Pregnancy-associated plasma protein-A and insulin-like growth factor binding protein mRNAs in granulosa cells of dominant and subordinate follicles of preovulatory cattle.

To determine if (1) levels of pregnancy-associated plasma protein-A (PAPP-A) mRNA and insulin-like growth factor binding protein (IGFBP) (-2, -3, -4 and -5) mRNAs differ between the dominant and subordinate follicles during the follicular phase of an estrous cycle, and (2) these differences are associated with differences in follicular fluid (FFL) concentrations of steroids (estradiol, androstenedione, and progesterone), total and free IGF-I, or IGFBPs, estrous cycles of non-lactating Holstein dairy cows (n = 16) were synchronized with two injections of prostaglandin (PGF2 alpha) 11 days apart. Granulosa cells and FFL were collected either 24 h or 48 h after the second injection of PGF2 alpha. FFL from dominant follicles had lower concentrations of progesterone (P < 0.08) and higher concentrations of estradiol (P < 0.05), androstenedione (P < 0.0001), estradiol:progesterone ratio (P < 0.0001), free IGF-I (P < 0.0001), and calculated percentage free IGF-I (P < 0.01) than large subordinate follicles. Levels of IGFBP-2, -4, and -5 in FFL were 3.0- (P < 0.05), 2.4- (P < 0.06), and 3.4-fold (P < 0.05) greater, respectively, in subordinate than in dominant follicles. IGFBP-3, IGFBP-4 and PAPP-A mRNA expression and IGF-II concentration did not differ (P > 0.10) between dominant or subordinate follicles. Levels of IGFBP-2 and -5 mRNA were severalfold greater (P < 0.05) in subordinate than dominant follicles. IGFBP-5 mRNA in granulosa cells decreased (P < 0.05) 62% to 92%, between 24h and 48 h post-PGF2 alpha. We conclude that decreased levels of IGFBP-2 and -5 mRNA in granulosa cells may contribute to the decrease in FFL IGFBP-2 and -5 protein levels of preovulatory dominant follicles, and that changes in granulosa cell IGFBP-3 and -4 mRNA and PAPP-A mRNA levels do not occur during final preovulatory follicular development in cattle.

Santiago CA ，Voge JL ，Aad PY ，Allen DT ，Stein DR ，Malayer JR ，Spicer LJ ... -  《DOMESTIC ANIMAL ENDOCRINOLOGY》

Alterations in follicular IGFBP mRNA expression and follicular fluid IGFBP concentrations during the first follicle wave in beef heifers.

The objective was to determine the pattern of IGFBP-2, -3 and -4 gene expression and follicular fluid concentrations of IGFBP-2, -3, -4 and -5 during emergence, selection and dominance of the first follicle wave of the estrous cycle in cattle and during exogenous steroid treatment. Heifers (n = 35) were ovariectomized at 36 (n = 7), 66 (n = 8), 84 (n = 12) and 108 (n = 8) h after the onset of estrus. Heifers in the 84 h ovariectomy group were sub-divided to receive either no treatment (n = 6) or were treated with a progesterone-releasing intravaginal device (n = 6, PRID) and 0.75 mg estradiol benzoate i.m. at the approximate time of ovulation, 30 h post estrus until ovariectomy. Within heifers the four largest follicles recovered following ovariectomy were ranked on size (F1, F2, F3 and F4). At 36 h IGFBP gene expression and follicular fluid IGFBP concentrations were similar in all follicles (F1-F4). Mean diameter of the F1 follicle increased (P < 0.05) between 36 and 84 h with no difference between 84 and 108 h. The F1 follicle had the highest (P < 0.05) concentration of estradiol compared with the F2, F3 and F4 at 84 and 108 h. There was no granulosa cell IGFBP-2 mRNA in F1 follicles at 84 or 108 h. Intrafolliclar IGFBP-2 concentrations were lower (P < 0.05) in the F1 compared with F3 and F4 follicles at 108 h. There was no difference in theca cell IGFBP-4 mRNA expression at 108h, but amounts of follicular fluid IGFBP-4 were lower (P < 0.05) in F1 follicles compared with F3 and F4 follicles at 108 h. IGFBP-3 mRNA was localized in the theca layer of all follicles examined with no difference in expression or follicular fluid concentrations during emergence, selection and dominance of the first follicle wave. IGFBP-5 concentrations were higher (P < 0.05) in follicular fluid of F3 follicles at 108 h compared with the F3 at 36 h. In conclusion follicular dominance was associated with low or decreased follicular fluid concentrations of IGFBP-4 and -5, increased estradiol and differential regulation of IGFBP production.

Canty MJ ，Boland MP ，Evans AC ，Crowe MA ... -  《ANIMAL REPRODUCTION SCIENCE》

Effect of days after calving on insulin-like growth factor-I, insulin-like growth factor binding proteins, progesterone, androstenedione, estradiol, and aromatase mRNA in dominant follicles of postpartum beef cows.

The effect of days after calving on IGF-I, IGFBP, progesterone, androstenedione, estradiol, and aromatase mRNA in dominant ovarian follicles (DF) was evaluated in Angus x Hereford cows. Growth of DF (>9 mm) was monitored daily by ultrasonography and fluid from DF was collected in vivo at either 30+/-2 d or 47+/-2 d postpartum. Follicular fluid (FF) was also aspirated from DF of contemporary ovulatory cows at proestrus. Estrous behavior was monitored continuously using the HeatWatch system, and progesterone in plasma collected twice weekly was used to assess luteal activity. Anovulatory DF aspirated 30 and 47 d postpartum had similar concentrations of IGF-I, IGFBP, progesterone, estradiol and androstenedione in FF and IGF-I and IGFBP in plasma. The intervals from aspiration to estrus were similar for cows aspirated 30 and 47 d postpartum. Proestrous follicles had greater (P<0.01) estradiol (435+/-79 ng/mL) than DF at 30 d (107+/-63 ng/mL) or 47 d (68+/-53 ng/mL) after calving. Concentrations of androstenedione in FF were also greater (P<0.01) in proestrous follicles than in DF aspirated at 30 or 47 d after calving. Concentrations of insulin-like growth factor-1 (IGF-I) and insulin-like growth factor binding proteins (IGFBP) in FF and plasma, and aromatase mRNA in granulosa cells were similar for anovulatory and proestrous cows. In conclusion, estradiol production by DF of postpartum anovulatory cows may be limited by inadequate production of androstenedione during the postpartum anovulatory interval and this may influence follicular maturation. Concentrations of IGF-I and IGFBP were similar in anovulatory and proestrous cows, an indication that alterations in the IGF-I system in the DF at 30-47 d after calving are not associated with delayed follicular development in postpartum beef cows.

White FJ ，Rubio I ，Lents CA ，Ciccioli NH ，Wettemann RP ，Spicer LJ ... -  《-》

Gonadotrophin responsiveness, aromatase activity and insulin-like growth factor binding protein content of bovine ovarian follicles during the first follicular wave.

The aim of this study was to examine the function of granulosa cells and hormone concentrations in follicular fluid in bovine ovarian follicles during selection of the first dominant follicle. Ovaries were obtained from beef heifers on days 1-5 after ovulation: follicles > 4 mm in diameter were dissected and follicular fluid and granulosa cells were collected from individual follicles. Oestradiol production by granulosa cells after culture with testosterone was used to determine aromatase activity and responsiveness to gonadotrophins was determined by cAMP production after culture with FSH or LH. Concentrations of oestradiol, progesterone and insulin-like growth factor binding proteins (IGFBPs)-4 and -5 were measured in follicular fluid. Follicles were classified as largest or smaller (days 1 and 2), or dominant or subordinate (days 3-5). Aromatase activity was greater in granulosa cells from the largest follicle than in granulosa cells from smaller follicles on days 1, 3, 4 and 5 (P < 0.05). Responsiveness to LH was not detected in granulosa cells on day 1, but from day 2 to day 5 cells from the largest follicle were significantly more responsive than cells from smaller follicles (P < 0.05). Responsiveness to FSH was detected in granulosa cells from all follicles from day 1 onwards and did not differ between cells from the largest follicle or smaller follicles on any day. Follicular fluid concentrations of oestradiol and the ratio of oestradiol:progesterone were greater and concentrations of IGFBP-4 and -5 were lower in the largest follicle than in smaller follicles from day 2 to day 5 (P < 0.05). In conclusion, selection of the dominant follicle is associated with increased granulosa cell aromatase activity followed by increased cAMP response to LH and follicular fluid oestradiol concentrations, and decreased follicular fluid concentrations of IGFBP-4 and -5 within 2 days after ovulation.

Rhodes FM ，Peterson AJ ，Jolly PD 《REPRODUCTION》

Levels of insulin-like growth factor (IGF) binding proteins, luteinizing hormone and IGF-I receptors, and steroids in dominant follicles during the first follicular wave in cattle exhibiting regular estrous cycles.

Objectives of this study were to determine if concentrations of steroids, insulin-like growth factor -I (IGF-I), and IGF binding proteins (IGFBP) in follicular fluid and numbers of LH and IGF-I receptors change during growth of the dominant follicle. Ovarian follicular development was monitored daily via ultrasound in lactating Holstein cows. Animals underwent bilateral ovariectomy when the dominant follicle was first identified (days 4-6; estrus = day 0; early; n = 5) or when it stopped growing (days 8-12; late; n = 8). All follicles were classified as dominant (DF), large (LG; > = 6 mm in diameter, excluding DF) or small (SM; < 6 mm), follicular fluid was aspirated, and theca and granulosa cells were collected. Levels of IGFBP-2, assessed via ligand blotting, were greater (P < 0.05) in LG and SM follicles compared with DF in early cows. Levels of IGFBP-3 in follicular fluid were unaffected by follicle class. Numbers of specific 125I-hCG/LH binding sites in thecal cells were greater (P < 0.01) in DF compared with LG and SM follicles of both early and late cows. Numbers of specific 125I-hCG/LH binding sites in granulosa cells were similar for follicle sizes in early cows, but, in late cows, were greater (P < 0.01) in DF compared with SM follicles and were severalfold greater (P < 0.01) in late DF compared with early DF. Numbers of receptors for IGF-I in thecal cells were 2-fold greater (P < 0.05) in DP and LG compared with SM in late cows. Numbers of IGF-I receptors in granulosa cells were unaffected by size or growth of follicles, but were severalfold greater than in theca cells. Concentrations of estradiol were severalfold greater (P < 0.01) in DF compared with LG and SM in both early and late cows. Concentrations of androstenedione in early cows were greater (P < 0.05) in DF and SM compared with LG follicles. Concentrations of progesterone and IGF-I did not differ (P > 0.10) among follicle classes, but both were greater (P < 0.10) in late LG compared with early LG follicles. Concentrations of IGF-II in follicular fluid did not differ (P > 0.10) between early and late cows but were greater (P < 0.10) in SM than DF or LG follicles. We conclude that low amounts of IGFBP-2 and increased thecal binding sites for hCG/LH appear to be related to establishment of the dominant follicle during the first follicular wave in cattle exhibiting regular estrous cycles during late lactation.

Stewart RE ，Spicer LJ ，Hamilton TD ，Keefer BE ，Dawson LJ ，Morgan GL ，Echternkamp SE ... -  《ENDOCRINOLOGY》