Background At present, atmospheric PM2.5 polluton is serious in large areas of northern China, and women are more likely to consume high fat food during pregnancy and lactaton. Exposure to PM2.5 in combinaton with high fat diet (HFD) may signifcantly affect physiological development and motor functon of offspring.
Objectve This experiment is conducted to study the effect of exposure to PM2.5 and HFD on physiological development and motor functon in offspring rats.
Methods Healthy 7-week-old SPF SD rats (n=72) mated with a male to female rato of 2:1. Pregnant rats were randomly divided into six groups, including control group (CC group, normal diet), high fat diet group (HFD group), low PM2.5 group (L-PM2.5 group, normal diet), high PM2.5 group (H-PM2.5 group, normal diet), high fat diet+low PM2.5 group (HFD+L-PM2.5 group), and high fat diet+high PM2.5 group (HFD+H-PM2.5 group), with eight rats in each group. The low and high PM2.5 concentrations in dynamic exposure cabinet were approximately two times and four times higher than the annual average PM2.5 concentraton in Tangshan city respectvely. The exposure started from pregnant day 0, 5 hours every day, 5 days every week, untl postnatal day 21 (PND21) of offspring rats. Afer weaning, the offspring rats continued to be exposed to PM2.5 until PND42 and PND60. The mother rats and their newborn rats in the CC and HFD groups were kept in clean rooms, so were the PM2.5-exposed rats and their offspring rats afer daily PM2.5 exposure. Afer weaning, the offspring rats in all groups were given normal diet. The time of pinna detachment, body hair growth, incisor erupton, and eye opening of the newborn rats were observed, and motor functon was tested using open feld test on PND21, PND42, and PND60.
Results The clean room, outdoor, low, and high PM2.5 concentrations during the exposure period were (3.52±1.73), (60.47±21.01), (127.38±43.16), and (256.45±81.34) μg/m3 respectively. PM2.5 treatment prolonged the eye opening time of pups. The eye opening time of pups in the L-PM2.5 and H-PM2.5 groups(14.33±0.89) d and (14.75±0.97) d respectvely were longer than that of the CC group(13.96±0.86) d (P < 0.05). HFD treatment prolonged the body hair growth time of pups. The body hair growth time of pups in the HFD group(15.04±0.72) d was longer than that of the CC group(14.42±0.60) d (P < 0.05). There was no interaction between PM2.5 and HFD on birth weight, pinna detachment time, incisor eruption time, eye opening time, and body hair growth time of newborns (P>0.05). Regarding the results of open feld test, PM2.5 treatment reduced the total distance of PND42 pups and shortened the central area residence time of PND21 and PND42 pups. The total distances of PND42 pups in the L-PM2.5 and H-PM2.5 groups were (2 266.77±404.18)cm and (2104.31±212.72)cm respectvely, shorter than that of the CC group(2 381.58±413.33) cm (P < 0.05). The central area residence time of PND21 pups in the L-PM2.5 and H-PM2.5 groups were (11.92±7.83) s and (9.86±6.76) s respectvely, shorter than that of the CC group(17.61±11.04) s (P < 0.05). The central area residence time of PND42 pups in the L-PM2.5 and H-PM2.5 groups were (12.00±7.54) s and (9.68±5.85) s respectvely, shorter than that of the CC group(15.73±9.21) s (P < 0.05). HFD reduced the total distance of PND21 pups and the central area entry frequency of PND42 pups. The total distance of PND21 pups in the HFD group(1 942.51±225.20) cm was shorter than that of the CC group(2 207.56±287.30)cm (P < 0.05). The central area entry frequency of PND42 pups in the HFD group(3.83±2.41) times was shorter than that of the CC group(4.50±2.88) times (P < 0.05). There was no interacton between PM2.5 and HFD on the total distance, residence time, and entry frequency in central area of PND21, PND42, and PND60 pups (Ps>0.05).
Conclusion PM2.5 and HFD could delay physiological development and decrease motor functon of rat pups, and there is no interacton between PM2.5 and HFD.
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