Gestational exposure to particulate air pollution exacerbates the growth phenotypes induced by preconception paternal alcohol use: a multiplex model of exposure

Abstract

It is now clear that parental histories of drug use, toxicant exposure, and social stress all have a significant influence on the health and development of the next generation. However, the ability of epigenetic parental life memories to interact with subsequent gestational exposures and cumulatively modify the developmental trajectory of the offspring remains an unexplored perspective in toxicology. Studies from our laboratory have identified male-specific postnatal growth restriction in a mouse model of chronic, preconception paternal alcohol exposure. The goal of the current study was to determine if paternal alcohol use, before conception, could modify the susceptibility of the offspring to a completely separate exposure encountered by the mother during pregnancy. In independent experiments, we previously identified altered developmental programming and increased markers of severe asthma induced by gestational exposure to particulate air pollution. In this study, male mice were exposed to either the control or alcohol preconception treatments, then mated to naive females, which we subsequently exposed to an ultrafine mixture of particulate matter via inhalation. Individually, neither preconception paternal drinking nor gestational exposures to particulate air pollution impacted the postnatal growth of female offspring. However, when both exposures were combined, females displayed a 30% reduction in weight gain. Unexpectedly, this exposure paradigm resulted in a dramatic postnatal increase in litter loss due to maternal cannibalism, which prevented additional measures of offspring health. These preliminary studies provide evidence of a complex interplay between preconception life history and intrauterine environmental factors in the control of postnatal growth.

Keywords: developmental programming; early life exposure; epigenetic programming; fetal growth restriction; multiplex model of exposure; particulate air pollution; preconception exposure.

Figure 1:

Experimental design. Schematic representation of the experimental model employed to assay interactions between preconception paternal drinking and intrauterine exposures to particulate air pollution. Males were exposed to either the control or alcohol preconception treatments for 70 days, which is roughly equivalent to two spermatogenic cycles. Exposed males were then mated to naive dams, which were then placed into exposure chambers for 6 h each day, from gestational day 0.5 to 18.5, then returned to their original cages and allowed to spontaneously deliver. Postnatal growth was monitored for 30 days.

Figure 2:

Preconception paternal alcohol exposure induces heritable fetal growth restriction in the offspring. (A) Comparisons of average weights of the male and female offspring sired by three control and three alcohol-exposed males. (B) Placental weights compared between offspring sired by control and ethanol-exposed males (control male n = 9, alcohol male n = 12, control female n = 8, and alcohol female n = 9). Differences in fetal and placental weights were assayed using a two-way ANOVA followed by Sidak’s post-hoc test of contrast. Errors bars represent the SEM. *P < 0.05 and **P < 0.01.

Figure 3:

Preconception paternal alcohol exposures interact with intrauterine exposure to particulate air pollution to induce postnatal growth restriction in the offspring. (A) Average daily mass loads over the prenatal experimental course. (B) Litter size compared between the four treatment groups (Control-FA n = 5, Control-PM n = 5, EtOH-FA n = 5, and EtOH-PM n = 8 litters). (C) Average daily weight gain for the male offspring (Control-FA n = 13, Control-PM n = 9, EtOH-FA n = 4, and EtOH-PM n = 7 pups). (D) The slope of the growth curves depicted in C was compared between the four treatment groups. (E) Average daily weight gain for the female offspring (Control-FA n = 15, Control-PM n = 9, EtOH-FA n = 6, and EtOH-PM n = 6 pups). (F) The slope of the growth curves depicted in E was compared between the four treatment groups. Differences induced by the combined preconception and postnatal treatments were identified using a two-way ANOVA, and differences among the means evaluated using Sidak’s post-hoc test of contrast. Errors bars represent the SEM. For comparisons between Control-PM and EtOH-PM *P < 0.05, **P < 0.01, and ***P < 0.001; for comparisons between EtOH-FA and EtOH-PM ^†P < 0.05, ^††P < 0.01, and ^†††P < 0.001.

Figure 4:

Postnatal loss due to cannibalism of exposed litters. Comparison of the number of litters lost to cannibalism over time between the different treatment groups. Across the treatment groups, Control-FA 0/5, Control-PM 3/5, EtOH-FA 2/5, and EtOH-PM 5/8 litters were lost.