Changes in microvascular density differentiate metabolic health outcomes in monkeys with prior radiation exposure and subsequent skeletal muscle ECM remodeling.

Radiation exposure accelerates the onset of age-related diseases such as diabetes, cardiovascular disease, and neoplasia and, thus, lends insight into in vivo mechanisms common to these disorders. Fibrosis and extracellular matrix (ECM) remodeling, which occur with aging and overnutrition and following irradiation, are risk factors for development of type 2 diabetes mellitus. We previously demonstrated an increased incidence of skeletal muscle insulin resistance and type 2 diabetes mellitus in monkeys that had been exposed to whole body irradiation 5-9 yr prior. We hypothesized that irradiation-induced fibrosis alters muscle architecture, predisposing irradiated animals to insulin resistance and overt diabetes. Rhesus macaques (Macaca mulatta, n = 7-8/group) grouped as nonirradiated age-matched controls (Non-Rad-CTL), irradiated nondiabetic monkeys (Rad-CTL), and irradiated monkeys that subsequently developed diabetes (Rad-DM) were compared. Prior radiation exposure resulted in persistent skeletal muscle ECM changes, including a relative overabundance of collagen IV and a trend toward increased transforming growth factor-ß1. Preservation of microvascular markers differentiated the irradiated diabetic and nondiabetic groups. Microvascular density and plasma nitrate and heat shock protein 90 levels were lower in Rad-DM than Rad-CTL. These results are consistent with a protective effect of abundant microvasculature in maintaining glycemic control within radiation-induced fibrotic muscle.

Decidualization of Endometriosis in Macaques.

The decidua is the superficial portion of endometrium that transforms, or decidualizes, under the influence of progesterone to nourish the early embryo during pregnancy. Deciduae outside the uterus are found in nearly 100% of human pregnancies. This condition, known as deciduosis, may mimic malignancy, resulting in additional diagnostic procedures that place the mother, baby, or both at risk. Deciduosis has been described in both Old World and New World nonhuman primates in conjunction with pregnancy and after treatment with exogenous progestins. Here the authors present 6 cases of deciduosis associated with endometriotic lesions in female rhesus and cynomolgus macaques (Macaca mulatta and Macaca fascicularis). Full diagnostic necropsies with histologic analyses were performed on all animals. Deciduae were stained with hematoxylin and eosin and by immunohistochemistry for vimentin, CD10, progesterone receptor, estrogen receptor, desmin, cytokeratin, kermix P8, chorionic gonadotropin, human placental lactogen, and calretinin. The most common clinical signs were abdominal pain (4 of 6) and anorexia (2 of 6). At necropsy, macaque uteri were often enlarged or disfigured (4 of 6) with abundant fibrous adhesions (5 of 6). Affected tissue consisted of epithelial-lined cysts and decidualized stroma with scattered gamma/delta T cells. Decidualized stromal cells were large and polyhedral with abundant cytoplasm and round vesicular nuclei. They stained positive for vimentin, CD10, progesterone, and estrogen. In summary, these cases illustrate deciduosis in 6 nonhuman primates with endometriosis. Understanding decidualization in nonhuman primates will aid in elucidating the pathophysiology of deciduosis during pregnancy or endometriosis and potentially lead to new interventions.

17-ß Estradiol reduces atherosclerosis without exacerbating lupus in ovariectomized systemic lupus erythematosus-susceptible LDLr(-/-) mice.

OBJECTIVE: To test the hypothesis that estrogen treatment in a radiation chimera mouse model of systemic lupus erythematosus (SLE) and atherosclerosis will increase SLE-associated atherosclerosis by increasing autoantibody production and inflammation. METHODS: We used a radiation chimera mouse model in which bone marrow from the polygenic B6.Sle1.2.3 model of SLE was transferred to the low density lipoprotein receptor knock out (LDLr(-/-)) model of atherosclerosis on a C57BL/6 background (Sle/LDLr(-/-)). Ovariectomized chimeric mice were treated for 10 weeks with either 5.6 µg/day of 17ß-estradiol or placebo; outcomes included atherosclerosis plaque size, anti-dsDNA autoantibody production and renal pathology. RESULTS: Mean atherosclerosis plaque size was 67.4 ± 7.6% smaller in the estrogen treated group (p < 0.0001). Estrogen treated Sle/LDLr(-/-) mice had no significant difference in serum cholesterol concentration, lipoprotein distribution, anti-dsDNA autoantibody concentration, antibody isotype concentration and renal histopathology score compared to placebo. However, they had significantly lower mean urine protein to urine creatinine ratio (UP:UC). There was no correlation between atherosclerosis lesion size and either the renal histology score or UP:UC ratio in Sle/LDLr(-/-) mice. CONCLUSION: These results indicate that 17ß-estradiol is atheroprotective within the context of murine SLE independent of changes in serum cholesterol concentration, autoantibody concentration, or renal pathology. The SLE phenotype in Sle/LDLr(-/-) mice is not exacerbated by exogenous 17ß-estradiol administration, and the reduced UP:UC ratio suggests a protective effect against lupus nephritis.

Meeting report: Spontaneous lesions and diseases in wild, captive-bred, and zoo-housed nonhuman primates and in nonhuman primate species used in drug safety studies.

The combination of loss of habitat, human population encroachment, and increased demand of select nonhuman primates for biomedical research has significantly affected populations. There remains a need for knowledge and expertise in understanding background findings as related to the age, source, strain, and disease status of nonhuman primates. In particular, for safety/biomedical studies, a broader understanding and documentation of lesions would help clarify background from drug-related findings. A workshop and a minisymposium on spontaneous lesions and diseases in nonhuman primates were sponsored by the concurrent Annual Meetings of the American College of Veterinary Pathologists and the American Society for Veterinary Clinical Pathology held December 3-4, 2011, in Nashville, Tennessee. The first session had presentations from Drs Lowenstine and Montali, pathologists with extensive experience in wild and zoo populations of nonhuman primates, which was followed by presentations of 20 unique case reports of rare or newly observed spontaneous lesions in nonhuman primates (see online files for access to digital whole-slide images corresponding to each case report at http://www.scanscope.com/ACVP%20Slide%20Seminars/2011/Primate%20Pathology/view.apml). The minisymposium was composed of 5 nonhuman-primate researchers (Drs Bradley, Cline, Sasseville, Miller, Hutto) who concentrated on background and spontaneous lesions in nonhuman primates used in drug safety studies. Cynomolgus and rhesus macaques were emphasized, with some material presented on common marmosets. Congenital, acquired, inflammatory, and neoplastic changes were highlighed with a focus on clinical, macroscopic, and histopathologic findings that could confound the interpretation of drug safety studies.

Novel betapapillomavirus associated with hand and foot papillomas in a cynomolgus macaque.

Betapapillomavirus is a genus of papillomaviruses (PVs) commonly found in human skin and associated with both benign and malignant skin lesions. Only 2 previous beta-PVs have been fully characterized in nonhuman species. This report describes a novel beta-PV, named Macaca fascicularis PV type 2 (MfPV2), isolated from exophytic skin papillomas on the hands and feet of a 2-year-old male cynomolgus monkey (M. fascicularis). On histology the papillomas were composed of diffusely thickened epidermis with superficial foci of cytomegaly, cytoplasmic pallor, marginalized chromatin, and rare eosinophilic intranuclear inclusion bodies. Positive immunostaining for p16 and the proliferation marker Ki67 was present multifocally within affected epidermis, most prominently within basal-type cells. Complete sequence identity (100%) was noted between PV genomes fully sequenced from hand and foot lesions. The MfPV2 genome was 7632 base pairs in length and included putative open reading frames (ORFs) for E1, E2, E4, E6, E7, L1, and L2 genes, similar to other PVs. The closest relatives to MfPV2 based on the L1 ORF sequence were all beta-PVs. These included human PV (HPV) 9, HPV115, HPV76, HPV75, and MfPV1 (60-70% pairwise identity for all), the latter of which was also isolated from hand and foot papillomas in a cynomolgus macaque. Phylogenetic analysis placed MfPV2 in a new species group (beta-6), distinct from HPVs (beta-1 to beta-5) and MfPV1 (beta-1). These findings characterize a new nonhuman beta-PV and provide additional support for the idea that tissue tropism among ancestral primate PVs developed prior to divergence of certain Old World primate lineages.

Expression of the androgen receptor and syndecan-1 in breast tissue during different hormonal treatments in cynomolgus monkeys.

OBJECTIVES: To analyze the expression of the androgen receptor(AR) and syndecan-1 in breast tissue during long-term hormonal treatment in cynomolgus monkeys. METHODS: Sixty oophorectomized macaques were randomized to receive either tibolone, conjugated equine estrogens (CEE), CEE + medroxyprogesterone acetate (MPA) or no hormonal treatment. Breast tissue was collected at necropsy after 2 years and stained for AR and syndecan-1. RESULTS: Apparent differences were seen between treatment groups as compared to untreated animals. AR expression was markedly increased by tibolone and suppressed by combined CEE/MPA. Both treatments increased syndecan-1 in stromal tissue, whereas CEE alone had no significant effect. CONCLUSIONS: We found alternative regimens for hormonal therapy to differ in their influence on two markers of importance for the development of breast cancer. The results may be relevant for the ongoing clinical discussion on the long-term safety of different hormonal treatments.

Effects of tibolone and conventional HRT on the expression of estrogen and progesterone receptors in the breast.

OBJECTIVE: There is evidence that long-term hormone replacement therapy (HRT) is associated with an increased breast cancer risk. The aim of this study was to assess the effects of tibolone on estrogen and progesterone receptors in comparison to the effects of conventional HRT in the breast of surgically postmenopausal macaques. METHOD: Sixty macaques were bilaterally ovariectomized 3 months before hormonal treatment was initiated. The animals were randomized into four treatment groups, including tibolone (TIB), conjugated equine estrogens (CEE), conjugated equine estrogens+medroxyprogesterone acetate (CEE+MPA) and control animals (C). After 2 years treatment, breast tissues were collected, fixed and paraffin embedded. Immunohistochemistry assays with monoclonal antibodies for estrogen receptors (ERalpha and ERbeta) and progesterone receptors (PRA and PRB) were performed. RESULTS: The expression of ERalpha was markedly decreased in the CEE+MPA group as compared to C and TIB groups. The TIB group was not different from the C and CEE groups. No significant differences were found for ERbeta immunostaining. The expression of PRA was strongly increased in the TIB group as compared to the C and CEE+MPA groups. Immunostaining of PRB was increased in the CEE and TIB treated animals as compared to both C and CEE+MPA groups. CONCLUSIONS: Tibolone increased the expression of both PRA and PRB, without affecting ERalpha and ERbeta expression in the macaque breast. These findings indicate that the effects of tibolone in breast tissue could be mediated via differential regulation of PRA and PRB isoforms and therefore distinct from those observed with conventional HRT.

Effects of prior oral contraceptive use and soy isoflavonoids on estrogen-metabolizing cytochrome P450 enzymes.

Estrogen exposure and metabolism may play an important role in the development of estrogen-sensitive cancers in postmenopausal women. In this study we investigated whether past oral contraceptive (OC) administration or current dietary isoflavonoids (IF) affected expression and/or activity of steroid hormone-metabolizing cytochrome P450 (CYP) enzymes using complementary primate and cell culture models. One-hundred-eighty-one female cynomolgus macaques were randomized to receive OC or nothing for 26 months premenopausally, then ovariectomized and randomized to one of three diets for 36 months: an IF-depleted soy protein isolate (Soy-) diet, a Soy diet with IF (Soy+), or a Soy- diet supplemented with conjugated equine estrogens (CEE). Prior OC-treatment significantly reduced CYP gene expression in the mammary gland (< or =60% of OC-). Dietary IFs had no effect on CYP expression, while CEE-treatment decreased CYP1A1 and increased CYP3A4 mRNA in a tissue-specific manner. For in vitro studies, we measured effects of the isoflavonoids genistein, daidzein and equol on CYP activity using intact V79 cells stably transfected to express CYP1A1, CYP1B1, or CYP3A4. All three IFs significantly altered CYP activity in a dose-dependent and isoform-specific manner (20-95% inhibition versus controls). These results suggest potential mechanisms for prior OC and dietary IF effects on cancer risk in estrogen-responsive tissues.

Polycystic ovary syndrome with endometrial hyperplasia in a cynomolgus monkey (Macaca fascicularis).

A 13-year-old, obese, female cynomolgus monkey (Macaca fascicularis) was observed in a 5-year neurobehavioral study and was humanely euthanatized for experimental purposes. During this observational study, the monkey was noted to ovulate only rarely (0-3 times a year), with a prolonged menstrual cycle length (up to 161 days), hyperandrogenism (androstenedione area under the curve in response to adrenocorticotropic hormone up to 27.64 ng/ml), and hyperinsulinemia (fasting insulin up to 65.85 microIU/ml). This animal's body mass index was 65.46 kg/m(2), with central obesity. On postmortem examination, the uterus was moderately enlarged, with an eccentric lumen and a broad-based endometrial polyp that consisted of complex glandular hyperplasia with atypia. Both ovaries contained many 2- to 3-mm follicles, without any corpora lutea. A diagnosis of polycystic ovary syndrome was made based on the clinical history, endocrinology, and gross and histopathologic findings.

Progestin treatment induces apoptosis and modulates transforming growth factor-beta in the uterine endometrium.

BACKGROUND: Epidemiologic, animal, and human data suggest that progestins are potent endometrial cancer preventive agents. In the ovarian surface epithelium, progestins have been hypothesized to confer a cancer preventive effect via apoptosis and modulation of transforming growth factor-beta (TGF-beta). Given that the ovarian epithelium and endometrium share a common embryologic origin and similar reproductive and hormonal risk factors for malignancy, we tested the hypothesis that progestins confer biological effects in the endometrium similar to those in the ovary. METHODS: Postmenopausal female macaques (n = 78) were randomized into four groups to receive a diet for 36 months containing no hormone versus conjugated equine estrogen (CEE), medroxyprogesterone acetate (MPA), or CEE + MPA. The endometrium was then examined immunohistochemically for treatment-specific changes using antibodies to activated caspase-3 (for apoptosis), Ki-67 (proliferation), and the TGF-beta1, TGF-beta2, and TGF-beta3 isoforms. RESULTS: Percentages of caspase-positive endometrial glandular cells were 3- to 5-fold higher in CEE + MPA-treated animals compared with all others (P < 0.05). Caspase-expressing cells were six times more numerous in the endometrial stroma of animals treated with MPA alone relative to other groups (P < 0.0001). Induction of endometrial glandular cell apoptosis in the CEE + MPA-treated group was associated with a dramatic increase in expression of TGF-beta2 and TGF-beta3 in the stromal compartment of the endometrium (P < 0.0001). CONCLUSION: Progestin treatment activates chemopreventive biological effects in the endometrium that are similar to those in the ovarian surface epithelium. These data may facilitate identification of a chemopreventive approach that dramatically lessens the risk of both uterine and ovarian cancer.

Uterine infarctions in cynomolgus monkeys (Macaca fascicularis).

Uterine infarctions have not been reported in domestic animals, and there are few reports in the human medical literature. In a retrospective study, uterine infarctions were identified in 9 of 323 (2.8%) female cynomolgus monkeys (Macaca fascicularis) necropsied over a 13-year period. The infarctions were grossly visible, after fixation, on the serosal surface of the uterus in 2 monkeys; the remainder were first recognized in histologic sections. Histologically, the lesions consisted of well-demarcated regions of endometrial and myometrial necrosis and of hemorrhage. All affected monkeys had histologic evidence of a previous pregnancy, which included enlarged myometrial vessels with an expanded perivascular matrix. In all monkeys with uterine infarctions, there was clinical evidence of severe systemic illness, which included trauma, diarrhea, hypovolemia, or septicemia. The major pathologic findings in affected monkeys included cutaneous or skeletal muscle necrosis (n = 5), enterocolitis (n = 4), pulmonary edema or diffuse alveolar damage (n = 3), and intestinal amyloidosis (n = 1). Histopathologic evidence of intravascular fibrin thrombi in multiple organs of 5 monkeys was consistent with a diagnosis of disseminated intravascular coagulopathy (DIC). Based on these findings, it appears that uterine infarction is an uncommon finding in cynomolgus monkeys and may occur secondary to a severe systemic illness, predisposing to DIC.

Histologic and immunohistochemical characterization of spontaneous pituitary adenomas in fourteen cynomolgus macaques (Macaca fascicularis).

Pituitary adenomas were identified in 14 of 491 (2.9%) cynomolgus macaques evaluated from 1994 to 2004. Cases included male (8) and female (6) cynomolgus macaques ranging from 18 to 32 years of age. Seven of the pituitary adenomas caused gross enlargement of the pituitary gland that was visible on postmortem examination, whereas the remaining 7 were multifocal microadenomas identified on histologic examination. A total of 35 adenomas were identified in the 14 macaques, 6 of which were being treated for diabetes mellitus. Mean (+/- SD) pituitary weight was 0.31 +/- 0.42 g, compared with 0.07 +/- 0.02 g for 430 historical control animals (P < 0.0001). Immunohistochemical staining for follicle-stimulating hormone, luteinizing hormone, prolactin, human growth hormone, thyroid-stimulating hormone, and adrenocorticotropic hormone was applied to pituitary tissue from all cases. Immunostaining revealed 22 of 35 (62.9%) lactotroph adenomas, 5 of 35 (14.3%) plurihormonal cell adenomas, 3 of 35 (8.6%) corticotroph adenomas, 2 of 35 (5.7%) null cell adenomas, 1 of 35 (2.9%) somatotroph adenomas, 1 of 35 (2.9%) mixed corticotroph-somatotroph adenomas, 1 of 35 (2.9%) mixed lactotroph-corticotroph adenomas, 0 of 35 gonadotroph adenomas, and 0 of 35 thyrotroph adenomas. This study represents the first extensive retrospective case series performed to evaluate the histologic and immunohistochemical characteristics of pituitary adenomas in cynomolgus macaques. Our findings indicated that macaque pituitary adenomas frequently had mixed histologic appearance and hormone expression, and that, similar to human pituitary adenomas, prolactin-secreting neoplasms were the most prevalent type.

Hyperplastic and neoplastic lesions of the mammary gland in macaques.

Macaques provide an important animal model for the study of hormonal agents and their effects on risk biomarkers for breast cancer. A common criticism of this model is that spontaneous breast cancer has rarely been described in these animals. In this report, we characterize 35 mammary gland lesions ranging from ductal hyperplasia to carcinoma in situ and invasive ductal carcinoma in cynomolgus and rhesus macaques. Based on a retrospective analysis, we estimated the lifetime incidence of mammary gland neoplasia in aged female macaques to be about 6%. Hyperplastic lesions (n = 19) occurred segmentally along ducts and included such features as columnar alteration, micropapillary atypia, and fibroadenomatous change. In situ carcinomas (n = 8) included solid, comedo, cribriform, and micropapillary elements, encompassing 4 of the major architectural patterns seen in human lesions. Invasive ductal carcinomas (n = 8) were generally solid, with prominent central necrosis and mineralization, often on a background of micropapillary ductal hyperplasia and in situ carcinoma. Cytologic changes of invasive lesions included increased mitoses, nuclear pleomorphism, extensive microinvasion, and stromal desmoplasia. Axillary lymph-node metastases were confirmed in 5 of the 8 invasive carcinomas. On immunohistochemistry, intraductal and invasive carcinomas had increased Ki67/MIB1 and HER2 expression and selective loss of estrogen and progesterone receptors. These findings suggest that breast cancer is an underreported lesion in macaques and highlight unique morphologic and molecular similarities in breast cancer between human and macaque species.

Mitochondrial trifunctional protein defects: molecular basis and novel therapeutic approaches.

Mitochondrial trifunctional protein (MTP) is a complex protein that catalyzes the last three steps of long chain fatty acid oxidation. MTP defects have emerged recently as important inborn errors of metabolism because of their clinical implications. These disorders are recessively inherited and display a spectrum of clinical phenotypes in affected children including hepatic dysfunction, cardiomyopathy, neuro-myopathy, and may cause sudden unexpected infant death if undiagnosed and untreated. Interestingly, mothers who carry fetuses with MTP defects develop life-threatening complications during pregnancy. Recently, we delineated disease-causing mutations in MTP and reported the molecular basis for the pediatric and fetal-maternal genotype-phenotype correlations. Current management of patients with MTP defects include long-term dietary therapy of fasting avoidance, low fat diet with the restriction of long chain fatty acid intake and substitution with medium chain fatty acids. The long-term outcome of patients treated by dietary modifications remains unknown. Thus, treatment that aims at correcting the metabolic defect remains the therapy of choice for this disorder. Currently, we are exploring the potential use of protein transfection domains (PTD) for treatment of these disorders. We have shown that the transactivator of transcription (TAT) peptide from the human immunodeficiency virus can deliver proteins to mitochondria. We have further developed methods to localize these proteins to mitochondria by including a mitochondrial targeting in the fusion protein construct. Finally, we have shown that the fusion protein can cross the placenta and was detectable in the fetus and newborn pups. The practical therapeutic implications of this novel approach will be discussed.

Multisystem evaluations of the long-term effects of tibolone on postmenopausal monkeys.

This long-term study (2 years) was designed to compare the effects of tibolone (LoTib at 0.05 mg/kg and HiTib at 0.2 mg/kg) with those of conjugated equine oestrogens (CEE) alone (0.042 mg/kg) and CEE continuously combined with medroxyprogesterone acetate (MPA) (0.167 mg/kg) on coronary artery atherosclerosis, bone, mammary gland and uterus in ovariectomised cynomolgus monkeys fed a moderately atherogenic diet. Despite reductions in plasma concentrations of high density lipoprotein cholesterol in tibolone-treated monkeys, there was no exacerbation of coronary artery atherosclerosis. Tibolone was equivalent to, or slightly better than, CEE and CEE + MPA in protecting against postmenopausal bone loss and loss of bone strength. Tibolone also resulted in less stimulation of breast and endometrial tissue compared with CEE and CEE + MPA. In conclusion, the results suggest that tibolone is a cardiovascular-safe treatment that is effective for the prevention of osteoporosis and that may have advantages over CEE or CEE + MPA with regard to endometrial and breast safety.

Cervical and vaginal epithelial neoplasms in cynomolgus monkeys.

Papillomavirus-associated cervical cancer is the second most common neoplasm in women but has rarely been reported in animals. This report describes cervical and vaginal intraepithelial neoplasms identified in routine histologic specimens obtained from 20 (5.2%) of 385 female cynomolgus macaques (Macaca fascicularis) being used in long-term studies. Lesion incidence was similar in both control and hormonally treated animals (4.7% and 5.5%, respectively). Neoplasms included benign vaginal papillomas, mild to severe intraepithelial dysplasias, and two invasive cervical carcinomas. Common morphologic features included koilocytosis, nuclear atypia, and expansion of the basal epithelium. Selective staining of lesions with at least one of three papillomavirus antibodies was observed in all cases (20 of 20). In contrast, immunostaining of lesions was negative for Epstein-Barr-related virus proteins (0 of 20). The unique similarities between the observed lesions and those seen in women suggest that macaques may provide a suitable animal model for study of papillomavirus oncogenesis.

Effects of long-term HRT and tamoxifen on the expression of progesterone receptors A and B in breast tissue from surgically postmenopausal cynomolgus macaques.

Estrogen is a well-known mitogen in breast epithelium but the role of progesterone is complex and incompletely understood. In contrast to what is seen in the endometrium, combined estrogen/progestogen treatment for postmenopausal replacement (HRT) may carry a risk for breast cancer beyond that of estrogen alone. The ratio of the two progesterone receptor (PR) isoforms, PRA/PRB may define the response to progesterone in reproductive tissues. In a primate model for long-term HRT, surgically, postmenopausal cynomolgus macaques were treated for 35 months with conjugated equine estrogens (CEE), medroxyprogesterone acetate (MPA), CEE + MPA and tamoxifen (n = 5 in all groups). The immunohistochemical expression of PRA, PRB and the androgen receptor (AR) in breast tissue was quantified by image analysis. Over all, the total PR immunostaining in glandular epithelium was more abundant during CEE (mean 12%) and tamoxifen ( 1%) treatment as compared to CEE/MPA (5%), MPA (4%) and untreated controls (6%). Differences in PRB expression were observed between treatment groups (p < 0.05). In the CEE group levels of PRA were unchanged while there was a decline in the CEE/MPA group. The mean PRA/PRB ratio in the CEE group was 2.7 and in the CEE/MPA group 0.2. Treatment with tamoxifen had effects similar to those of estrogen. There was in all groups a weak positive nuclear AR immunostaining. This is the first in vivo study on the effects on long-term hormonal treatment on the expression of PR isoforms in normal primate breast tissue. The results suggest that hormonal treatments have a different influence on the PRA/PRB balance in the breast.

The effect of long-term treatment with steroid hormones or tamoxifen on oestrogen receptors (alpha and beta) in the endometrium of ovariectomized cynomolgus macaques.

The effects of oestrogen are mediated by two specific intracellular receptors, oestrogen receptors (ER) alpha and beta, which function as ligand-activated transcriptional regulators. Ovariectomized macaques (Macaca fascicularis) were used to study the regulation of ERalpha and ERbeta in the endometrium by immunohistochemistry and in situ hybridization after long-term hormone treatment. Animals were treated continuously for 35 Months with either conjugated equine oestrogen (CEE), medroxyprogesterone acetate (MPA), combined CEE/MPA, or tamoxifen (TAM). Treatment with CEE/MPA down-regulated ERalpha in the superficial glands. In the superficial stroma the ERalpha level was lower in the CEE/MPA group than in the CEE and MPA groups. ERbeta immunostaining was faint with minor variation in response to treatment, but increased in the superficial stroma after MPA treatment. The ratio of ERbeta/ERalpha increased in superficial stroma and gland after CEE/MPA treatment, and also in stroma after MPA and TAM. Cystic endometrial hyperplasia was observed in TAM-treated animals, in combination with a high level of ERalpha protein expression. The present data show that long-term hormone treatment affects the ERalpha and ERbeta protein levels in the endometrium. The balance between ERalpha and ERbeta seems to be important for the proliferative response to oestrogen.

Intracranial lymphomas in simian retrovirus-positive Macaca fascicularis.

Two young adult Macaca fascicularis each had unilateral mydriasis and ptosis. Both animals were euthanatized, monkey No. I for progressive neurologic signs and monkey No. 2 because of a positive intradermal tuberculin test. At necropsy, each animal had a single intracranial mass on the ventral surface of the midbrain, surrounding the oculomotor nerve. Histologically, both masses were immunoblastic lymphomas. Immunohistochemical staining revealed the neoplasms to be of B-cell origin. Simian retrovirus (SRV) was isolated from both monkeys, but simian immunodeficiency virus was not found. Both animals lacked antibody to SRV. Both animals had antibodies to Epstein-Barr-like virus (EBV), but EBV antigens were not found by immunohistochemistry. Polymerase chain reaction analysis for integrated EBV DNA was unproductive. One of the animals (monkey No. 2) had a pulmonary infection with Mycobacterium avium, suggesting that immunosuppression was present. These cases represent a unique and previously undescribed type of solitary lymphoma in SRV-infected macaques.