Objective The developmental toxicity caused by polycyclic aromatic hydrocarbons represented by benzoapyrene (BaP) is a major public health concern. However, studies show that the gene of activity regulated cytoskeleton associated protein (Arc) plays an important role in neurogenesis and learning and memory of offspring. This article aims to investigate the effects of prenatal BaP exposure on neurobehavior and mRNA expression of Arc in hippocampus of offspring rats.
Methods Sixty healthy 3-month-old SPF SD rats (male:female=1:1) were mated, and the 30 pregnant rats were randomly divided into blank control group, olive oil group, and 10, 20, and 40 mg/kg BaP groups, and each group contained six rats. BaP was administrated intraperitoneally at 0.2 mL/kg in terms of weight at 17, 18, and 19 days after pregnancy once a day for 3 consecutive days, olive oil was used as solvent control, while the blank control group did not receive any administration. The attainment rates of cliff avoidance on postnatal day 7 (PND7) and air righting reflex on PND14, as well as escape latency, time spent in the target quadrant, and number of crossing platforms on PND37 were counted. The mRNA levels of Arc in hippocampus on PND1, PND7, PND14, and PND45 were measured.
Results On PND7, compared with the olive oil group (97.56%), the cliff avoidance attainment rates of the 20 mg/kg BaP group (63.64%) and the 40 mg/kg BaP group (60.98%) decreased (P < 0.05). On PND14, compared with the olive oil group (65.71%), the attainment rate of air righting reflex of the 40 mg/kg group (29.73%) decreased (P < 0.05). The results of place navigation test showed that compared with the olive oil group, the escape latencies on days 1, 3, and 4 of testing in the groups administrated with BaP were significantly increased (P < 0.05). The results of probe trial showed that compared with the olive oil group, the time spent in target quadrant and the number of crossing platforms on PND37 in the groups administrated with BaP were significantly reduced (P < 0.05). For hippocampal Arc mRNA expression level at different time points, on PND1 and PND7, compared with the olive oil group, the Arc mRNA expression levels of all the BaP administered groups were significantly lower (P < 0.05); on PND14, compared with the olive oil group (14.86±2.48), the Arc mRNA expression level of the 40 mg/kg group (7.31±1.94) was reduced significantly (P < 0.05); on PND45, there was a statistically significant decrease in Arc mRNA level in the 40 mg/kg BaP group (19.98±8.21) compared with the olive oil group (39.66±6.39) (P < 0.05).
Conclusion Prenatal BaP exposure can cause offspring abnormal neurobehavior in early life and defected spatial learning and memory ability in late stage of development, and declined Arc mRNA in hippocampus may participate in inducing the neurodevelopmental toxicity of BaP.
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