Hormonal control of apoptosis in hamster uterine luminal epithelium

The evolution of universal adaptations of life is driven by universal properties of matter: energy, entropy, and interaction

The evolution of multicellular eukaryotes expresses two sorts of adaptations: local adaptations like fur or feathers, which characterize species in particular environments, and universal adaptations like microbiomes or sexual reproduction, which characterize most multicellulars in any environment. We reason that the mechanisms driving the universal adaptations of multicellulars should themselves be universal, and propose a mechanism based on properties of matter and systems: energy, entropy, and interaction. Energy from the sun, earth and beyond creates new arrangements and interactions. Metabolic networks channel some of this energy to form cooperating, interactive arrangements. Entropy, used here as a term for all forces that dismantle ordered structures (rather than as a physical quantity), acts as a selective force. Entropy selects for arrangements that resist it long enough to replicate, and dismantles those that do not. Interactions, energy-charged and dynamic, restrain entropy and enable survival and propagation of integrated living systems. This fosters survival-of-the-fitted - those entities that resist entropic destruction - and not only of the fittest - the entities with the greatest reproductive success. The "unit" of evolution is not a discrete entity, such as a gene, individual, or species; what evolves are collections of related interactions at multiple scales. Survival-of-the-fitted explains universal adaptations, including resident microbiomes, sexual reproduction, continuous diversification, programmed turnover, seemingly wasteful phenotypes, altruism, co-evolving environmental niches, and advancing complexity. Indeed survival-of-the-fittest may be a particular case of the survival-of-the-fitted mechanism, promoting local adaptations that express reproductive advantages in addition to resisting entropy. Survival-of-the-fitted accounts for phenomena that have been attributed to neutral evolution: in the face of entropy, there is no neutrality; all variations are challenged by ubiquitous energy and entropy, retaining those that are "fit enough". We propose experiments to test predictions of the survival-of-the-fitted theory, and discuss implications for the wellbeing of humans and the biosphere.

The evolution of universal adaptations of life is driven by universal properties of matter: energy, entropy, and interaction

The evolution of multicellular eukaryotes expresses two sorts of adaptations: local adaptations like fur or feathers, which characterize species in particular environments, and universal adaptations like microbiomes or sexual reproduction, which characterize most multicellulars in any environment. We reason that the mechanisms driving the universal adaptations of multicellulars should themselves be universal, and propose a mechanism based on properties of matter and systems: energy, entropy, and interaction. Energy from the sun, earth and beyond creates new arrangements and interactions. Metabolic networks channel some of this energy to form cooperating, interactive arrangements. Entropy, used here as a term for all forces that dismantle ordered structures (rather than as a physical quantity), acts as a selective force. Entropy selects for arrangements that resist it long enough to replicate, and dismantles those that do not. Interactions, energy-charged and dynamic, restrain entropy and enable survival and propagation of integrated living systems. This fosters survival-of-the-fitted - those entities that resist entropic destruction - and not only of the fittest - the entities with the greatest reproductive success. The "unit" of evolution is not a discrete entity, such as a gene, individual, or species; what evolves are collections of related interactions at multiple scales. Survival-of-the-fitted explains universal adaptations, including resident microbiomes, sexual reproduction, continuous diversification, programmed turnover, seemingly wasteful phenotypes, altruism, co-evolving environmental niches, and advancing complexity. Indeed survival-of-the-fittest may be a particular case of the survival-of-the-fitted mechanism, promoting local adaptations that express reproductive advantages in addition to resisting entropy. Survival-of-the-fitted accounts for phenomena that have been attributed to neutral evolution: in the face of entropy, there is no neutrality; all variations are challenged by ubiquitous energy and entropy, retaining those that are "fit enough". We propose experiments to test predictions of the survival-of-the-fitted theory, and discuss implications for the wellbeing of humans and the biosphere.

The evolution of universal adaptations of life is driven by universal properties of matter: energy, entropy, and interaction

The evolution of multicellular eukaryotes expresses two sorts of adaptations: local adaptations like fur or feathers, which characterize species in particular environments, and universal adaptations like microbiomes or sexual reproduction, which characterize most multicellulars in any environment. We reason that the mechanisms driving the universal adaptations of multicellulars should themselves be universal, and propose a mechanism based on properties of matter and systems: energy, entropy, and interaction. Energy from the sun, earth and beyond creates new arrangements and interactions. Metabolic networks channel some of this energy to form cooperating, interactive arrangements. Entropy, used here as a term for all forces that dismantle ordered structures (rather than as a physical quantity), acts as a selective force. Entropy selects for arrangements that resist it long enough to replicate, and dismantles those that do not. Interactions, energy-charged and dynamic, restrain entropy and enable survival and propagation of integrated living systems. This fosters survival-of-the-fitted - those entities that resist entropic destruction - and not only of the fittest - the entities with the greatest reproductive success. The "unit" of evolution is not a discrete entity, such as a gene, individual, or species; what evolves are collections of related interactions at multiple scales. Survival-of-the-fitted explains universal adaptations, including resident microbiomes, sexual reproduction, continuous diversification, programmed turnover, seemingly wasteful phenotypes, altruism, co-evolving environmental niches, and advancing complexity. Indeed survival-of-the-fittest may be a particular case of the survival-of-the-fitted mechanism, promoting local adaptations that express reproductive advantages in addition to resisting entropy. Survival-of-the-fitted accounts for phenomena that have been attributed to neutral evolution: in the face of entropy, there is no neutrality; all variations are challenged by ubiquitous energy and entropy, retaining those that are "fit enough". We propose experiments to test predictions of the survival-of-the-fitted theory, and discuss implications for the wellbeing of humans and the biosphere.

The shell gland in laying and natural moulting commercial egg-type chickens: A histomorphological and ultrastructural study

The purpose of the present study was to determine the histological and ultrastructural changes in the luminal epithelium of the shell gland associated with natural moulting. Samples of the shell gland from laying (32 weeks old) and moulting (75 weeks old) hens were studied using histological, histochemical and electron microscopic techniques. In addition, TUNEL was used to demonstrate the distribution of apoptotic cells in the luminal epithelium of the shell gland. Autophagy, characterized by the presence of autophagosomes and autolysosomes, was evident in the early stages of degeneration in non-ciliated, ciliated and mitochondrial cells. The intermediate and advanced stages of regression in non-ciliated as well as mitochondrial cells occurred via apoptosis, while both apoptotic and necrotic ciliated cells were observed during the later stages of degeneration. The results of the present study suggest that a synergy of autophagy, apoptosis and necrosis is involved in the involution of the shell gland during natural moulting.

Estrogen and progesterone dependent expression of visfatin/NAMPT regulates proliferation and apoptosis in mice uterus during estrous cycle

Visfatin is an adipokine which has an endocrine effect on reproductive functions and regulates ovarian steroidogenesis. There is scant information about the expression, regulation, and functions of visfatin in the mammalian uterus. The present study examined expression and localization of visfatin in the mouse uterus at various stages of the natural estrous cycle, effects of estrogen and progesterone on localization and expression of visfatin in the ovariectomised mouse uterus and effect of visfatin inhibition by a specific inhibitor, FK866 on proliferation and apoptosis in the uterus. Western blot analysis of visfatin showed high expression in proestrus and metestrus while it declined in estrus and diestrus. Immulocalization study also showed strong immunostaining in the cells of endometrium, myometrium, luminal and glandular epithelium during proestrus and metestrus that estrus and diestrus. The uterine visfatin expression closely related to the increased estrogen levels in proestrus and suppressed when progesterone rose to a high level in diestrus. The treatment with estrogen to ovariectomised mice up-regulates visfatin, PCNA, and active caspase3 whereas progesterone up-regulates PCNA and down-regulates visfatin and active caspase3 expression in mouse uterus. The co-treatment with estrogen and progesterone up-regulates visfatin and down-regulates PCNA and active caspase3. In vitro study showed endogenous visfatin inhibition by FK866 increased expression of PCNA and BCL2 increased catalase activity while FK866 treatment decreased expression of active caspase3 and BAX with decreased SOD and GPx activity. BrdU labeling showed that inhibition of visfatin modulates the uterine proliferation. This study showed that expression of visfatin protein is steroid dependent in mouse uterus which is involved in the regulation of proliferation and apoptosis via modulating antioxidant system in the uterus of mice during the reproductive cycle.

Comparative histomorphological and ultrastructural study of the luminal epithelium of the isthmus in laying and moulting domestic fowls (Gallus domesticus)

This study describes ciliated, nonciliated and mitochondrial luminal epithelial cells of the isthmus in laying and moulting domestic fowls using histological and ultrastructural techniques. The ciliated cells were nonsecretory, while numerous electron-dense secretory granules were present in the nonciliated cells of laying birds. Mitochondrial cells, occurring in two morphologically distinct forms, constituted the third type of epithelial cell present in the isthmus. The SEM study showed that the luminal epithelium was dominated by ciliated cells, the cilia of which partially obscured adjacent nonciliated cells. The involution of the luminal epithelium in moulting birds occurred via autophagy, apoptosis and necrosis. Autophagic inclusions, which included autophagosomes and autolysosomes, were present in the early degenerative phases of ciliated, nonciliated and mitochondrial cells. Nonciliated cells underwent degeneration via apoptosis, which was characterized by nuclear and cytoplasmic condensation. Apoptotic and necrotic ciliated cells were evident during the intermediate and advanced stages of regression. The presence of apoptotic cell death was confirmed using the TUNEL assay. Loss of cilia via the formation of cilia packets was observed using TEM and SEM. Necrotic cell death occurred in mitochondrial cells during the intermediate and late stages of degeneration. In conclusion, the findings of the study on isthmus involution in moulting birds suggest that autophagy is a process confined to the early stages of degeneration, while apoptosis and/or necrosis occur in the terminal stages of regression.

Remodeling of bovine endometrium throughout the estrous cycle

The mammalian endometrium changes morphologically and functionally throughout the estrous cycle. In some species, endometrial cells also undergo periodic proliferation and degeneration. However, the remodeling of bovine endometrium throughout the estrous cycle remains unclear. In the present study, we examined how the remodeling of bovine endometrium varied through the estrous cycle by measuring the relative rates of cell proliferation and apoptosis. Cells positive for both KI-67 (a proliferation marker) and cleaved caspase-3 (CCP3: an apoptotic cell marker) were immunohistochemically evaluated throughout the estrous cycle in the luminal and glandular epithelia, and the stroma of bovine endometrium. Percentages of KI-67-positive cells tended to be higher at the early luteal and follicular stages than at the mid and late luteal stages in all cell types. Similarly, percentages of CCP3-positive cells were higher at the early luteal stage than at the mid and late luteal stages in the luminal epithelium and stroma. Furthermore, CCP3 expression levels by Western blot analysis agreed with these immunohistological observations. On the other hand, DNA fragmentation was detected in the bovine endometrium without significant differences during the estrous cycle by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method. Together, these results show that cell proliferation and apoptosis undergo cyclic patterns in the bovine endometrium, and suggest that the bovine endometrium is remodeled in each estrous cycle.

Germinated brown rice and its bioactives modulate the activity of uterine cells in oophorectomised rats as evidenced by gross cytohistological and immunohistochemical changes

Background

Germinated brown rice (GBR) is gaining momentum in the area of biomedical research due to its increased use as a nutraceutical for the management of diseases. The effect of GBR on the reproductive organs of oophorectomised rats was studied using the gross, cytological, histological and immunohistochemical changes, with the aim of reducing atrophy and dryness of the genital organs in menopause.

Methods

Experimental rats were divided into eight groups of six rats per group. Groups 1, 2 and 3 (sham-operated (SH), oophorectomised without treatment (OVX) and oophorectomised treated with 0.2 mg/kg oestrogen, respectively) served as the controls. The groups 4,5,6,7 and 8 were treated with 20 mg/kg Remifemin, 200 mg/kg of GBR, ASG, oryzanol and GABA, respectively. All treatments were administered orally, once daily for 8 weeks. Vaginal smear cytology was done at the 7^th week on all the rats. The weight and dimensions of the uterus and vagina were determined after sacrifice of the rats. Uterine and vaginal tissues were taken for histology and Immunohistochemical examinations.

Results

GBR and its bioactives treated groups significantly increased the weight and length of both the uterus and the vagina when compared to Oophorectomised non-treated group (OVX-non-treated) (p < 0.05). Significant changes were observed in the ratio of cornified epithelial cells and number of leucocytes in the vaginal cytology between the oophorectomised non-treated and treated groups. There was also an increase in the luminal and glandular epithelial cells activity in the treated compared with the untreated groups histologically. Immunohistochemical staining showed specific proliferating cell nuclear antigen (PCNA) in the luminal and glandular epithelium of the treated groups, which was absent in the OVX-non-treated group. GBR improved the length and weight of the uterus and also increased the number of glandular and luminal cells epithelia of the vagina.

Conclusion

GBR and its bioactives could be a potential alternative in improving reproductive system atrophy, dryness and discomfort during menopause.

Apoptosis and inflammation

During the last few decades it has been recognized that cell death is not the consequence of accidental injury, but is the expression of a cell suicide programme. Kerr et al. (1972) introduced the term apoptosis. This form of cell death is under the influence of hormones, growth factors and cytokines, which depending upon the receptors present on the target cells, may activate a genetically controlled cell elimination process. During apoptosis the cell membrane remains intact and the cell breaks into apoptotic bodies, which are phagocytosed. Apoptosis, in contrast to necrosis, is not harmful to the host and does not induce any inflammatory reaction. The principal event that leads to inflammatory disease is cell damage, induced by chemical/physical injury, anoxia or starvation. Cell damage means leakage of cell contents into the adjacent tissues, resulting in the capillary transmigration of granulocytes to the injured tissue. The accumulation of neutrophils and release of enzymes and oxygen radicals enhances the inflammatory reaction. Until now there has been little research into the factors controlling the accumulation and the tissue load of granulocytes and their histotoxic products in inflammatory processes. Neutrophil apoptosis may represent an important event in the control of intlamtnation. It has been assumed that granulocytes disintegrate to apoptotic bodies before their fragments are removed by local macrophages. Removal of neutrophils from the inflammatory site without release of granule contents is of paramount importance for cessation of inflammation. In conclusion, apoptotic cell death plays an important role in inflammatory processes and in the resolution of inflammatory reactions. The facts known at present should stimulate further research into the role of neutrophil, eosinophil and macrophage apoptosis in inflammatory diseases.

Hormonal regulation of apoptosis in the endometrium of common marmosets (Callithrix jacchus)

Phase-dependent apoptotic changes in the human endometrium during an ovarian cycle imply a potential role of steroids in the regulation of apoptosis. The present study was undertaken to determine the direct role of hormones in endometrial apoptosis in marmosets (Callithrix jacchus), a primate species which shows similarity to humans in terms of the cycle length and pattern. Endometrial apoptosis was detected by 3'-end labeling (TUNEL) in various phases of ovarian cycle in naturally cycling healthy marmosets (n=14) and also in ovariectomized marmosets (n=13) treated with either estradiol alone (E) or progesterone alone (P) or estradiol followed by progesterone (E+P). Expressions of apoptosis associated genes such as Bcl-2 family members (Bax and Bcl-2), proliferating cell nuclear antigen (PCNA)--a proliferation marker and steroid receptors, ERalpha and PR A were analysed by immunohistochemical methods. Apoptosis was intense in the glandular epithelial cells of endometrium during the mid-luteal phase as compared to other phases in naturally cycling animals; in the E+P group as compared to other groups of ovariectomized animals (P<0.05). Pronounced apoptosis in the mid-luteal phase was accompanied by the increased expression of Bax in glandular epithelial cells; while Bcl-2 immunoreactivity remained unchanged. PCNA expression was higher in the naturally cycling animals in the follicular phase and in the E group of the ovariectomized animals as compared those in the other groups. Immunoreactive ERalpha and PR A in glandular epithelial cells were most abundant during early follicular phase in naturally cycling animals and in both E and E+P groups among the ovariectomized animals. The present study highlights the importance of apoptosis in endometrial remodeling during the ovarian cycle and secondly, the role of both estradiol and progesterone in the regulation of apoptosis.

Importance of uterine cell death, renewal, and their hormonal regulation in hamsters that show progesterone-dependent implantation

This study was initiated to investigate the significance of uterine cell death and proliferation during the estrous cycle and early pregnancy and their correlation with sex steroids in hamsters where blastocyst implantation occurs in only progesterone-primed uteri. The results obtained in hamsters were also compared with mice where blastocyst implantation occurs in progesterone-primed uteri if estrogen is provided. Apoptotic cells in the uterus were detected by using terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) technique. Uterine cell proliferation was determined by 5-bromo-2'-deoxyuridine labeling followed by immunohistochemistry and methyl-tritiated [(3)H]thymidine labeling. Active caspase-3, an executor protein of cell death, expression was assayed by immunohistochemistry/immunofluorescence. Our results demonstrate that epithelial proliferation on the second day after mating marks the initiation of pregnancy-related uterine changes in both species despite their differences in hormonal requirements. Hamsters and mice showed subtle differences in uterine proliferative and apoptotic patterns during early pregnancy and in response to steroids. There existed almost a direct correlation between apoptosis and caspase-3 expression, suggesting uterine cell death mostly involves the caspase pathway. Consistent with these findings, we showed, for the first time, that execution of uterine epithelial cell apoptosis by caspase-3 is important for blastocyst implantation because a caspsase-3 inhibitor N-acetyl-DEVD-CHO when instilled inside the uterine lumen on d 3 of pregnancy inhibits implantation in hamsters and mice. The overall results indicate that uterine cell apoptosis and proliferation patterns are highly ordered cell-specific phenomena that play an important role in maintaining the sexual cycle and pregnancy-associated uterine changes.

The significance of benign endometrial cells in cervicovaginal smears

The success of the routine Papanicolaou (pap) smear in reducing the incidence and mortality of cervical cancer has been chronicled extensively. Unfortunately, endometrial cancer, the most common malignancy of the gynecologic tract, continues to lack a screening modality of comparable efficacy. It is generally accepted that the Papanicolau test has a low sensitivity for detecting endometrial disease. Nonetheless, it remains true that endometrial cells are not uncommonly identified on routine cervicovaginal smears and along with each case comes an associated responsibility for pathologists to assess cytologic features, assign a potential clinical significance, and make a decision on reporting this finding. When endometrial cells with an entirely normal cytologic appearance are identified on an otherwise unremarkable cervicovaginal smear, the central question raised is whether such cells are exfoliating physiologically or whether their exfoliation is pathologic in response to an underlying endometrial disease. Additionally, in the former scenario, could subsets of patients be defined in which the reporting of this finding is deemed unnecessary in the cytologic report? In this contribution, we explore the clinical significance of finding normal endometrial cells in cervicovaginal smears based on a review of the medical literature of the last half-century. The historical and evidentiary basis for the Bethesda 2001 recommendations, which calls for the reporting of cytologically benign endometrial cells only in patients 40 years and older, is reviewed in detail.

Wnt7a Is a Suppressor of Cell Death in the Female Reproductive Tract and Is Required for Postnatal and Estrogen-Mediated Growth1

The murine female reproductive tract is undifferentiated at birth and undergoes pronounced growth and cytodifferentiation during postnatal life. Postnatal reproductive tract development proceeds in the absence of high levels of circulating estrogens and is disrupted by precocious exposure to estrogens. The WNT gene family is critical in guiding the epithelial-mesenchymal interactions that direct postnatal uterine development. We have previously described a role for Wnt7a in controlling morphogenesis in the uterus. In addition to patterning defects, Wnt7a mutant uteri are atrophic in adults and do not show robust postnatal growth. In the present study, we examine immature female Wnt7a mutant and wild-type uteri to assess the cellular processes that underlie this failure in postnatal uterine growth. Levels of proliferation are higher in wild-type versus Wnt7a mutant uteri. Exposure to the potent estrogen-agonist diethylstilbestrol (DES) leads to an increase in cell proliferation in the uterus in wild-type as well as in mutant uteri, indicating that Wnt7a is not required in mediating cell proliferation. In contrast, we observe that Wnt7a mutant uteri display high levels of cell death in response to DES, whereas wild-type uteri display almost no cell death, revealing that Wnt7a plays a key role as a cell death suppressor. The expression pattern of other key regulatory genes that guide uterine development, including estrogen receptor (alpha), Hox, and other WNT genes, reveals either abnormal spatial distribution of transcripts or abnormal regulation in response to DES exposure. Taken together, the results of the present study demonstrate that Wnt7a coordinates a variety of cell and developmental pathways that guide postnatal uterine growth and hormonal responses and that disruption of these pathways leads to aberrant cell death.

Effect of steroid hormones on tissue remodelling and progesterone receptors in the uterus of seasonally anoestrous brushtail possums (Trichosurus vulpecula)

This study describes progesterone receptor (PR) location within uterine cells and associated morphological changes to the uterine luminal and glandular epithelium in seasonally anoestrous brushtail possums treated with oestradiol and/or progesterone.

Twenty-four adult female possums (n= 6/group) were treated with oestradiol, progesterone, oestradiol followed by progesterone or with the oil vehicle alone for 6-day periods. Uterine tissue was recovered, weighed and processed for light and transmission electron microscopy and for immunohistochemistry for PRs. Stereological techniques were used to quantify epithelial cell and constituent volumes for both luminal and glandular tissues. Plasma concentrations of oestradiol and progesterone were determined by radioimmunoassay.

Mean uterine wet weights were significantly heavier (P< 0.001) following oestradiol/progesterone treatment and maximum gland dilation, cellular and stromal growth, maximum cell height, and cell and constituent volumes were recorded after this treatment regimen. Cell nuclei and debris were commonly observed in gland lumina, and nuclear PRs were found predominantly in stromal cells following oestradiol-only treatment. Sequential treatment with oestradiol and then progesterone caused a decline in the number of positively stained cells. Epithelial cells contained extensive secretory organelles and degenerating cells were common within the glands.

Oestradiol treatment induced cell and cell constituent growth and promoted PR formation in anoestrous possum uterine tissue. Subsequent exposure to progesterone stimulated uterine tissues to reach maximum wet weights and led to the cellular maturation necessary to remodel the uterus in preparation for pregnancy.

Apoptosis in the canine endometrium during the estrous cycle

Apoptotic cell death in the endometria of 58 female dogs in different stages of the estrous cycle was assessed (in formalin-fixed, paraffin-embedded sections) with both the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling (TUNEL) assay and immunohistochemical detection of caspase-3 activity. For both techniques, the apoptotic index was determined in the surface epithelium, stroma, crypts, and basal glands by counting the percentage of stained cells in a total of 500 cells in each category. In the surface epithelium and stroma, TUNEL- and caspase-3-positive cells were rare (apoptotic index<1) throughout the estrous cycle. However, caspase-3 detection showed a significant increase in the apoptotic index in the stroma during anestrus as well as an increase in the index in both the stroma and surface epithelium in late metestrus. The apoptotic index increased during late metestrus and anestrus in the crypts and basal glands; in the crypts, this increase was significant only when caspase-3 detection was used, whereas in basal glands, significant differences were found for both techniques. In conclusion, apoptosis was present in canine endometrial cells during the estrous cycle, but caspase-3 detection showed more significant differences than the TUNEL assay. Furthermore, a high apoptotic index (suggestive of endometrial desquamation) was not detected in the surface epithelium and there was no significant correlation between the apoptotic index in any cell group and serum progesterone concentrations.

Regulation of Akt expression and phosphorylation by 17beta-estradiol in the rat uterus during estrous cycle

Molecular and intra-cellular mechanisms involved in the regulation of apoptosis processes in endometrial cells are poorly understood and documented. We have investigated the possibility that Akt survival pathway might be involved in the regulation of apoptosis in the uterus during the estrous cycle. Rats with regular estrous cycle (4 days) were killed at different days of estrous cycle (diestrus, proestrus, estrus and metestrus). Uteri were collected and fixed for immunohistochemical staining (IHC) and apoptotic cell death detection by [TdT]-mediated deoxyuridinetriphosphate nick end-labelling (TUNEL) or endometrial protein extracts collected for Western analysis. TUNEL analysis revealed that apoptosis was mainly found at estrus compared to other day of estrous cycle. TUNEL positive cells were apparent in luminal epithelial cells only. No apoptotic cells were observed at proestrus. In contrast, proliferation was maximal at proestrus as confirmed with the expression of CDC47/MCM7 (a cell proliferation marker). Intact form of caspase-3 was maximal at proestrus and was reduced only at estrus. Likewise, presence of a specific cleaved caspase-3 fragment was observed only at estrus and IHC revealed that cleaved caspase-3 signal was found in luminal epithelial cells. PTEN protein, a phosphatase involved in the regulation of Akt phosphorylation, was present at all days of estrous cycle and showed no significant regulation in relation to cycle. Expression of phospho-Akt (the activated form of Akt) was present at metestrus, diestrus, and proestrus but decreased significantly at estrus. Akt protein expression was maximal at estrus. IHC revealed that Akt expression was high in both stromal and epithelial cells at estrus. Further studies using ovariectomized rats demonstrated that 17beta-estradiol increased endometrial cell proliferation which was accompanied by an increase of both Akt expression and phosphorylation. These results suggest that increased Akt expression and activity in response to estradiol may be an important mechanism to protect endometrial cells from apoptotic triggering and to induce endometrial cell proliferation, whereas inhibition of Akt activity leads to caspase-3 activation and apoptosis in endometrial cells.

Multiple mechanisms are involved in apoptotic cell death in the mouse uterus and vagina after ovariectomy

Withdrawal of sex hormones by gonadectomy results in rapid involution of mouse reproductive organs. To study the regression mechanism in the uterus and vagina after ovariectomy, histologic and biochemical changes were examined. Apoptotic cells were detected by in situ 3'-DNA nick end labeling method and electron microscopy, while the number of cells showing incorporation of bromo-deoxyuridine (BrdU) decreased in the uterus and vagina after ovariectomy. DNA fragmentation in the uterus was observed even at estrus and the degree of fragmentation increased after ovariectomy. DNA fragmentation in the vagina occurred 1-5 days after ovariectomy. Semi-quantitative RT-PCR revealed that expression of Fas-ligand and tumor necrosis factor-alpha (TNF-alpha) mRNA in the uterus and vagina was increased by ovariectomy. These results suggest that apoptotic cell death is induced by ovariectomy through the mediation of both Fas and TNF-alpha in the mouse uterus and vagina; however, uterine and vaginal cells in CBA lpr(cg)/lpr(cg) mice lacking functional Fas showed apoptosis, indicating that Fas is not the sole regulator of apoptosis in female reproductive organs in mice.

Mouse uterine epithelial apoptosis is associated with expression of mitochondrial voltage-dependent anion channels, release of cytochrome C from mitochondria, and the ratio of Bax to Bcl-2 or Bcl-X

The release of cytochrome c from mitochondria, which is regulated by Bcl-2 family members and is considered to take place through voltage-dependent anion channels (VDACs) on the outer membranes of mitochondria, results in activation of effector caspases, such as caspase-3, which induce apoptosis. We studied the involvement of the mitochondrial apoptosis pathway in uterine epithelial apoptosis. Estradiol-17beta pellets were implanted into ovariectomized mice and removed 4 days later (Day 0). The apoptotic index (percentage of apoptotic cells) of the luminal epithelium increased markedly, peaking on Day 2, whereas that of the glandular epithelium increased much less. Expression of VDAC1, 2, and 3 mRNAs increased in the luminal epithelium in correlation with the apoptotic index of the luminal epithelium. No increases in VDAC1, 2, and 3 mRNA levels were observed in the stroma or muscle, where no apoptosis occurs. VDAC1 protein levels in the uterus also correlated well with the apoptotic index of the luminal epithelium. In addition, the apoptotic index showed good correlation with the release of cytochrome c from mitochondria, activation of caspase-3, which was immunohistochemically detected only in the epithelium, and the mRNA and protein ratios of Bax:Bcl-2 and Bax:Bcl-X in the uterus. The present results suggest that the release of cytochrome c from mitochondria, which is regulated by Bcl-2 family members, plays a role in uterine epithelial apoptosis after estrogen deprivation. The increase in VDAC expression may facilitate the release of cytochrome c during apoptosis.

Apoptotic cell death of oestrogen activated lactotrophs induced by tamoxifen

Stimulation and inhibition of lactotroph cells cause remarkable morphological and functional changes. In keeping with these changes, the size of the lactotroph cell population undergoes striking alterations due to proliferation or cell death. Factors involved in the induction of apoptosis of pituitary cells are not well established. We demonstrated earlier that oestrogens prevent lactotroph cells of female rats to die by apoptosis induced by bromocryptine treatment, a fact that can be reversed in ovariectomised rats. In this study, we developed experimental models for in vivo and in vitro studies to gain further insight on the survival effect of oestrogens on lactotrophs. In rats pretreated with oestrogens, tamoxifen generates a massive cell death by apoptosis as validated by the TUNEL technique and DNA electrophoresis of pituitary gland. On electron microscope observations, numerous lactotrophs exhibited progressive morphological changes in the nuclei compatible with the apoptotic process. The cells remaining intact also exhibit signs of inhibition due to a significant transformation of regular lactotrophs in atypical subtypes. In pituitary cell cultures exposed to tamoxifen and oestrogen simultaneously, most of the lactotrophs displayed features of apoptosis in the nucleus. The present reports gathered new evidences on the apoptogenic potential of tamoxifen on lactotroph cells, and corroborates the contribution of oestrogens to sustain both a balanced population of lactotrophs and a competent secretory activity. The concept that opposed activities, such as inhibition and stimulation, can activate apoptosis is also strengthen by these observations.

Oral contraceptives suppress cell proliferation and enhance apoptosis of eutopic endometrial tissue from patients with endometriosis

OBJECTIVE

To evaluate the effects of administering combination oral contraceptives (COCs) to patients with endometriosis on the regulation of cell growth in the eutopic endometrium.

DESIGN

Prospective study.

SETTING

Research institute and clinical fertility center.

PATIENT(S)

Thirteen women with untreated endometriosis and 13 controls.

INTERVENTION(S)

Biopsy specimens of the eutopic endometrium were obtained from all subjects. Apoptosis, cell proliferation, and Bcl-2 and Bax expression were examined at the epithelial and stromal levels in the eutopic endometrium from patients with endometriosis before and after 30 days of daily exposure to COCs and from controls.

MAIN OUTCOME MEASURE(S)

Apoptotic cells were detected by using the dUTP nick-end labeling assay; Ki-67, Bcl-2, and Bax expressions were assessed by using immunohistochemical techniques.

RESULT(S)

After exposure to COCs, apoptosis was significantly increased in the eutopic endometrium compared with before COC administration, both at epithelial and stromal levels. Cell proliferation was significantly lowered by COCs.

CONCLUSION(S)

COCs showed a positive effect on patients with endometriosis by down-regulating cell proliferation and enhancing apoptosis in the eutopic endometrium.

Expression of p53 in luminal and glandular epithelium during the growth and regression of rat uterus during the estrous cycle

It has been well recognized that epithelial cells of the rat endometrium cyclically proliferate and die during the estrous cycle. The aim of the present study was to determine p53 expression pattern and correlate it with the the apoptotic pattern of epithelial cells of the rat uterus during the estrous cycle. The p53 mRNA and protein expression pattern was assessed by in situ hybridization and immunohistochemistry. The apoptotic index was determined by using terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and electron microscopy. The highest p53 mRNA content, detected by in situ hybridization, was observed on the metestrus day both in the luminal and the glandular epithelia. During this period both epithelia presented high proliferation. The content of p53 mRNA markedly decreased in the following days, presenting its minimal values on the estrus day. The highest number of p53 immunopositive nuclei, in both the luminal and the glandular epithelia, was also detected on the metestrus day, while the lowest one was found on estrus day. On the proestrus day, p53 protein was predominantly detected in the glandular epithelium. However, on the estrus day, p53 protein was detected both in the nuclei and in the cytoplasm of luminal epithelial cells, predominantly in the cytoplasm. The highest apoptotic index in both the luminal and the glandular epithelia was observed on the estrus day whereas the lowest one was observed on the proestrus day. The apoptotic index values were higher in the luminal than in the glandular epithelia. The overall results indicate that p53 expression at both mRNA and protein levels is higher on the metestrus day when the apoptotic index is low. This suggests that p53 should play an important physiological role during proliferative phases of the estrous cycle in the rat uterus.

The effect of drugs and toxins on the process of apoptosis

In this review we examine the modifying effect of specific drugs on apoptosis. Apoptosis is a type of cell death prevalent during many physiological and pathological conditions, consisting of several steps, namely, initiating stimuli, transduction pathways, effector mechanisms, nuclear fragmentation, and phagocytosis. Pharmacological substances such as glucocorticoids can either induce or inhibit the process of apoptosis in various cells depending on the type of drug and its concentration. Understanding the mechanisms of interaction of drugs with cells undergoing apoptosis could encourage novel therapeutic approaches to human diseases in which apoptosis has a critical role.

Paracrine regulation of apoptosis by steroid hormones in the male and female reproductive system

In males, androgens are essential in maintaining the integrity of the prostate. Androgen-ablation induces apoptosis of the prostatic epithelium. In females, ovariectomy induces apoptosis in uterine epithelium while progesterone inhibits this process. The objective of this study was to determine whether androgen and progesterone inhibit apoptosis, respectively, in mouse prostatic and uterine epithelia via steroid receptors in the epithelium or in the stroma. To address this question, prostatic tissue recombinants were prepared with rat urogenital sinus mesenchyme plus bladder epithelium from wild-type or testicular feminization mutant (Tfm) mice. Thus, prostatic tissue was generated having androgen receptor (AR) in both epithelium and stroma or in the stroma only. Castration of hosts induced apoptosis in the AR-negative Tfm prostatic epithelium with an epithelial apoptotic index virtually identical to prostatic tissue recombinants containing wild-type epithelium. Moreover, this castration-induced prostatic epithelial apoptosis was blocked by testosterone and dihydrotestosterone in both wild-type and Tfm prostatic tissue recombinants. Likewise, uterine tissue recombinants were prepared in which epithelium and/or stroma was devoid of progesterone receptor (PR) by using uterine epithelium and stroma of wild-type and PR knockout mice. Progesterone inhibited uterine epithelial apoptosis only in tissue recombinants prepared with PR-positive stroma. The PR status of the epithelium did not affect epithelial apoptotic index. Therefore, the apoptosis in prostatic and uterine epithelia is regulated by androgen and progesterone via stromal AR and PR, respectively. In both cases, epithelial AR or PR is not required for hormonal regulation of epithelial apoptosis in prostatic and uterine epithelium.

Hormonal regulation of physiological cell turnover and apoptosis

Physiological cell turnover plays an important role in maintaining normal tissue function and architecture. This is achieved by the dynamic balance of cellular regeneration and elimination, occurring periodically in tissues such as the uterus and mammary gland, or at constant rates in tissues such as the gastrointestinal tract and adipose tissue. Apoptosis has been identified as the prevalent mode of physiological cell loss in most tissues. Cell turnover is precisely regulated by the interplay of various endocrine and paracrine factors, which modulate tissue and cell-specific responses on proliferation and apoptosis, either directly, or by altering expression and function of key cell proliferative and/or death genes. Although recent studies have provided significant information on specific tissue systems, a clearly defined pathway that mediates cell turnover has not yet emerged for any tissue. Several similarities exist among the various tissues with regard to the intermediates that regulate tissue homeostatis, enabling a better understanding of the general mechanisms involved in the process. Here we review the mechanisms by which hormonal and cytokine factors mediate cell turnover in various tissues, emphasizing common themes and tissue-specific differences.

Effects of oral administration of tamoxifen, toremifene, dehydroepiandrosterone, and vorozole on uterine histomorphology in the rat

Tamoxifen, toremifene, DHEA, and vorozole inhibit tumor growth in rodent mammary carcinoma models and are promising chemotherapeutic agents for use against breast cancer development. In the present study, the effect of these agents on uterine histomorphology following oral administration to mature ovary-intact rats (n = 380) was examined. Animals received diet only (control), tamoxifen (0.4 and 1 mg/kg of diet; 10 mg/kg BW by daily gavage), toremifene (3-30 mg/kg of diet), DHEA (24-2000 mg/kg of diet), or vorozole (0.08-1.25 mg/kg BW by daily gavage) for 28 days and were either sacrificed or returned to a basal diet and then sacrificed 21 days later. Treatment with toremifene (all doses) or tamoxifen (1 and 10 mg/kg) for 28 days produced a decrease (P<0.05) in overall uterine size and myometrial thickness; however, uterine luminal and glandular epithelia cell height increased (P<0.05) compared with control. These compartmentalized uterotrophic and antiestrogenic effects of toremifene and tamoxifen were still apparent after 21 days post-treatment. Administration of DHEA (2000 mg/kg of diet) for 28 days had dramatic uterotrophic effects, increasing (P<0.05) overall uterine size and stimulating all three uterine compartments (epithelia, stroma, and myometrium). The other doses of DHEA, however, were not uterotrophic. Interestingly, after removal of DHEA from the diet, uterine weight and myometrial thickness decreased (P<0.05). Vorozole (1.25 mg/kg) administration for 28 days had differential, compartmentalized uterine effects, producing an increase (P<0.05) in epithelial cell height, a decrease (P<0.05) in stromal size, but no change in myometrial thickness. After 21 days postadministration of vorozole, luminal epithelial cell height was increased (P<0.05) compared with control. The data suggest that oral administration of tamoxifen, toremifene, DHEA, and vorozole results in differential, compartmentalized effects in the uterus that are highly dependent on treatment dose. The data may have implications for risk assessment of these agents prior to administration to healthy, cancer-free women.

Differential activity of diethylstilbestrol versus estradiol as neonatal endocrine disruptors in the female hamster (Mesocricetus auratus) reproductive tract

The synthetic estrogen diethylstilbestrol (DES) is a potent neonatal endocrine disruptor in the hamster. To test the specificity of this phenomenon, newborn animals were treated with 100 microgram of either DES or the natural estrogen, estradiol-17beta (E2). Of the two, neonatal DES exposure caused greater morphological disruption throughout the female reproductive tract in prepubertal animals and in adults that either retained their ovaries or were ovariectomized and then given the same levels of chronic E2 stimulation. In the uterus, a characteristic histopathological profile, including enhancement of both hyperplastic and apoptotic activity, was initiated prepubertally and exclusively in the endometrial epithelial cell compartment from the neonatally DES-treated animals and then was promoted by E2 stimulation during adulthood. Interestingly, apoptotic activity was not detected in an area of endometrial epithelium that progressed to the neoplastic state in a DES-exposed animal. Lastly, chronic estrogen induction of lactoferrin was also restricted to the DES-exposed endometrium. We conclude that 1) DES is more active than E2 as a perinatal endocrine disruptor in the hamster and 2) this experimental system should be generally useful as a means to screen compounds for such activity and then probe their mechanism of action.

Apoptosis, proliferation, and sex hormone receptors in superficial parts of human endometrium at the end of the secretory phase

Apoptosis with one regulator, Bcl-2, and proliferation with the marker Ki-67 were studied in 75 endometrial biopsies representing superficial parts of endometrium from 35 regularly menstruating women premenstrually and menstrually. Hormonal withdrawal was studied in serum samples and potentiated in epithelium by the decreasing 17beta-estradiol and progesterone receptor scores 4 days premenstrually. The apoptotic index increased 2 days before the onset of menstruation and peaked on the second menstrual day. The high apoptotic index together with low proliferation in endometrial epithelium at the end of the menstrual cycle are similar to the involution process seen in other hormone-dependent organs. In stroma, the apoptotic index increased later, at the onset of menstruation, and the increase was lower than that in epithelium. The Ki-67 index increased during the last 3 days of the secretory phase, parallel with an increasing progesterone receptor score and decreasing Bcl-2 staining, and peaked at the onset of menstruation. The findings in stroma concur with high proliferation at the end of the menstrual cycle and high cell turnover during menstruation, suggesting the participation of stroma in the renewal process of endometrium.

Mode of cell death in the rat metrial gland during peripartum regression

In the rodent uterus, the metrial gland develops during midpregnancy and undergoes regression prior to parturation. The involution of the gland is reported to be accompanied by the loss of gland cells due to their death in situ. Cell death has been classified by using morphological criteria into two types: necrosis and apoptosis. To study the mechanism involved in the peripartum regression of the rat metrial gland, we examined the mode of cell death in the gland during the last week of gestation. We identified apoptotic cells in the regressing metrial gland by using DNA fragmentation, in situ DNA 3'-end labeling, and electron microscopy. Expression of progesterone receptor (PR) and estrogen receptor (ER) was also demonstrated by immunohistochemistry in the gland. The mean weight of metrial gland nodes decreased after day 18 of pregnancy. The apoptotic granulated metrial gland (GMG) cells that were detected by using the in situ DNA 3'-end labeling method were observed on day 16 of pregnancy, and they increased in number after day 20 of pregnancy. Intense fragmentation of DNA was also found from day 20 to day 22 of pregnancy. Electron microscopy demonstrated apoptotic GMG cells in the regressing metrial glands, confirming the results of the labeling studies. Immunohistochemical study revealed that expression of PR and ER, which were localized mainly in fibroblast-like stromal cells but not in GMG cells, was almost unchanged during late pregnancy. Apoptotic cell death is the major mode of rat metrial gland cell death in the peripartum loss of metrial gland cells.

Paracrine regulation of menstruation

Endometrial proliferation, secretion, vascular neoformation and modification to shedding is under direct and/or indirect control of steroid hormones. The progressive modification of the endometrial architecture is due to its growth and differentiation. The new tissue regenerates monthly from a 2-5 mm to a 12-18 mm of complex tissue until it sheds under a co-ordinated network of bioactive molecules produced and activated during the menstrual cycle. The steroid hormones, the HLA-DR and integrin molecules, the intense production of several proteins, the vascular damage, and the disconnection of cell-cell and cell-matrix interaction are participating in both the endometrial preparation for embryonic implantation and the shedding and bleeding of the tissue itself. Menstruation is a process associated with damage to the epithelium, endothelium and extracellular matrix, ending on controlled bleeding, tissue dissolution and repair. Endometrial proteinases and tissue factor (TF) contribute to systemic factors to control the mechanisms of regulation of tissue dissolution, tissue shedding, and vascular bleeding during menstruation.

Lipidosis induced in rat uteri by high doses of tamoxifen

The anti-estrogenic drug tamoxifen is an amphiphilic cationic compound and might therefore be expected to interfere with intralysosomal catabolism of polar lipids as has been previously reported with several other amphiphilic cationic drugs. The purpose of this study was to investigate whether there is lipidosis induction in the uterus. High oral doses of tamoxifen (100 mg/kg) were administered to 9 adult rats for 6-14 weeks. Their uteri were examined by light and electron microscopy. Lipidosis-like alterations were seen in the glandular epithelia and in the myometrium. The luminal epithelium was most severely affected. The highest degree of intraepithelial change was already observed after a short-term treatment (6 weeks). The results support the previously proposed concept of a relationship between the amphiphilic cationic character of a compound and its ability to cause intralysosomal storage of polar lipids after a high dosage treatment of these drugs in animals.

Progesterone therapy for endometrial carcinoma reduces cell proliferation but does not alter apoptosis

BACKGROUND

Although the anticancer effects of progesterone therapy for patients with endometrial carcinoma are widely acknowledged, a detailed assessment of the resultant morphologic alterations in tumor tissue kinetics has hitherto been lacking.

METHODS

Biopsy and hysterectomy specimens of 14 endometrial carcinomas (endometrioid-type) before and during progesterone therapy were studied to clarify changes in apoptosis and cell proliferation and their relation to morphologic alterations. The extent of squamous differentiation within tumor lesions was also examined.

RESULTS

In the good-response group, tumor cells took on characteristics of normal endometrial gland cells in the secretory phase. A positive correlation between reduction in the mitotic index and the degree of morphologic alterations during hormone therapy was observed, but the frequency of apoptotic cells did not vary. In both the good-response and poor-response groups, development or enlargement of squamous areas was observed, in comparison with the initial biopsy specimens.

CONCLUSIONS

These results suggest that prolonged progesterone administration can suppress cell proliferation in endometrial carcinomas through tumor cell differentiation without altering apoptosis, resulting in a shift in tissue kinetics toward a relative predominance of cell deletion. In addition, increases in the occurrence of squamous areas within tumors do not always appear to be related to treatment efficacy.

Ovarian steroids reduced apoptotic death in SV40 temperature-sensitive mutant virus transformed uterine epithelial cells

Ovarian steroids have been shown to inhibit uterine cell death in vivo. In this study, we investigated whether ovarian steroids regulated cell death in an uterine epithelial cell line transformed with SV40 temperature-sensitive (ts) mutant virus. To assess cell death rate, cells were grown at permissive temperature (34 degrees C) and pulsed with 3H-thymidine. The retention of incorporated radioactivity was then examined after a temperature shift to nonpermissive temperature (40 degrees C) in the absence or presence of estradiol and progesterone. When cells were continuously cultured at 34 degrees C, cell number increased rapidly and most of radioactivity was retained in the attached cells. However, the temperature shift from 34 degrees C to 40 degrees C resulted in a decrease in cell number and radioactivity in attached cells. Estradiol and progesterone attenuated this temperature shift-induced cell death. Morphological examination with Hoechst 33258 staining revealed that the temperature shift increased the percentage of apoptotic death. The treatment of ovarian steroids reduced the extent of apoptotic death. Our studies demonstrated that ovarian steroids could act directly on uterine epithelial cells to reduce apoptotic death in culture.

Polycystic ovarian condition in the dehydroepiandrosterone-treated rat model: hyperandrogenism and the resumption of meiosis are major initial events associated with cystogenesis of antral follicles

BACKGROUND

The purpose of this study was to elucidate the early effects of dehydroepiandrosterone (DHEA) in the polycystic rat model by charting cytological changes in the early antral follicle of the ovary and constructing a serum hormonal profile. Histological examinations of ovaries from DHEA-treated rats for ten consecutive days revealed that the oocyte of antral follicles, ranging from 1.5 mm to 3.4 mm in diameter, had become activated, i.e., had resumed meiosis. Tabulation and statistical analysis revealed a highly significant difference in the percentage of oocyte activation between the ovaries of DHEA-treated and control rats. Granulosa cells associated with those antral follicles included in our statistical analysis showed no evidence of atresia. A few follicles not included in our analysis contained oocytes that had resumed meiosis and whose associated granulosa cells were atretic. The observed resumption of meiosis occurred in the absence of surges of follicle stimulating hormone (FSH) and luteinizing hormone (LH). During meiosis, a period when many oocytes become activated, levels of serum androgens (DHEA, testosterone, and androstenedione) were high, while FSH, LH, and prolactin (PRL) levels did not differ significantly from those in the controls. Follicles that resume meiosis may be members of a group of follicles that produces a signal(s) when the oocyte becomes uncoupled from the granulosa cell. This signal(s) permit(s) a reprogramming of the accompanying granulosa cells of the follicle to engage in certain developmental processes of cystogenesis. Just what cascade of signals is necessary to achieve this selection remains elusive at this time and is the subject of our continuing investigations.

Progestins prevent apoptosis in a rat endometrial cell line and increase the ratio of bcl-XL to bcl-XS

Endometrial cell proliferation and cell death are regulated by ovarian hormones. The fall of ovarian progesterone in late secretory phase, or the artificial withdrawal of ovarian hormones during early pregnancy, are followed by programmed cell death of uterine epithelial cells. Aspects of this cell-specific response have been reproduced in a newly established rat endometrial cell line which expresses functional progesterone receptor. At low concentrations of serum and in the absence of glucocorticoids, these cells were dependent on progestins for survival. Removal of progesterone or addition of the antiprogestins RU38486 or ZK98299 led to a substantial increase of apoptotic cells indicated by the accumulation of internucleosomally degraded DNA. The hormonal control of cell proliferation and cell death correlated with the overall quantity and distribution of the different bcl-X transcripts. Progesterone administration not only increased total bcl-X mRNA level but also shifted the quantitative ratio between the different mRNA isoforms in favor for the apoptosis inhibiting form, bcl-XL, compared with the apoptosis promoting form, bcl-XS. These effects were rapid and could not be prevented by inhibitors of protein synthesis. As the low level of bcl-2 and bax mRNA was not influenced by progesterone treatment, the observed changes in total amount of bcl-X transcripts and spliced isoforms could represent the mechanism by which progesterone controls cell death in epithelial cells of the endometrium.

Apoptotic cell death during the estrous cycle in the rat uterus and vagina

BACKGROUND

Rodent uterus and vagina show marked histological changes during the estrous cycle. Apoptotic cell death has been demonstrated in hamster and rat uterine epithelium during the estrous cycle by electron microscopy: numerous epithelial cells undergo apoptosis at estrus. We examined cell death and cell proliferation in rat uterus and vagina during estrous cycle.

METHODS

To examine the rate of proliferation in uterine and vaginal cells at each estrous stage, the numbers of cells at metaphase were counted separately in epithelial and stromal cells. We identified the apoptotic cells in uterus and vagina at each estrous stage by using DNA fragmentation, in situ DNA 3'-end labeling, and electron microscopy.

RESULTS

Mitotic rates in uterine luminal and glandular epithelial cells were low at metestrus and estrus, respectively. Intense fragmentation was found in the uterus at metestrus and in the vagina at proestrus and metestrus. In uterine luminal and glandular epithelial cells, apoptotic index showed peaks at metestrus and estrus, respectively. In vaginal epithelial cells, many apoptotic cells were encountered in the superficial layer at proestrus, which may contribute to keratinization. In the middle and basal layer of vaginal epithelial cells, apoptotic index was high at metestrus, when mitotic rate was low. Electron microscopy confirmed the results of the labeling studies.

CONCLUSIONS

Apoptotic cell death was encountered in the uterus and vagina during estrous cycle in rats. There is an inverse correlation between cell death and cell proliferation in rat uterine and vaginal epithelial cells during the estrous cycle.

The polycystic ovarian (PCO) condition: apoptosis and epithelialization of the ovarian antral follicles are aspects of cystogenesis in the dehydroepiandrosterone (DHEA)-treated rat model

This investigation was designed to study apoptosis and epithelialization during cystogenesis of the dehydroepiandrosterone rat model. Using in situ DNA 3'- end-labeling with non-radioactive digoxigenindidesoxy-UTP (dig-ddUTP), apoptosis is initially seen in cumulus granulosa cells and other granulosa cells facing the antrum. During cystogenesis, apoptosis systematically progresses from the cumulus towards the mural granulosa layer. In contrast, granulosa cells of atretic follicles undergo apoptosis in a random manner. The outer layer of mural granulosa cells during cystogenesis escapes apoptosis. Granulosa cells contain vimentin. However, the outer mural granulosa cell layer that lines the cyst acquires keratin. In addition to being associated with each other via gap junctions, the outer layer of granulosa cells acquire tight junctions. With the characterization of the transformation of the outer mural granulosa cells into a characteristic epithelium and the orderly progression of apoptosis, we further the understanding of the multifaceted process of cystogenesis of the ovarian antral follicle.

Fate of hamster oviductin in the oviduct and uterus during early gestation

Oviductins are a family of glycoproteins which are synthesized and secreted by oviductal secretory cells and which, upon their secretion in the lumen of the oviduct, become associated with postovulatory oocytes and developing embryos. Recently, we showed that hamster oviductin is maximally secreted in the oviduct at the time of ovulation and is later associated with a certain population of uterine epithelial cells, where it is subsequently endocytosed and degraded. In light of these results, this study was conducted to follow the fate of hamster oviductin in the oviduct and uterus during early gestation. Using a monoclonal antibody against hamster oviductin, immunofluorescence and immunogold labeling revealed that during early gestation, immunoreactivity to oviductin in the uterus gradually diminished to an almost total disappearance at time of implantation. However, the strong labeling intensity remained unchanged in the oviduct. Biochemical analyses demonstrated that a degradation of oviductin occurs in the uterus, and a loss of immunoreactivity was also observed as gestation progressed, so that by the time of implantation, immunoreactivity to oviductin was barely detectable. The decrease of oviductin along the uterine epithelium at the time of blastocyst attachment and its final disappearance at implantation suggest that this glycoprotein could be a potential modulator of uterine receptivity.

Coordinated expression of matrilysin during TPA-induced apoptosis of LNCaP cells: two parallel processes affected by TPA

Matrix metalloproteinases (MMPs) are upregulated by growth factors and 12-O-tetradecanoyl-phorbol-13-acetate (TPA). TPA (10 nM) induced apoptosis in LNCaP cells grown in serum-free medium at high seeding density, and increased mRNA and secreted protein levels for the MMP matrilysin. While the TPA-augmented increase in matrilysin mRNA was seen at 4 h, secreted matrilysin protein levels at 8 h, TPA-induced DNA ladder formation was seen only at 10 h and the TPA-induced apoptosis was detected at 12 h. The sequence of events suggested a functional role for matrilysin in apoptosis. However, when the MMP inhibitor BB-2516 was used (25 microM, with IC50 of 20 nM for matrilysin), there was no effect of BB-2516 on TPA-induced apoptosis in LNCaP cells (P = 0.2072). This observation indicates that MMPs including matrilysin do not play a primary role in TPA-induced apoptosis in LNCaP cells. We conclude that the TPA-induced apoptosis and the regulation of matrilysin (a TPA-response element (TRE)-containing gene), are independent and parallel processes.

Apoptosis: a programmed cell death involved in ovarian and uterine physiology

Apoptosis is a form of programmed cell death which occurs through the activation of a cell-intrinsic suicide machinery. The biochemical machinery responsible for apoptosis is expressed in most, if not all, cells. Contrary to necrosis, an accidental form of cell death, apoptosis does not induce inflammatory reaction noxious for the vicinity. Apoptosis is primarily a physiologic process necessary to remove individual cells that are no longer needed or that function abnormally. Apoptosis plays a major role during development, homeostasis. Many stimuli can trigger apoptotic cell death, but expression of genes can modulate the sensibility of the cell. The aim of this review is to summarise current knowledge of the molecular mechanisms of apoptosis and its roles in human endometrium and ovary physiology.

Estrogen and apoptosis in the developing sexually dimorphic preoptic area in female rats

Effect of estrogen on apoptotic cell death was studied in the two sexually dimorphic neuronal groups in the developing rat preoptic area (POA): the anteroventral periventricular nucleus of the POA (AVPvN-POA); and the sexually dimorphic nucleus of the POA (SDN-POA). A specific labelling of nuclear fragmentation was performed by terminal deoxynucleotydyl transferase(TdT)-mediated dUTP-biotin nick end-labeling method (TUNEL method) to demonstrate apoptosis. In the AVPvN-POA whose size is larger in females than in males, the number of TUNEL-positive cells was not significantly different between day 5 control and female pups sacrificed 10 h after 25 micrograms estradiol benzoate (EB) injection. However, TUNEL-positive cells showed a significant increase in the female pups sacrificed 24 h after EB injection, compared to that shown in the control female pups. In the SDN-POA whose size is larger in males than in females, EB injection significantly decreased TUNEL-positive cells in the female pups sacrificed 24 h after EB injection, compared to that in controls. These results suggest that estrogen regulates the neuronal number by facilitating apoptotic cell death in the developing AVPvN-POA or by inhibiting it in the developing SDN-POA.

Follicular dendritic cells inhibit apoptosis in human B lymphocytes by a rapid and irreversible blockade of preexisting endonuclease

During germinal center reactions, a minority of B lymphocytes are selected after successful binding to follicular dendritic cells (FDCs). The majority of the B cells, however, die by apoptosis. One of the characteristics of apoptosis is rapid fragmentation of DNA by an endogenous endonuclease. The regulation of apoptosis and endonuclease activity in germinal center (GC) B cells is largely unknown. In this study we have investigated the induction and inhibition of endonuclease activity in GC B cells. We also investigated the role of FDCs, surface Ig (sIg), sIgM, CD21, CD22 CD40, and intracellular Zn2+ in the regulation of endonuclease activity. We have found that DNA fragmentation in GC B cells is caused by a preexisting endonuclease very similar to NUC-18 (an 18-kD endonuclease identified in rat thymocytes). Endonuclease activity in GC B cells appears to be rapidly and irreversibly blocked after interaction with FDCs, but not after cross-linkage of sIg, sIgM, CD21, CD22, or CD40. Addition of soluble CD40-human IgM fusion protein (sCD40) to FDC-B cell cultures also did not interfere with FDC-mediated B cell rescue. Chelation of intracellular Zn2+ during FDC-B cell cultures resulted in abrogated B cell rescue. These data suggest that FDCs inhibit apoptosis in GC B cells by a rapid inactivation of preexisting endonuclease using a mechanism distinct from CD40 ligation.

Apoptosis and the cell cycle

In this review, we consider apoptosis as a process intimately linked to the cell cycle. There are several reasons for thinking of apoptosis as a cell cycle phenomenon. First, within the organism, apoptosis is almost exclusively found in proliferating tissues. Second, artificial manipulation of the cell cycle can either prevent or potentiate apoptosis, depending on the point of arrest. Data from such studies have suggested that molecules acting late in G1 are required for apoptosis. Since passage through late G1 into S phase in mammalian cells is known to be regulated by p53 and by activation of cyclin-dependent kinases, we also examine recent studies linking these molecules to the apoptotic pathway.

Apoptosis. Its significance in cancer and cancer therapy

Apoptosis is a distinct mode of cell death that is responsible for deletion of cells in normal tissues; it also occurs in specific pathologic contexts. Morphologically, it involves rapid condensation and budding of the cell, with the formation of membrane-enclosed apoptotic bodies containing well-preserved organelles, which are phagocytosed and digested by nearby resident cells. There is no associated inflammation. A characteristic biochemical feature of the process is double-strand cleavage of nuclear DNA at the linker regions between nucleosomes leading to the production of oligonucleosomal fragments. In many, although not all of the circumstances in which apoptosis occurs, it is suppressed by inhibitors of messenger RNA and protein synthesis. Apoptosis occurs spontaneously in malignant tumors, often markedly retarding their growth, and it is increased in tumors responding to irradiation, cytotoxic chemotherapy, heating and hormone ablation. However, much of the current interest in the process stems from the discovery that it can be regulated by certain proto-oncogenes and the p53 tumor suppressor gene. Thus, c-myc expression has been shown to be involved in the initiation of apoptosis in some situations, and bcl-2 has emerged as a new type of proto-oncogene that inhibits apoptosis, rather than stimulating mitosis. In p53-negative tumor-derived cell lines transfected with wild-type p53, induction of the gene has, in rare cases, been found to cause extensive apoptosis, instead of growth arrest. Finally, the demonstration that antibodies against a cell-surface protein designated APO-1 or Fas can enhance apoptosis in some human lymphoid cell lines may have therapeutic implications.