SCF and APC: the Yin and Yang of cell cycle regulated proteolysis

Uterine Cell proliferation was studied in intact Sprague-Dawley (SD) and Fischer 344 (F344) rats exposed to the antiestrogens tamoxifen (TAM; 5, 10, 20, or 40 mg/kg) and toremifene (TOR: 21.2 or 42.4 mg/kg). The antiestrogens were administered to animals via gavage daily for 2 or 12 wk. Uterine proliferation was assessed using markers for the proliferating cell nuclear antigen (PCNA) and by the bromodeoxyuridine (BrdU) method. Diethylstilbestrol (DES) was used as an estrogenic reference compound. The antiestrogens either reduced or prevented changes of myometrial and stromal proliferation indices (PI). TAM and TOR caused a time-dependent reduction of endometrial glands without an associated decrease in cell proliferation. In the luminal columnar epithelium, the antiestrogens depressed PCNA PI but enhanced BrdU PI, indicating a low continuous DNA synthesis in otherwise quiescent cells. The antiestrogens induced focal hyperplastic multilayered epithelia with PCNA-positive basal cells along segments of the luminal uterine epithelium. We suggest that this hyperplastic epithelium represents remnants from the glandular epithelium. DES was less efficient in inducing these changes but induced squamous metaplasias in the F344 rats. Uterine effects of the 2 antiestrogens were comparable with the exception of I TAM-exposed (40 mg/kg) SD rat that showed squamous metaplasia. F344 rats were more sensitive to the estrogenic action of DES than were the SD rats.     

Bisphenol A interacts with the estrogen receptor alpha in a distinct manner from estradiol

We investigated the interaction of bisphenol A (BPA, an estrogenic environmental contaminant used in the manufacture of plastics) with the estrogen receptor alpha (ERalpha) transfected into the human HepG2 hepatoma cell line and expanded the study in vivo to examine the effect of BPA on the immature rat uterus. Bisphenol A was 26-fold less potent in activating ER-WT and was a partial agonist with the ERalpha compared to E2. The use of ERalpha mutants in which the AF1 or AF2 regions were inactivated has permitted the classification of ER ligands into mechanistically distinct groups. The pattern of activity of BPA with the ERalpha mutants differed from the activity observed with weak estrogens (estrone and estriol), partial ERalpha agonists (raloxifene or 4-OH-tamoxifen), or a pure antagonist (ICI 182, 780). Intact immature female Sprague-Dawley rats were exposed to BPA alone or with E2 for 3 days. Unlike E2, BPA had no effect on uterine weight; however, like E2, both peroxidase activity and PR levels were elevated, though not to the level induced by E2. Following simultaneous administration, BPA antagonized the E2 stimulatory effects on both peroxidase activity and PR levels but did not inhibit E2-induced increases of uterine weight. These results demonstrate that BPA is not merely a weak estrogen mimic but exhibits a distinct mechanism of action at the ERalpha.     

Bacterial infection and endotoxin in female reproductive tract in rats: correlation with the developmental status of preimplantation embryos

During mammalian preimplantation development, a substantial numbers of embryos are believed to be lost for reasons that are unclear. Using female rats, we investigated whether the developmental status of embryos is influenced by bacterial infection and endotoxin in the reproductive tract. From the vagina of cycling rats (n = 11), 21 bacterial isolates were identified; they were Streptococcus faecalis (S. faecalis; 38%), Escherichia coli (E. coli; 19%), Acinetobactor calcoaceticus (A. calcoaceticus; 14%), and coagulase negative staphylococcus (14%), Micrococcus sp. (5%), Bacillus subtilis (B. subtilis; 5%) and Proteus vulgaris (P. vulgaris; 5%). From the vagina of day 4 pregnant rats (n = 12), 26 isolates were identified; they were S. faecalis (23%), A. calcoaceticus (23%), E. coli (15%), Micrococcus sp. (15%), B. subtilis (8%), P. vulgaris (4%), Staphylococcus aureus (4%), beta-hemolytic streptococcus (4%) and Pseudomonas aeruginosa (4%). Gram negative bacteria found in the vagina of cycling and day 4 pregnant rats were 38% and 46%, respectively. In both, bacterial load was 10(3)-10(5) colony forming units and there was no association with the abnormality of the recovered embryos. However, in two day 4 pregnant animals, pathogenic bacteria (Staphylococcus aureus and beta-hemolytic streptococcus) were isolated and embryos recovered from them were degenerated and deformed. The vagina of day 9 pregnant animals (n = 7) were, however, sterile. Consistently, in all animals, the upper reproductive tract (uterus and oviduct) was devoid of any bacteria and no anaerobic bacteria were isolated from any part of the tract. The levels of endotoxin in the vagina of cycling and day 4 pregnant rats were 1.35 +/- 0.1 and 1.17 +/- 0.1 endotoxin units (EU), respectively. It was undetectable in the oviduct and uterus of all animals (n = 5) except one which showed high levels of endotoxin in uterus (4.5 EU) and oviduct (2.2 EU) and the animal also produced degenerated and deformed embryos. These results indicate that common bacterial flora of vagina may not affect embryo development and the presence of pathogenic bacteria in the vagina and/or endotoxin in reproductive tract could be detrimental to viability of gametes and preimplantation embryos in rats.     

Pharmacokinetics of a novel benzodiazepine partial inverse agonist in the F344 rat, SD rat and B6C3F1 mouse

1. The pharmacokinetics of a novel benzodiazepine partial inverse agonist (S-8510) were studied in the Fischer 344 (F344) rat and B6C3F1 mouse to obtain information for the planning of carcinogenicity studies. Sprague-Dawley (SD) rats were also included for comparison. 2. Clear non-linear elimination of S-8510 was observed after single oral administration of S-8510 in all animals tested (F344 rat, 1-50 mg/kg; SD rat and B6C3F1 mouse, 1-150 mg/kg). 3. Exposure of S-8510 after single oral administration was in the order F344 rat > B6C3F1 mouse > SD rat. 4. Multiple oral administration to F344 rat and B6C3F1 mouse decreased the exposure to S-8510. 5. These results indicate that it is very important to evaluate pharmacological and toxicological studies based on exposure and to be careful in selecting the species and strains of animal used in toxicology studies.     

The role of 2D-doppler electrocardiography in the early diagnosis of massive acute pulmonary embolism and therapeutic monitoring

To clarify the histopathological progression of invasive tumors in the pituitary pars distalis due to estrogen, female Fischer 344 (F344) rats were treated subcutaneously with 5 mg/animal of estradiol dipropionate (ED) once every 2 wk for 13 wk. The animals were killed serially at 2-wk intervals during the investigation. The pituitaries with surrounding tissues were examined light microscopically. At week 7, pituitary cells showed proliferation and atypia with formation of blood-filled spaces. Lesions with these characteristics were diagnosed as adenomas. At week 9 or later, neoplastic cells exhibited extensive proliferation and infiltration into the surrounding tissues, suggesting development of carcinoma. Both proliferating cell nuclear antigen (PCNA) and 5-bromo-2'-deoxyuridine (BrdU) labeling index, markers of cell proliferation, were significantly increased in animals with adenoma or carcinoma. To detect sequential changes in pituitary weight, its signal intensity was periodically monitored in identical rats by using magnetic resonance (MR) imaging. The estimated pituitary weights revealed by MR imaging were comparable to the tumor weights obtained from rats at scheduled sacrifices. These results indicate that ED possesses the potential to cause carcinoma in rat pituitary and MR imaging is an effective tool for estimating the pituitary weight.     

Mechanism of interaction of digitalis with estradiol binding sites in rat uteri

Digitalis preparations have a weak estrogenic effect in man. The data in animals are equivocal. We have studied.the biologic effect of both digitoxin and digoxin on the rat uterus in vivo and the interaction of these drugs with the rat uterus estrogen receptor in vitro. Digitoxin and estradiol significantly increased the uterine weight of immature rats, while digoxin did not. The interaction of digitoxin and digoxin with the rat uterus estrogen cytosol receptor was studied using protamine sulfate precipitation and dextran-coated charcoal (DCC) assays. Both methods gave a Kd for the estradiol-receptor interaction between 0.8-3.1 X 10(-9) M (n = 20). Digitoxin at concentrations of 0.5-2.0 X 10(-6) M significantly inhibited the binding of estradiol to the specific or saturable binding sites with minimal inhibition of hormonal binding to nonspecific sites. The binding was competitive with a calculated Ki for digitoxin of 5.2-7.8 X 10(-7) M (n = 18). Digoxin failed to inhibit estradiol binding to the receptor protein in vitro. We conclude that digitoxin probably acts directly as a weak estrogen and that this effect probably explains the estrogen-like side effects seen with digitoxin therapy in man.     

Dexamethasone: increased weights and decreased [3H] estradiol retention of uterus, vagina and pituitary in the ovariectomized rat

Ovariectomized rats given 100 mug dexamethasone per day for 5 days had significantly heavier dry weights for uterus, vagina and pituitary, indicating a growth promoting activity of dexamethasone on these tissues in which estrogen normally promotes growth changes. The dexamethasone treated animals also retained significantly less [3H]estradiol per mug dry weight of tissue for uterus, vagina and pituitary. When[3H]estradiol retention was examined in vitro for the nuclear fraction, a significant decrease in retention was found for uterus, vagina and pituitary but not for hypothalamus or cerebral cortex. The decreased ability to bind [3H]estradiol, shown by the estrogen target tissues of the dexamethasone-treated rats, along with the increased growth of the estrogen target tissues, demonstrates that these tissues were able to show trophic responses even when greater levels were one-third of normal. Dexamethasone-treated animals tested for sexual receptivity in the presence or absence of progesterone priming did not show induction of facilitation of sexual receptivity. However, estrogen plus progesterone injections induced sexual receptivity in the presence of dexamethasone. When dexamethasone was combined with a dosage of estrogen, which by itself did not induce sexual receptivity, there was a significant response with 6 to 10 animals showing a low level of receptivity. Thus, dexamethasone can apparently synergize with estrogen to facilitate sexual receptivity.     

Differential regulation by estrogens of growth and prolactin synthesis in pituitary cells suggests that only a small pool of estrogen receptors is required for growth

PR1 cells are a prolactin (PRL)-secreting cell line derived from a pituitary lactotroph tumor found in 17beta-estradiol-treated Fischer 344 rats. We examined the effect of estrogen on cell proliferation and PRL synthesis under various culture conditions. Estrogen, at extremely low concentrations, induces cell proliferation in this cell line, whereas antiestrogen inhibits proliferation. Interestingly, the proliferation response is much more sensitive than the PRL response because 0.01 pM estradiol or diethylstilbestrol induces half-maximal growth induction [ approximately 0.1% estrogen receptor (ER) occupancy is required], whereas 0.01 nM concentration is required for half-maximal PRL induction ( approximately 50% ER occupancy is required). The proliferation response is not as sensitive to antiestrogen as the PRL response, because 10 nM concentration of the pure antiestrogen ICI 182,780 could not inhibit 1 nM estradiol- or diethylstilbestrol-induced proliferation. The same concentration of ICI 182,780 decreased PRL secretion to 1% of estradiol- or diethylstilbestrol-induced prolactin secretion suggesting a possible dichotomy of ER control of proliferation and PRL synthesis. The Kd of ER binding in these cells is about 3 x 10(-11) M. These results with the PR1 cells extend previous studies in other estrogen- regulated systems and suggest that only a small pool of ER is required for cell proliferation in contrast with the regulation of expression of specific genes. They also raise questions as to how a dimeric receptor functions when only one ligand site is occupied or when both an estrogen and an antiestrogen occupy one dimer.     

Strain comparisons of DFP neurotoxicity in rats

The purpose of this study was to assess intraspecies differences in behavioral and autonomic function in three strains of rat following administration of diisopropyl fluorophosphate (DFP), an irreversible inhibitor of acetylcholinesterase activity. Male rats of the Long-Evans (LE), Fischer 344 (F344), and Sprague-Dawley (SD) strains wer administered DFP at doses of 0-1.5 mg/kg (sc). The animals were placed 60 min later into one of two motor activity chambers and tested for 30 min. Motor activity was measured using either a Doppler-based system or a commercial photocell device. Following measurement of motor activity in the Doppler system, body temperature (Tb) was measured and blood was then withdrawn by cardiac puncture and analyzed for serum cholinesterase activity (ChE). The remaining rats were retested 1 d after DFP administration in the photocell device. The results showed a significant influence of strain on the effects of DFP. Motor activity of LE rats was reduced by DFP at doses of 1.0 and 1.5 mg/kg, whereas the activity of F344 rats was reduced only at 1.5 mg/kg. The relative sensitivity of SD rats depended on the device used to measure motor activity. The SD rats resembled F344 rats in their response to DFP when motor activity was measured in the photocell device, and LE rats when motor activity was measured in the Doppler system. The Tb of F344 rats was unaffected by DFP, while the LE and SD rats became hypothermic at 1.5 mg/kg. The DFP-induced inhibition of serum ChE activity was significantly less in F344 rats. All three strains retested the day after DFP still showed significant decreases in motor activity. Overall, it appears that the F344 strain is relatively resistant to the behavioral and autonomic effects of DFP. This intraspecies variability should be considered in selecting appropriate experimental models for assessing the neurotoxicological hazards of cholinesterase-inhibiting pesticides.     

Mucinous cystadenocarcinoma of the lung

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for obese-type, non-insulin-dependent diabetes mellitus (NIDDM) in humans. The OLETF rat has poor capacity for pancreatic proliferation, which may be the critical pathogenetic event in NIDDM development. Our investigation was designed to identify quantitative trait loci (QTLs) responsible for poor pancreatic proliferation by examining compensatory proliferation of the pancreatic remnant after partial pancreatectomy and performing a genome-wide scan in an F2 intercross obtained by mating the OLETF and the Fischer-344 (F344) rats. We identified a highly significant QTL on rat Chromosome 14 with a maximum lod score of 16.7, which accounts for 55% of the total variance. The QTL co-localizes with the gene encoding cholecystokinin type A receptor (CCKAR) which is likely to mediate the trophic effect of cholecystokinin on pancreas and is defective in the OLETF rat.     

A multicentre study to investigate the prevalence of abnormal carbohydrate metabolism in Chinese pregnant women

Bacterial lipopolysaccharide (LPS) has been previously shown to down-regulate the mRNA and protein expression of the hepatic cytochrome P450 (P450) isozymes 2C11 and 2C12. In this study, we examined the effects of LPS on the constitutive expression of P4503A2, P4502E1, and the P4504A subfamily in the rat. Fischer 344 and Sprague-Dawley rats were each administered 1 mg/kg LPS intraperitoneally and killed for hepatic RNA and microsome isolation at different times. LPS treatment was found to suppress P4502C11, P4503A2, and P4502E1 protein and mRNA expression in both strains of rat. Total microsomal P450 levels decreased by 30%, which was smaller than the effects on the levels of individual isozymes. The magnitude of suppression exhibited in the Sprague-Dawley rats, however, seemed to be more variable than that in the F344 strain. The mRNAs of all three of the P4504A subfamily members were induced 2- to 6-fold in the F344 rat livers after LPS administration. P4504A3 protein expression increased 2-fold, whereas P4504A1/2 protein levels decreased by 30%. Lauric acid omega-hydroxylase activity increased 1.6-fold in LPS-treated Fischer 344 rats and omega-1-hydroxylase activity decreased by 38%. In the Sprague-Dawley strain, however, decreases were seen in both omega- and omega-1-hydroxylase activities after LPS treatment. Our data demonstrate that LPS administration induces P4504A subfamily mRNA and P4504A3 protein expression. Furthermore, our findings also suggest strain differences in both suppression and induction of P450s between the Sprague-Dawley and F344 rats.     

Wnt-7a maintains appropriate uterine patterning during the development of the mouse female reproductive tract

The murine female reproductive tract differentiates along the anteroposterior axis during postnatal development. This process is marked by the emergence of distinct cell types in the oviduct, uterus, cervix and vagina and is dependent upon specific mesenchymal-epithelial interactions as demonstrated by earlier heterografting experiments. Members of the Wnt family of signaling molecules have been recently identified in this system and an early functional role in reproductive tract development has been demonstrated. Mice were generated using ES-mediated homologous recombination for the Wnt-7a gene (Parr, B. A. and McMahon, A. P. (1995) Nature 374, 350-353). Since Wnt-7a is expressed in the female reproductive tract, we examined the developmental consequences of lack of Wnt-7a in the female reproductive tract. We observe that the oviduct lacks a clear demarcation from the anterior uterus, and acquires several cellular and molecular characteristics of the uterine horn. The uterus acquires cellular and molecular characteristics that represent an intermediate state between normal uterus and vagina. Normal vaginas have stratified epithelium and normal uteri have simple columnar epithelium, however, mutant uteri have stratified epithelium. Additionally, Wnt-7a mutant uteri do not form glands. The changes observed in the oviduct and uterus are accompanied by a postnatal loss of hoxa-10 and hoxa-11 expression, revealing that Wnt-7a is not required for early hoxa gene expression, but is required for maintenance of expression. These clustered hox genes have been shown to play a role in anteroposterior patterning in the female reproductive tract. In addition to this global posterior shift in the female reproductive tract, we note that the uterine smooth muscle is disorganized, indicating development along the radial axis is affected. Changes in the boundaries and levels of other Wnt genes are detectable at birth, prior to changes in morphologies. These results suggest that a mechanism whereby Wnt-7a signaling from the epithelium maintains the molecular and morphological boundaries of distinct cellular populations along the anteroposterior and radial axes of the female reproductive tract.     

Immunohistochemical studies on the expression and estrogen dependency of EGF and its receptor and C-fos proto-oncogene in the uterus and vagina of normal and neonatally estrogen-treated mice

BACKGROUND: The final target cell response to estrogen is dependent not only on the estrogen receptor, but also on autocrine/paracrine interactions with growth factors (e.g., EGF) and proto-oncogenes (e.g., c-fos). Because neonatal estrogen treatment results in permanent changes in the female mouse genital tract (permanent vaginal cornification, cervical adenosis and tumors, changed growth control mechanisms in uterus), it was of interest to study possible acute and permanent effects of such treatment on distribution and levels of EGF, its receptor (EGF-r), and c-fos and to relate such changes to morphological development and appearance of epithelial abnormalities. METHODS: Immunohistochemical techniques using frozen sections from the uterus and vagina of neonatal and adult (ovariectomized, estradiol-treated) females, treated with olive oil or diethylstilbestrol in neonatal life. RESULTS: A difference in stromal-epithelial distribution of EGF was demonstrated with respect to region studied (uterus, vagina) and age (neonatal, adult). EGF was localized mainly in the uterine stroma but in both vaginal epithelium and stroma (with a different pattern compared to uterus). In neonatal females, EGF occurred in both tissue components in both regions, and the distribution pattern was quite different from that in adult females. The EGF level was increased by estrogen in adult but not in neonatal females. EGF-r and c-fos occurred in both uterine epithelium and stroma and in the vaginal epithelium; levels and distribution pattern were affected by estrogen. Neonatal estrogen treatment increased the levels of uterine EGF and c-fos in adult life. CONCLUSIONS: There are distinct developmental changes in the distribution and estrogen sensitivity of EGF. Only further studies can prove or disprove the association between the earlier reported disturbed growth control mechanisms in the uterus of adult but neonatally estrogen-treated females and the increased levels of uterine EGF and c-fos. The present results do not seem to explain mechanisms involved in the origin of neonatally estrogen-induced cervicovaginal epithelial abnormalities, nor do they explain the earlier described difference in estrogen-induced proliferative response between the uterine cervix and uterus proper.     

The effect of anti-prolactin antibody on in vitro synthesis of a pregnancy-associated rat uterine glycoprotein

Experiments were conducted to study the hormonal (estrogen [E2], progesterone [P4] and prolactin [PRL]), regulation of synthesis of a pregnancy-associated glycoprotein (named Uterine Agglutinin or UA) in the Day 4 post coital (p.c.) rat uterus with antibody administration and immunohistochemistry. Of the antibodies used, it was shown that anti-PRL antibody was the most effective in reducing in vitro UA synthesis. The results suggested that in vitro UA synthesis could be correlated to serum PRL levels as analyzed by radio-immunoassay. Binding studies revealed that PRL bound specifically to the stromal cells of the rat uterus where UA is produced and localized.     

Biochemical parameters in the anterior pituitary during the course of tumorigenesis induced by diethylstilbestrol treatment

Treatment of F344 rats with diethylstilbestrol (DES) for 1-2 months induces a prolactin (PRL)-secreting pituitary adenoma. After 8 weeks of DES treatment, we have shown that the ratio of regulatory subunits of the cAMP-dependent protein kinase (RI/RII) increased in the tumors. Presently we report the variations in RI/RII ratio, pituitary weight, DNA content, serum PRL, nuclear estrogen receptor (E2R) and of ornithine decarboxylase (ODC) activity from the time of DES pellet implantation until 8 weeks. Pituitary weight, DNA content and serum PRL rose significantly at 4 weeks with a maximum at 6-8 weeks, and significantly correlated with each other. E2R and ODC activity increased from week 1 onwards, with a maximum at 2 weeks and decreased at 8 weeks. Both variables showed a positive correlation but neither E2R nor ODC activity correlated with pituitary weight, DNA or serum PRL. Values for RI remained stable with time, but RII decreased progressively. The RI/RII ratio was maintained around unity between 1-4 weeks, increasing to 1.6-2 thereafter. This ratio positively correlated with pituitary weight and DNA. It is suggested that during tumor induction by estrogen in a sensitive strain of rats, growth signals with different time-courses become activated. Increases in pituitary weight and DNA content, indicators of mammotroph hypertrophy and hyperplasia, were preceded by early rises in E2R and ODC activity. Increases in the RI/RII ratio accompanied the adenomatous change, suggesting their role in cell transformation after 6 weeks of estrogen exposure.     

Enhanced hepatocyte growth factor expression associated with prolonged rat hepatic allograft survival in recipients pretreated with donor-specific blood

3,3',4,4'-Tetrachlorobiphenyl (tetraCB) binds to the aryl hydrocarbon receptor (AhR), and several reports have demonstrated that AhR agonists exhibit antiestrogenic and antitumorigenic activities in human breast cancer cells, the rodent uterus and breast. In contrast, a recent study showed that 3,3',4,4'-tetraCB bound the estrogen receptor (ER) and exhibited ER agonist activities, and we therefore have reinvestigated the estrogenic and antiestrogenic activities of 3,3',4,4'-tetraCB. Our results showed that 3,3',4,4'tetraCB and a structurally related analog, 3,3',4,4',5-pentaCB, did not bind the mouse uterine or human ER, did not induce proliferation of MCF-7 or T47D human breast cancer cells or induce reporter gene activity in cells transfected with E2-responsive constructs derived from the creatine kinase B (pCKB) or cathepsin D (pCD) gene promoters. Moreover, 3,3',4,4'-tetraCB and 3,3',4,4',5-pentaCB did not induce an increase in uterine wet weight, peroxidase activity or progesterone receptor binding in the 21-25-day-old female B6C3F1 mouse uterus. In contrast, both compounds inhibited 17beta-estradiol (E2)-induced cell proliferation and transactivation in MCF-7/T47D cells and uterine responses in B6C3F1 mice; surprisingly inhibition of E2-induced reporter gene activity was not observed in T47D cells transfected with pCKB, and this was observed as a cell-specific response with other AhR agonists. Additionally, 3,3',4,4'-tetraCB significantly inhibited mammary tumor growth in female Sprague-Dawley rats initiated with 7,12-dimethylbenzanthracene. Our results indicate that 3,3',4,4'-tetraCB does not exhibit ER agonist activity but exhibits a broad spectrum of antiestrogenic responses consistent with ligand-mediated AhR-ER crosstalk.     

Flow cytometric analysis of leukocytes in the human female reproductive tract: comparison of fallopian tube, uterus, cervix, and vagina

PROBLEM: The tissues of the human female reproductive tract (Fallopian tube, uterus, cervix, and vagina) may play different roles in the provision of mucosal immunity. The purpose of this study was to develop a uniform method suitable for quantitative comparison of the leukocytes from all these tissues. METHOD OF STUDY: Tissues, typically 0.5-1.0 g, were dispersed by enzyme treatment. A flow cytometric gating procedure based on CD45-positivity and low far-red autofluorescence permitted unfractionated, freshly dispersed cells to be phenotyped with respect to T lymphocytes, B lymphocytes, macrophages, and granulocytes. RESULTS: Reproductive tract tissues contain leukocytes that represent approximately 6-20% of the total number of cells, with the Fallopian tubes and uterus containing a higher proportion of leukocytes than the cervix and vagina. The uterine endometrium from post-menopausal women has fewer leukocytes than does uterine endometrium from pre-menopausal women. T lymphocytes are a major constituent (30-60%) of leukocytes from all tissues. The Fallopian tube contains granulocytes as another major constituent; granulocytes are significantly less numerous in the other tissues. All tissues contain B lymphocytes and macrophages as clearly detectable but minor components. CONCLUSIONS: Three-color flow cytometry is an appropriate method for quantitative comparison of leukocytes from the different tissues of the female reproductive tract, during all phases of the menstrual cycle and within post-menopausal samples. Results indicate that the tissues differ from each other, particularly with respect to the large number of granulocytes in the Fallopian tubes.     

Taste responses in the greater superficial petrosal nerve: Substantial sodium salt and amiloride sensitivities demonstrated in two rat strains.

A great quantity of research has focused on neural responses of the chorda tympani nerve (CT) to taste stimuli. This report examined salt and sugar sensitivity of the greater superficial petrosal nerve (GSP) and the effect of amiloride on these neural responses. In addition to Sprague-Dawley (SD) rats that have CT responses typical of most rat strains, we included Fischer 344 (F344) rats whose CT responses to sodium chloride (NaCl) are higher than those of other strains. After a stimulation series in which water served as the rinse, a series of stimuli was presented in 100 μM amiloride. The GSP was highly responsive to NaCl, sodium acetate (NaAc), ammonium chloride, and sucrose; NaCl and NaAc responses were strongly suppressed by amiloride. Relative responses to NaCl were significantly higher in F344 than in SD rats. In summary, the GSP is highly sensitive to salt and sugar stimulation, and palatal taste receptors have a considerable degree of amiloride sensitivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of a quantitative trait locus influencing plasma insulin levels after 70% pancreatectomy using the OLETF rat

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for obese-type non-insulin-dependent diabetes mellitus (NIDDM) in humans. The OLETF rat has poor capacity for proliferation of pancreatic beta-cells after partial pancreatectomy, which may be the critical pathogenetic event in NIDDM development. The poor pancreatic beta-cell proliferation in this model is characterized by reduction in beta-cell mass and decrease in insulin content in the remnant pancreas. Our investigation was designed to identify quantitative trait loci (QTLs) responsible for beta-cell mass and plasma insulin levels after partial pancreatectomy by performing a genome-wide scan in an F2 intercross obtained by mating the OLETF and the Fischer-344 (F344) rats. We have identified a suggestive QTL for the plasma insulin levels, near D20Mgh5 on rat chromosome 20, with a maximum lod score of 3.75 which accounts for 20% of the total variance, while no QTLs were detected for beta-cell mass. This chromosome 20 QTL, whose OLETF allele is associated with low plasma insulin levels through acting in an incompletely recessive manner, may affect insulin secretion itself rather than beta-cell proliferation.