The biochemistry of female reproductive tissues studied by phosphorus nuclear magnetic resonance spectroscopy: effects of pregnancy, hormonal manipulation, and disease

Metabolite Profiling in the Pursuit of Biomarkers for IVF Outcome: The Case for Metabolomics Studies

Background. This paper presents the literature on biomarkers of in vitro fertilisation (IVF) outcome, demonstrating the progression of these studies towards metabolite profiling, specifically metabolomics. The need for more, and improved, metabolomics studies in the field of assisted conception is discussed. Methods. Searches were performed on ISI Web of Knowledge SM for literature associated with biomarkers of oocyte and embryo quality, and biomarkers of IVF outcome in embryo culture medium, follicular fluid (FF), and blood plasma in female mammals. Results. Metabolomics in the field of female reproduction is still in its infancy. Metabolomics investigations of embryo culture medium for embryo selection have been the most common, but only within the last five years. Only in 2012 has the first metabolomics investigation of FF for biomarkers of oocyte quality been reported. The only metabolomics studies of human blood plasma in this context have been aimed at identifying women with polycystic ovary syndrome (PCOS). Conclusions. Metabolomics is becoming more established in the field of assisted conception, but the studies performed so far have been preliminary and not all potential applications have yet been explored. With further improved metabolomics studies, the possibility of identifying a method for predicting IVF outcome may become a reality.

Biochemical heterogeneity in hysterectomized uterus measured by 31P NMR using SLIM localization

Ultrasound and magnetic resonance imaging show contrast between the inner and outer myometrium, which is useful in the diagnosis of gynecological disorders. To determine whether the image contrast is associated with biochemical differences between these myometrial regions, phosphorus metabolite concentrations in the inner one third of the myometrium (the junctional zone; JZ) were compared with the outermost one third of the myometrium (OM) in hysterectomized uteri using 31P spectral localization by imaging (SLIM). The technique was validated by comparing the results of SLIM with the results of standard Fourier-encoded spectroscopic imaging (FSI) analysis using phantoms, and by nonlocalized spectroscopy on biopsies taken from the same hysterectomy specimens. As expected theoretically, SLIM yielded better localization than FSI, as judged by spectral intensity and leakage measurements on phantom compartments of known composition. SLIM localization revealed that the JZ has a higher intracellular phosphomonoester (PME) concentration than does the OM, which was confirmed by nonlocalized spectroscopy, and that there is very little NMR-visible phosphorus in the cervix.

31P NMR study of phosphorus containing metabolites in the uterus of hamster: changes during the estrous cycle and the effect of hormonal manipulation

Changes in the concentrations of phosphorus containing metabolites were monitored by 31P NMR in the uteri of hamsters during the estrous cycle. Concentrations of phosphocreatine (PCr) and ATP were significantly increased in estrus animals compared to diestrus animals. Concentrations of these metabolites were also increased in immature female hamsters and ovariectomized (OVX) adult hamsters treated with estradiol indicating that estradiol was responsible for this effect. However, the steroid hormones progesterone and testosterone did not increase the concentrations of the phosphorus containing metabolites. Further, immature female hamsters also following treatment with estradiol showed an initial decline in phosphomonoester (PME), PCr, ATP and inorganic phosphate but by 24 h of treatment the concentrations returned to control levels. The NMR study also revealed that the intracellular pH of the hamster uterus was around 7.4 all through the estrous cycle.

13C NMR kinetic studies of the rapid stimulation of glucose metabolism by estrogen in immature rat uterus

Glucose metabolism in control and estrogen stimulated rat uteri was investigated using 13C NMR spectroscopy. By employing an NMR adapted perifusion system, and developing protocols and methods based on the application of [1-13C]glucose labeling, it was possible to measure, with a temporal resolution of 10 min, the kinetics of glucose consumption, lactate production and 13C incorporation into glutamate, alanine and glycogen. In control immature rat uteri, under aerobic conditions, the rates (+/- SEM) of [1-13C]glucose consumption and [3-13C]lactate production were 24 +/- 2 and 7.5 +/- 0.5 mmol/g wet weight/h. The rates of synthesis of [4-13C]glutamate, [3-13C]alanine and 13C labeling of glycogen at C1 of its glucose moieties were significantly lower and were in the range 0.3-0.6 mmol/g wet weight/h. Thus, ca 35% of the labeled glucose was accounted for by the glycolytic and other observed pathways. In vitro stimulation of the uteri by estrogen was found to increase significantly, within 1 h, glucose consumption by 80%, lactate production by 150% and glutamate and glycogen synthesis by 150%, in parallel to a rapid hormonal induction of mRNA for the brain type isozyme of creatine kinase.

Phosphorus 31 magnetic resonance spectroscopy of perifused human placental villi under varying oxygen concentrations

OBJECTIVE

Initial phosphorus magnetic resonance spectroscopy observations on the oxygen metabolism of placental villi from normal term pregnancies are described.

STUDY DESIGN

Villi were suspended in medium and perifused within a custom-designed 30 mm nuclear magnetic resonance probe in a superconducting vertical nuclear magnetic resonance magnet where pH, temperature, and oxygenation were monitored.

RESULTS

Phosphorus resonances were observed from adenosine triphosphate, phosphomonoesters. inorganic phosphate, and phosphodiesters. No phosphocreatine signal was observed. The placental villus tissue responded to an increase in oxygen concentration of the perifusate with a rise in the adenosine triphosphate level and a concomitant decline in the inorganic phosphate and the phosphomonoester signals.

CONCLUSION

The changes observed reflect continuing dynamic glycolysis and oxidative phosphorylation. The absence of a phosphocreatine peak suggests that aerobic pathways not driven by creatine kinase are important for placental metabolism. Our system demonstrates dynamic oxygen metabolism in perifused viable placental villus tissue by means of magnetic resonance spectroscopy.

Phosphorus metabolites in the human placenta estimated in vivo by magnetic resonance spectroscopy

Normal human placental metabolism has been studied in vivo by image localised 31P magnetic resonance spectroscopy in 13 women with anterior placentas; five, however, were too fat for useful spectral signals to be obtained. Magnetic resonance spectra of good quality which were considered to have arisen from the placenta were obtained from seven women with uncomplicated pregnancies (median gestational age 35 weeks, range 28-39). One other woman had a twin pregnancy in which one fetus had died a few days before. The phosphodiester signal from the placenta of the dead fetus was outside the 95% confidence intervals for normal placentas, suggesting that this technique may potentially be useful in the assessment of placental function.

Characterization of ovarian follicular fluids of sheep, pigs and cows using proton nuclear magnetic resonance spectroscopy

Proton NMR spectra were produced for Graafian follicular fluids obtained by aspiration from sheep, pig and cow ovaries. The following low molecular mass, non-protein-bound metabolites were detected at concentrations exceeding 0.1 mM: acetate, alanine, creatinine/creatine, glycine, D-3-hydroxybutyrate, lactate, valine. Glucose was difficult to quantify and N-acetyl sugars gave a broad resonance at 2.06 ppm, presumably representing side-chains of glycoproteins. Ethanol was detected at up to millimolar concentrations in some specimens, though the physiological significance of this finding was not clear. The concentrations of all metabolites were comparable to those of plasma. These results have therefore shown that NMR spectroscopy is useful for gaining a broad and semiquantitative impression of the more abundant metabolites in the fluids of preovulatory Graafian follicles.

Biochemical evaluation of endometrial biopsies by magnetic resonance spectroscopy--preliminary data

Biochemical study of tissue biopsy samples by magnetic resonance spectroscopy involves relatively small capital and running costs and could become a routine diagnostic or screening procedure if its utility were to be adequately demonstrated. We have demonstrated feasibility of evaluation of endometrial biopsy samples by magnetic resonance previous to histopathologic examination. Preliminary comparisons of magnetic resonance spectra with histopathologic evaluation indicates that in at least some instances, magnetic resonance may be the more sensitive indicator of disease.

Phosphorus 31 nuclear magnetic resonance examination of female reproductive tissues

Nuclear magnetic resonance spectroscopy is a powerful method of investigating the relationship between metabolism and function in living tissues. We present evidence that the phosphorus 31 spectra of myometrium and placenta are functions of physiologic state and gestational age. Specific spectroscopic abnormalities are observed in association with disorders of pregnancy and gynecologic diseases. Our results suggest that noninvasive nuclear magnetic resonance spectroscopy examinations may sometimes be a useful addition to magnetic resonance imaging examinations, and that nuclear magnetic resonance spectroscopy of biopsy specimens could become a cost-effective method of evaluating certain biochemical abnormalities.