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RNAscope is a quantitative in situ gene expression measurement technique that preserves the spatial aspect of intact tissue; thus, allowing for comparison of specific cell populations and morphologies. Reliable and accurate measurement of gene expression in tissue is dependent on preserving RNA integrity and the quantitative nature of RNAscope. The purpose of this study was to determine if the quantitative nature of RNAscope was retained following processing and carmine staining of mammary gland whole-mounts, which are commonly used to identify lesions, such as hyperplasia and ductal carcinoma in situ (DCIS). We were concerned that handling and procedures required to visualize microscopic disease lesions might compromise RNA integrity and the robustness of RNAscope. No effect on the quantitative abilities of RNAscope was detected when mammary gland whole-mounts were pre-screened for lesions of interest prior to RNAscope. This was determined in comparison to tissue that had been formalin-fixed and paraffin embedded (FFPE) immediately after collection. The ability to pre-screen whole-mounts allowed unpalpable diseased lesions to be identified without labor-intensive serial sectioning of tissue samples to find diseased tissue. This method is applicable to evaluate mammary gland whole-mounts during normal mammary gland development, function, and disease progression.

Alteration in gravitational load impacts homeorhetic response in rat dams which affects neonatal pup survival. However, the effects of hypergravity (HG) exposure on the abundance of apoptosis-associated proteins in mammary epithelial cells (MECs) have not been characterized. Therefore, we examined whether chronic exposure to HG from midpregnancy alters the abundance of proapoptotic proteins in MECs during the late pregnancy and early lactation. A group of pregnant Sprague Dawley rats were exposed to either HG (2g) or normo-gravity (1g: stationary control [SC]) from days 11 to 20 of gestation (G20). Another set of animals were investigated from day 11 of pregnancy through days 1 and 3 (P1 and P3, respectively) postpartum. Quantitative (pixels [px]/lobule) immunohistochemistry at G20 of Cleaved Caspase-3 (CC-3), Tumor Protein p53 (P53), and vitamin D receptor (VDR) revealed that all the three proteins were increased (p

BackgroundCLARITY-BPA is a rare collaboration of guideline-compliant (core) studies and academic hypothesis-based studies to assess the effects of bisphenol A (BPA).Objectives1) determine BPA’s effects on the developing rat mammary gland using new quantitative and established semi-quantitative methods in two labs, 2) develop a software tool for semi-automatic evaluation of quantifiable aspects of the mammary ductal tree, and 3) compare those methods.MethodsSprague Dawley rats were exposed to BPA, vehicle, or positive control (ethinyl estradiol, EE2) by oral gavage beginning on gestational day 6 and continuing with direct dosing of the pups after birth. There were two studies; sub-chronic and chronic. The latter used two exposure regimes, one stopping at PND21 the other continuing until tissue harvest. Glands were harvested at multiple time points; whole mounts and histological specimens were analyzed blinded to treatment.ResultsThe subchronic study’s semiquantitative analysis revealed no significant differences between control and BPA dose groups at PND21; whereas at PND90 there were significant differences between control and the lowest BPA dose and between control and the lowest EE2 dose in animals in estrus. Quantitative, automatized analysis of the chronic PND21 specimens displayed non-monotonic BPA effects with a breaking point between the 25 and 250μg/kg/day doses. This breaking point was confirmed by a global statistical analysis of chronic study animals at PND90 and 6 months analyzed by the quantitative method. The BPA response was different from the EE2 effect for many features.ConclusionsBoth the semiquantitative and the quantitative methods revealed non-monotonic effects of BPA. The quantitative unsupervised analysis used 91 measurements and produced the most striking non-monotonic dose-response curves. At all-time points, lower doses resulted in larger effects, consistent with the core study which revealed a significant increase of mammary adenocarcinoma incidence in the stop-dose animals at the lowest BPA dose tested.

Postnatal treatment with glyphosate-based herbicides (GBHs) induces endocrine-disrupting effects on the male rat mammary gland. In this study, the effects of developmental exposure to GBH on mammary gland growth and development, and the possible molecular mechanisms involved, were evaluated in pre- and post-pubertal male rats. To this end, pregnant rats were orally exposed through the food to 0, 3.5 or 350 mg GBH/kg bw/day from gestational day 9 until weaning. Mammary gland development and estradiol (E2) and testosterone (T) serum levels of male offspring were evaluated on postnatal day (PND)21 and PND60. Besides, prolactin (PRL) serum levels, proliferation index, androgen (AR) and estrogen receptor alpha (ESR1) expression, ESR1 alternative transcript mRNA levels, and DNA methylation status of ESR1 promoters were assessed on PND60. No differences between groups were observed in mammary gland development at PND21 or in E2 and T levels on both PNDs studied. On PND60, GBH3.5-exposed animals presented similar mammary gland histology but higher AR protein expression than controls, whereas GBH350-exposed males presented a less developed mammary gland, accompanied by a lower proliferation index, similar AR levels, and slightly increased PRL serum levels than controls. In both exposed groups, ESR1 expression was lower than in control rats, being lower in GBH350-exposed rats. GBH also altered the abundance of ESR1 transcript variants by hypermethylation of ESR1 promoters. GHB3.5 decreased only ESR1-OS expression, whereas GBH350 affected ESR1-O, OT and E1 expression. Our results show that developmental exposure to GBH induces epigenetic changes in ESR1, which could be responsible for the altered male mammary gland development observed in GBH350-exposed animals. Fil: Gomez, Ayelen Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; Argentina Fil: Altamirano, Gabriela Anahí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; Argentina Fil: Leturia, Jorgelina Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; Argentina Fil: Bosquiazzo, Veronica Lis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; Argentina Fil: Muñoz de Toro, Monica Milagros. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; Argentina Fil: Kass, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; Argentina

The aim of the study was to evaluate the distribution and number of mast cells and eosinophils in rat mammary gland tumours induced by N-Nitroso-N-methylurea. The highest density of mast cells was found in cystic papillary adenocarcinomas of grade II. Eosinophils were detected only in the cystic papillary adenocarcinoma of grades I and II, in non-invasive cribriform adenocarcinoma and comedo-type carcinoma. Mast cell populations were observed perivascularly in the tumour stroma, in the host tumour interface, as well as in necrotic areas of neoplasms. Mast cells were observed to be intact according to their morphological changes, collectively referred to as degranulation. The obtained results indicate that mast cells and eosinophils play an important role in tumour micro-environment formation. The increased density of these cells in experimentally-induced rat mammary gland tumours suggests a poor prognosis in these cancers. Our results also confirmed that rat mammary gland tumours are good models for the study of breast cancers.

Our aim was to evaluate whether exposure to Bisphenol A (BPA) modifies the male rat mammary gland (MG) development and to compare the effects on male and female MG. From gestational day 9, pregnant rats were exposed either subcutaneously to 0, 25 or 250µg BPA/kgbw/day until parturition or orally to 0 and 64µg BPA/kgbw/day until weaning. MG development was analyzed on postnatal days (PND) 5, 15 and 30. On PND30, steroid hormone receptor expression and mammary growth were also evaluated. On PND30, the exposure to 64BPA and 250BPA induced a delay in male MG development, evidenced by reduced ductal growth, decreased number of terminal structures and lower expression of androgen receptor (AR). In contrast, female mammary ductal growth was altered only by 250BPA. Regardless of the administration route and length of the exposure period, BPA induced a delay in MG development and modified AR expression in prepubertal male rats. Fil: Kass, Laura. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Fisiología. Laboratorio de Endocrinología y Tumores Hormonodependientes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Durando, Milena de Lourdes. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Fisiología. Laboratorio de Endocrinología y Tumores Hormonodependientes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Altamirano, Gabriela Anahí. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Fisiología. Laboratorio de Endocrinología y Tumores Hormonodependientes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Manfroni Ghibaudo, Gisela E.. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Fisiología. Laboratorio de Endocrinología y Tumores Hormonodependientes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Luque, Enrique Hugo. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Fisiología. Laboratorio de Endocrinología y Tumores Hormonodependientes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Muñoz de Toro, Monica Milagros. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Fisiología. Laboratorio de Endocrinología y Tumores Hormonodependientes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

Studies that utilize the rodent mammary gland (MG) as an endpoint for assessing the developmental toxicity of chemical exposures typically employ either basic dimensional measurements or developmental scoring of morphological characteristics as a means to quantify MG development. There are numerous means by which to report these developmental changes, leading to inconsistent translation across laboratories. The Sholl analysis is a method historically used for quantifying neuronal dendritic patterns. The present study describes the use of the Sholl analysis to quantify MG branching characteristics. Using this method, we were able to detect significant differences in branching density in MG of peripubertal female Sprague Dawley rats that had been exposed to vehicle or a potent estrogen. These data suggest the Sholl analysis can be an effective tool for quantitatively measuring an important characteristic of MG development and for examining associations between MG growth and density and adverse effects in the breast.

The rat mammary gland has been studied extensively as a model for cancer. Factors such as the strain of rat, age, parity, hormones, and diet must all be considered in the proper interpretation of apparent increases in mammary gland neoplasms following exposure to chemicals, radiation, or environmental agents. Nonneoplastic mammary gland changes are also seen in rats. These nonneoplastic changes include degenerative, inflammatory, vascular, hyperplastic, miscellaneous, and toxicologic changes. The accurate assessment of mammary gland changes and understanding their importance is critical, particularly when evaluating drug-related toxicity and carcinogencity.

An increasing number of studies are utilizing the rodent mammary gland as an endpoint for assessing the developmental toxicity of a chemical exposure. The effects these exposures have on mammary gland development are typically evaluated using either basic dimensional measurements or by scoring morphological characteristics. However, the broad range of methods for interpreting developmental changes could lead to inconsistent translations across laboratories. A common method of assessment is needed so that proper interpretations can be formed from data being compared across studies. The present study describes the application of the Sholl analysis method to quantify mammary gland branching characteristics. The Sholl method was originally developed for use in quantifying neuronal dendritic patterns. By using ImageJ, an open-source image analysis software package, and a plugin developed for this analysis, the mammary gland branching density and the complexity of a mammary gland from a peripubertal female rat were determined. The methods described here will enable the use of the Sholl analysis as an effective tool for quantifying an important characteristic of mammary gland development.

BackgroundE-cadherin (E-cad) is a cell adhesion molecule, essential for the maintenance of the epithelial phenotype.Aim of workThe current study aimed at showing the histological changes and the pattern of E-cad expression in the female rat mammary gland during different stages of their fertile peri

Extant technologies for the detection of breast cancer exploit changes in the morphology of the mammary ductal epithelial network and can involve ionizing radiation. Intraductal surveillance of mammary epithelium has the potential to allow for earlier detection based on changes in function of the epithelium. This study investigated the feasibility of using intraductal impedance spectroscopy (IIS) to assess changes in resistance in the mammary epithelium in a small group of female rats in resting, pregnant and ultimately lactating states. In resting rats, intraductal surveillance was able to detect only a single resistive capacitance (RC). In pregnant animals, a second RC became evident in the frequency range between 1 and 190 Hz. The real resistance of this low frequency RC increased when measurements were made after the animals had begun lactating. Equivalent circuit modeling revealed this increase to be a 1.7-fold change from pregnancy to lactation. A model of tight junction closure in the context of ductal expansion is proposed. These results suggest that physiologic measurements can be made in rodent mammary epithelium using this technique allowing for assessment of function in normal and disease states.

Rat mammary gland proteomes at day 21 (prepubertal) and day 50 (late puberty) were compared by 2D difference gel electrophoresis. Two-hundred fifty-one spots were significantly different ( p0.05) in abundance. Peptide mass fingerprint analysis of a subset of these proteins identified two significantly over-represented classes including structural and blood proteins (increased), and metabolism-relevant proteins (reduced) in day 50 relative to day 21 glands. This is a first report of mammary gland proteome differences at these important breast cancer-relevant time-points.

Objective To investigate the relationship between the level of caspase-3 and 8 expression and intracellular Ca2+ levels in BCML-TA299 breast cancer cells in the process of apoptosis.

OBJETIVO: avaliar os efeitos das isoflavonas e dos estrogênios sobre a morfologia, a morfometria e a expressão do fator de crescimento vascular (VEGF) na mama de ratas adultas. MÉTODOS: Quarenta e cinco ratas, após 28 dias de ooforectomia, foram divididas em três grupos: CON - controle e os grupos que receberam medicação: ISO - isoflavona (100 mg/Kg) e ECE - estrogênios conjugados eqüinos (50 µg/Kg). Após 60 dias, parte das mamas foram fixadas em formol a 10% para processamento histológico, e outra parte congelada para a análise da expressão do VEGF pela técnica da reação em cadeia da polimerase com transcrição reversa (RT-PCR). Para análise dos resultados obtidos foram utilizados inicialmente a análise de variância (ANOVA). Quando houve significância, foi complementada com o teste de comparações múltiplas de Tukey-Kramer. RESULTADOS: Nos grupos CON e ISO as mamas apresentaram glândulas mamárias atróficas, sendo mais desenvolvidas no grupo ECE, onde se notou a presença de inúmeros ductos e de alvéolos mamários. A morfometria mostrou maior número de alvéolos no grupo ECE (12,3 ± 7,1* por mm²; p< 0,05%) do que nos outros grupos (CON = 1,4 ± 2,1 e ISO = 1,6 ± 3,8), sendo o volume dessas células maior (ECE = 27,4 ± 9,7 µm³, p < 0,05%) do que nos grupos CON (14,9 ± 4,9 µm³) e ISO (11,4 ± 6,9 µm³). O mesmo ocorreu em relação ao número de vasos sanguíneos [16,4 ± 1,5 por mm²(CON), 18,4 ± 2,1 (ISO) < 37,1 ± 4,1* (ECE), p < 0,05%]. Na análise do VEGF o grupo ECE apresentou maior expressão do que os grupos CON e ISO. CONCLUSÃO: nossos dados não evidenciaram efeito proliferativo no tecido mamário de ratas ooforectomizadas tratadas com isoflavona na dose de 100 mg/Kg durante 60 dias consecutivos. PURPOSE: to analyze the effects of isoflavones and estrogens on the morphology, morphometry and VEGF expression of the adult female rat mammary gland. METHODS: Forty-five adult female rats were oophorectomized; 28 days after surgery they were divided into 3 groups of 15 animals each: CON - control (treated with propylenoglycol); ISO - isoflavones (100 mg/kg) and CEE - conjugated equine estrogens (50 µg/Kg). Drugs or vehicle were given orally once a day for 60 days. After this, the animals were killed and the first pair of inguinal mammary glands was immediately removed; part of the material was processed for routine histological study and the remaining tissue was frozen for further analyses of the expression of VEGF mRNA by means of the RT-PCR technique. RESULTS: We observed that mammary ducts were atrophic in the control (CON) and isoflavone-treated (ISO) groups. In these groups the mammary glands were composed of a large concentration of adipose tissue with some ducts and rare alveolar structures. In the CEE group the ducts were well developed with many buds and alveolar structures. The number of mammary gland alveoli was higher in CEE than in the other groups (CON = 1.4 ± 2.1; ISO = 1.6 ± 3.8; CEE = 12.3 ± 7.1 alveoli/mm²; p

Dibenzo[a,l]pyrene (DB[a,l]P) is the most potent carcinogenic polycyclic aromatic hydrocarbon and has been identified in the environment. Comparative tumorigenicity studies in mouse skin and rat mammary gland indicate that DB[a,l]P is slightly more potent than DB[a,l]P-11,12-dihydrodiol and much more potent than (±)-syn-DB[a,l]P-11,12-dihydrodiol-13,14-epoxide {(±)-syn-DB[a,l]PDE} and (±)-anti-DB[a,l]PDE. We report here the identification and quantification of the depurinating adducts formed in mouse skin treated with DB[a,l]P, DB[a,l]P-11,12-dihydrodiol, (±)-syn-DB[a,l] PDE, or (±)-anti-DB[a,l]PDE and rat mammary gland treated with DB [a,l] P. The biologically formed adducts were compared with standard adducts by their retention times on HPLC and their spectra obtained by fluorescence line-narrowing spectroscopy at low temperature. In mouse skin treated with DB[a,l]P, depurinating adducts comprised 99% of the total adducts. Most of the depurinating adducts were formed by one-electron oxidation, with 63% at Ade and 12% at Gua. The remainder were formed by the diol epoxide, with 18% at Ade and 6% at Gua. When mouse skin was treated with DB[a,l]P-11,12-dihydrodiol, depurinating adducts comprised 80% of the total, and the predominant one was with Ade (69%). Treatment of skin with (±)-syn-DB[a,l]PDE resulted in 32% depurinating adducts, primarily at Ade (25%), whereas treatment with (±)-anti-DB[a,l]PDE produced 97% stable adducts. The formation of depurinating adducts following treatment of rat mammary gland with DB[a,l]P resulted in approximately 98% depurinating adducts, with the major adducts formed by one-electron oxidation. Only one depurinating diol epoxide adduct was formed. Tumorigenicity, mutations, and DNA adduct data suggest that depurinating Ade adducts play a major role in the initiation of tumors by DB[a,l]P. © 2005 American Chemical Society.

We have investigated mammary gland tissues of female rats treated with 7,12-dimethylbenz[a]anthracene in sesame oil by a near infrared (NIR) spectroscopy finding that the DNA and water contents in the cancerous tissues were larger than those in the normal tissues but that the lipid content in the former was less than that in the latter. With protein contents, however, little difference was observed between the two. Thus, we used a lipid band around 1725 nm (the first overtone of n-alkane) and a protein band around 2054 nm (a combination band of amide A and amide II of polypeptides) for a quantitative evaluation of malignant changes in the mammary gland tissues. The lipid/protein band intensity ratios were calculated from the spectra of the mammary glands in the control animals and those of the noncancerous and cancerous sites in the treated animals. The lipid/protein ratios in the control animals, in the noncancerous sites, and in the cancerous sites were 1.452 +/- 0.221 (n = 5), 0.728 +/- 0.069 (n = 5), and 0.362 +/- 0.060 (n = 5), respectively. These values were significantly different from each other (P0.001). The lipid changes observed by near-infrared (NIR) spectroscopy were confirmed by the results obtained from chemical methods for the evaluation of lipid levels in the same samples. Thus, our NIR spectroscopic method would be able not only to discriminate between cancerous and normal tissues but also to distinguish animals with cancers from normal animals. In addition, as the cancer grew, the lipid band intensity decreased, this band was shifted to higher wavelengths, and collagen peaks appeared in the tissues. These findings were supported by histological examinations of the cancerous and normal tissues. The present study indicates that NIR spectroscopy has high specificity and sensitivity in discriminating cancerous tissues from normal mammary glands in animals and it may offer potential for noninvasive, in vivo diagnosis of female breast cancer in the near future.

The heterocyclic amines (HCAs) are a family of mutagenic/carcinogenic compounds found in cooked meats. Several HCAs are mammary gland carcinogens in rats. Of these compounds, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is the major one present in the human diet. This report reviews the studies on rat mammary gland carcinogenesis by HCAs; discusses what is currently known regarding mechanisms of mammary gland carcinogenesis of PhIP, especially the significance of metabolic processing; and further highlights the evidence for the possible role of PhIP in human breast cancer.

Premalignant and malignant stages of mammary carcinogenesis can be rapidly induced by injecting female rats i.p. with 1-methyl-1-nitrosourea (MNU)3 at 21 days of age. In this paper, the characteristics of this model are briefly reviewed and the histology of the lesions induced is presented and compared to those that occur in humans. Malignant mammary lesions induced in rats injected with MNU at 21 days of age are compared with the lesions that develop when MNU is administered to 50-day-old female rats.

Mammary gland development and hyperprolactinemia of rats were induced by estradiol (E2) treatment. The condition of the animals resembled that of during lactation. When it focused on high PRL levels, we studied the molecular phenotype of the rat mammary gland following E2 treatment, targeting prolactin (PRL) mRNA, using the sensitive techniques of solution and in situ reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, we compared the PRL mRNA and plasma PRL level with those in the mammary glands of both pregnant and lactating rats. In the E2-treated groups, the plasma PRL levels were increased. No mammary PRL mRNA was detected in E2-treated rats by either solution or in situ RT-PCR. The plasma PRL level was extremely high and associated with the mammary gland development in lactating rats. In addition, mammary PRL mRNA was detected in both pregnancy and lactation by solution and in situ RT-PCR. These results suggested a lack of PRL mRNA in the mammary gland of E2-treated rats, despite similar plasma PRL levels and morphological changes to those in lactating rats. The induction of PRL mRNA coincident with the development of mammary gland in the pregnant and lactating rats, differed from that in the E2-treated rats in molecular biology, particularly in PRL mRNA expression, and suggested that PRL mRNA in mammary gland contributes to de novo synthesis of PRL in milk which is under the multihormonal regulation.

Background The mammary gland is one of the few organ systems in mammals that completes its morphologic development postnatally. Due to this unique developmental property, it serves as an excellent model for studying ductal morphogenesis beyond embryonic life. The primary objective of this study was to investigate the development of terminal end bud (TEB) structure in the prepubertal-pubertal mouse mammary gland. Methods Seventy-five mice, weaned at 21 days of age, were fed a high fat, nonrestricted intake diet for optimum mammary gland growth. Wholemount preparations and a computer-assisted image analyzer were used to record the size and number of TEB structures in the thoracic and inguinal mammary glands. A light microscope was used to determine the number of cap cells present in select TEB structures. Results In the prepubertal age group, the size and number (No.) of TEBs in the No. 2 and No. 3 thoracic glands were significantly greater than those in the No. 4 inguinal gland. In the pubertal age group, the size and number of TEBs in the No. 2 gland significantly decreased, indicating that for this particular gland the largest size and greatest number of TEBs are present during the prepubertal growth period. In contrast, the size and number of TEBs in the No. 3 and No. 4 glands remained relatively constant throughout the prepubertal-pubertal growth period. Conclusions The results of this study show: (1) like the rat mammary gland, there is asynchronous growth among the mouse mammary glands, (2) the maximum size and number of TEBs in the prepubertal-pubertal mouse mammary glands are a function of the gland of origin and the age of the mouse, and (3) the number of cap cells per TEB structure is directly correlated with the size of the TEB structure. Anat. Rec. 250:459–464, 1998. © 1998 Wiley-Liss, Inc.

to the editor: Matsumoto et al. ([3][1]) have reported that the lactating rat mammary gland maintains a large transepithelial l-glutamate concentration gradient in favor of milk and provide a model for the production of free l-glutamate in milk. They suggest that l-leucine is the major source of

           There are many causes of non-lactation after delivery in some dairy mammals and human female. In present investigation study was carried out to find out effect of Ageratum conyzoides leaf extract on histological structure of non lactating mammary gland of wistra white albino rat female. Ageratum conyzoides is supposed to induce lactation in non-lactating mammalian female including woman1. The effect of extract on non-lactating mammary gland after seven and fourteen days was observed on non – lactating mammary gland showed small size mammary gland with no secretion. After 7 days the epithelial lining showed growth and increasing size of secretary glands. Ducts were also seen increasing a proliferation. After 14 days secretory gland showed more tortures structure and secretion was accumulated in to lumen and gland. The 14 days treated female rat mammary gland showed more secretary activity indicating lactation was induced in lactating gland of mammary gland1. Key Words: albino rat, Phytochemical, Gangotry species, Ageratum conyzoides

Concerns about adverse health effects of environmental exposure to 50/60 Hz magnetic fields (MF) have initiated numerous studies on laboratory animals with varying outcomes. Previously, we reported that rat strains responded differently to MF regarding mammary cell proliferation and tumor development indicating that (epi)genetic factors might influence MF effects in the breast tissue, yet without any identified mechanism. In the present study, α-amylase, recently introduced as a stress marker in humans, was investigated in the mammary gland of Fischer 344 (F344) and Lewis rats, two strains with distinct stress sensitivity.F344 rats were sham- and MF-exposed (50 Hz, 100 μT) for different time periods, Lewis rats for two weeks. For comparison, diethylstilbestrol was administered at single or repeated doses.α-Amylase activity was significantly enhanced in the F344 mammary glands after 2 and 4 weeks of MF, whereas no reproducible effects were observed in Lewis rats. Diethylstilbestrol increased the α-amylase after repeated dosing.Although α-amylase represents a difficult parameter in animal studies because of its stress sensitivity, it should be considered for investigations in humans and cell cultures as a biomarker for MF susceptibility and a target to examine possible MF mechanisms since α-amylase affects cell growth.

In summary, dietary deficiency of lipotropic nutrients or labile methyl supply enhances “spontaneous” and chemical carcinogenesis in the liver of rats. The deficiency also enhances DMH carcinogenesis in the rat colon and PCZ carcinogenesis in the rat mammary gland. In the PCZ model, parallel studies using MTX to induce biochemical changes analogous in some characteristics to the lipotrope-deficient model also showed evidence suggestive of enhancement of carcinogenesis, although the results were not statistically significant. PCZ interfered with hepatic choline metabolism, particularly in lipotrope-deficient and MTX-treated rats. This effect may be related to the enhanced carcinogenicity of PCZ in the mammary gland.

Experiments were undertaken to obtain neurochemical evidence of the presence of sympathetic nerve terminals in the rat mammary gland and the changes occurring in them during the lactogenic cycle. The norepinephrine (NE) content of the gland changed during the lactogenic cycle. Higher levels of NE were found during virginity and involution, whereas a lower level was found at 14 days of lactation. Surgical and chemical (with 6-hydroxydopamine) denervation reduced the norepinephrine content of the gland by 61 and 90%, respectively. Uptake of [(3)H]norepinephrine by the mammary gland was saturable and specifically blocked by cocaine. No changes in the maximal capacity of incorporation during the lactogenic cycle were found, but the affinity of NE for the transmembrane carrier was low during lactation, as was the NE content, suggesting a decrease in the sympathetic nerve activity during this stage of the lactogenic cycle. In support of this, we found a decrease in total NE released after stimulation with 80 mM KCI. The neurochemical evidence obtained during this research strongly suggests that rat mammary gland is innervated by sympathetic nerves and that their activity changes during the lactogenic cycle.

Degradation of newly synthesized casein in rat mammary gland perfused in situ was measured by a pulse-chase method using [3H]proline. Casein degradation during secretion was observed in the absence of prolactin, but not with prolactin present. Partial inhibition by chloroquine showed that hormone-dependent degradation occurred intracellularly by a lysosomal mechanism. The study indicates that this post-translational mechanism is a physiological regulator of net casein secretion.

Comparative studies of tumor-initiating activity in mouse skin and carcinogenicity in rat mammary gland were conducted with 7,12-dimethylbenz[a]anthracene (DMBA) and selected derivatives. Female SENCAR mice were initiated with DMBA, 1,2,3,4-tetrahydro-DMBA, 2-, 4-, 5-, 9-, and 10-fluoro DMBA, (FDMBA), and promoted with tetradecanoyl phorbol acetate. The same compounds were tested by intramammillary injection in female Sprague-Dawley rats. DMBA, 9-FDMBA, 10-FDMBA and 1,2,3,4-tetrahydr DMBA were strongly tumorigenic in both mouse skin and rat mammary gland, whereas 2-, 4- and 5-FDMBA were weakly active or inactive. In a third experiment DMBA, benzo[a]pyrene, 1,2,3,4-tetrahydro DMBA and 9,10-dimethylanthracene were tested by repeated application on the dorsal skin of Swiss mice. DMBA was the most carcinogenic, followed by benzo[a]pyrene and 1,2,3,4-tetrahydro DMBA, whereas 9,10-dimethylanthracene was inactive. The potent activity of 1,2,3,4-tetrahydro DMBA suggests that the bay-region diol epoxide p...

International audience; The main sulphated proteins secreted by rat mammary gland tissue have Mr of approximately 32 000, 27 000 and 25 000 Da. In addition, there are high Mr components which have a diffuse electrophoretic mobility (Mr $>$ 200 000) and most likely corresponded to proteoglycans. The sulphate groups in the proteins with discrete Mr are most likely all linked to carbohydrates. These sulphated molecules were partially purified and identified to isoforms of rat $\alpha $-lactalbumin for the 25-27 kDa bands and to $\kappa $-casein for the 32 kDa band. This pattern of protein sulphation is, as far as we know, quite specific to rat mammary epithelial cells.