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Actions of Tumor Necrosis Factor‐α on Oocyte Maturation and Embryonic Development in Cattle 1
Author(s) -
Soto P.,
Natzke R. P.,
Hansen P. J.
Publication year - 2003
Publication title -
american journal of reproductive immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.071
H-Index - 97
eISSN - 1600-0897
pISSN - 1046-7408
DOI - 10.1034/j.1600-0897.2003.00101.x
Subject(s) - andrology , blastocyst , tumor necrosis factor alpha , oocyte , embryogenesis , human fertilization , embryo , biology , insemination , blastomere , apoptosis , endocrinology , medicine , sperm , anatomy , microbiology and biotechnology , genetics
Problem: Infertility can accompany mastitis in cattle. Involvement of tumor necrosis factor‐ α (TNF‐ α ) in this phenomenon is suggested by observations that circulating concentrations of TNF‐ α are elevated after intramammary infection or infusion of endotoxin. It was hypothesized that (1) TNF‐ α acts on the oocyte during maturation to decrease the percent of oocytes that cleave and develop following fertilization; (2) exposure of embryos to TNF‐ α after fertilization reduces development to the blastocyst stage; and (3) TNF‐ α increases the proportion of blastomeres that undergo apoptosis in a stage‐of‐development dependent manner. Method of study: In one experiment, oocytes were matured with various concentrations of TNF‐ α and then fertilized and cultured without TNF‐ α . In another study, embryos were cultured with TNF‐ α for 8 days beginning after fertilization. Finally, embryos were collected at the two or four‐cell stage (at 28–30 hr after insemination) or when ≥9‐cells (at day 4 after insemination) and cultured ± TNF‐ α for 24 hr. The proportion of blastomeres undergoing apoptosis was then determined by the TUNEL procedure. Results: Addition of TNF‐ α to maturation medium did not affect the proportion of oocytes that cleaved. However, the percent of oocytes that developed to the blastocyst stage at day 8 after insemination was reduced ( P = 0.05) at all TNF‐ α concentrations tested (0.1–100 ng/mL). When added during embryo culture, there was no significant effect of TNF‐ α on the proportion of oocytes that became blastocysts. In addition, TNF‐ α did not induce apoptosis in two and four‐cell embryos. For embryos ≥9‐cells, however, 10 and 100 ng/mL TNF‐ α increased ( P < 0.05) the percent of blastomeres labeling as TUNEL‐positive. Conclusion: TNF‐ α can have deleterious actions on oocyte maturation that compromise development of the resultant embryo. While exposure of fertilized embryos to TNF‐ α did not inhibit development to the blastocyst stage, TNF‐ α increased the percentage of blastomeres undergoing apoptosis when exposure occurred for embryos ≥9‐cells. Increased blastomere apoptosis could conceivably compromise subsequent embryo survival.