Conjugated Estrogens and Tibolone Modify the Gonadotrophin Glycosylation Pattern in Postmenopausal Women

Abstract

Objective: The purpose of this study was to evaluate the changes in the percentage of glycosylation of FSH and LH when using conjugated estrogens and tibolone as hormonal therapy (HT) in postmenopausal compared with regular menstrual cycles. Design: The study had three groups, with 10 participants in each group. The control group consisted of 10 women with normal menstrual cycles, a second group with 10 postmenopausal patients who received conjugated estrogens (Premarin 0.625 mg), and a third group had 10 patients who received tibolone (Livial 2.5 mg). All patients had hormonal determinations before and 6 months after the use of HT. Concavalin-A was used to separate the different glycosylated species of gonadotrophins, defined as unbound (UB: triantennary and bisecting oligosaccharides), weakly bound (WB: biantennary and truncated oligosaccharides), and firmly bound isoforms (FB: hybrid- and high-mannose-type oligosaccharides) in patients serum. Elusions containing the fractions with the isoforms were concentrated using Centriprep membranes (Amicon, Beverly, Mass., USA) and the different gonadotrophins isoforms were quantified by chemiluminescence using an automated system Immulite. Results: The pattern of distribution of gonadotrophins glycosylation in patients treated with conjugated estrogens and tibolone was similar to that observed in the control group with normal menstrual cycles, although with different glycosylation percentage. When the glycosylation percentages were compared for FSH, in the fraction UB the glycosylation did not have significant differences, but the fraction WB that has isoforms with high amounts of oligosaccharides showed a different percentage of glycosylation, where the recovery percentage was bigger with tibolone use (p < 0.05). The FB fraction had similar hormonal glycosylation with estrogens and tibolone use. When compared, LH glycosylation showed significant differences (p < 0.05) in the fraction UB with a bigger glycosylation degree, and in the fraction FB with a smaller glycosylation percentage, both in the tibolone group compared with conjugated estrogens use. Conclusions: Our results show that there are different percentages of glycosylation of gonadotrophins depending on type of HT (conjugated estrogens vs tibolone), and this could be of utility in young women with ovarian problem since to know the isoform that more favors to cellular activity could help a better therapeutic.

Changes in Glycosylation of Pituitary Gonadotropins in Polycystic Ovary Syndrome

“…Characteristics of women enrolled at the moment of PCOS diagnosis, and at the end of the treatment are shown in table 1 as responder and no-responders. The molecular isoforms of FSH determined at time of diagnosis of PCOS (basal) showed a distribution pattern described as normal in young women [29], with predominance of molecular forms UB to lectin by its low content of glycosylation with a decline in the rest of the glycoforms WB and FB. In women who persisted with ovarian cysts despite medical treatment, there was an increase in the FB fraction, with forms with a high content of glycosylation that showed a statistically significant difference (p <0.05) when compared with women who responded to the administered treatment.…”