Short- and long-term reproductive effects of prenatal and lactational growth restriction caused by maternal diabetes in male rats

Reproductive toxicity of maternal exposure to di(2-ethylhexyl)phthalate and butyl paraben (alone or in association) on both male and female Wistar offspring

Parabens and phthalates are commonly found as contaminants in human fluids and are able to provoke reproductive toxicity, being considered endocrine disruptors. To evaluate the effects of phthalate and paraben, alone or in combination, on reproductive development of the offspring, female pregnant Wistar rats were allocated in six experimental groups: Three control groups (gavage [CG], subcutaneous [CS], and gavage + subcutaneous) received corn oil as vehicle, and the remaining groups were exposed to di(2-ethylhexyl)phthalate (DEHP) (500 mg/kg, gavage), butyl paraben (BP) (100 mg/kg, subcutaneously), or MIX (DEHP + BP), from Gestational Day 12 until Postnatal Day (PND) 21. The following parameters were assessed on the offspring: anogenital distance and weight at PND 1, nipple counting at PND 13, puberty onset, estrous cycle, weights of reproductive and detoxifying organs, histological evaluation of reproductive organs, and sperm evaluations (counts, morphology, and motility). Female pups from MIX group presented reduced body weight at PND 1, lower AGD, and decreased endometrium thickness. Male animals showed decreased body weight at PND 1 and lower number of Sertoli cells on DEHP and MIX groups, MIX group revealed increase of abnormal seminiferous tubules, DEHP animals presented delayed preputial separation and higher percentage of immotile sperms, and BP males presented diminished number of Leydig cells. In conclusion, the male offspring was more susceptible to DEHP toxicity; even when mixed to paraben, the main negative effects observed seem to be due to antiandrogenic phthalate action. On the other hand, DEHP seems to be necessary to improve the effects of BP on reducing estrogen-dependent and increasing androgen-dependent events.

Histomorphometric and oxidative evaluation of the offspring's testis from type 2 diabetic female rats treated with metformin and pentoxifylline

Type 2 diabetes mellitus (T2D) during pregnancy is characterized by high levels of reactive oxygen species and pro-inflammatory factors in the placenta. Once these reactive species reach the foetus, they trigger physiological adaptations that allow the foetus to survive, but programme the organism to develop metabolic disorders in adulthood. The male reproductive system is highly susceptible to foetal programming. This study aimed to investigate the effects of intrauterine exposure to T2D on testicular histomorphometry and redox homeostasis of adult rats and evaluate the effects of maternal treatment with metformin and pentoxifylline. Female rats were induced to T2D, then treated with metformin and pentoxifylline, or co-treated with both drugs. The females were mated, the male offspring were sacrificed on postnatal day 90, and the testicles were collected for analysis. Metformin protected the tubular compartment, with the maintenance of the Sertoli cell population and daily sperm production. Pentoxifylline attenuated the effects of diabetes on Leydig cells, in addition to stimulating testosterone production and lowering lipid peroxidation. Intrauterine exposure to T2D results in important testicular alterations that compromise gonadal function, and the co-treatment with metformin and pentoxifylline may represent a promising therapy that attenuates these effects by combining the positive influences in both the tubular and interstitial compartments of the testicular parenchyma.

Looking at the Future Through the Mother's Womb: Gestational Diabetes and Offspring Fertility

Altered nutrition or intrauterine exposure to various adverse conditions during fetal development or earlier in a mother's life can lead to epigenetic changes in fetal tissues, predisposing those tissues to diseases that manifest when offspring become adults. An example is a maternal obesity associated with gestational diabetes (GDM), where fetal exposure to a hyperglycemic, hyperinsulinemic, and/or hyperlipidemic gestational environment can provoke epigenetic changes that predispose offspring to various diseased conditions later in life. While it is now well established that offspring exposed to GDM have an increased risk of developing obesity, metabolic disorders, and/or cardiovascular disease in adult life, there are limited studies assessing the reproductive health of these offspring. This mini-review discusses the long-term effect of in utero exposure to GDM-associated adverse prenatal environment on the reproductive health of the offspring. Moreover, using evidence from various animal models and human epidemiological studies, this review offers molecular insight and understanding of how epigenetic reprogramming of genes culminates in reproductive dysfunction and the development of subfertility or infertility later in adult life.

Fetal Programming Effects of a Mild Food Restriction During Pregnancy in Mice: How Does It Compare to Intragestational Ghrelin Administration?

To explore in mice if a 15% food restriction protocol during pregnancy programs the offspring postnatal development, with emphasis on reproductive function, and to assess if ghrelin (Ghrl) administration to mouse dams exerts effects that mimic those obtained under mild caloric restriction. Mice were 15% food-restricted, injected with 4 nmol/animal/day of Ghrl, or injected with the vehicle (control) thorough pregnancy. After birth, the pups did not receive further treatment. Pups born from food-restricted dams (FR pups) were lighter than Ghrl pups at birth, but reached normal weight at adulthood. Ghrl pups were heavier at birth and gained more weight than control pups (C pups). This effect was not associated with plasma IGF-1. FR pups showed a delay in pinna detachment and eye opening, while an advance was observed in Ghrl pups. FR pups showed also impairment in the surface-righting reflex. In both female FR and Ghrl pups, there was an advance in vaginal opening and, in adulthood, FR pups showed a significant decrease in their own litter size and plasma progesterone, and an increase in embryo loss. A delay in testicular descent was evident in male Ghrl pups. Changes in puberty onset were not associated with differences in the expression of Kiss1 in hypothalamic nuclei. Finally, in adulthood, FR pups showed a significant decrease in sperm quality. In conclusion, a mild food restriction thorough gestation exerted programming effects on the offspring, affecting also their reproductive function in adulthood. These effects were not similar to those of intragestational Ghrl administration.

Severity of prepregnancy diabetes on the fetal malformations and viability associated with early embryos in rats†

Preexisting/pregestational diabetes enhances the risk of birth defects. Several factors have been involved during the implantation process, such as cytokines (granulocyte-macrophage-colony-stimulating factor [GM-CSF]). The objective was to evaluate the effects of two levels of diabetes on the redox status of preimplantation embryos during the implantation process to comprehend how both are involved in embryo and fetal viability against maternal diabetes. Female Sprague-Dawley rats received streptozotocin at birth (mild diabetes [MD]) or at adulthood (severe diabetes [SD]) to obtain two experimental diabetes intensities. After confirming the diabetic status, the nondiabetic and diabetic groups were mated around day 110 of life. At gestational day (GD) 21, fetuses were assessed for viability and malformations and ovaries for embryo loss before implantation. Other pregnant nondiabetic and diabetic rats were sacrificed at GD2-4 for maternal and preimplantation embryo oxidative stress markers, maternal serum insulin, uterine fluid GM-CSF, and preimplantation embryo morphological analysis. MD and SD caused abnormal redox levels, lower GM-CSF and insulin levels during the preimplantation period, and embryonic loss before implantation. SD caused lower fetal viability and higher fetal malformation percentages at GD21. The SD dam-derived preimplantation embryos presented lower glutathione levels and higher thiobarbituric acid reactive substances concentration at GD3 and an increased frequency of abnormal preimplantation embryos at GD4. In conclusion, preexisting diabetes leads to complications in the implantation process. Furthermore, maternal oxidative stress and other metabolic changes alter the redox state and morphological structure of preimplantation embryos, contributing to damaged growth and development in late pregnancy.

In Vivo and In Vitro Models of Diabetes: A Focus on Pregnancy

Diabetes in pregnancy is associated with an increased risk of poor outcomes, both for the mother and her offspring. Although clinical and epidemiological studies are invaluable to assess these outcomes and the effectiveness of potential treatments, there are certain ethical and practical limitations to what can be assessed in human studies.Thus, both in vivo and in vitro models can aid us in the understanding of the mechanisms behind these complications and, in the long run, towards their prevention and treatment. This review summarizes the existing animal and cell models used to mimic diabetes, with a specific focus on the intrauterine environment. Summary of this review.

Gut microbiota and probiotic intervention as a promising therapeutic for pregnant women with cardiometabolic disorders: Present and future directions

Maternal cardiometabolic disorders, such as gestational diabetes mellitus, pre-eclampsia, obesity, and dyslipidemia, are the most common conditions that predispose offspring to risk for future cardiometabolic diseases, needing appropriate therapeutic approach. The implications of microbiota in the pathophysiology of maternal cardiometabolic disorders are progressively emerging and probiotics may be a simple and safe therapeutic strategy for maternal cardiometabolic management. In this review, we argue the importance of cardiometabolic dysfunction during pregnancy and/or lactation on the offspring risk for cardiometabolic disease in later life. In addition, we comprehensively discuss the microbial diversity observed in maternal cardiometabolic disorders and we present the main findings on probiotic intervention as a potential strategy for management of maternal cardiometabolic disorders. Current data reveal that gut microbiota may be transmitted from mother to offspring. Whether targeting microbiota with probiotic intervention during the periconceptional period prevents or delays the onset of cardiometabolic disorders in adult offspring should be tested in future clinical trials.

Effects of insulin and metformin on fetal kidney development of streptozotocin-induced gestational diabetic albino rats

Gestational diabetes mellitus is one of common medical complications of pregnancy. Hyperglycemia in utero impairs renal development and produces renal anomalies. Metformin has antioxidant properties and better glycemic control. Aim: assessment insulin and metformin effects on renal development of streptozotocin-induced gestational diabetic albino rats. Sixty virgin female albino rats were used. Once pregnancy confirmed, animals were randomly assigned into control, metformin, diabetic, diabetic plus insulin, diabetic plus metformin and diabetic plus insulin and metformin treated groups. Rats were sacrificed on the 20th day of gestation; fetuses were extracted and weighted. Fetal kidneys were extracted prepared for light, morphometric and electron microscopic examination. Diabetic followed by diabetic plus metformin treated groups revealed retardation of glomerular development in the cortical and Juxtaglomerular zones with a significant increase in the early immature glomerular stages and immature to mature glomerular ratio compared to other groups. Diabetic group also showed morphometric changes, shrunken and empty glomeruli, vacuolar degeneration and hemorrhage. Diabetic plus metformin group showed minimal improvement while diabetic plus insulin and diabetic plus insulin and metformin groups showed developmental, histopathological and morphometric improvement with best results in the combination group. Gestational diabetes mellitus (GDM) possess deleterious effects on fetal kidney development. Insulin improves the glycemic state and decreases GDM effects on fetal kidneys. Metformin produces mild protection while the combination of insulin and metformin produces the best glycemic control and protect fetal kidneys.

Diabetes Mellitus in Pregnancy Leads to Growth Restriction and Epigenetic Modification of the Srebf2 Gene in Rat Fetuses

Diabetic pregnancy is correlated with increased risk of metabolic and neurological disorders in the offspring putatively mediated epigenetically. Little is known about epigenetic changes already present in fetuses of diabetic pregnancies. We aimed at characterizing the perinatal environment after preexisting maternal diabetes mellitus and at identifying relevant epigenetic changes in the fetus. We focused on the transcription factor Srebf2 (sterol regulatory element binding transcription factor 2), a master gene in regulation of cholesterol metabolism. We tested whether diabetic pregnancy induces epigenetic changes in the Srebf2 promoter and if they become manifest in altered Srebf2 gene expression. We worked with a transgenic rat model of type 2 diabetes mellitus (Tet29) in which the insulin receptor is knocked down by doxycycline-induced RNA interference. Doxycycline was administered preconceptionally to Tet29 and wild-type control rats. Only Tet29 doxycycline dams were hyperglycemic, hyperinsulinemic, and hyperlipidemic. Gene expression was analyzed with quantitative real-time reverse transcriptase polymerase chain reaction and CpG promoter methylation with pyrosequencing. Immunohistochemistry was performed on fetal brains. Fetuses from diabetic Tet29 dams were hyperglycemic and growth restricted at the end of pregnancy. They further displayed decreased liver and brain weight with concomitant decreased microglial activation in the hippocampus in comparison to fetuses of normoglycemic mothers. Importantly, diabetic pregnancy induced CpG hypermethylation of the Srebf2 promoter in the fetal liver and brain, which was associated with decreased Srebf2 gene expression. In conclusion, diabetic and hyperlipidemic pregnancy induces neurological, metabolic, and epigenetic alterations in the rat fetus. Srebf2 is a potential candidate mediating intrauterine environment-driven epigenetic changes and later diabetic offspring health.

Effect of gestational diabetes mellitus on testis and pancreatic tissues of male offspring

The purpose of this study was to determine the effect of gestational diabetes mellitus (GDM) on some reproductive characteristics, testicular and pancreatic oxidative status and pancreatic endocrine receptor densities of male offspring at post-pubertal stage. A total of 36 1-day-old Wistar Albino male offspring including 12 pups of nontreated mothers (control group), 14 pups of 40 mg/kg STZ-injected mothers (STZ-40 group) and 10 pups of 60 mg/kg STZ-injected mothers (STZ-60 group) were used. The offspring were euthanised on post-natal day 60, their blood, reproductive organs and pancreatic tissues were obtained and examined. When compared with the control group, there was a significant decrease in body and absolute reproductive organ weights, serum testosterone level, testicular and pancreatic catalase activities, pancreatic glutathione level, epididymal sperm concentration of both STZ-40 and STZ-60 groups as well as in testicular glutathione level of only STZ-60 group. Significant increases were determined in testicular and pancreatic malondialdehyde level and glutathione peroxidase activity in both groups and in fasting serum glucose of only STZ-60 group in comparison with the control group. Although some histopathological damages were observed in testes of both STZ-40 and STZ-60 groups, there were no detectable differences between the groups in density of insulin, glucagon and somatostatin receptors in pancreas. In conclusion, GDM has negative effects on reproductive efficiency and testicular-pancreatic tissue oxidant/antioxidant balance of male offspring at post-pubertal stage.

Effects of flour or flaxseed oil upon testis mass in rats subjected to early weaning

Study evaluates testis mass in rats subjected to early weaning and subsequently nourished with diet containing flour or flaxseed oil. Pups were weaned for separation from mothers at 14 days (early weaning, EW) and 21 days (control, C). After 21 days, the control group (C60) was nourished with control diet. EW was divided as: control (EWC60), flaxseed flour (EWFF60) and flaxseed oil (EWFO60) group diets for the next 60 days. At 21st and 60th day, body mass, serum cholesterol and triglycerides and testis mass were evaluated. At 21 day, EW group showed lower (p < 0.05) body mass, serum cholesterol and testis mass. At 60 days, EWC60 and EWFO60 groups showed lower (p < 0.05) body mass (vs. C60 and EWFF60). EWFF60 group showed lower (p < 0.05) serum cholesterol (vs. EWC60 and EWFO60) and higher (p < 0.05) testis mass (vs. C60, EWC60 and EWFO60). Flaxseed flour (vs. oil) was associated with higher testis mass following early weaning.

Maternal diabetes impairs the initiation of meiosis in murine female germ cells

Gestational diabetes mellitus (GDM) is characterized by an initial diagnosis of glucose intolerance during pregnancy. There is increasing evidence supporting the association between GDM and the inhibited development of several organs in offspring. In the present study, a murine GDM model was established in mice by intraperitoneal injection of streptozotocin to evaluate the effect of maternal diabetes on the initiation of meiosis in female germ cells of offspring. The effect of GDM on the initiation of meiosis in the offspring was evaluated by reverse transcription-quantitative polymerase chain reaction, flow cytometry and hematoxylin and eosin staining. The results showed that, compared with the control group, fetal ovary growth was inhibited, the expression levels of meiosis-specific genes, stimulated by retinoic acid gene 8, synaptonemal complex protein, and DNA meiotic recombinase were inhibited, and the number of primordial/primary follicles was reduced in the GDM group. These may have been induced by an increase of apoptosis and inhibition of growth, as the mRNA levels of p21, a vital G1 cell cycle inhibitor, and apoptotic genes were upregulated, whereas the expression levels of genes important in folliculogenesis were decreased in the GDM group. In conclusion, the data obtained in the present study suggested that maternal diabetes may impair the initiation of meiosis and ovarian growth via growth inhibition, cell cycle arrest and the induction of apoptosis.

Streptozotocin-Induced Maternal Hyperglycemia Increases the Expression of Antioxidant Enzymes and Mast Cell Number in Offspring Rat Ventral Prostate

Gestational diabetes mellitus (GDM) has increased in recent years. Although the cellular and molecular mechanisms involved in GDM-increased risk factors to offspring remained poorly understood, some studies suggested an association between an increase in oxidative stress induced by maternal hyperglycemia and complications for both mothers and newborns. Here, we investigated the impact of maternal hyperglycemia followed by maternal insulin replacement during lactation on the expression of antioxidant enzymes and mast cell number in offspring ventral prostate (VP) at puberty. Pregnant rats were divided into three groups: control (CT); streptozotocin-induced maternal hyperglycemia (MH); and MH plus maternal insulin replacement during lactation (MHI). Male offspring were euthanized at postnatal day (PND) 60 and the VP was removed and processed for histology and Western blotting analyses. Maternal hyperglycemia delayed prostate maturation, and increased mast cell number catalase (CAT), superoxide dismutase (SOD), glutatione-s-transferase (GST-pi), and cyclooxygenase-2 (Cox-2) expression in the offspring of hyperglycemic dams. Maternal insulin replacement restored VP structure, mast cell number and antioxidant protein expression, except for Cox-2, which remained higher in the MHI group. Thus, an increase in oxidative stress induced by intrauterine hyperglycemia impacts prostate development and maturation, which persists until puberty. The overall improvement of maternal metabolism after insulin administration contributes to the restoration of prostate antioxidant enzymes and secretory function. Taken together, our results highlighted that imbalanced physiological maternal-fetal interaction contributes to the impairment of reproductive performance of the offspring from diabetic mothers. Anat Rec, 300:291-299, 2017. © 2016 Wiley Periodicals, Inc.

Maternal hyperglycemia at different stages of gestation and its effects on male reproductive functions in rats

The critical period during which maternal hyperglycemia predisposes offspring to develop reproductive disorders in adult life is not known. The relationship between maternal hyperglycemia at different stages and reproductive functions of male offspring was investigated. A single intraperitoneal injection of alloxan (90 mg/kg body weight) was administered at gestation days (GD) 1, 8 and 15. Animals were subsequently given 10% glucose solution daily as drinking water until parturition. All male pups were sacrificed on the 63rd day of postnatal life. Birth weight, anogenital distance index (AGDi), testes descent day, preputial separation day, sperm profile, serum testosterone, luteinizing hormone and follicle-stimulating hormone levels and the histology of the testis were assessed. Data significance test was based on 95% confidence interval. GD1 pups showed a significant increase in mean birth weight, whereas GD8 pups and GD15 pups had significantly reduced birth weight as compared with control. AGDi was significantly increased in GD8 and GD15 pups. Testes descent and preputial separation in all the experimental groups were significantly earlier. There was a significant reduction in sperm count and viability in GD8 offspring. Sperm motility was reduced in all test groups. Testosterone level was reduced in all test groups. Histology of the testis showed varying degrees of pathologies. It was deduced from this study that maternal hyperglycemia caused alterations in reproductive functions in male offspring of Wistar rats irrespective of the period of gestation involved, although GD8 pups were most severely affected.

Blockage of the Neonatal Leptin Surge Affects the Gene Expression of Growth Factors, Glial Proteins, and Neuropeptides Involved in the Control of Metabolism and Reproduction in Peripubertal Male and Female Rats

Leptin (Lep) is important in the development of neuroendocrine circuits involved in metabolic control. Because both Lep and metabolism influence pubertal development, we hypothesized that early changes in Lep signaling could also modulate hypothalamic (HT) systems involved in reproduction. We previously demonstrated that a single injection of a Lep antagonist (Antag) on postnatal day (PND)9, coincident with the neonatal Lep peak, induced sexually dimorphic modifications in trophic factors and markers of cell turnover and neuronal maturation in the HT on PND13. Here, our aim was to investigate whether the alterations induced by Lep antagonism persist into puberty. Accordingly, male and female rats were treated with a pegylated super Lep Antag from PND5 to PND9 and killed just before the normal appearance of external signs of puberty (PND33 in females and PND43 in males). There was no effect on body weight, but in males food intake increased, subcutaneous adipose tissue decreased and HT neuropeptide Y and Agouti-related peptide mRNA levels were reduced, with no effect in females. In both sexes, the Antag increased HT mRNA levels of the kisspeptin receptor, G protein-coupled recepter 54 (Gpr54). Expression of the Lep receptor, trophic factors, and glial markers were differently affected in the HT of peripubertal males and females. Lep production in adipose tissue was decreased in Antag-treated rats of both sexes, with production of other cytokines being differentially regulated between sexes. In conclusion, in addition to the long-term effects on metabolism, changes in neonatal Lep levels modifies factors involved in reproduction that could possibly affect sexual maturation.

Effects of maternal separation on the dietary preference and behavioral satiety sequence in rats

This study investigated the effects of maternal separation on the feeding behavior of rats. A maternal separation model was used on postnatal day 1 (PND1), forming the following groups: in the maternal separation (MS) group, pups were separated from their mothers each day from PND1 to PND14, whereas in the control (C) group pups were kept with their mothers. Subgroups were formed to study the effects of light and darkness: control with dark and light exposure, female and male (CF and CM), and maternal separation with dark and light exposure, female and male (SDF, SDM, SLF and SLM). Female rats had higher caloric intake relative to body weight compared with male controls in the dark period only (CF=23.3±0.5 v. CM=18.2±0.7, P<0.001). Macronutrient feeding preferences were observed, with male rats exhibiting higher caloric intake from a protein diet as compared with female rats (CF=4.1±0.7, n=8 v. CM=7.0±0.5, n=8, P<0.05) and satiety development was not interrupted. Female rats had a higher adrenal weight as compared with male rats independently of experimental groups and exhibited a higher concentration of serum triglycerides (n=8, P<0.001). The study indicates possible phenotypic adjustments in the structure of feeding behavior promoted by maternal separation, especially in the dark cycle. The dissociation between the mother's presence and milk intake probably induces adjustments in feeding behavior during adulthood.

Impact of gestational diabetes and lactational insulin replacement on structure and secretory function of offspring rat ventral prostate

Clinical and experimental studies have shown that exposure to adverse conditions during the critical stages of embryonic, fetal or neonatal development lead to a significantly increased risk of later disease. Diabetes during pregnancy has been linked to increased risk of obesity and diabetes in offspring. Here, we investigated whether mild gestational diabetes mellitus (GDM) followed or not by maternal insulin replacement affects the ventral prostate (VP) structure and function in male offspring at puberty and adulthood. Pregnant rats were divided into the following 3 groups: control (CT); streptozotocin (STZ)-induced diabetes (D); and D plus insulin replacement during lactation (GDI). The male offspring from different groups were euthanized at postnatal day (PND) 60 and 120. Biometrical parameters, hormonal levels and prostates were evaluated. Mild-GDM promoted reduction in the glandular parenchyma and increased collagen deposition. Insulin replacement during lactation restored the VP morphology. Most importantly, mild-GDM decreased the androgen-induced secretory function as determined by prostatein expression, and insulin replacement reversed this effect. Our results demonstrated that mild GDM impairs VP parenchyma maturation, which is associated with an increase in the fibromuscular stroma compartment. Functionally, the reduction in the VP parenchyma decreases the glandular secretory activity as demonstrated by low expression of prostatein, a potent immunosuppressor factor that protects sperm from immunologic damage into the feminine reproductive tract. This change could lead to impairment of reproductive function in male offspring from diabetic mothers. Maternal insulin replacement during the weaning period apparently restores the prostate function in male offspring.

Maternal obesity and diabetes may cause DNA methylation alteration in the spermatozoa of offspring in mice

BACKGROUND

The adverse effects on offspring of diabetic and/or obese mothers can be passed to the next generation. However, the mechanisms behind this are still unclear. Epigenetics may play a key role during this process.

METHODS

To confirm the hypothesis, we investigated the DNA methylation of several imprinted genes in spermatozoa of offspring from diabetic and/or obese mothers utilizing streptozotocin (STZ)- and high-fat-diet (HFD)-induced mouse models.

RESULTS

We found that the DNA methylation of Peg3 was significantly increased in spermatozoa of offspring of obese mothers compared to that in spermatozoa of offspring of normal mothers. The DNA methylation of H19 was significantly higher in spermatozoa of offspring of diabetic mothers than that in spermatozoa of offspring of non-diabetic mothers.

CONCLUSIONS

These results indicate that pre-gestational diabetes and/or obesity can alter DNA methylation in offspring spermatozoa.

Standard operating procedures for maintaining cleanliness in a novel compact facility for breeding SPF mice

A compact facility for SPF mice that was not equipped with a large autoclave used disposable mouse cages instead. The SPF clean room was 5.7 × 8.1 × 2.7 m(3), with a breeding capacity of 1008 cages (168 cages on each of 6 racks). We evaluated cleanliness in the SPF clean room under the conditions of an occupation rate of 60% to 70% and typically 1 to 3 personnel (maximum, 4 to 6) daily on weekdays. Personnel were taught standard procedures and received training beforehand. During the 15-mo study period, the maximal concentration of airborne particles 0.5 μm or larger was 1.0 × 10(4) particles/m3 and that of particles 5.0 μm or larger was 5.0 × 10(2) particles/m(3)--well below the maximal permissible concentrations of 3.52 × 10(5) and 2.93 × 10(3) particles/m(3), respectively. During the study period, no mice exhibited clinical symptoms of infection. Testing of 2 representative, overtly healthy mice for 16 pathogens including Staphylococcus aureus, Pseudomonas aeruginosa, and Helicobacter bilis failed to detect any of the target agents. The current study demonstrates the feasibility of the compact facility for breeding SPF mice in the academic environment.