Toxic effect of acrylamide on the development of hippocampal neurons of weaning rats

Although numerous studies have examined the neurotoxicity of acrylamide in adult animals,the effects on neuronal development in the embryonic and lactational periods are largely unknown.Thus,we examined the toxicity of acrylamide on neuronal development in the hippocampus of fetal rats during pregnancy.Sprague-Dawley rats were mated with male rats at a 1：1 ratio.Rats were administered 0,5,10 or 20 mg/kg acrylamide intragastrically from embryonic days 6–21.The gait scores were examined in pregnant rats in each group to analyze maternal toxicity.Eight weaning rats from each group were also euthanized on postnatal day 21 for follow-up studies.Nissl staining was used to observe histological change in the hippocampus.Immunohistochemistry was conducted to observe the condition of neurites,including dendrites and axons.Western blot assay was used to measure the expression levels of the specific nerve axon membrane protein,growth associated protein 43,and the presynaptic vesicle membrane specific protein,synaptophysin.The gait scores of gravid rats significantly increased,suggesting that acrylamide induced maternal motor dysfunction.The number of neurons,as well as expression of growth associated protein 43 and synaptophysin,was reduced with increasing acrylamide dose in postnatal day 21 weaning rats.These data suggest that acrylamide exerts dose-dependent toxic effects on the growth and development of hippocampal neurons of weaning rats.

Dietary Control of Lactase Expression in the Weaning Rat

The decline in lactase activity during weaning has been well established. However, its molecuIar mechanism remains to be explored. We studied changes in the expression of lactase in terms of the transcription and translation processes in rat microvillus membrane by Northern blot and Western blot analysis, respectively. To examine the effect of dietary change from a milk to a non-milk diet on the developmental pattern of lactase expression, weaning was prevented by keeping the rats under suckling conditions for 27 days after birth. This treatment only suppressed the extent of decline: while the weanlings showed 17 percent activity compared to that of 4-day-old rats, the prolonged suckling rats showed only 42 percent. The changes in the expression of lactase mRNA and protein were parallel with the change of lactase activity. In other words, the fundamental pattern of significant depression of lactase expression occurred relatively independent of dietary modification.This observation indicates that the regulation of lactase expression is firmly determined at the transcriptional level, and that dietary factor such as the termination of lactose ingestion has only a relatively minor effect

Effects of spermine supplementation on the morphology, digestive enzyme activities, and antioxidant capacity of intestine in weaning rats

The main objective of this study was to investigate the effects of different doses of spermine and its extended supplementation on the morphology, digestive enzyme activities, and intestinal antioxidant capacity in weaning rats. Nineteen-day-old male rats received intragastric spermine at doses of 0.2 and0.4 μmol/g BW for 3 or 7 d, whereas control rats received similar doses of saline. The results are as follows: 1) In the jejunum, the seven-day supplementation with both doses of spermine significantly increased crypt depth(P < 0.05) compared with the control group; the supplementation extension of the high spermine dose increased villus height and crypt depth(P < 0.05); in the ileum, the low spermine dose significantly increased villus height and crypt depth compared with the control group for 7 days(P < 0.05). 2) The 3-day supplementation with high spermine dose increased alkaline phosphatase activity in the jejunum(P < 0.05). 3) In the jejunum, the anti-hydroxyl radical(AHR), total superoxide dismutase(T-SOD), catalase(CAT), and total antioxidant capacity(T-AOC) activities were increased(P < 0.05); however, the malondialdehyde(MDA) content was reduced(P < 0.05) in groups supplemented with the high spermine dose relative to those in the control groups after 3 and 7 d; moreover, the anti-superoxide anion(ASA) and glutathione(GSH) contents increased with the high spermine dose that lasted for 3 days(P < 0.05). Furthermore, the T-SOD and CAT activities(after 3 and 7 d), ASA(after 3 d),and AHR(after 7 d) increased with the high spermine dose compared with those of the low spermine dose(P < 0.05). Extending the supplementation duration(7 d) of the high spermine dose decreased the MDA content and ASA and T-AOC activities(P < 0.05). These results suggested that spermine supplementation can modulate gut development and enhance the antioxidant status of the jejunum in weaning rats, and a dosage of 0.4 μmol spermine/g BW had better effects than the dosage of 0.2 μmol spermine/g BW on accelerating gut development and increasing antioxidant capacity.