamide is an alkene known to induce neurotoxicity in humans and experimental animals. However, the effects of acrylamide on the development of myelin sheath are unclear. The present study was to explore the effects of acrylamide exposure during pregnancy and lactation on the development of myelin sheath in offspring rats. Four groups of thirty-two pregnant Sprague-Dawley rats were exposed to 0, 4.5, 9 and 18 mg/kg BW acrylamide by gavage from gestational day 15 to postnatal day 13. The corpus callosum of nine offspring rats per group were dissected in postpartum day 14. Structural changes and lipid contents in myelin sheaths were examined by transmission electron microscopy(TEM) and Luxol Fast Blue staining(LFB). The expression of MBP and PLP was evaluated by immunohistochemistry and Western blotting. TEM showed that the myelin sheaths in the 18 mg/kg group were disordered compared with control group. Luxol Fast Blue staining gradually decreased with increasing acrylamide maternal exposure. The immunohistochemistry and Western Blotting results showed that maternal exposure to acrylamide caused a decreasing trend in MBP and PLP in the corpus callosum of rats at postnatal day 14. Furthermore, these reduced protein levels may be neurodevelopmental toxicity's mechanism in response to maternal exposure to acrylamide.

Keywords: Corpus callosum; acrylamide; myelin basic protein (MBP); myelin proteolipid protein (PLP); offspring rats.

Fig. 1

A schematic of how animals were assigned to each of the endpoints.

Fig. 2

Maternal exposure to acrylamide for three weeks is linked with changes in body weight of P14 offspring rats. N = 9. ^*P < .05 vs the control group; ⁺⁺P < .01 vs the 4.5 mg/kg group; ^##P < .01 vs the 9 mg/kg group.

Fig. 3

Maternal exposure to acrylamide for three weeks is linked with microstructure of myelin sheath in the corpus callosum, which is used by transmission electron microscopy. A) control group and B) 18 mg/kg group. Scale bar = 2 μm; A1 and B1 are partially enlarged images of a and B. Scale bar = 1 μm.

Fig. 4

Maternal exposure to acrylamide for three weeks is linked with structure of myelin sheath in the corpus callosum, which is used by LFB staining. A) control group, B) 4.5 mg/kg group, C) 9 mg/kg group and D) 18 mg/kg group. Bar = 10 μm.

Fig. 5

Maternal exposure to acrylamide for three weeks is linked with the expression levels of PLP and MBP in the corpus callosum of P14 rats, which was detected by immunohistochemistry. N = 3. A) the expression level of PLP in the corpus callosum. B) the expression level of MBP in the corpus callosum. a1-a3: Control group; b1-b3: 4.5 mg/kg group; c1-c3:9 mg/kg group; d1-d3: 18 mg/kg group; a1, b1, c1, d1: Scale bars = 50 μm; a2, b2, c2, d2: Scale bars = 20 μm; a3, b3, c3, d3: Scale bars = 10 μm. C) the IOD value of PLP positive expression in the corpus callosum of P14 rats. D) the number of MBP-positive cells in the corpus callosum of P14 rats. N = 3. ^**P < .01 vs the control group; ⁺P < .05 vs the 4.5 mg/kg group; ⁺⁺P < .01 vs the 4.5 mg/kg group. The localization atlas is referenced from the third edition of the People’s health publishing house, translated by Zhuge Qichu, “Stereotaxic Atlas of the Rat Brain.”

Fig. 6

Maternal exposure to acrylamide for three weeks is linked with expression levels of myelin sheath related proteins PLP and MBP. A) the expression levels of PLP and MBP in the corpus callosum of P14 rats in each group were analyzed by western blotting. B) the gray value ratio of PLP to β-tubulin in each group was measured. C) the gray value ratio of MBP to β-tubulin in each group was measured. The data is representative of similar results obtained in 3 independent experiments performed with both groups. N = 3. ^*P < .05 vs the control group; ^**P < .01 vs the control group; ⁺P < .05 vs the 4.5 mg/kg group; ⁺⁺P < .01 vs the 4.5 mg/kg group; -P < .05 vs the 9 mg/kg group.