On the nature of the follicle-stimulating signal delivered to the ovary during exogenously controlled follicular maturation. A search into the immunological and biological attributes and the molecular composition of two preparations of urofollitropin.

In the present study, we analyzed the immunological and biological potencies as well as the molecular composition of urinary follicle-stimulating hormone (FSH) present in determined lots of regular and highly purified (HP) commercial preparations of urofollitropin in order to obtain additional insights on the particular type of gonadotropin signal received by the ovary during exogenously regulated ovarian stimulation. In both preparations, a high degree of FSH charge heterogeneity was detected as disclosed by chromatofocusing analysis (pH range 7.5 to < 4.0). Urinary FSH present in the HP compound was consistently more acidic and exhibited a longer survival in rat circulation than the regular formulation. Inter-batch variability for FSH heterogeneity and in vitro bioactivity was higher in the partially purified preparation than in the HP analog. In the regular preparation, the amount of immunoreactive and bioactive FSH per ampule was two times higher than that present in the HP preparation; the resultant in vitro B/I ratios were similar. Although both urinary FSH preparations showed detectable amounts of immunoreactive and bioactive luteinizing hormone and choriogonadotropin hormone material, the degree of activity present in the less purified formulation was considerably higher than that shown by the HP analog. When the capability of each urinary FSH preparation to induce ovarian tissue-type plasminogen activator enzyme activity in hypophysectomized rats was determined, both formulations exhibited similar potencies despite the existing differences in plasma clearance rate and charge distribution profile. The present study indicates that the isoform composition of urinary FSH in the two commercial preparations analyzed differs according to the degree of purity of the formulation. More FSH material is needed in the partially purified FSH preparation to induce biological effects similar in magnitude to those exhibited by the highly purified analog. The possible impact of these variations in the molecular composition of the FSH signal on other biological functions of the ovary during the course of exogenously controlled follicular growth and maturation still remains to be ascertained.