Viscosity and refractive index of follicular fluid in relation to in vitro fertilization

Obesity is not a descriptive factor for oxidative stress and viscosity in follicular fluid of in vitro fertilization patients

BACKGROUND

Obesity's impact on micro-environmental oxidative stress and follicular fluid (FF) viscosity and whether or not it has any effect on in vitro fertilization (IVF) success is a matter of debate.

AIMS

In this study, our aim was to evaluate the levels of oxidative stress markers and the FF viscosity in obese and non-obese patients.

METHODS

Eighty norm-responder patients undergoing IVF were prospectively grouped according to their body mass indexes (BMI). Group 1 (n = 40) and group 2 (n = 40) had BMI values of ≤24.9 and ≥25.0, respectively. Total sulfhydryl (RSH) levels (nmol/m) and the formation of thiobarbituric acid-reactive substances (malondialdehyde, or MDA) (µmol/ml) in FFs were quantified. For the first time in our study, FF viscosity with changing BMI values was also determined.

RESULTS

The mean levels of MDA (µmol/ml) and RSH (nmol/ml) were not significantly different between groups (1.37 ± 0.51; 1.51 ± 0.51; p > 0.05 for MDA and 0.42 ± 0.30; 0.41 ± 0.20; p > 0.05 for RSH, respectively). Similarly, the FF viscosity (centipoise) was not different between groups (1.28 ± 0.28; 1.30 ± 0.19; p < 0.05, respectively). Independent of BMI, no correlation was found between FF levels of oxidative markers and the number of oocytes retrieved or the fertilization rates.

CONCLUSIONS

In our study, we found no difference in the levels of follicular oxidative and anti-oxidative markers or the follicular fluid viscosity with changing BMI values. We also demonstrated that the levels of oxidative stress markers and the viscosity of follicular fluid did not affect clinical outcomes.

Follicular fluid responds endothermically to aqueous dilution

BACKGROUND

Studies suggest that ovarian follicles are cooler than their surrounding tissues. The mechanism of this remarkable phenomenon is unclear. We postulate that endothermic reactions accompany the growth-associated hydration of follicular fluid.

METHODS

We performed two types of experiment, using human and animal follicular fluids. In the first, saline (50 microl) was injected into follicular fluid (500 microl) held in an equilibrated incubator, with monitoring of sample temperature. In the second, an adiabatic microcalorimeter recorded thermal shifts after injection of buffer (10 microl) into previously dialysed samples (1.4 ml). The relevance of changes observed was assessed by mathematical modelling.

RESULTS

In the incubator study, 9/17 bovine and 6/12 human fluids showed a temperature fall (0.05-0.2 degrees C). Cooling was delayed by up to 2 min but sustained for 7-25 min. Remaining fluids showed no change. In the microcalorimeter, 4/9 human, 4/6 bovine, 5/5 porcine and 1/4 equine samples showed an endothermic response. Remaining samples showed either no response (bovine) or exothermy (human, equine). Pre-concentration of human follicular fluid amplified the endothermy or reversed the exothermy. Modelling indicated that the incubator-type response was of appropriate magnitude to explain follicular hypothermy.

CONCLUSION

Follicular fluid responds endothermically to aqueous dilution and may contribute to follicular cooling during growth.