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Effects of impaired insulin secretion on the fertilization of mouse oocytes
1Institute of Animal Physiology, Slovak Academy of Sciences, Kosice, Slovak Republic.
Abstract:
We have studied the effect of moderately impaired maternal insulin secretion on oocyte chromosomal constitution, fertilization and zygote DNA synthesis. Female mice were injected with a single dose of streptozotocin (65 mg/kg) 14 days before fertilization/ovulation. Zygotes/oocytes were recovered from control and subdiabetic mice on day 1 of pregnancy. Compared with control animals, subdiabetic females showed a significant difference in the proportion of zygotes/oocytes. The subdiabetic mothers had a lower percentage of zygotes and a higher percentage of unfertilized and degenerated oocytes in comparison with control animals. The investigation of [3H]thymidine incorporation did not show any influence of the maternal subdiabetes on the initial zygote DNA synthesis. An analysis of the ovulated oocytes at the metaphase II stage isolated from subdiabetic mice did not reveal increased chromosomal anomalies in comparison with the controls. Control and subdiabetic mothers had a similar percentage of oocytes with a normal haploid set of chromosomes, and the incidence of aneuploidy/diploidy did not differ significantly. These observations suggest that insulin changes in subdiabetic mothers had a deleterious influence on oocyte fertilization in mice, but apparently they did not have any effect on the nuclear events.
Insights
Subdiabetic mothers exhibit impaired oocyte fertilization and increased degeneration. However, maternal insulin changes did not affect chromosomal constitution or DNA synthesis in mouse zygotes.
Area of Science:
- Reproductive biology
- Endocrinology
- Developmental biology
Background:
- Maternal diabetes can negatively impact reproductive outcomes.
- The specific effects of subdiabetic states on oocyte quality and early embryonic development require further investigation.
Purpose of the Study:
- To investigate the impact of moderately impaired maternal insulin secretion on oocyte chromosomal constitution, fertilization, and zygote DNA synthesis in mice.
- To determine if subdiabetes affects nuclear events in oocytes and zygotes.
Main Methods:
- Subdiabetic female mice were induced using streptozotocin (65 mg/kg) 14 days prior to fertilization/ovulation.
- Zygotes and oocytes were recovered from control and subdiabetic groups on day 1 of pregnancy.
- Oocyte chromosomal analysis and [3H]thymidine incorporation assays were performed.
Main Results:
- Subdiabetic mothers showed a significantly lower proportion of zygotes and a higher percentage of unfertilized and degenerated oocytes compared to controls.
- Maternal subdiabetes did not influence initial zygote DNA synthesis, as assessed by [3H]thymidine incorporation.
- Chromosomal analysis revealed no significant differences in aneuploidy or diploidy rates between control and subdiabetic groups.
Conclusions:
- Moderately impaired maternal insulin secretion negatively affects oocyte fertilization and increases oocyte degeneration in mice.
- Subdiabetes in mothers does not appear to impact the chromosomal constitution or initial DNA synthesis of zygotes.
