Comparison of immunocytologic localization of insulin-like growth factor binding protein-4 in normal and polycystic ovary syndrome human ovaries

Insulin-like growth factor I in sera, ovarian follicles and follicular fluid of cows with spontaneous or induced cystic ovarian disease

The objective of this research was to determine changes in IGF-I levels in serum and follicular fluid, and immunoreactivity of the follicle wall of cows with spontaneous (slaughter specimens) or ACTH-induced follicular cysts, and to compare results to normal cycling (control) cows after selection of the ovulatory follicle. Concentrations of IGF-I in serum did not differ between control and cystic animals (p=0.76). Fluid from the ovulatory follicle in control cows had 41% higher concentrations of IGF-I than that from cystic follicles collected at slaughter (spontaneous cysts; p<0.05) and 70% higher than that in induced follicular cysts (p<0.05). An intense positive immunostaining with anti-IGF-I was observed in granulosa cells (p<0.05) and in the theca interna (p<0.05) of secondary and tertiary follicles in all three groups of animals, but staining was less intense in cystic (p<0.05) and atretic follicles (p<0.05). This study provides evidence to suggest that cystic ovarian disease in cattle is associated with decreased concentrations of IGF-I in follicular fluid, but not in serum, and decreased production of IGF-I in the follicular wall. These data support the notion that IGF-I plays a role in the regulation of folliculogenesis, and may participate in the pathogenesis of cystic ovarian disease in cattle.

Intraovarian Localization of Growth Factors in Induced Cystic Ovaries in Rats

We hypothesized that the special hormonal environment present in animals with cystic ovarian disease (COD) interferes with cellular production of growth factors (GFs). The objective of the present study was to characterize the expression of insulin-like growth factor (IGF)-I, fibroblast growth factor (FGF)-2 and vascular endothelial growth factor (VEGF) in induced COD using immunohistochemistry. We used an experimental model based on the exposure to constant light of adult rats during 15 weeks. We quantified the expression of GFs in cystic and normal ovaries by the Immunohistochemical Stained Area (IHCSA). In animals with COD, a significant reduction in the IHCSA of IGF-I in the follicular fluid, theca and granulosa layers of cysts occurred; and an increase in the interstitial tissue with regard to the control group. We found moderate immunoreactivity of FGF-2 in granulosa and theca layers of secondary and tertiary follicles and lower expression in the granulosa and theca interna layers of cystic follicles. Immunoexpression of VEGF was found in granulosa and theca cells of secondary and tertiary follicles. This study shows changes in the ovarian expression of IGF-I, FGF-2 and VEGF in induced COD. We can propose that an alteration in the control of the follicular dynamic, through the GFs, added to other features, could be involved in the ovarian cyst pathogenesis.

Regulation of insulin-like growth factor binding protein secretion by human granulosa luteal cells in a polycystic ovary-like environment

OBJECTIVE

To determine the effect of androstenedione (A), insulin, and LH on secretion of insulin-like growth factor binding proteins (IGFBPs) from human granulosa luteal cells.

DESIGN

Human granulosa cells were cultured for a total of 4 days in serum-free medium containing A (10(-6) mol/L), with or without insulin (100 microU/mL-800 microU/mL), LH (1 microU/mL-10 microg/L), and A (10(-5) mol/L).

SETTING

Granulosa cells were obtained from IVF procedures.

PATIENT(S)

Women undergoing IVF for tubal disease.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Immunoassay and autoradiographs of Western ligand blotting detected IGFBP accumulations in the medium.

RESULT(S)

Cultured granulosa cells secreted IGFBP-1 through IGFBP-4. Insulin (100 microU/mL-800 microU/mL), LH (1 microg/L-10 microg/L), and A (10(-5) mol/L) caused a significant decrease in IGFBP-1 accumulation in the medium both alone and when added in combination. The release of IGFBP-2 and IGFBP-4 was significantly stimulated by insulin, whereas LH had no effect. Elevated levels of androgen (10(-5) mol/L) significantly stimulated the secretion of IGFBP-2, whereas the release of IGFBP-4 was reduced.

CONCLUSION(S)

These results demonstrate that androgen and insulin are important regulators of IGFBP release and that elevated levels of the two hormones may contribute to the altered IGFBP profile found in PCOS follicles, compared with the case of estrogen-dominant follicles.

Identification of potential intrafollicular factors involved in selection of dominant follicles in heifers

A surgical procedure to aspirate follicular fluid concurrently from individual follicles from the same heifer was validated and used to determine if intrafollicular amounts of estradiol, progesterone, inhibins, activin-A, follistatins, and insulin-like growth factor binding proteins (IGFBP) differed for the future dominant compared with subordinate follicles during selection of the first wave dominant follicle. Heifers were subjected to surgery and aspiration of follicular fluid from the two or three largest follicles on Day 3 of the estrous cycle (approximately 1.5 days after emergence). Ultrasound was used to determine the fate of each aspirated follicle after surgery. At aspiration, diameter of the future dominant and largest subordinate follicle was similar in heifers. However, estradiol was higher, whereas IGFBP-4 was lower in the future dominant compared with the largest or next largest subordinate follicles. Also, the future dominant follicle in most cohorts had the highest estradiol and lowest IGFBP-4 compared with future subordinate follicles. We concluded that: IGFBP-4 and estradiol may have key roles in determining the physiological fate of follicles during selection of the first wave dominant follicle in heifers, and that both are reliable markers to predict which follicle in a growing cohort of 5- to 8.5-mm follicles becomes dominant.

Growth factor action on ovarian function in polycystic ovary syndrome

Insulin-like growth factors, their receptors, binding proteins, and binding protein proteases are important in normal and abnormal ovarian follicle development. IGFs stimulate ovarian cellular mitosis and steroidogenesis and inhibit apoptosis. Patterns of expression of IGF family members are characteristic of whether follicles are estrogen- or androgen-dominant. The PCOS follicle is androgen-dominant but does not appear to be atretic and has characteristic IGF family expression. Available data strongly support an intraovarian, as opposed to endocrine, role for this growth factor family in ovarian follicle growth, steroidogenesis, and atresia.