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Biomedical subjects

D A Redmer

Publications and source records attributed to D A Redmer.

At least 37 records · Page 2Linked to original sources
PubMed1999

Cell-to-cell communication and expression of gap junctional proteins in human diabetic and nondiabetic skin fibroblasts: effects of basic fibroblast growth factor.

Wound healing involves the interactions of many cell types, and is controlled in part by growth factors. Intercellular communication mediated by gap junctions is considered to play an important role in the coordination of cellular metabolism duringthe growth and development of tissues and organs. Basic fibroblast growth factor (bFGF), known to be important in wound healing, has been found to increase Cx43 expression and intercellular communication in endothelial cells and cardiac fibroblasts. It has been proposed that an increased coupling is necessary for the coordination of these cells in wound healing and angiogenesis, and that one of the actions of bFGF is to modulate intercellular communication. The aim of our study was to evaluate the effects of bFGF on gap junctional intercellular communication (GJIC) in vitro, and the presence of gap junctional proteins connexin (Cx) 26, Cx32, and Cx43 in fibroblasts of diabetic and nondiabetic individuals. Fibroblast cell lines (n = 10) were cultured for 3 d in serum-free media with or without bFGF (3 ng/mL). Cells were evaluated for the rate of GJIC by using laser cytometry, and for the presence of Cx26, Cx32, and Cx43 by immunohistochemical and Western analyses. All cell types communicated via contact-dependent mechanisms. The rate of GJIC was greater (p < 0.01) for diabetic than for nondiabetic fibroblasts (4.1 +/- 0.01 vs 3.3 +/- 0.01%/min). bFGF increased (p < 0.01) the rate of GJIC for diabetic (4.9 +/- 0.01 vs 4.1 +/- 0.01%) and nondiabetic (4.1 +/- 0.01 vs 3.3 +/- 0.01%) fibroblasts. Immunohistochemistry identified Cx26 in the cytoplasm, Cx32 was not detected, and Cx43 was present on the cellular borders in all cultures. Image analysis of immunofluorescent staining demonstrated that bFGF increased (p < 0.05) Cx43 expression in diabetic and nondiabetic fibroblasts. Western immunoblot analysis revealed bands at 43-46 kD that were similar in volume for diabetic and nondiabetic fibroblasts. Thus, gap junctions involving Cx43 and GJIC among fibroblasts appear to be targets for bFGF. Fibroblasts of diabetic individuals appear to have an increased rate of cell-cell coupling, correlating with a decreased rate of proliferation.

Adult↗
PubMed1999

Expression of gap junctional proteins connexin 43, 32, and 26 throughout follicular development and atresia in cows.

Detection of connexin (Cx) proteins has been used as an indicator of the presence of structural and functional gap junctions in tissues. To examine the role of gap junctions during follicular growth and atresia, the presence of three major connexins, Cx43, Cx32, and Cx26, was evaluated in bovine ovaries by using immunohistochemistry and Western immunoblot analysis. Cx43 was not present in primordial follicles, but was present in granulosa cells of primary/secondary and antral follicles. Cx43 also was present on the borders between granulosa cells and the oocyte. Expression of Cx43 increased in healthy developing antral follicles, but decreased during follicular atresia. Cx32 was not present in healthy follicles but was present in granulosa cells of atretic antral, and especially small antral follicles. Cx26 was present in the oocyte of primordial and primary/secondary follicles, and in the granulosa and/or thecal cell layers of healthy antral follicles. The percentage of healthy antral follicles that expressed Cx26 also increased during follicular development, but decreased during atresia. Cx32 and Cx26 also were detected in ovarian blood vessels and in stromal tissues adjacent to the tunica albuginea in some ovaries. The pattern of expression of these Cx indicates that gap junctional proteins may be involved in the control of follicular growth and atresia in cows.

Animals↗
PubMed1999

Growth and cellular proliferation of pig corpora lutea throughout the oestrous cycle.

Corpora lutea were obtained from gilts on days 2, 4, 8, 12, 15 or 18 after oestrus. Luteal fresh masses and DNA contents increased linearly (P < 0.01) from day 2 to day 12 and day 2 to day 15, respectively. Changes in the ratio of protein:DNA were greatest between days 2 and 4 and days 15 and 18, whereas changes in DNA content were relatively small during the same intervals. Thus, a major component of changes in the size of the corpus luteum during the early and late periods of the luteal phase was cellular hypertrophy. Proliferation of luteal cells in vivo (nuclear incorporation of 5-bromo-2-deoxyuridine, a thymidine analogue) was greatest on day 2 and decreased exponentially (P < 0.01) throughout the oestrous cycle. Results from co-localization of 5-bromo-2-deoxyuridine and factor VIII (von Willebrand factor), a marker of endothelial cells, or 5-bromo-2-deoxyuridine and 3 beta-hydroxysteroid dehydrogenase, a marker of steroidogenic cells, indicated that some of the luteal steroidogenic cells proliferated early in luteal development. However, during early and mid-cycle, most of the luteal cell proliferation occurred in the endothelial cells. Thus, during growth of the pig corpus luteum, which is extremely rapid, most of the proliferating luteal cells are vascular endothelial cells. This observation is consistent with the high vascularity and blood flow of the mature corpus luteum and implies a critical role for angiogenesis in luteal development in the pig, as has been proposed for several other mammalian species.

3-Hydroxysteroid Dehydrogenases↗
PubMed1999

Ruminally undegraded intake protein in sheep fed low-quality forage: effect on weight, growth, cell proliferation, and morphology of visceral organs.

To determine the influence of increasing levels of supplemental ruminally undegraded intake protein (UIP) on visceral organ weights, growth, cell proliferation, and morphology, 20 mature ewes of mixed breeding were fed a 6.55% CP grass hay:straw mixture (40:60) and assigned to one of four supplemental treatments. Supplements were control (no supplement) and low, medium, and high levels of UIP. After 42 to 46 d on treatment, ewes were infused i.v. with 5-bromo-2-deoxy-uridine (BrdU, a thymidine analog used to provide an index of the rate of intestinal cell proliferation) and slaughtered 1 h later. Visceral organs were weighed, and subsamples were obtained to evaluate visceral DNA, RNA, and protein contents (frozen samples) as well as intestinal morphology (fixed samples). Final BW; eviscerated BW (EBW); total visceral weight; and liver fresh, dry, and dry fat-free weights were increased (P<.10) in protein-supplemented ewes compared with controls, but were not influenced by increasing levels of UIP. Tissue weights of duodenum, jejunum, ileum, cecum, and colon were not greatly influenced by treatment. There were no differences among treatments in intestinal DNA and protein concentrations and the ratios RNA:DNA and protein:DNA. Jejunal RNA concentration and content was increased (P<.10) in low compared with medium and high treatments. Jejunal RNA content also was decreased (P<.10) in high compared with the medium UIP treatment. Liver RNA and protein contents were increased (P<.10) with protein supplementation. In contrast, contents of RNA, DNA, and protein in duodenum, ileum, cecum, and colon were not influenced by treatment. In addition, neither the rate of intestinal proliferation (BrdU labeling) nor intestinal morphology (crypt depth, villus length, or villus width) were affected by treatment. These data indicate that the influence of protein supplementation on visceral growth involves primarily the liver and not the intestines. These data also indicate that visceral growth, except in jejunum, are not altered by differing levels of UIP supplementation.

Animal Feed↗
PubMed1999

Growth and development of the corpus luteum.

The mammalian corpus luteum, which plays a central role in the reproductive process because of its production of hormones such as progesterone, is an exceptionally dynamic organ. Growth and development of the corpus luteum are extremely rapid, and even when the corpus luteum is functionally mature cellular turnover remains high. Associated with this high rate of cell turnover, the mature corpus luteum receives the greatest blood supply per unit tissue of any organ, and also exhibits a relatively high metabolic rate. Central to the growth and development of the corpus luteum, therefore, is luteal vascular growth, which appears to be regulated primarily by the angiogenic growth factors, basic fibroblast growth factor and vascular endothelial growth factor. In addition, the corpus luteum is a complex tissue composed of parenchymal (small and large steroidogenic) and nonparenchymal (for example fibroblasts, vascular smooth muscle, pericytes and endothelial) cells. Recent studies evaluating the expression, location and regulation of gap junctions in the corpus luteum indicate an important role of gap junctional intercellular communication in the coordination of function among these diverse cell types during luteal growth and development. These studies will lead to an improved understanding not only of luteal function but also of tissue growth and development in general.

Animals↗
PubMed1998

Time-course of the uterine response to estradiol-17beta in ovariectomized ewes: uterine growth and microvascular development.

The time-course of uterine growth, cell proliferation, and microvascular development was evaluated during the first 72 h after implanting estradiol-17beta (E2) into ovariectomized (OVX) ewes. Uterine fresh weight increased 2.3-fold by 24 h and increased further (3.3-fold) by 48 h. The majority (approximately 75%) of this growth response was associated with tissue growth rather than a change in the tissue dry weight:fresh weight ratio. Both uterine cell number (DNA content) and cell size (RNA:DNA ratio) increased from 0 to 24 h (1.8-fold and 1.7-fold, respectively). Cell proliferation also increased dramatically between 8 h and 24 h after E2 implantation. Endometrial microvascular volume density (percentage of tissue volume occupied by microvessels) increased approximately 1.8-fold by 24 h and then remained constant or declined slightly through 72 h. The total endometrial microvascular volume, however, increased approximately 5-fold from 0 to 24 h and increased further by 72 h. Thus, treatment of OVX ewes with E2 caused a dramatic increase in uterine fresh and dry weights by 24 h, due primarily to hyperplasia and hypertrophy, with only a relatively small change in tissue dry weight:fresh weight ratio. This dramatic uterine growth was associated with a profound increase in endometrial microvascular volume.

Animals↗
PubMed1998

Time-course of the uterine response to estradiol-17beta in ovariectomized ewes: expression of angiogenic factors.

Uterine expression of angiogenic factors (vascular endothelial growth factor [VEGF] and basic fibroblast growth factor [bFGF]) was evaluated in ovariectomized ewes at 0, 2, 4, 8, 24, 48, or 72 h after estradiol (E2) treatment. Endometrial VEGF mRNA increased more than 5-fold from 0 to 4 h, remained elevated at 8 h, and then declined through 72 h after E2 treatment. In contrast, endometrial bFGF mRNA remained constant from 0 to 4 h, increased 2.2-fold from 4 to 8 h, remained elevated at 24 h, and then declined through 72 h. Immunostaining for VEGF was present in myometrial and endometrial microvessels (arterioles, venules, and/or capillaries) and also in myometrial smooth muscle; the pattern of VEGF immunostaining followed that of mRNA expression, being elevated at 4 and 8 h after E2 treatment. Immunostaining for bFGF was present exclusively in uterine glands; the pattern of bFGF immunostaining also followed that of its mRNA, being elevated at 8 and 24 h after E2. On the basis of these observations, we suggest that VEGF and bFGF are probably important factors responsible for the dramatic uterine microvascular response that occurs 8 to 24 h after E2 treatment in ovariectomized ewes.

Animals↗
PubMed1998

Characterization of heparin-binding endothelial mitogen(s) produced by the ovine endometrium during early pregnancy.

To characterize mitogenic factors produced by ovine endometrium during early pregnancy, endometrial explant-conditioned media (ECM) were obtained from ewes on day 12, 18, 24, or 30 after mating. These ECM contained mitogenic activity for both endothelial and 3T3 cells across all days. The endothelial mitogenic activity was greatest on day 24, whereas mitogenic activity for 3T3 cells did not differ across days. By ultrafiltration, ion exchange, and heparin-affinity chromatography, the endothelial mitogenic activity was found to have a molecular mass greater than 100 kDa, to be anionic, and to be heparin binding, respectively. Three peaks of endothelial mitogenic activity were recovered from heparin-affinity chromatography. The major peak, H3, was mitogenic for endothelial but not for 3T3 cells. H3 was further purified, and the single peak of heparin-binding activity, designated H3b, represented a 681-fold purification of endothelial mitogenic activity from endometrial ECM. H3 and H3b were heat labile and trypsin sensitive, and their biological activity was heparin enhanced. The majority of the endothelial mitogenic activity was immunoneutralized by antibodies against acidic and basic FGF. Nevertheless, we were unable to detect bFGF in H3 or H3b by Western immunoblot analysis. Thus, in this study we have extended our previous observations and demonstrated that (i) during early pregnancy the ovine endometrium produces mitogenic activity for both endothelial and 3T3 cells, (ii) the endothelial mitogenic activity is greatest on day 24 after mating. which corresponds with the onset of endometrial vascular growth, and (iii) the major endothelial mitogen has a high affinity for heparin, and although it is immunologically related to FGF, it differs from known FGF in its apparent molecular size and biological activities.

3T3 Cells↗
PubMed1998

Gap junctional proteins, connexin 26, 32, and 43 in sheep ovaries throughout the estrous cycle.

Ovarian follicles from days 13, 14, 15, and 16 and corpora lutea (CL) from days 2, 4, 8, 12, and 15 of the estrous cycle were evaluated for the presence of connexins by immunohistochemistry. In addition, CL from days 5, 10, and 15 of the estrous cycle were used for immunofluorescent detection of Cx43 followed by image analysis, and for Western immunoblot. In all tissues, staining for all connexins appeared punctate, indicating the presence of assembled gap junctions. Cx26 was present in the ovarian surface epithelium, stroma, and blood vessels within the stroma and hilus, and in the CL. In healthy antral follicles, Cx26 was present only in the theca layer, whereas Cx43 was present in granulosa and theca layers. In the majority of atretic follicles, connexins were not detected, but in 13% of the atretic follicles, Cx43 was present in the theca layer. Cx32 was detected in the blood vessels of ovarian stroma and in the CL, and Cx43 was detected in the CL. Localization and/or expression of connexins depended on stage of luteal development. Western analysis demonstrated that expression of Cx32 in luteal tissues was similar across the estrous cycle. The area of positive staining for Cx43 and expression of Cx43 in luteal tissues decreased (p < 0.05) as the estrous cycle progressed. The pattern of expression of connexins indicates that gap junctional proteins may be important in the regulation of folliculogenesis and follicular atresia, as well as growth, differentiation, and regression of the CL.

Animals↗
PubMed1998

Expression of the angiogenic factors, basic fibroblast growth factor and vascular endothelial growth factor, in the ovary.

In adult tissues, vascular growth (angiogenesis) occurs normally during tissue repair, such as in the healing of wounds and fractures. Inappropriate vascular growth is associated with various pathological conditions. These conditions include tumor growth, retinopathies, hemangiomas, fibroses, and rheumatoid arthritis in the case of rampant vascular growth and nonhealing wounds and fractures in the case of inadequate vascular growth. The female reproductive organs exhibit dramatic, periodic growth and regression, accompanied by equally dramatic changes in their rates of blood flow. Thus, it is not surprising that they are some of the few adult tissues in which angiogenesis occurs as a normal process. Ovarian follicles and corpora lutea contain and produce angiogenic factors. These angiogenic factors bind heparin and seem to belong to the fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) families of proteins. Based on our studies of the pattern of expression of FGF and its major receptors in bovine, ovine, and porcine corpora lutea, we have suggested that FGF may influence not only luteal cell proliferation but also cell death, thereby regulating cell turnover in the luteal vascular and nonvascular compartments. In addition, we recently have shown that luteal expression of VEGF is greatest during the early luteal phase, coincident with luteal vascularization. Moreover, VEGF is present exclusively in luteal connective tissue and perivascular (arteriolar smooth muscle and capillary pericyte) cells. In fact, the first thecal-derived cells to invade the granulosa-derived regions immediately after ovulation seem to be VEGF-containing pericytes. We have therefore hypothesized that ovarian pericytes play a key role in vascularization of developing follicles and corpora lutea. Further understanding of the specific physiological roles of these factors in follicular and luteal growth, development, and function will ultimately lead to improved methods of regulating fertility.

Angiogenesis Inducing Agents↗
PubMed1998

Fibroblast growth factor receptor (FGFR)-1 and -2 in the ovine corpus luteum throughout the estrous cycle.

Fibroblast growth factors (FGFs) probably play an important role in development and maintenance of the vasculature of the corpus luteum (CL). The objective of the present study was to evaluate the distribution and levels of fibroblast growth factor receptors (FGFRs) in the ovine CL from the early, mid- and late stages of the estrous cycle. Presence of FGFR-1 and -2 receptors was evaluated in CL by using Western analysis, immunohistochemistry and topical autoradiography. Western analysis demonstrated that the levels of FGFR-1 and -2 were similar in the early and mid-cycle CL but increased (p < 0.05) in the late stage of the estrous cycle. Immunohistochemistry and topical autoradiography demonstrate that both parenchymal (steroidogenic) and nonparenchymal (e.g. endothelial, fibroblastic) cells express FGFR-1 and -2. FGFR-1 was localized to the luteal vasculature throughout the estrous cycle; in the parenchymal cells, it was present during mid-cycle but was barely detectable in the late stage. Conversely, FGFR-2 was present in the parenchymal cells at all stages of the estrous cycle but localized to the larger microvessels only at the late stage. These data demonstrate that FGF receptors are present in the parenchyma as well as the vasculature of the CL which suggests that FGF is involved in the regulation of luteal parenchymal and vascular function.

Animals↗
PubMed1997

Effect of gonadotropin treatment on size, number, and cell proliferation of antral follicles in cows.

To determine the effects of gonadotropins on the size, number, and cell proliferation of antral ovarian follicles, cows received FSH-P or vehicle beginning on Day 2 after estrus, and ovaries were collected 6, 12, 24, or 48 hr after the initiation of FSH-P treatment or 24 or 48 hr after the initiation of vehicle treatment. Ovaries also were collected from untreated cows on Day 2 after estrus (pretreatment). Before fixation, all visible antral follicles were counted and their surface diameters were recorded. Proliferating cells were immunolocalized in fixed follicles by using a specific primary antibody against proliferating cell nuclear antigen (PCNA), and the labeling index (LI; percentage of cells staining positively for PCNA) was determined for granulosa and thecal cells. After 48 hr of treatment, FSH-P-treated cows had fewer (P < 0.01) small antral follicles and more medium and large antral follicles (P < 0.01 and P < 0.05, respectively) compared with vehicle-treated cows. Granulosa cell LI was negatively correlated (P < 0.05) with follicular diameter for vehicle-treated but not for FSH-P-treated cows. Analysis of covariance using follicular diameter as a covariate to adjust to a common diameter indicated that granulosa cell LI was greater (P < 0.05) at 24 and 48 hr in FSH-P-treated than in vehicle-treated cows; conversely, thecal cell LI was greater (P < 0.01) at 48 hr in FSH-P-treated compared with vehicle-treated cows but did not differ at 24 hr. Across all groups, the LI of cells located within the antral half of the granulosa cell layer was greater (P < 0.01) than that of cells located within the basal half. In conclusion, the stimulation of follicular development by exogenous gonadotropins increased or maintained the proliferation of granulosa and thecal cells concomitant with continued follicular growth. Therefore, enhanced follicular cell proliferation may be an important mechanism by which FSH-P superinduces the growth of antral follicles in cows.

Animals↗
PubMed1997

Cellular interactions in the corpus luteum.

The corpus luteum (CL) is an organ that exhibits extremely rapid growth, development, and regression during the course of each nonpregnant cycle. The CL consists of steroidogenic (parenchymal) and nonsteroidogenic (nonparenchymal) cells. The small and large parenchymal cells differ in numerous morphological and functional characteristics, and are thought to interact with each other to maintain normal luteal function. These steroidogenic luteal cells also interact with the nonsteroidogenic cells; for example, they produce factors that stimulate proliferation and migration of endothelial cells and proliferation of fibroblasts; they also may enhance or suppress immune cell function. Conversely, endothelial cells produce factors that modulate steroidogenesis, and immune cells produce cytokines that modify the secretory function of steroidogenic cells. Cellular interactions may be mediated by several mechanisms, including humoral (endocrine and paracrine) pathways as well as contact-dependent (gap junctional) pathways. Thus, hormones, growth factors and cytokines produced locally by steroidogenic or nonsteroidogenic cells may be transferred from cell to cell indirectly or directly to regulate luteal function. Gap junctions are present in luteal tissues of several species, and gap junctional intercellular communication is affected by the stage of luteal development and systemic and local regulators of luteal function. Such cellular interactions probably are important in luteal hormone production, signal transduction, angiogenesis, and luteolysis because of their role in coordinating function among the various luteal cell types.

Animals↗
PubMed1997

Uterine growth, cell proliferation, and c-fos proto-oncogene expression throughout the estrous cycle in ewes.

Uterine growth, cell proliferation, and endometrial expression of the c-fos proto-oncogene were evaluated for nonpregnant ewes (n = 6 ewes per day) on Days 0 (estrus), 2, 4, 8, 12, and 15 of the estrous cycle. Fresh and dry weights of uterine horns decreased (p < 0.01) linearly from Days 0 to 8 and then remained similar from Day 8 through Day 15. Tissue water content (1 - [dry weight/fresh weight]) was greater on Day 0 (p < 0.01) than on Days 2, 4, and 8, and the latter values were greater (p < 0.01) than on Days 12 and 15. DNA content was similar on Days 0, 2, 4, 8, and 15 but increased (p < 0.01) on Day 12. Although DNA content was greatest on Day 12, the ratios of RNA to DNA and of protein to DNA were least (p < 0.01) on that day. Thus, changes in uterine fresh weight were associated primarily with changes in tissue hypertrophy (RNA:DNA and protein:DNA ratios) and water content. In addition, changes in uterine fresh weight were associated with changes in the ratio of estradiol to progesterone in systemic blood, which was greatest (p < 0.01) on Days 0 and 2, decreased (p < 0.01) from Day 2 to Day 8, remained low through Day 12, and then was elevated again (p < 0.01) on Day 15. Moreover, compartmentalized changes in endometrial cell proliferation (labeling index [LI]; percentage of cells exhibiting nuclear incorporation of bromodeoxyuridine, a thymidine analogue) also were associated with the changes in fresh weight. The epithelium of the uterine lumen and luminal glands exhibited the greatest changes in rate of cell proliferation and accounted for most of the changes in LI seen across days of the estrous cycle. Endometrial expression of c-fos mRNA and protein also reflected changes in uterine weight and the systemic estradiol:progesterone ratio. The level of c-fos mRNA was greatest at estrus, low on Days 2-8, and elevated slightly on Days 12 and 15; Fos protein was greatest on Days 0 through 4, least on Day 8, and intermediate on Days 12 and 15. Characterization of uterine growth, cell proliferation, and c-fos expression throughout the estrous cycle will provide a foundation for future studies of gene expression regulating growth of the nonpregnant uterus.

Animals↗
PubMed1997

Effects of ovarian steroids on uterine growth, morphology, and cell proliferation in ovariectomized, steroid-treated ewes.

Uterine growth, morphology, and endometrial cell proliferation were evaluated in intact estrous (EST; Day 0 of the estrous cycle) or luteal (LUT; Day 10 of the estrous cycle) ewes or in ovariectomized ewes receiving no hormone (OVX); estradiol-17beta (OVX+E); progesterone for 8 (OVX+P8), 30 (OVX+P30), or 60 (OVX+P60) days; estradiol followed by progesterone (OVX+E+P); or progesterone followed by estradiol (OVX +P+E). Uterine weights were greater for EST than for LUT ewes, were reduced 2- to 4-fold in OVX ewes, and were increased in estradiol-treated (OVX+E, OVX+E+P, and OVX+P+E) ewes. The effects of estradiol treatment on uterine growth in OVX ewes were primarily on cellular hypertrophy rather than hyperplasia. Endometrial labeling index (LI) was greater for EST than for LUT ewes and was low in OVX ewes. Compared with OVX ewes, OVX+E and OVX+P+E ewes had increased LI for all endometrial tissues, whereas OVX+P8 and OVX+E+P ewes had increased LI only for luminal epithelium. These data will help us determine the mechanisms by which ovarian steroids regulate uterine growth in ewes.

Animals↗
PubMed1997

Cellular proliferation and fibroblast growth factors in the corpus luteum during early pregnancy in ewes.

To determine the relationship between cellular proliferation and the presence of FGF-1 and FGF-2 in the ovine corpus luteum (CL) during early pregnancy, ewes received an intravenous injection of bromodeoxyuridine (BrdU) 1 h before slaughter (n = 3/day) on day 12 after estrus (nonpregnant) or on days 12, 18, 24 or 30 after mating (pregnant). The labeling index (LI; number of BrdU-labeled nuclei expressed as a percentage of total nuclei) of each CL was determined by immunohistochemistry and subsequent image analysis. FGF-1 and FGF-2 were immunolocalized by using specific antibodies, and indirect immunoperoxidase detection. Moreover, FGF-2 was immunolocalized by using a primary antibody and fluorescein isothiocyanate (FITC)-labeled secondary antibody, and immunofluorescence was quantified by using an interactive laser cytometer and image analysis. Results demonstrated that the LI was similar for CL of nonpregnant and pregnant ewes on day 12 (4.27 +/- 0.23 vs 5.10 +/- 0.14%) and decreased (P < 0.05) from days 12-30 of pregnancy (2.73 +/- 0.08, 2.02 +/- 0.09 and 1.70 +/- 0.04% on days 18, 24 and 30, respectively). FGF-1 was present in the cytoplasm of large and a few small parenchymal luteal cells, and the distribution and intensity of staining was similar for nonpregnant and pregnant ewes on day 12 as well as across days of pregnancy. In contrast, FGF-2 immunoreactivity was present only in luteal nonparenchymal cells and interstitial areas and was greater (P < 0.05) for pregnant than nonpregnant CL on day 12 (2.34 +/- 0.12 vs 0.14 +/- 0.01%). Although FGF-2 immunoreactivity decreased (P < 0.01) from days 12-30 of pregnancy (0.70 +/- 0.04, 0.22 +/- 0.01 and 0.06 +/- 0.02% on days 18, 24, and 30, respectively), it was highly correlated (r = 0.99, P < 0.01) with luteal LI. We therefore suggest that FGF, and especially FGF-2, play a role in luteal cell proliferation or turnover during early pregnancy, and may thereby contribute to the maintenance of luteal function, which is critical for the successful establishment of pregnancy.

Animals↗
PubMed1996

Gap junctional intercellular communication of bovine luteal cells from several stages of the estrous cycle: effects of prostaglandin F2 alpha, protein kinase C and calcium.

Cellular interactions mediated by both contact-dependent and contact-independent mechanisms are probably important to maintain luteal function. The present studies were performed to evaluate the effects of luteotropic and luteolytic hormones, and also intracellular regulators, on contact-dependent gap junctional intercellular communication (GJIC) of bovine luteal cells from several stages of luteal development. Bovine corpora lutea (CL) from the early, mid and late luteal phases of the estrous cycle were dispersed with collagenase and incubated with no treatment, LH, PGF or LH + PGF (Experiment 1), or with no treatment, or agonists or antagonists of protein kinase C (TPA or H-7) or calcium (A23187 or EGTA; Experiment 2). After incubation, media were collected for determination of progester-one concentrations. Then the rate of GJIC was evaluated for small luteal cells in contact with small luteal cells, and large luteal cells in contact with small luteal cells by using the fluorescence recovery after photobleaching technique and laser cytometry. Luteal cells from each stage of the estrous cycle exhibited GJIC, but the rate of GJIC was least (P < 0.05) for luteal cells from the late luteal phase. LH increased (P < 0.05) GJIC between small luteal cells from the mid and late but not the early luteal phase. PGF increased (P < 0.05) GJIC between small luteal cells from the mid luteal phase and diminished (P < 0.05) LH-stimulatory effects on GJIC between small luteal cells from the late luteal phase. Throughout the estrous cycle, TPA decreased (P < 0.05) the rate of GJIC between large and small, and between small luteal cells, and A23187 decreased (P < 0.05) the rate of GJIC between large and small luteal cells. LH and LH + PGF, but not PGF alone increased (P < 0.05) progesterone secretion by luteal cells from the mid and late luteal phases. Agonists or antagonists of PKC or calcium did not affect progesterone secretion by luteal cells. These data demonstrate that both luteal cell types communicate with small luteal cells, and the rate of communication depends on the stage of luteal development. LH and PGF affect GJIC between small luteal cells during the fully differentiated (mid-luteal) and regressing (late luteal) stages of the estrous cycle. In contrast, at all stages of luteal development, activation of PKC decreases GJIC between small and between large and small luteal cells, whereas calcium ionophore decreases GJIC only between large and small luteal cells. Luteotropic and luteolytic hormones, and intracellular regulators, may be involved in regulation of cellular interactions within bovine CL which likely is an important mechanism for coordination of luteal function.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗