Objective: The menstrual cycle represents a continuous state of change in terms of female sex steroid environment which are believed to affect fat storage and distribution in women. Progesterone is linked to increased fat storage while estrogen exerts anti- lipogenic effects. In this study, we investigate variations in the potent lipogenic factor, the acylation stimulating protein (ASP), and examine its association with hormonal alterations across the menstrual cycle.
Methods and design: Nineteen non-obese women with regular menstrual cycles were investigated longitudinally during the follicular, ovulatory and mid-luteal phases of the cycle. ASP, LH, FSH, progesterone, estradiol, insulin, lipid profile and apoproteins were measured and compared between different phases of the cycle.
Results: Repeated measures analysis-of-varience showed that ASP levels changed significantly throughout the menstrual cycle. Interestingly, these changes followed a similar pattern as variations in progesterone levels across the cycle as no significant change in ASP levels was seen across the follicular phases of the cycle, followed by a marked increase in the mid-luteal phase. Importantly, this increase in ASP levels correlated positively with progesterone levels normally elevated in the mid-luteal phase. No significant association of ASP levels was seen with estrogen or any other measured female hormone. Multiple regression analysis including BMI, age and lipid profile measures showed that progesterone was the only significant predictor of ASP levels in this study.
Conclusion: Our findings suggest that ASP production is increased in the luteal phase associated with high progesterone levels, which may contribute to enhanced fat storage in women.