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P S Cooke

Publications and source records attributed to P S Cooke.

At least 19 recordsLinked to original sources
PubMed2003

The phytoestrogen genistein suppresses cell-mediated immunity in mice.

The soy phytoestrogen, genistein, induces thymic atrophy when administered to ovariectomized mice by injection or in the diet. Injected genistein also causes decreased humoral immunity, but the effects of genistein on cell-mediated immunity have not been addressed. Here we examined effects of injected and dietary genistein on cell-mediated immune responses. Female C57BL/6 mice (25- to 27-days-old) were ovariectomized, then placed on phytoestrogen-free feed 5 days later. Seven days after ovariectomy, they were given daily subcutaneous injections of either dimethylsulfoxide (DMSO) or genistein (8, 20, 80 mg/kg) for 28 days; some mice were given 80 mg/kg genistein plus the anti-estrogen ICI 182,780 (5 mg/kg/week). Cell-mediated immune response was tested by analyzing the delayed-type hypersensitivity (DTH) response to a hapten, 4-hydroxy-3-nitrophenyl acetyl succinimide (NP-O-SU), at the end of treatment. Reversibility of the effects of genistein was tested by measuring the DTH response in mice that were given genistein (20 or 80 mg/kg) for 28 days, then allowed to recover for 28 days. To determine if dietary genistein could affect cell-mediated immunity, mice ovariectomized as above were fed genistein at 0, 1000 or 1500 parts per million (ppm) for 28 days. There was a 46-67% decrease in the DTH response in the footpads of mice injected with 8-80 mg/kg genistein compared with controls (P<0.05 vs control for all treatment groups); these effects were reversible. On histopathological examination of the feet, there was decreased cell infiltration in genistein-treated animals compared with controls, and the numbers of CD4(+) and CD8(+) T cells in popliteal lymph nodes were reduced. The effects of genistein are mediated through both estrogen receptor (ER) and non-ER pathways, as the anti-estrogen ICI 182,780 only partially blocked the effects of genistein on the DTH response. Dietary genistein (1000 or 1500 ppm) decreased cell-mediated immunity while producing serum genistein concentrations in the physiological range for humans under certain nutritional conditions. Further work is needed to determine if dietary genistein and phytoestrogen exposure can produce effects on cell-mediated immunity in humans or other animals under various nutritional conditions.

Animals↗
PubMed2001

Epithelial-stromal tissue interaction in paramesonephric (Müllerian) epithelial differentiation.

During organogenesis, the middle to caudal portion of Müllerian epithelium differentiates into uterine and vaginal epithelia in females. Functional differentiation of uterine and vaginal epithelia occurs in adulthood, and is regulated by 17beta-estradiol (E(2)) and progesterone. In this report, the roles of mesenchyme/stroma in differentiation of uterine and vaginal epithelia were studied in tissue recombination experiments. At birth, Müllerian epithelium was negative for uterine and vaginal epithelial markers. Tissue recombinant experiments showed that uterine and vaginal gene expression patterns were induced in neonatal Müllerian epithelium by the respective mesenchymes. Differentiated adult uterine and vaginal epithelia did not change their original gene expression in response to heterotypic mesenchymal induction. In the adult vagina, E(2) induced expression of involucrin, a CCAAT/enhancer-binding protein beta and cytokeratin 1 via estrogen receptor alpha (ERalpha). Tissue recombination experiments with wild-type and ERalpha knockout mice demonstrated that epithelial gene expression is regulated by E(2) via epithelial-stromal tissue interactions. Uterine/vaginal heterotypic tissue recombinations demonstrated that functional differentiation of uterine and vaginal epithelia required organ-specific stromal factors. In contrast, stromal signals regulating epithelial proliferation appeared to be nonspecific in the uterus and vagina.

Animals↗
PubMed2001

Role of the aryl hydrocarbon receptor in the development of control and 2,3,7,8-tetrachlorodibenzo-p-dioxin-exposed male mice.

Experiments were conducted to determine the role of the aryl hydrocarbon receptor (AhR) in the development of control and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-exposed C57Bl/6 male mice. Male and female mice heterozygous for the AhR (Ahr+/-) were mated, and pregnant females were dosed orally on gestation day 13 with corn oil vehicle or TCDD (5 microg/kg). Pups were necropsied on postnatal day (PND) 21, 35, and 90. Comparison of vehicle-exposed wild-type (Ahr+/+) pups with vehicle-exposed AhR knockout (AhRKO; Ahr-/-) pups confirmed and extended previous reports that development of the liver, heart, spleen, thymus, and kidney is affected by absence of the AhR. Lung, submandibular gland, testis, and epididymis weights were also affected, indicating that the AhR plays a role in normal development of these organs as well. The presence or absence of the AhR had no effect on the incidence of hydronephrosis, daily sperm production, or cauda epididymal sperm numbers in vehicle-exposed mice. TCDD caused numerous effects in wild-type mice that were absent in AhRKO mice; specifically, hydronephrosis, increases in relative liver and heart weight, decreases in absolute heart and lung weight, and decreases in absolute and relative thymus, submandibular gland, epididymis, and testis weight. In several cases, TCDD produced one effect in wild-type mice (reductions in body weight and absolute thymus, submandibular gland, and epididymis weight on PND 21; and reductions in absolute and relative submandibular gland and absolute testis weight on PND 35) but caused the opposite effect in AhRKO mice. In yet other cases (reduced relative spleen weight on PND 21 and reductions in absolute and relative thymus weight on PND 35), TCDD produced similar effects in wildtype and AhRKO mice. There were also cases in which TCDD significantly affected AhRKO mice without significantly altering the same endpoint in wild-type mice; absolute liver, lung, and kidney weight were increased and relative submandibular gland weight was decreased on PND 21; relative heart weight was reduced and absolute lung weight increased on PND 35; and relative liver weight was decreased on PND 90. Although many effects of TCDD required the presence of the AhR, these results provide evidence either for multiple forms of the AhR in mice (one or more of which are still present in AhRKO mice), or for AhR-independent effects of low-level TCDD exposure.

Animals↗
PubMed2001

The role of estrogen and estrogen receptor-alpha in male adipose tissue.

Males and females both express estrogen receptor (ER) in white adipose tissue (WAT), and estrogens appear to play an important role in regulating WAT in females. However, the role of ER in male WAT was unclear. In this review, we describe our work, which used wild type (WT) and ERalpha-knockout (alphaERKO) male and female mice to determine the role of ERalpha in regulating WAT and brown adipose tissue (BAT). There were progressive increases in WAT with advancing age in alphaERKO compared with WT males; weights of various WAT depots in alphaERKO males were increased by more than 100% compared with WT controls during adulthood. Conversely, BAT weight was similar in alphaERKO and WT males at all ages. Adipocyte areas and numbers were also increased in WAT from alphaERKO compared with WT males. Compared with WT controls, alphaERKO females also had increases in WAT. The alphaERKO mice also had insulin resistance and impaired glucose tolerance, similar to humans lacking ERalpha or aromatase. The obesity in alphaERKO males appeared to involve decreased energy expenditure rather than hyperphagia. In summary, ERalpha absence causes adipocyte hyperplasia and hypertrophy in WAT, but not BAT, and is accompanied by insulin resistance and glucose intolerance in both males and females. These results are the first evidence that the estrogen/ERalpha signaling system is critical in female and male WAT deposition, and may have clinical implications.

Adipose Tissue↗
PubMed2001

Altered prostate growth and daily sperm production in male mice exposed prenatally to subclinical doses of 17alpha-ethinyl oestradiol.

Approximately 2 million women in the USA and Europe continue taking oral contraceptives each year during undetected pregnancy due primarily to non-compliance and also to individual variation in sensitivity to hormones in the contraceptives. Prenatal exposure to oral contraceptives containing 17alpha-ethinyl oestradiol (EE) has generally not been associated with an increased incidence of externally observable malformations at birth. The purpose of this study was to assess effects on reproductive organs in adult male mice that had been exposed during gestation day 0 through 17 (equivalent to gestation week 16 in humans) to clinically relevant (approximately 0.5 microg/kg/day) and lower doses of EE. Doses used in this study ranged from 0.002 to 2 microg/kg/day. By 5 months of age, prostate weight was significantly (P < 0.05) higher than controls in most treatment groups of EE (0.02-2 microg/kg). Prostatic androgen receptor populations were significantly elevated only in the 0.02 microg/kg group, suggesting different mechanisms for the increase in prostate weight at different doses. Daily sperm production (DSP) and DSP per gramme of testis were reduced in all treatment groups during adolescence, but not later in adulthood. These findings are consistent with prior studies showing that prenatal exposure of mice to very low doses of a number of oestrogenic chemicals can alter the adult male reproductive system without causing gross external malformations.

Aging↗
PubMed2001

Regulation of progesterone receptors and decidualization in uterine stroma of the estrogen receptor-alpha knockout mouse.

Regulation of progesterone receptor (PR) in uterine stroma (endometrial stroma plus myometrium) by estrogen was investigated in estrogen receptor-alpha (ERalpha) knockout (alphaERKO) mice. 17 beta-Estradiol (E(2)) increased PR levels in uterine stroma of ovariectomized alphaERKO mice, and ICI 182 780 (ICI) inhibited this E(2)-induced PR expression. Estrogen receptor-beta(ER beta) was detected in both uterine epithelium and stroma of wild-type and alphaERKO mice by immunohistochemistry. In organ cultures of alphaERKO uterus, both E(2) and diethylstilbestrol induced stromal PR, and ICI inhibited this induction. These findings suggest that estrogen induces stromal PR via ERbeta in alphaERKO uterus. However, this process is not mediated exclusively by ERbeta+, because in ERbeta knockout mice, which express ERalpha, PR was up-regulated by E(2) in uterine stroma. In both wild-type and alphaERKO mice, progesterone and mechanical traumatization were essential and sufficient to induce decidual cells, even though E(2) and ERalpha were also required for increase in uterine weight. Progesterone receptor was strongly expressed in decidual cells in alphaERKO mice, and ICI did not inhibit decidualization or PR expression. This study suggests that up-regulation of PR in endometrial stroma is mediated through at least three mechanisms: 1) classical estrogen signaling through ERalpha, 2) estrogen signaling through ERbeta, and 3) as a result of mechanical stimulation plus progesterone, which induces stromal cells to differentiate into decidual cells. Each of these pathways can function independently of the others.

Animals↗
PubMed2000

Increased adipose tissue in male and female estrogen receptor-alpha knockout mice.

Estrogen regulates the amount of white adipose tissue (WAT) in females, but its role in males and whether WAT effects involve estrogen receptor-alpha (ERalpha) or ERbeta were unclear. We analyzed the role of ERalpha in WAT and brown adipose tissue by comparing these tissues in wild-type (WT) and ERalpha-knockout (alphaERKO) male and female mice. Brown adipose tissue weight was similar in alphaERKO and WT males at all ages. Progressive increases in WAT were seen in alphaERKO males with advancing age. Epididymal, perirenal, and inguinal WAT weighed 139-185% more in alphaERKO than in WT males by 270-360 days of age. Epididymal and perirenal adipocyte size was increased 20% in alphaERKO males. Adipocyte number was 82-168% greater in fat pads of alphaERKO vs. WT males. Compared with WT, 90-day-old alphaERKO females had increases in fat pad weights (54-103%), adipocyte size, and number. Both alphaERKO males and females had insulin resistance and impaired glucose tolerance, similar to humans lacking ERalpha or aromatase. Energy intake was equal in WT and alphaERKO males, indicating that obesity was not induced by hyperphagia. In contrast, energy expenditure was reduced by 11% in alphaERKO compared with WT males, indicating that altered energy expenditure may be important for the observed obesity. In summary, ERalpha absence causes adipocyte hyperplasia and hypertrophy, insulin resistance, and glucose intolerance in both sexes. These results are evidence that estrogen/ERalpha signaling is critical in female and male WAT; obesity in alphaERKO males involves a mechanism of reduced energy expenditure rather than increased energy intake.

Adipocytes↗
PubMed2000

Paracrine mechanisms of mouse mammary ductal growth.

Ductal growth during puberty is stimulated by estrogens, which elicit their effects via specific estrogen receptors, ER alpha and ER beta. Analysis of mice with targeted disruption of ER alpha or ER beta has emphasized the importance of ER alpha in mammary gland development. In the mouse mammary gland, ER alpha are expressed in both epithelial and stromal cells (Kurita and Cunha, unpublished), which raises the possibility that the growth and morphogenetic effects of estrogen could be mediated via either epithelial or stromal ER. The aim of this paper is to review the role of epithelial versus stromal ER in mammary ductal-alveolar growth to assess the importance of paracrine mechanisms.

Aging↗
PubMed2000

Paracrine regulation of epithelial progesterone receptor by estradiol in the mouse female reproductive tract.

Regulation of progesterone receptor (PR) by estradiol-17beta (E(2)) in mouse uterine and vaginal epithelia was studied. In ovariectomized mice, PR expression was low in both vaginal stroma and epithelium, but high in uterine epithelium. E(2) induced PR in vaginal epithelium and stroma, but down-regulated PR in uterine epithelium. Analysis of estrogen receptor alpha (ERalpha) knockout (ERKO) mice showed that ERalpha is essential for E(2)-induced PR expression in both vaginal epithelium and stroma, and for E(2)-induced down-regulation, but not constitutive expression of PR in uterine epithelium. Regulation of PR by E(2) was studied in vaginal and uterine tissue recombinants made with epithelium and stroma from wild-type and ERKO mice. In the vaginal tissue recombinants, PR was induced by E(2) only in wild-type epithelium and/or stroma. Hence, in vagina, E(2) induces PR directly via ERalpha within the tissue. Conversely, E(2) down-regulated epithelial PR only in uterine tissue recombinants constructed with wild-type stroma. Therefore, down-regulation of uterine epithelial PR by E(2) requires stromal, but not epithelial, ERalpha. In vitro, isolated uterine epithelial cells retained a high PR level with or without E(2), which is consistent with an indirect regulation of uterine epithelial PR in vivo. Thus, E(2) down-regulates PR in uterine epithelium through paracrine mechanisms mediated by stromal ERalpha.

Animals↗
PubMed2000

Postulated human sperm count decline may involve historic elimination of juvenile iodine deficiency: a new hypothesis with experimental evidence in the rat.

Human sperm count studies, historic dietary iodination, and an animal model where neonatal goitrogen administration causes unprecedented testis enlargement, together suggest an hypothesis relevant to the postulated fall in human sperm counts. We present the hypothesis with a supporting study extending the model to include iodine deficiency. In a one-generation rat reproduction study, dams were fed an iodine sufficient (control, 200 ppb I) or deficient (low iodine diet [LID], <20 ppb I) diet from prebreeding through weaning, when male offspring were divided into three groups: 1) controls from iodine sufficient dams, 2) neonatal LID (NLID) from the LID dams, fed control diet postweaning, and 3) chronic LID (CLID) from LID dams, fed a moderate LID (40 ppb I) postweaning. F1 males were euthanized on postnatal day (PND) 133+/-1. Each of the three diet groups comprised two subgroups in which testicular parameters were evaluated: 1) daily sperm production (DSP), sperm motility, morphology, and histopathology, and 2) Sertoli cell and round spermatid morphometry. In the first subgroup, NLID and CLID testes weights were 8.5% and 14.0% heavier than their unusually heavy controls (3.921 g; historical control mean approximately 3.5 g), with proportional DSP increases. Sperm motility, morphology, and testis histopathology were unaffected. In the morphometry subgroup, respective increases in NLID and CLID rats included testes weights (+28.6% and +20.3%), Sertoli cells (+24.8% and +23.9%), and round spermatids (+20.4% and +15.8%). The results indicate that neonatal iodine deficiency can significantly increase spermatogenic function in rats, and support our hypothesis concerning human sperm counts.

Animals↗
PubMed2000

Antiestrogenic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in mouse uterus: critical role of the aryl hydrocarbon receptor in stromal tissue.

The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and the role of aryl hydrocarbon receptor (AhR) in estradiol (E(2))-induced uterine epithelial mitogenic activity and secretory protein mRNA expression were determined. Ovariectomized wild-type (wt) and AhR-knockout (AhRKO) mice received oil, E(2), or 5 microg/kg TCDD+E(2). E(2) stimulated similar large increases in the uterine epithelial labeling index (LI) and mRNA abundance for the E(2)-dependent epithelial secretory protein, lactoferrin (LF), in both wt and AhRKO mice. However, uterine epithelial LI and LF mRNA were significantly reduced by TCDD+E(2) in wt but not AhRKO mice. To determine the roles of stromal and epithelial AhR in the TCDD effect, uterine stroma and epithelium from AhRKO and wt mice were enzymatically separated and recombined into four types of tissue recombinants that either contained or lacked AhR in one or more tissue compartments. Tissue recombinants were grafted into nude mice, which were later ovariectomized and given oil, E(2), or TCDD+E(2). Epithelial LI was significantly reduced by TCDD in grafts containing stromal AhR, regardless of epithelial AhR status. However, LI was unaffected by TCDD in grafts lacking stromal AhR, even when epithelial AhR was present. Thus, TCDD inhibits E(2)-induced uterine epithelial mitogenic and secretory activity, and this requires AhR. Anti-proliferative effects of TCDD on uterine epithelia appear to be mediated indirectly through stromal AhR, suggesting that liganded AhR alters epithelial function by disrupting normal E(2)-induced stromal activity. This is the first demonstration that TCDD impairs uterine epithelial function by altering normal stromal-epithelial interactions in vivo.

Animals↗
PubMed2000

Paracrine regulation of epithelial progesterone receptor and lactoferrin by progesterone in the mouse uterus.

The objective of this study was to determine whether uterine stromal and/or epithelial progesterone receptor (PR) is required for the antagonism by progesterone (P(4)) of estradiol-17beta (E(2)) action on expression of PR and lactoferrin in uterine epithelium. Uterine tissue recombinants were prepared with epithelium (E) and stroma (S) from wild-type (wt) and PR knockout (PRKO) mice: wt-S+wt-E and PRKO-S+wt-E. P(4) action on epithelial PR expression was studied in wt-S+wt-E and PRKO-S+wt-E tissue recombinants. E(2) down-regulated epithelial PR in both types of tissue recombinants, but P(4) blocked E(2)-induced down-regulation of epithelial PR only in wt-S+wt-E tissue recombinants. Thus, P(4) requires stromal PR to inhibit E(2)-induced down-regulation of epithelial PR. Epithelial PR is not sufficient in itself. The inhibitory effect of P(4) on lactoferrin expression was studied in 4 types of tissue recombinants (wt-S+wt-E, PRKO-S+wt-E, wt-S+PRKO-E, and PRKO-S+PRKO-E). E(2) induced lactoferrin in all 4 types of tissue recombinants. P(4) blocked E(2)-induced lactoferrin expression only in wt-S+wt-E tissue recombinants. In wt-S+PRKO-E tissue recombinants, P(4) inhibited lactoferrin expression only partially. P(4) failed to block E(2)-induced lactoferrin expression in PRKO-S+wt-E and PRKO-S+PRKO-E tissue recombinants. Thus, both epithelial and stromal PR are essential for full P(4) inhibition of E(2)-induced lactoferrin expression.

Animals↗
PubMed2000

Myocardial ischemia-reperfusion injury in estrogen receptor-alpha knockout and wild-type mice.

We investigated the function of estrogen receptor-alpha in global myocardial ischemia and reperfusion injury in male estrogen receptor-alpha knockout (ERKO) and wild-type mice. Mouse hearts were subjected to 45 min of global ischemia followed by 180 min of reperfusion. The hearts were excised, cannulated, and maintained in a chilled (4 degrees C) cardioplegia solution until warm (37 degrees C) oxygenated Krebs-Henseleit bicarbonate buffer was perfused through the coronary arteries. ERKO hearts started beating later and had a higher incidence of ventricular fibrillation and/or tachycardia than control hearts. Coronary flow rate was significantly lower in ERKO hearts during the 90- and 120-min periods of reperfusion. Ca(2+) accumulation was significantly greater following 30, 90, 120, 150, and 180 min of reperfusion in ERKO hearts. Nitrite production was significantly less in ERKO hearts following 90, 120, and 150 min of reperfusion. Myocardial reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was significantly lower in experimental ERKO hearts. Marked interstitial edema and contraction bands were seen in hematoxylin-eosin-stained sections of ischemia-reperfused ERKO hearts but not in control tissues. Hematoxylin-basic fuchsin-picric acid-stained sections from experimental ERKO hearts had fewer viable myocytes compared with controls. Transmission electron microscopy revealed swollen and fragmented mitochondria with amorphous and granular bodies, loss of matrix, and rupture of cristae in experimental ERKO hearts. This is the first demonstration that estrogen receptor-alpha plays a cardioprotective role in ischemia-reperfusion injury in males.

Animals↗
PubMed2000

The differential fate of mesonephric tubular-derived efferent ductules in estrogen receptor-alpha knockout versus wild-type female mice.

We investigated mesonephric tubular-derived efferent ductules in female wild-type (WT) and estrogen receptor-alpha knockout (ERalphaKO) mice from late fetal to adult life. On gestational day 17, efferent ductules in both fetal WT and ERalphaKO females were well developed and morphologically similar, although one third the size of the male counterpart. Unexpectedly, efferent ductules with a ciliated epithelium were still present on postnatal day 10 in WT and ERalphaKO females. By day 23, however, marked phenotypic differences occurred in efferent ductules of WT and ERbetaKO vs. ERalphaKO female mice. In the latter, efferent ductules became hypertrophied and dilated, whereas only small tubules remained in WT and ERbetaKO adult mice. The serum testosterone concentrations were similar in 21- to 25-day-old ERalphaKO, heterozygous, and WT female mice, suggesting that increased testosterone was not inducing enlargement of efferent ductules in ERalphaKO females. In conclusion, remnants of efferent ductules persisted in normal adult female mice, although these structures were greatly reduced in size compared with efferent ductules in ERalphaKO female mice. The underlying mechanism inducing hypertrophy and dilation of efferent ductules in ERalphaKO females is not clear, but secretory and/or reabsorptive function of female efferent ductules may involve ERalpha.

Animals↗
PubMed2000

Normal development of thymus in male and female mice requires estrogen/estrogen receptor-alpha signaling pathway.

Estrogen receptors (ERs) are expressed in the thymus of both males and females, but their role in thymic development and function is unclear. To determine whether ERalpha plays a role in thymic function of either males or females, we compared thymuses of male and female wild-type (WT) and ERalpha knockout (alphaERKO) mice from birth to adulthood. Although thymic size was similar in both male and female WT and alphaERKO mice at birth (d 0), by postnatal d 5 and at all subsequent ages, both male and female alphaERKO mice had significant (30-55%) reductions in thymic weight. Morphometric analysis revealed a reduction in thymic medullary areas in adult alphaERKO mice compared with age-matched WT controls that paralleled thymic involution. There were changes in relative percentages of CD4+ and CD4+CD8+ T-cells, and large decreases (70-80%) in overall absolute numbers of CD4+ and CD4+CD8+ T-cells. Serum corticosterone and testosterone levels were not different in either neonatal or adult male WT or alphaERKO mice, and serum levels of 17beta-estradiol (E2) were similar in neonatal WT and alphaERKO males, indicating that increases in these thymolytic hormones are not responsible for the decreased thymic weight in alphaERKO males. Additionally, delayed-type hypersensitivity was significantly increased in male alphaERKO mice compared with WT mice. In summary, ERalpha deficiency does not inhibit initial differentiation or fetal thymic development, but the absence of ERalpha results in marked decreases in thymic size in both sexes during the postnatal period. These results are the first direct demonstration that the E2/ERalpha signaling system is necessary for maintenance of normal postnatal function of the female thymus gland. The similar results obtained in males demonstrate a role for the E2/ERalpha signaling system in the male thymus and emphasize that estrogens play a more critical role in the male than previously realized.

Animals↗
PubMed1999

Ah receptor and ARNT protein and mRNA concentrations in rat prostate: effects of stage of development and 2,3,7, 8-tetrachlorodibenzo-p-dioxin treatment.

Effects of stage of development and 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) exposure on aryl hydrocarbon receptor (AhR) and AhR nuclear translocator (ARNT) protein concentrations in reproductive organs of male rats were determined. AhR protein levels in developing rat ventral and dorsolateral prostate decreased with age, declining approximately 70% between Postnatal Days (PND) 1 and 21. ARNT protein levels also decreased with age in dorsolateral, but not ventral prostate. The developmental decreases in prostatic AhR and ARNT protein were associated with decreases in AhR and ARNT mRNA. AhR and ARNT protein concentrations in fetal urogenital sinus on Gestation Days (GD) 16, 18, and 20 were similar to levels in ventral prostate on PND 7. TCDD exposure of adult male rats (0.2, 1, 5, or 25 micrograms/kg po, 24 h) decreased AhR but not ARNT protein in ventral and dorsolateral prostate, vas deferens, and epididymis. In utero and lactational TCDD exposure (1.0 micrograms/kg dam po, GD 15) did not alter ARNT levels but reduced prostatic AhR protein levels on PND 7 and delayed the developmental decrease in AhR protein in ventral and dorsolateral prostate. Finally, pretreatment of rat pups for 24 h with TCDD (5 micrograms/kg ip) down-regulated prostatic AhR protein on PND 7, but not on PND 1. Thus, prostatic AhR and ARNT protein and mRNA levels are regulated with age, whereas only AhR protein concentration is altered by TCDD exposure. Because in utero and lactational TCDD exposure only decreased prostatic AhR on PND 7, it is unlikely that down-regulation of AhR is the mechanism by which perinatal TCDD exposure impairs prostate development.

Animals↗
PubMed1999

Tissue compartment-specific estrogen receptor-alpha participation in the mouse uterine epithelial secretory response.

17Beta-estradiol (E2) acts through the estrogen receptor (ER) to regulate uterine epithelial cell growth, proliferation, differentiation, and secretory protein production. We have previously shown that E2-induced uterine epithelial proliferation is mediated indirectly by ER alpha-positive stroma; epithelial ER alpha is neither necessary nor sufficient for E2-induced uterine epithelial mitogenesis. In the present study, we addressed the question of whether production of uterine epithelial secretory proteins and their messenger RNAs (mRNAs) requires ER alpha in stroma, epithelium, or both by analyzing tissue recombinations composed of uterine tissue from adult ER alpha knockout (ko) and neonatal BALB/c (wt) mice. Stroma (S) and epithelium (E) were separated by trypsinization, and four types of uterine tissue recombinants were prepared: wt-S + wt-E, wt-S + ko-E, ko-S + wt-E, and ko-S + ko-E. These tissue recombinants were grown as subrenal capsule grafts in intact female nude mice for 4 weeks, at which time the hosts were ovariectomized. To assess the production of secretory proteins and their mRNAs, 1 week after ovariectomy the hosts were given three daily injections of oil or E2 (100 ng), and then 24 h later the grafts were recovered and used for either ER or lactoferrin (LF) immunohistochemistry. To assess steady state mRNA levels by Northern blotting, hosts received one injection of oil or E2 24 h before harvest. ER immunohistochemistry was used to monitor the completeness of tissue separation. In wt-S + wt-E tissue recombinants from E2-treated hosts, the epithelium stained intensely for LF (an abundant E2-dependent uterine secretory protein), whereas similar tissue recombinants from oil-treated hosts showed minimal immunostaining. Conversely, LF immunostaining was minimal in wt-S + ko-E grafts from both oil- and E2-treated hosts. LF staining was also minimal in ko-S + ko-E and ko-S + wt-E tissue recombinants regardless of hormone treatment. For Northern analyses, the epithelial content of the tissue recombinants was monitored using the reference epithelial transcript, E-cadherin. While all tissue recombinant groups expressed E-cadherin mRNA, wt-S + wt-E tissue recombinants from E2-treated hosts produced a strong, single 2.6-kb band of LF mRNA. LF transcripts were minimal or absent in all other tissue recombinant types. Northern blotting results identical to those seen for LF were also observed for the uterine secretory protein complement component C3. Our data demonstrate that both stromal and epithelial ER alpha are required for the production of LF protein and of LF or C3 mRNAs in response to E2. Thus, in contrast to E2-induced epithelial mitogenesis, which requires only stromal ER alpha, both epithelial and stromal ER alpha are necessary for the production of E2-dependent epithelial secretory proteins.

Animals↗