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Phosphate is required for inhibition by glucose of development of hamster 8-cell embryos in vitro
1Department of Veterinary Science, University of Wisconsin-Madison 53706.
Insights
Phosphate and glucose negatively impact hamster embryo development, especially when combined. Pyruvate or lactate support development, but phosphate and glucose together inhibit blastocyst formation significantly.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Embryology
Background:
- Understanding nutrient requirements for early embryo development is crucial for improving assisted reproductive technologies.
- The roles of specific metabolites like phosphate and glucose in supporting or inhibiting embryo development are not fully elucidated.
- Hamster embryos are a valuable model for studying early mammalian development due to their accessibility and synchronized cell cycles.
Purpose of the Study:
- To investigate the effects of sodium dihydrogen phosphate (Pi) and glucose on hamster 8-cell embryo development.
- To determine how these substances influence embryo development when energy substrates are pyruvate, amino acids, or lactate.
Main Methods:
- Modified Tyrode's medium (TLP-PVA, TA-PVA, TL-PVA) was used to culture hamster 8-cell embryos.
- Embryos were exposed to varying concentrations of sodium dihydrogen phosphate (Pi) and glucose.
- Blastocyst formation rates were assessed as the primary measure of embryo development.
Main Results:
- Pyruvate and lactate supported high blastocyst formation rates, but the addition of both Pi and glucose significantly reduced development.
- Amino acid-based medium showed reduced blastocyst formation when Pi and glucose were present together compared to when they were absent.
- Glucose inhibited embryo development in the presence of Pi, with lower concentrations of glucose and Pi showing marked inhibition.
Conclusions:
- Both sodium dihydrogen phosphate and glucose can inhibit hamster embryo development, particularly when present together.
- The energy substrate used influences the sensitivity of embryos to Pi and glucose, with pyruvate and lactate being more robust.
- Careful control of Pi and glucose concentrations in culture media is essential for optimizing early embryo development in vitro.
Abstract:
The influence of sodium dihydrogen phosphate (Pi) and glucose on the development of hamster 8-cell embryos mediated by pyruvate (P) or amino acids (A) or lactate (L) was investigated using modified Tyrode's medium, TLP-PVA. When pyruvate was tested as the only energy substrate in medium TP-PVA for embryo development, blastocyst formation ranged from 81.3 to 90.9% whether or not the medium contained 0.35 mM Pi or 5 mM glucose; but, when these two compounds were present together, blastocyst formation fell to 51.8%. Similarly, in TA-PVA medium containing four amino acids: Phe, Ile, Met, and Gln), embryo development to blastocyst ranged from 74.1% to 90.4% whether or not the medium contained 0.35 mM Pi or 5 mM glucose; but, when these compounds were present together, blastocyst formation fell to 16.0%. In TL-PVA medium, 10 mM sodium lactate supported embryo development (84.4% blastocysts); the addition of 0.35 mM Pi decreased blastocyst development to 65.6%. However, addition of glucose to Pi-free TL-PVA medium did not decrease blastocyst formation (81.3%); when the medium contained 0.35 mM Pi, glucose curtailed blastocyst development to 7.5%. When glucose and Pi interactions were studied at different concentrations, glucose up to 1 mM was not inhibitory in Pi-free TL-PVA medium (74.3% blastocysts), but 0.25 mM glucose in the presence of 0.35 mM Pi markedly inhibited embryo development (7.7% blastocysts). Phosphate at a relatively high concentration (1 mM) was inhibitory (37.9% blastocysts), even in the absence of glucose.(ABSTRACT TRUNCATED AT 250 WORDS)