Effects of prenatal exposure to chrysotile asbestos on hippocampal neurogenesis and long-term behavioral changes in adult male rat offspring

Our plain-English summary of Effects of prenatal exposure to chrysotile asbestos on hippocampal neurogenesis and long-term behavioral changes in adult male rat offspring, by E. Raeis-Abdollahi, F. Nabavizadeh, L. Tajik, et al (Behavioural Brain Research, 2019).

The study

• Authors: E. Raeis-Abdollahi, F. Nabavizadeh, L. Tajik, H.R. Sadeghipour
• Journal: Behavioural Brain Research
• Published: 2019;371:111962
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Prenatal development is a critical period of life that many environmental pollutants have been suggested to influence fetal growth. Nevertheless, there are still a few investigations into the prenatal exposure to chrysotile asbestos and its neurodevelopmental and behavioral outcome in offspring. In this study, twenty-eight pregnant Wistar rats were divided into four groups and received three-times repeated intraperitoneal injections of normal saline, chrysotile, ascorbic acid and the combination of chrysotile and ascorbic acid on gestational days 11, 14 and 17. The maternal serum levels of malondialdehyde (MDA) and prooxidant-antioxidant balance (PAB) and hippocampal MDA content in adult male offspring were measured. At postnatal day (PND) 60, elevated plus maze was performed to determine anxiety-like behavior, also depression-like behavior was examined using a forced swim test at PND 61- 62. Thereafter, the quantitative analysis of Ki-67, NeuN and GFAP positive cells in the hippocampal dentate gyrus were studied by immunostaining. Our data showed that prenatal exposure to chrysotile increased the maternal serum level of MDA and PAB as well as hippocampal MDA content in adult male offspring, also increased the depression- and anxiety-like behaviors of adult male offspring and decreased the hippocampal Ki-67+, NeuN+ and GFAP+ cells in dantate gyrus of adult male offspring. However, co-administration of ascorbic acid and chrysotile decreased hippocampal lipid peroxidation and increased the Ki-67+, NeuN+ and GFAP+ cells in adult male offspring. In summary, these results indicated that oxidative stress induced by prenatal exposure to chrysotile, lead to the long-lasting decrease of the hippocampal cell proliferation and neuronal differentiation as well as astrogliosis of adult male offspring that exhibit more depression- and anxiety-like behaviors in adulthood and co-treatment of ascorbic acid with chrysotile asbestos attenuated the changes.

Copyright © 2019. Published by Elsevier B.V.

In plain English

This was an animal experiment in pregnant Wistar rats. Twenty-eight pregnant rats were split into four groups of seven. On gestational days 11, 14 and 17, each group received injections into the abdominal cavity of one of four treatments: saline, chrysotile asbestos (10 mg/kg) from a mine in eastern Iran, ascorbic acid (500 mg/kg), or chrysotile plus ascorbic acid. Male offspring were tested as young adults. Compared with offspring of saline-treated mothers, offspring of chrysotile-treated mothers stayed still longer in a forced swim test, which the authors used as a measure of depression-like behavior. A smaller proportion of their maze-arm entries were into the open arms, a measure of anxiety-like behavior. Chrysotile raised oxidative stress markers (MDA and PAB) in the mothers' blood and MDA in the offspring's hippocampus. Offspring of chrysotile-treated mothers had fewer cells stained for Ki-67, NeuN and GFAP in the hippocampal dentate gyrus. Adding ascorbic acid raised these cell counts compared with chrysotile alone, but they stayed below controls. The authors concluded it "seems plausible" that chrysotile during pregnancy causes oxidative stress leading to lasting changes in these rats.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Animal experiment (prenatal exposure in pregnant rats, four treatment groups)
• Who was studied: 28 pregnant female Wistar rats (7 per group) in Tehran, Iran. Ten to twelve male offspring per group were selected at postnatal day 21 and tested at postnatal days 60 to 63. Figure legends give n = 7 for the behavioral tests and n = 3 per group for the hippocampal cell counts.
• Exposure: Chrysotile asbestos from Hajat Mine (Nehbandan, eastern Iran), suspended in saline and injected intraperitoneally at 10 mg/kg body weight on gestational days 11, 14 and 17. Comparison groups received saline, ascorbic acid (500 mg/kg), or chrysotile plus ascorbic acid.
• Main results:
  • Male offspring of chrysotile-treated mothers had longer immobility time in the forced swim test than offspring of control mothers (p less than 0.05). Offspring of mothers given chrysotile plus ascorbic acid had shorter immobility time than the chrysotile-only group (p less than 0.01).
  • In the elevated plus maze, the percentage of entries that were into the open arms was lower for male offspring of chrysotile-treated mothers than for control offspring (p less than 0.01).
  • For time spent in the open arms, the chrysotile offspring group differed significantly from the control offspring group (p less than 0.05).
  • Mothers given chrysotile had higher serum MDA, a marker of lipid peroxidation, than control mothers. Co-administration of ascorbic acid reduced serum MDA compared with chrysotile alone (p less than 0.05).
  • Serum PAB was higher in chrysotile-treated mothers than in control mothers (p less than 0.001). The difference between the chrysotile plus ascorbic acid mothers and the chrysotile-only mothers was not significant.
  • Hippocampal MDA was higher in male offspring of chrysotile-treated mothers than in control offspring. It was lower in offspring of mothers given chrysotile plus ascorbic acid than in the chrysotile-only group (p less than 0.0001).
  • Offspring of chrysotile-treated mothers had fewer Ki-67 positive cells (the authors' marker for cell proliferation) in the dentate gyrus than control offspring (p less than 0.0001). The chrysotile plus ascorbic acid group had more Ki-67 positive cells than the chrysotile-only group but still fewer than controls (p less than 0.01).
  • Offspring of chrysotile-treated mothers had fewer NeuN positive cells (the authors' marker for mature neurons) than control offspring (p less than 0.0001).
  • Offspring of chrysotile-treated mothers had fewer GFAP positive cells (the authors' marker for astrocytes, described by them as decreased astrogliosis) than control offspring (p less than 0.001). Offspring of mothers given ascorbic acid alone had more GFAP positive cells than controls (p less than 0.05).
• The authors' conclusion: The authors concluded that it seems plausible that chrysotile exposure during pregnancy induces prenatal oxidative stress. In their view, this leads to a long-lasting decrease of cell proliferation, mature neurons and astrogliosis in the hippocampal dentate gyrus of adult male rat offspring, which showed more depression-like and anxiety-like behavior. They also concluded that ascorbic acid may give partial protection in this animal model.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Ki-67, Oxidative Stress.

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