Oral Presentation The Annual Scientific Meeting of the Endocrine Society of Australia and the Society for Reproductive Biology 2014

Combined parental obesity negatively affects mouse preimplantation embryo kinetics and quality (#148)

Bethany Finger 1 , Alexandra J Harvey 1 , Mark P Green 1 , David K Gardner 1
  1. Zoology, University of Melbourne, Parkville, VIC, Australia

Over 25% of Australia’s population is classified as obese. It is now widely accepted that obesity detrimentally impacts oocyte and sperm quality, and the reproductive success of a couple. Recent studies reveal paternal or maternal obesity leads to increased disease risk for offspring in later life. However, little is known about the effect of combined parental obesity upon early embryonic development and offspring health.  This study aimed to delineate the impact of individual or combined parental obesity upon pre-implantation embryo kinetics and quality. Male and female C57BL6 mice were fed normal chow (lean) or a 22% fat ‘Western style’ chow diet (obese) for 8 weeks. Lean and obese mice, from the four reciprocal combinations, were mated and resultant embryos placed into a time-lapse incubator to determine the kinetics of critical developmental events. Zona pellucida measurements and differential cell staining were used to assess embryo quality. Arcsine transformed blastocyst rate was reduced (P≤0.05) in obese groups (combined=0.42, n=107; paternal=0.52, n=96; maternal=0.56, n=87) compared to lean (0.71, n=183). Differences were evident in the timing of the 2-cell division between groups (lean=2.35±0.26hr, combined obesity=3.39±0.53hr maternal obesity=2.10±0.12hr, paternal obesity=2.52±0.49hr post PN disappearance; P≤0.05). Combined parental obesity reduced total cell numbers  (P≤ 0.05), attributable to decreased trophectoderm cell numbers (P≤ 0.05), an effect not evident in maternal or paternal obese only groups. Day 1 embryos from obese parents had a thinner zona pellucida (7.56±0.18μm, P≤0.05) than those from lean parents (8.16±0.14μm) but not in maternal (7.97±0.12µm) or paternal (8.16±0.14µm) obese only groups. Together these data show that combined parental obesity, compared to maternal or paternal obesity alone, alters preimplantation embryo developmental kinetics and quality. These findings may have important ramifications for obese couples, highlighting both the importance of the pre-conception diet and parameters that could better inform clinical assessment and management of these embryos.