Study of the vascularization of corpora lutea during the initial luteal phase in superovulated ewes with different doses of exogenous FSH

Abstract

The present study aims to evaluate the effect of exogenous FSH dose in the gonadotropin treatment on the vascularization of the corpora lutea in embryo donor ewes. Ultrasound images will be the object of analysis, referring to the ovarian monitoring during the initial luteal phase performed in 27 Santa Inês sheep, which were submitted to different superovulation protocols. Females received an intravaginal progesterone device (CIDR®) on Day 0, maintained until Day 8. At the beginning of the protocol and CIDR removal (Days 0 and 8), equivalent doses of D-Cloprostenol (Prolise®, 37,5¼g) were given intramuscularly. The superovulatory treatment started on Day 6, when females were randomly divided into three groups according to the total dose of exogenous FSH (Folltropin®): G200 (control, n = 8) - 200 mg FSH; G133 (n = 8) - 133 mg FSH; and G100 (n = 8) - 100 mg FSH. Total doses were given in eigh applications every 12 hours (20, 20, 15, 15, 10, 10, 5 and 5% FSH). On Day 6, concomitantly with the first application of FSH, the females also received intramuscularly injection of 300 IU of eCG (Novormon®). B-mode and color Doppler ultrasound exams of ovaries were performed between Days 11 (onset of luteogenesis) and 15 (corresponding to embryo collection), which will be fully reviewed (saved videos) to select new photographic images; this step will be performed in specific software on the MyLab® ultrasound equipment. The selected ultrasonographic sections should consider the visualization of the largest area of vascularization of each studied corpus luteum. For each corpus luteum, the percentage of luteal area with detectable blood flow will be determined by the formula: area of vascularization / total area of CL x 100, using Image J® software. Data will be analyzed by a comparison between experimental groups by the Tukey test (P<0.05). (AU)