Diabetes (db/db) Mutation-Induced Ovarian Involution: Progressive Hypercytolipidemia

Differential sex-dependent susceptibility to diastolic dysfunction and arrhythmia in cardiomyocytes from obese diabetic HFpEF model

AIM

Sex-differences in heart failure with preserved ejection fraction (HFpEF) are important, but key mechanisms involved are incompletely understood. While animal models can inform about sex-dependent cellular and molecular changes, many previous preclinical HFpEF models have failed to recapitulate sex-dependent characteristics of human HFpEF. We tested for sex-differences in HFpEF using a two-hit mouse model (leptin receptor-deficient db/db mice plus aldosterone infusion for 4 weeks; db/db+Aldo).

METHODS AND RESULTS

We performed echocardiography, electrophysiology, intracellular Ca2+ imaging, and protein analysis. Female HFpEF mice exhibited more severe diastolic dysfunction in line with increased titin N2B isoform expression and PEVK element phosphorylation, and reduced troponin-I phosphorylation. Female HFpEF mice had lower BNP levels than males despite similar comorbidity burden (obesity, diabetes) and cardiac hypertrophy in both sexes. Male HFpEF mice were more susceptible to cardiac alternans. Male HFpEF cardiomyocytes (versus female) exhibited higher diastolic [Ca2+], slower Ca2+ transient decay, reduced L-type Ca2+ current, more pronounced enhancement of the late Na+ current, and increased short-term variability of action potential duration (APD). However, male and female HFpEF myocytes showed similar downregulation of inward rectifier and transient outward K+ currents, APD prolongation, and frequency of delayed afterdepolarizations. Inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII) reversed all pathological APD changes in HFpEF in both sexes, and empagliflozin pretreatment mimicked these effects of CaMKII inhibition. Vericiguat had only slight benefits, and these effects were larger in HFpEF females.

CONCLUSION

We conclude that the db/db+Aldo preclinical HFpEF murine model recapitulates key sex-specific mechanisms in HFpEF and provides mechanistic insights into impaired excitation-contraction coupling and sex-dependent differential arrhythmia susceptibility in HFpEF with potential therapeutic implications. In male HFpEF myocytes, altered Ca2+ handling and electrophysiology aligned with diastolic dysfunction and arrhythmias, while worse diastolic dysfunction in females may depend more on altered myofilaments properties.

Phytochemical and antidiabetic analysis of Curatella americana L. aqueous extract on the rat pregnancy

ETHNOPHARMACOLOGICAL RELEVANCE

Curatella americana L. is employed in popular medicine for treating diabetes. However, the understanding around its outcomes during pregnancy is unclear.

AIM OF THE STUDY

To evaluate the phytochemical and hypoglycemic analysis of the C. americana extract and its maternal-fetal effect on diabetic rats.

MATERIALS AND METHOD

Diabetes was chemically induced 24 h after birth in Wistar female newborn rats. At adulthood, after diabetes status confirmation, the rats were mated and randomized into four experimental groups: Nondiabetic (Control): given water; Treated: given C. americana extract; Diabetic, and Treated Diabetic rats. The aqueous extract of C. americana leaves (300 mg/kg) was administered daily through oral route during pregnancy. Maternal toxicity and biochemical profile, reproductive outcomes, fetal development, and phenolic composition and biogenic amines in aqueous extract were analyzed.

RESULTS AND CONCLUSION

Phytochemical analysis revealed that the main phenolic components are 3-hydroxytyrosol, kaempferol, and quercetin, while tryptophan and putrescine derivatives were identified as the dominant amines. C. americana extract treatment improved the lipid profile, although no effect on hyperglycemic control in diabetic rats was observed. Maternal diabetes or C. americana extract caused embryo losses confirmed by the lower number of pre-embryos in early pregnancy and higher percentage of abnormal morphologically pre-embryos. C. americana extract previously caused premature pre-embryo fixation before implantation window in nondiabetic and diabetic mothers and intrauterine growth restriction in the fetuses of treated nondiabetic dams, complicating the embryo fetal development. These findings reinforce the caution of indiscriminate use of medicinal plants, especially during pregnancy.

Topical estrogen application promotes cutaneous wound healing in db/db female mice with type 2 diabetes

Female sex hormones are beneficial effects for wound healing. However, till date, whether topical estrogen application can promote cutaneous wound healing in diabetes remains unclear. Therefore, the present study aimed to validate the effect of topical estrogen application on cutaneous wound healing in a type 2 diabetes db/db mice model. In total, 22 db/db female mice with type 2 diabetes and eight C57BL/6J female mice were subjected to two full-thickness wound injuries. The mice were divided into the db/db, db/db + estrogen, db/db + vehicle, and wild type (WT) groups. Wound healing was assessed until day 14. The db/db group had a significantly high wound area ratio (wound area/initial wound area) on days 3–14 and a significantly low re-epithelialization ratio on days 7 and 14. Moreover, their angiogenesis ratio was significantly low on day 7 and high on day 14. In contrast, compared with the db/db group, the db/db + estrogen group had a significantly lower wound area ratio on days 1–14 and angiogenesis ratio on day 14, thereby indicating early withdrawal of new blood vessels, as well as a significantly higher re-epithelialization ratio on days 7 and 14 and Ym1⁺ M2 macrophage/macrophage ratio on day 7. Moreover, microarray analysis showed that the top 10 upregulated or downregulated genes in the db/db group were reversed by estrogen treatment, particularly on day 14, in comparison with the WT group. Thus, topical estrogen application reduced the wound area, promoted re-epithelialization and angiogenesis, and increased the number of M2 macrophages in mice with type 2 diabetes. Furthermore, it improved the differential regulation of genes in db/db mice. Therefore, such treatment can enhance cutaneous wound healing in female mice with type 2 diabetes.

Accelerated Ovarian Aging Among Type 2 Diabetes Patients and Its Association With Adverse Lipid Profile

BACKGROUND

The impact of diabetes on reproductive function is still not clearly defined. This study aimed to evaluate accelerated ovarian aging in women with type 2 diabetes mellitus (T2DM) and its association with adverse lipid profile.

METHODS

Female patients with T2DM (n=964) and non-T2DM controls (n=263) aging from 18-80 years were included. Levels of circulating sex hormones were measured at the follicular phase in menstruating women. We analyzed the age-specific trends in the levels of sex hormones between T2DM and controls. The correlations of sex hormones with the lipid profile, including low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC) and triglycerides (TG) were also evaluated.

RESULTS

In the temporal trends analysis, LH and FSH both started to increase obviously approximately from the age of 45 years among patients with T2DM, and displayed peaks of LH and FSH among patients with T2DM aged between 61 and 65, both of which were obviously earlier than that in non-T2DM controls and proved the accelerated ovarian aging among patients with T2DM. E2 of patients with T2DM was continuous lower than that of non-T2DM controls from approximately 45 years old, and LH and FSH of patients with T2DM were higher than those of non-T2DM controls between the age of 55 to 65 years. Multiple linear regression analyses revealed that LH was positively correlated with LDL-C (Coefficient=0.156, P=0.001) and TC (Coefficient=0.134, P=0.025), and was negatively correlated with HDL-C (Coefficient =-0.065, P=0.001) in patients with T2DM aged between 51 and 60, which was independent of age, T2DM duration, body mass index (BMI), glycosylated hemoglobin (HbA1c), FSH, E2 and other potential confounders. Higher E2 level was significantly and independently correlated with lower LDL-C (Coefficient= -0.064, P=0.033) in patients with T2DM aged between 51 and 60.

CONCLUSIONS

This study suggests that patients with T2DM have accelerated ovarian aging, and it is correlated with the occurrence of disturbed lipid profile in patients with T2DM. With an ever increasing number of female patients with T2DM diagnosed at younger ages, the accelerated ovarian aging and its adverse impacts in T2DM need to be carefully managed.

The Protective Effects of L-Carnitine and Zinc Oxide Nanoparticles Against Diabetic Injury on Sex Steroid Hormones Levels, Oxidative Stress, and Ovarian Histopathological Changes in Rat

Diabetes mellitus is a common chronic metabolic disorder. This study aimed to investigate the effects of co-treatment with L-carnitine (LC) and zinc oxide nanoparticles (ZnONPs) on serum levels of sex hormones, oxidative stress, and ovarian histopathology in streptozotocin (STZ)-induced diabetic rats. Female Wistar rats (n = 56, 180-220 g) received a single intraperitoneal (IP) injection of STZ (65 mg/kg). They were randomly assigned into the following groups: diabetic group (Dia), Dia+Met group (100 mg metformin/kg/day), Dia+LC group (200 mg/kg/day), Dia+ZnONPs group (10 mg/kg/day), and Dia+LC+ZnONPs group (200 mg LC/kg/day and 10 mg ZnONPs/kg/day). Control group (Ctl) received the same volume of STZ solvent. After 21 days of treatment, blood serum was centrifuged for sex hormone assays. The right ovary was used for biochemical analysis, and the left ovary was fixed in 10% neutral buffered formalin for histological assessment. The levels of estradiol, progesterone, FSH, and LH significantly increased in the Dia+ZnONPs+LC group (P < 0.001) compared with the Dia group. Co-treatment with LC and ZnONPs reduced malondialdehyde and carbonyl protein and increased glutathione, catalase, and superoxide dismutase activities in ovarian tissue compared with the Dia group (P < 0.05). Moreover, the number of all ovarian follicles significantly increased in this group compared with the Dia group (P < 0.05). The results of this study indicated that co-treatment with LC and ZnONPs could preserve ovarian function by increasing sex hormones levels and antioxidant activity and decreasing lipid peroxidation in diabetic rats. Therefore, this compound supplementation may improve ovulation and fertility in people with diabetes mellitus.

Genetic Rodent Models of Obesity-Associated Ovarian Dysfunction and Subfertility: Insights into Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy affecting women and a leading cause of female infertility worldwide. Defined clinically by the presence of hyperandrogenemia and oligomenorrhoea, PCOS represents a state of hormonal dysregulation, disrupted ovarian follicle dynamics, and subsequent oligo- or anovulation. The syndrome's prevalence is attributed, at least partly, to a well-established association with obesity and insulin resistance (IR). Indeed, the presence of severe PCOS in human genetic obesity and IR syndromes supports a causal role for IR in the pathogenesis of PCOS. However, the molecular mechanisms underlying this causality, as well as the important role of hyperandrogenemia, remain poorly elucidated. As such, treatment of PCOS is necessarily empirical, focusing on symptom alleviation. The generation of knockout and transgenic rodent models of obesity and IR offers a promising platform in which to address mechanistic questions about reproductive dysfunction in the context of metabolic disease. Similarly, the impact of primary perturbations in rodent gonadotrophin or androgen signaling has been interrogated. However, the insights gained from such models have been limited by the relatively poor fidelity of rodent models to human PCOS. In this mini review, we evaluate the ovarian phenotypes associated with rodent models of obesity and IR, including the extent of endocrine disturbance, ovarian dysmorphology, and subfertility. We compare them to both human PCOS and other animal models of the syndrome (genetic and hormonal), explore reasons for their discordance, and consider the new opportunities that are emerging to better understand and treat this important condition.

Oocyte environment: follicular fluid and cumulus cells are critical for oocyte health

Bidirectional somatic cell-oocyte signaling is essential to create a changing intrafollicular microenvironment that controls primordial follicle growth into a cohort of growing follicles, from which one antral follicle is selected to ovulate a healthy oocyte. Such intercellular communications allow the oocyte to determine its own fate by influencing the intrafollicular microenvironment, which in turn provides the necessary cellular functions for oocyte developmental competence, which is defined as the ability of the oocyte to complete meiosis and undergo fertilization, embryogenesis, and term development. These coordinated somatic cell-oocyte interactions attempt to balance cellular metabolism with energy requirements during folliculogenesis, including changing energy utilization during meiotic resumption. If these cellular mechanisms are perturbed by metabolic disease and/or maternal aging, molecular damage of the oocyte can alter macromolecules, induce mitochondrial mutations, and reduce adenosine triphosphate production, all of which can harm the oocyte. Recent technologies are now exploring transcriptional, translational, and post-translational events within the human follicle with the goal of identifying biomarkers that reliably predict oocyte quality in the clinical setting.

Decreased ovarian function is associated with obesity in very long-term female survivors of childhood cancer

OBJECTIVE

Obesity and gonadal dysfunction are known major side effects of treatment in adult childhood cancer survivors (CCS). In the general population, obesity has a negative influence on female fertility. We aimed to evaluate whether obesity and serum insulin are associated with decreased ovarian reserve markers in CCS.

DESIGN

Retrospective single-center cohort study.

METHODS

Data of 191 female survivors of childhood cancer were analyzed. Median follow-up time was 18.8 (2.348.8) years. Outcome measures were serum anti-Müllerian hormone (AMH) and total follicle count (FC). Potential risk factors were: BMI; body composition measures, determined by dual-energy X-ray absorptiometry (total fat percentage, lean body mass, and visceral fat percentage); and fasting insulin.

RESULTS

Lower serum AMH was found in obese subjects (β (%) -49, P=0.007) and in subjects with fasting insulin in the highest tertile (β (%) -43, P=0.039). Total fat percentage tends to be associated with serum AMH (β (%) -2.1, P=0.06). Survivors in the highest tertile of insulin had significantly lower FC than survivors in the lowest tertile (β -6.3, P=0.013). BMI and other measures of body composition were not associated with FC. Correlation between serum AMH and antral follicle count (AFC) was ρ=0.32 (P=0.08).

CONCLUSIONS

Obesity and insulin resistance are associated with gonadal damage, as reflected by decreased AMH and reduced FC in adult survivors of childhood cancer. In contrast to its highly predictive value for AFC in the healthy female population, serum AMH does not seem to correlate as well with AFC in CCS.

Alterations of the ovarian histomorphometry at pre-puberty in rat offspring from diabetic mothers

Purpose

Maternal diabetes leads to increased blood glucose concentration in the mother and consequently in the foetus, causing various neonatal problems. This study was conducted to evaluate the effects of maternal diabetes on foetal ovarian structure.

Methods

Sixteen adult female rats were allocated into two equal groups. Diabetes was induced in one group by alloxan. Both groups became pregnant by natural mating. Thirty days after birth, the female offspring were terminated, the body weight and blood glucose of the animals measured and their ovaries removed. Various histological and cellular parameters were determined using histological and electron microscopy techniques.

Results

Results revealed a significant increase in body weight and blood glucose in the offspring of the diabetic mothers (ODM) compared to that of the controls. The weight, volume and diameter of the ovary and the ovarian capsule thickness were inclined to decrease in ODM compared to that of controls. The number and diameter of primary, pre-antral and antral follicles were decreased in ovaries in the ODM. The electro-micrographs have demonstrated the organelle alterations in oocytes and granulosa cells that suggest the apoptosis progress and oxidative stress.

Conclusions

Maternal hyperglycaemia exhibited deleterious effects on the female reproductive system in the offspring.

A novel approach to quantifying ovarian cell lipid content and lipid accumulation in vitro by confocal microscopy in lean women undergoing ovarian stimulation for in vitro fertilization (IVF)

PURPOSE

To quantify intracellular lipid levels in cumulus cells (CCs) and mural granulosa cells (MGCs) of lean women undergoing gonadotropin therapy for in vitro fertilization (IVF), based upon different cell preparation methods.

METHODS

CCs and MGCs from 16 lean women undergoing ovarian stimulation for IVF were studied. Cells were pooled by cell type, with each type of cell separated into two groups for determination of initial lipid content (Method 1) and subsequent lipid accumulation in vitro (Method 2). Cells for initial lipid content were immediately fixed at the time of the oocyte retrieval with 4% paraformaldehyde in suspension, while those for subsequent lipid accumulation in vitro were cultured for 4 h with 5% fetal calf serum and then fixed. Cells were treated with lipid fluorescent dye BODIPY® FL C16 and nuclear marker DAPI. Intracellular lipid was quantified by confocal microscopy, using ImageJ software analysis.

RESULTS

There was no significant effect of cell type (P = 0.2) or cell type-cell preparation method interaction (P = 0.8) on cell area (Method 1: CC 99.7 ± 5.1, MGC 132.8 ± 5.8; Method 2: CC 221.9 ± 30.4, MGC 265.1 ± 48.5 μm(2)). The mean area of all cells combined was significantly less for cells prepared by Method 1 (116.2 ± 4.9 μm(2)) vs. Method 2 (243.5 ± 22.5 μm(2), P < 0.00005). Intracellular lipid level, however, was significantly altered by cell preparation method (P < 0.05; cell preparation method-cell type interaction, P < 0.00001). Initial lipid content was significantly lower in CC (74.5 ± 9.3) than MGC (136.3 ± 16.7 fluorescence/cell area, P < 0.00005), while subsequent lipid accumulation in vitro was significantly higher in CC (154.0 ± 9.1) than MGC (104.6 ± 9.9 fluorescence/cell area, P < 0.00001). The relatively diminished initial CC lipid content compared to subsequent CC lipid accumulation in vitro (P < 0.00001), and the opposite pattern for MGC (P < 0.05), significantly lowered the CC/MGC lipid ratio in Method 1 (0.55 ± 0.04) vs. Method 2 (1.58 ± 0.10, P < 0.00001).

CONCLUSIONS

Differential uptake or utilization of lipid by CC and MGC occurs during oocyte maturation and steroidogenesis, respectively, with the amount of lipid present in ovarian cells a function of both the follicular microenvironment at the time of the oocyte retrieval and the capacity of these cells to accumulate lipid in vitro over time.

Hypercytolipidemia-induced nuclear lipoapoptosis: cytochemical analysis and integrated review of hypogonadal, diabetes-obesity syndrome-induced female reproductive axis disruption

Expression of the diabetes (db/db) mutation (i.e., leptin receptor defect) in C57BL/KsJ mice results in the functional suppression of the female pituitary-gonadal axis accompanied by premature utero-ovarian lipocytoatrophy. The current studies define the cytostructural, metabolic and endocrine disturbances associated with hypercytolipidemia and coincident nuclear lipoapoptosis following expression of the db/db-mutation. Adult, female C57BL/KsJ control (+/+ and +/? genotypes) and db/db mutant littermates were monitored for systemic alterations in blood glucose, insulin, luteinizing hormone (LH) and 17-B-estradiol (E2) concentrations associated with db/db-enhanced cytolipid depositions and TUNEL-labeled 3'-DNA fragmentation indexed nuclear lipoapoptosis. Obesity, hyperglycemia and hyperinsulinemia, in addition to depressed LH and E2 concentrations, characterized all db/db-mutants relative to control indices. Structural and cytochemical analysis of basophilic gonadotroph cells, ovarian follicular granulosa cells and uterine endometrial epithelial layers indicated that db/db mutants demonstrated prominent hypercytolipidemia relative to control cytoarchitecture profiles. Vasolipidemia and interstitial cytoadiposity were prominent in all db/db tissue compartments. In each affected cell type within the db/db pituitary-reproductive tract axis, hypercytolipidemia was localized with pronounced nuclear lipo-infiltration and 3'-DNA TUNEL-labeled fragmentation. These data indicate that coincident cytostructural, endocrine and metabolic disturbances associated with hypogonadal pituitary-reproductive tract hypercytolipidemia are functional manifestations of the expressed diabetes-obesity syndrome in db/db-mutants. The progressive vaso-, interstitial-, and cyto-lipidemic alterations in cytoarchitecture correlated with the coincident nuclear lipoapoptotic dissolution and pronounced organo-involution, alterations which contributed to the functional disruption of the pituitary-hypogonadal axis in C57BL/KsJ-db/db mice.

Obesity does not aggravate vitrification injury in mouse embryos: a prospective study

BACKGROUND

Obesity is associated with poor reproductive outcomes, but few reports have examined thawed embryo transfer in obese women. Many studies have shown that increased lipid accumulation aggravates vitrification injury in porcine and bovine embryos, but oocytes of these species have high lipid contents (63 ng and 161 ng, respectively). Almost nothing is known about lipids in human oocytes except that these cells are anecdotally known to be relatively lipid poor. In this regard, human oocytes are considered to be similar to those of the mouse, which contain approximately 4 ng total lipids/oocyte. To date, no available data show the impact of obesity on vitrification in mouse embryos. The aim of this study was to establish a murine model of maternal diet-induced obesity and to characterize the effect of obesity on vitrification by investigating the survival rate and embryo developmental competence after thawing.

METHODS

Prospective comparisons were performed between six-eight-cell embryos from obese and normal-weight mice and between fresh and vitrified embryos. Female C57BL/6 mice were fed standard rodent chow (normal-weight group) or a high-fat diet (obese group) for 6 weeks. The mice were mated, zygotes were collected from oviducts and cultured for 3 days, and six-eight-cell embryos were then selected to assess lipid content in fresh embryos and to evaluate differences in apoptosis, survival, and development rates in response to vitrification.

RESULTS

In fresh embryos from obese mice, the lipid content (0.044 vs 0.030, P<0.01) and apoptosis rate (15.1% vs.9.3%, P<0.05)were significantly higher, the survival rate (83.1% vs. 93.1%, P<0.01) on day 5 was significantly lower, and embryo development was notably delayed on days 3-5 compared with the normal-weight group. After vitrification, no significant difference was found between thawed embryos from obese and normal-weight mice in apoptosis, survival, and development rates on days 4 and 5. In both groups, pre- and post-vitrification embryo apoptosis, survival, and development rates were similar.

CONCLUSIONS

This study demonstrated that differences in survival and developmental rates between embryos from obese and normal-weight mice were eliminated after vitrification. Thus, maternal obesity does not aggravate vitrification injury, but obesity alone greatly impairs pre-implantation embryo survival and development.

Effects of leptin and melanocortin signaling interactions on pubertal development and reproduction

Leptin and melanocortin signaling control ingestive behavior, energy balance, and substrate utilization, but only leptin signaling defects cause hypothalamic hypogonadism and infertility. Although GnRH neurons do not express leptin receptors, leptin influences GnRH neuron activity via regulation of immediate downstream mediators including the neuropeptides neuropeptide Y and the melanocortin agonist and antagonist, α-MSH, agouti-related peptide, respectively. Here we show that modulation of melanocortin signaling in female db/db mice through ablation of agouti-related peptide, or heterozygosity of melanocortin 4 receptor, restores the timing of pubertal onset, fertility, and lactation. Additionally, melanocortin 4 receptor activation increases action potential firing and induces c-Fos expression in GnRH neurons, providing further evidence that melanocortin signaling influences GnRH neuron activity. These studies thus establish melanocortin signaling as an important component in the leptin-mediated regulation of GnRH neuron activity, initiation of puberty and fertility.

Peroxisome proliferator-activated receptor-gamma agonist rosiglitazone reverses the adverse effects of diet-induced obesity on oocyte quality

Obesity and its physiological consequences are increasingly prevalent among women of reproductive age and are associated with infertility. To investigate, female mice were fed a high-fat diet until the onset of insulin resistance, followed by assessments of ovarian gene expression, ovulation, fertilization, and oocyte developmental competence. We report defects to ovarian function associated with diet-induced obesity (DIO) that result in poor oocyte quality, subsequently reduced blastocyst survival rates, and abnormal embryonic cellular differentiation. To identify critical cellular mediators of ovarian responses to obesity induced insulin resistance, DIO females were treated for 4 d before mating with an insulin-sensitizing pharmaceutical: glucose and lipid-lowering AMP kinase activator, 5-aminoimidazole 4-carboxamide-riboside, 30 mg/kg.d; sodium salicylate, IkappaK inhibitor that reverses insulin resistance, 50 mg/kg.d; or peroxisome proliferator activated receptor-gamma agonist rosiglitazone, 10 mg/kg.d. 5-aminoimidazole 4-carboxamide-riboside or sodium salicylate treatment did not have significant effects on the reproductive parameters examined. However, embryonic development to the blastocyst stage was significantly improved when DIO mice were treated with rosiglitazone, effectively repairing development rates. Rosiglitazone also normalized DIO-associated abnormal blastomere allocation to the inner cell mass. Such improvements to oocyte quality were coupled with weight loss, improved glucose metabolism, and changes in ovarian mRNA expression of peroxisome proliferator activated receptor-regulated genes, Cd36, Scarb1, and Fabp4 cholesterol transporters. These studies demonstrate that peri-conception treatment with select insulin-sensitizing pharmaceuticals can directly influence ovarian functions and ultimately exert positive effects on oocyte developmental competence. Improved blastocyst quality in obese females treated with rosiglitazone before mating indicates that peroxisome proliferator activated receptor-gamma is a key target for metabolic regulation of ovarian function and oocyte quality.

Influences of diabetes (db/db), obese (ob/ob) and dystrophic (dy/dy) genotype mutations on hind limb bone maturation: a morphometric, radiological and cytochemical indices analysis

The influences of single-gene missense mutations expressing diabetes (db/db), obese (ob/ob) or dystrophia (dy/dy) dysregulated metabolic syndromes on hind limb bone maturation and cytodevelopment in C57BL/KsJ mice were evaluated by radiological, macro- and cytomorphometric analysis of the resulting variances in os coxae, femur and tibia osteodevelopment indices relative to control parameters between 8 and 16 weeks of age. Associated with obesity and hyperglycaemic/hyperinsulinaemic states, both db/db and ob/ob mutants demonstrated significant suppression of hind limb maturation (length) and cytodensity indices relative to control growth parameters. By contrast, skeletal growth suppression induced by dy/dy mutation expression was associated with lean body mass and normoglycaemic/hypoinsulinaemic systemic endometabolic indices. In both db/db and ob/ob mutation syndromes, osteovascular, -interstitial and -cytolipidaemia were prominent cytochemical aberrations of the osteopaenic states relative to the dyslipidaemia/fibrodysplasia characteristic of dy/dy osteomaturation. Between 8 and 16 weeks of age, both ob/ob and db/db groups demonstrated extensive cortical interstitial (laminal) osteolipidaemia and suppressed cytodensities compared to control indices. These data demonstrate that the abnormal hyperglycaemic/hyperinsulinaemic endometabolic states associated with the expression of db/db and ob/ob genomutations promote extensive lipidaemia-induced osteopaenia, compromising hind limb osteomaturation and cytodensity indices, as compared to the hyperfibritic osteopaenia characteristic of dy/dy mutation syndromes. Recognized therapeutic modulation of the hypercytolipidaemic component of diabetes-obesity syndromes may prove to be effective towards amelioration of the deleterious influences of these expressed hyperglycaemic, dysregulated lipometabolic conditions on osteomaturation and cytodevelopment.

Hypercytolipidemia-induced cellular lipoapoptosis: Cytostructural and endometabolic basis of progressive organo-involution following expression of diabetes (db/db) and obese (ob/ob) mutation syndromes

Onset expression of Type 2 (NIDDM) diabetes and obesity metabolic syndromes (DOS) are characterized by premature, progressive cytoatrophy and organo-involution induced by dysregulated cellular gluco- and lipo-metabolic cascades. The consequential systemic, interstitial and intracellular hyperlipidemia disrupts normal cytointegrity and metabolic responsivity to the established hypercaloric pericellular environments. The sequential cytostructural, metabolic and endocrine disturbances associated with the development of progressive DOS-associated hypercytolipidemia compromises cellular metabolic response cascades and promotes cytochemical disturbances which culminate with nuclear lipoapoptosis and cytoatrophy. The dramatic alterations in interstitial glucose and lipid (free fatty acids/triglycerides) concentrations are recognized to influence interstitial and cytoplasmic microchemical environments, which markedly alter cellular nutrient diffusion and active trans-membrane flux rates. The progressive exacerbation of interstitial and cytoplasmic lipid imbibition has been demonstrated to be associated with DNA fragmentation by lipo-infiltration into the chromatin matrix, inducing structural disruption and physical dissolution, indexed as nuclear lipoapoptosis. Therapeutic reduction of the severity of hypercytolipidemia-induced structural and cytochemical compromise promotes the restoration of homeostatic metabolic support for normalized cytostructural indices and supportive cellular gluco- and lipo-metabolic cascades. The re-establishment of a homeostatic interstitial microenvironment moderates the severity of cytolipidemic compromise within affected cell types, reduces nuclear lipo-infiltration and DNA lipo-dissolution, resulting in the preservation of cytostructural integrity. Through the therapeutic restoration of extra- and intra-cellular microchemical environments in genetically dysregulated metabolic syndrome models, the coincident cytochemical, endocrine and metabolic disturbances associated with progressive hypercytolipidemia, resulting from the expressed systemic hypercaloric environmental and hepato-pancreatic endometabolic disturbances which characterize Type 2 (NIDDM) diabetes-obesity and metabolic (X) syndromes, may be ameliorated.

Influences of obese (ob/ob) and diabetes (db/db) genotype mutations on lumber vertebral radiological and morphometric indices: skeletal deformation associated with dysregulated systemic glucometabolism

Background

Both diabetes and obesity syndromes are recognized to promote lumbar vertebral instability, premature osteodegeneration, exacerbate progressive osteoporosis and increase the propensity towards vertebral degeneration, instability and deformation in humans.

Methods

The influences of single-gene missense mutations, expressing either diabetes (db/db) or obese (ob/ob) metabolic syndromes on vertebral maturation and development in C57BL/KsJ mice were evaluated by radiological and macro-morphometric analysis of the resulting variances in osteodevelopment indices relative to control parameters between 8 and 16 weeks of age (syndrome onset @ 4 weeks), and the influences of low-dose 17-B-estradiol therapy on vertebral growth expression evaluated.

Results

Associated with the indicative genotypic obesity and hyper-glycemic/-insulinemic states, both db/db and ob/ob mutants demonstrated a significant (P ≤ 0.05) elongation of total lumbar vertebrae column (VC) regional length, and individual lumbar vertebrae (LV1-5) lengths, relative to control VC and LV parameters. In contrast, LV1-5 width indices were suppressed in db/db and ob/ob mutants relative to control LV growth rates. Between 8 and 16 weeks of age, the suppressed LV1-5 width indices were sustained in both genotype mutant groups relative to control osteomaturation rates. The severity of LV1-5 width osteosuppression correlated with the severe systemic hyperglycemic and hypertriglyceridemic conditions sustained in ob/ob and db/db mutants. Low-dose 17-B-estradiol therapy (E2-HRx: 1.0 ug/ 0.1 ml oil s.c/3.5 days), initiated at 4 weeks of age (i.e., initial onset phase of db/db and ob/ob expressions) re-established control LV 1–5 width indices without influencing VC or LV lengths in db/db groups.

Conclusion

These data demonstrate that the abnormal systemic endometabolic states associated with the expression of db/db and ob/ob genomutation syndromes suppress LV 1–5 width osteomaturation rates, but enhanced development related VC and LV length expression, relative to control indices in a progressive manner similar to recognized human metabolic syndrome conditions. Therapeutic E2 modulation of the hyperglycemic component of diabetes-obesity syndrome protected the regional LV from the mutation-induced osteopenic width-growth suppression. These data suggest that these genotype mutation models may prove valuable for the evaluation of therapeutic methodologies suitable for the treatment of human diabetes- or obesity-influenced, LV degeneration-linked human conditions, which demonstrate amelioration from conventional replacement therapies following diagnosis of systemic syndrome-induced LV osteomaturation-associated deformations.

Gonadal steroid modulation of the diabetes (db/db) mutation-induced hyperlipometabolic, hypogonadal syndrome: Restoration of female reproductive tract cytochemical and structural indices

The gonadal steroids, 17-B-estradiol (E2) and progesterone (P), are recognized to stimulate cellular gluco- and lipo-metabolic compensatory cascades which counteract the deleterious influences of the diabetes (db/db) mutation (i.e., leptin membrane receptor defect) which promotes a progressive, hypercytolipidemia-induced premature involution of the female reproductive tract (FRT). The current studies define the therapeutic efficacy of E2 (1 microg/3.5 days) and P (1 mg/3.5 days) treatments (HRx) on utero-ovarian structural and cytochemical (gluco-/lipo-metabolic) maintenance, and the prevention of premature nuclear apoptosis and cytostructural disruption, following the expression of progressive db/db-induced hypercytolipidemia. Control (normal: +/+ and +/?) and diabetes (db/db) genotype groups of 8-week-old (i.e., overt phase of the db/db-hypogonadal syndrome) C57BL/KsJ mice were prepared for high resolution (HRLM) cytochemical and transmission electron (TEM) microscopic analysis of cytolipidemia and nuclear apoptosis (TUNEL-labeled 3'-DNA fragmentation) indices from uterine and ovarian secondary (early antral) follicular tissue samples. Compared to HRx controls, the db/db mutation induced a dramatic increase in cytolipid vacuole volume and density within all ovarian follicular granulosa cells (GC) and uterine endometrial epithelial (UEE) layers. The co-localization of nuclear apoptotic 3'-DNA fragments within identified hyperlipidemic granulosa cells was coincident with the cytochemical and ultrastructural identification of lipid penetration through the nuclear envelope in db/db mutants. P-HRx moderated the severity of db/db-induced GC and UEE hypercytolipidemia, reducing the cytodensity of lipid vacuole accumulations and maintaining cytoplasmic organelle structure, organization, and nuclear membrane integrity. In contrast, E2-HRx resulted in a dramatic reduction in db/db cytolipidemia in both ovarian GC and UEE tissue compartments. Following E2-HRx, UEE cells demonstrated non-pycnotic nuclear profiles, reduced nuclear apoptosis TUNEL-labeling, increased cytoplasmic organelle density profiles and a pronounced cytoplasmic cisternal expansion indicative of active cellular nutrient/metabolite trafficking. Ovarian follicular GC populations demonstrated minimal cytolipidemia, a restored cytoarchitecture with prominent organelle compartments and reduced TUNEL-indexed nuclear lipoapoptosis. These results are the first cytochemical and ultrastructural indications that P- and E2-HRx compensate for the genetic db/db mutation-induced metabolic disturbances, which promote utero-ovarian hypercytolipidemia and the coincident nuclear lipoapoptosis culminating in the expressed diabetes hypogonadal syndrome. The capability of P-HRx to moderate the severity of utero-ovarian involution in db/db mutants, and of E2-HRx to restore and maintain viable GC and UEE cyto-chemical and -structural indices under normoglycemic conditions, suggests that chronic, low-dose cyclic P- and E2-HRx stimulate cellular gluco- and lipo-metabolic cascades which compensate for the lack of leptin signaling in these single-gene, obese-Type II diabetic mutants. The compensatory endometabolic maintenance of utero-ovarian cellular and nuclear architecture suggests that the gluco- and lipo-metabolic disregulation may be therapeutically prevented or reversed, restoring reproductive tract cytointegrity and function, reducing the manifestation of hypogonadal reproductive sterility and db/db compromise of the female reproductive tract.

Cytochemical analysis of pancreatic islet lipoapoptosis: hyperlipidemia-induced cytoinvolution following expression of the diabetes (db/db) mutation

The diabetes (db/db) genotype mutation induces a hyperglycemic-hyperinsulinemic endometabolic state in C57BL/KsJ mice, manifesting a type II NIDDM diabetes-obesity syndrome (DOS) associated with intrinsic leptin receptor expression defects. The severity of the DOS-induced premature pancreatic dysfunction and cytoatrophic involution has been linked to the severity of hypercytolipidemia which develops in pancreatic islets following systemic lipoidosis. The current studies define the cytochemical changes associated with pancreatic islet and acinar vesicular degranulation (deproteinization), cytoinvolution and B-cell dysfunction relative to the onset of cellular (nuclear DNA fragmentation) apoptosis in 20- to 26-week-old chronic db/db mutants relative to control (+/?) indices. The db/db mutation induced dramatic increases in body weights, blood glucose as well as serum and tissue triglyceride concentrations relative to +/? parameters. In contrast, pancreatic tissue weights and insulin concentrations were significantly decreased in db/db groups in association with premature islet cytoatrophy relative to +/? indices. Concurrent elevations in db/db tissue triglyceride concentrations and islet cytolipid depositions accompanied the progressive pancreatic cytoatrophic alterations. Diminished B-cell vesicular (insulin) granulation was pronounced in atrophic pancreatic islets, which were also characterized by hyperplasic acinar cellular intrusion and subsequent proteolytic B-cell dissolution coincident with 3'-DNA fragmentation-indexed (TUNEL-labeled) nuclear apoptosis. The chronic expression of the db/db mutation exacerbated these pancreatic islet B-cell atrophy indices, characterized by insulin vesicular degranulation, suppressed systemic insulin concentrations, invasive hypercytolipidemia, progressive cellular atrophy and hyperplasic acinar proteolytic dissolution, culminating in islet volume/mass reduction and chronic db/db-related pancreatic involution. The results of these studies indicate that pancreatic islet B-cell apoptosis is coincident with the progressive hypercytolipidemia component of the type II DOS promoted by the db/db genotypic mutation. These data suggest that the severity of progressive pancreatic lipoapoptosis disrupts regulatory cellular metabolic cascades, resulting in nuclear fragmentation, organelle dissolution and the subsequent promotion of a nonhomeostatic cytochemical milieu which ultimately renders islet B-cell populations susceptible to acinar proteolytic dissolution and progressive pancreatic involution.

Ovarian follicular lipoapoptosis: structural, cytochemical and metabolic basis of reproductive tract atrophy following expression of the hypogonadal diabetes (db/db) syndrome

The diabetes (db/db) mutation (i.e., leptin membrane receptor defect) promotes a progressive, hypercytolipidemia within ovarian follicular granulosa, thecal and interstitial layers of C57BL/KsJ mice which manifests an infertile, acyclic hypogonadal syndrome. The current studies focus on the structural, cytochemical and gluco-/lipo-metabolic changes which induce cellular lipoapoptosis and the resulting cytostructural disruption of db/db follicular populations, relative to littermate control indices, following the expression of progressive ovarian hypercytolipidemia. Control (normal: +/+ and +/?) and diabetes (db/db) genotype groups were prepared for high resolution light microscopic (HRLM) analysis of cytolipidemia and nuclear apoptosis (TUNEL-labeled 3'-DNA fragmentation) indices and compared to the transmission electron (TEM) microscopic analysis of ovarian follicular samples collected from 8-16-week-old groups. Compared to controls, the db/db mutation induced a dramatic increase in cytolipid vacuole volume and density within all ovarian follicular layers. TEM analysis revealed that the lipid vacuoles initially aggregated along the inner membrane compartments of affected thecal and granulosa cells in response to the interstitial and vaso-lipidemic-hyperglycemic conditions which characterized the ovarian microenvironment of db/db follicles. Progressive cytoplasmic movement of lipid pools into the perinuclear compartment of affected granulosa cells induced nuclear isolation from cytoplasmic organelles that were displaced towards peripheral intracellular compartments. Cytochemical analysis of lipid vacuole accumulations indicated attraction towards, and incorporation within, the nuclear envelope of hyperlipidemic cells. Co-localization of nuclear apoptotic 3'-DNA fragments within identified hyperlipidemic granulosa cells was coincident with the cytochemical and ultrastructural identification of lipid penetration through the nuclear envelope in db/db mutants. These results are the first cytochemical evidence that the lipometabolic disturbances in db/db mutants, which promote hypercytolipidemia-induced premature ovarian involution, are coincident with lipoapoptosis-induced nuclear dissolution within follicular granulosa layers. The lipidemia-induced alterations in cellular and nuclear architecture suggests that the disturbances in glucose and lipid metabolic cascade activities in diabetes (db/db) mutants disrupts follicular cytointegrity, culminating in nuclear disregulation (as indicated by lipoapoptosis) which results in premature reproductive tract organo-involution and manifest reproductive sterility.

Diabetes (db/db) mutation-induced endometrial epithelial lipoapoptosis: ultrastructural and cytochemical analysis of reproductive tract atrophy

BACKGROUND

The diabetes (db/db) mutation in C57BL/KsJ mice promotes a progressive cytolipidemia within the endometrial epithelial (EE) layer of the female reproductive tract which results in premature cellular and organ atrophy. The current studies focus on the ultrastructural and cytochemical changes which promote nuclear apoptosis and cytostructural disruption following the expression of endometrial hypercytolipidemia which promotes diabetes-associated organoinvolution and manifest infertility.

METHODS

Control (normal:+/+) and diabetes (db/db) genotype groups were prepared for high resolution light microscopic analysis of cytolipidemia and nuclear apoptosis (TUNEL-labeled 3'-DNA fragmentation) indices and compared to the transmission electron (TEM) microscopic analysis of endometrial tissue samples collected from 8-16 week-old groups.

RESULTS

Compared to controls, db/db mutation expression induced a dramatic increase in EE cytolipid vacuole volume and density within the epithelial endometrial layer. TEM analysis revealed that cytolipid vacuole accumulations initially aggregated at the baso-polar regions of UEE cells in response to the systemic hyperglycemic/hypertriglyceridemic conditions which characterized the (db/db) groups. Progressive cytoplasmic movement of the lipid pools into perinuclear compartments of affected EE cells induced nuclear isolation from organelles that were displaced towards peripheral cytoplasmic compartments. Cytochemical analysis of lipid vacuole accumulations indicated attraction towards, and incorporation within, the nuclear envelope of hyperlipidemic cells. Co-localization of nuclear apoptotic 3'-DNA fragments within identified hyperlipidemic EE cells was coincident with the cytochemical and ultrastructural identification of lipid penetration through the nuclear envelope in db/db mutants.

CONCLUSION

These results are the first cytochemical indication that the metabolic disturbances in db/db mutants which promote hypercytolipidemia are coincident with lipoapoptosis-induced nuclear dissolution, as denoted by DNA fragmentation analysis. The lipidemia-induced alterations in intracellular organelle and nuclear architectures suggests that the metabolic disturbances in glucose and lipid metabolic cascades in diabetes (db/db) mutants disrupts cytointegrity, culminating in nuclear disregulation (as indicated by lipoapoptosis) and eventual premature reproductive tract organoinvolution and resultant, manifest, reproductive sterility.

Structural, metabolic and endocrine analysis of the diabetes (db/db) hypogonadal syndrome: relationship to hypophyseal hypercytolipidemia

Expression of the diabetes (db/db) mutation in C57BL/KsJ mice results in functional suppression of the female pituitary-gonadal axis accompanied by premature utero-ovarian cytolipoatrophy. Cellular gluco- and lipo-metabolic disturbances promoted by the db/db systemic hyperglycemic-hyperinsulinemic state suppress pituitary gonadotropin release in response to gonadotropin-releasing hormone and gonadal steroid stimulation and results in a hypogonadal-infertility syndrome. Adult female C57BL/KsJ control (+/+ and +/? genotypes) and db/db littermates were monitored for associations in systemic and cellular alterations in luteinizing hormone (LH), follicle-stimulating hormone (FSH), gonadal steroid (binding) levels, and pituitary glucometabolic indices associated with db/db-enhanced lipid imbibition and cytostructural disruption. Obesity, hyperglycemia, and hyperinsulinemia characterized all db/db mutants relative to controls. Serum and pituitary progesterone and estradiol concentrations were suppressed in db/db mutants, in association with serum LH and FSH levels, but not with pituitary LH and FSH concentrations, which were comparable between groups. Pituitary insulin receptor binding and glucose utilization rates were suppressed in db/db groups relative to +/? indices. Structural and cytochemical analysis of anterior (AP), intermediate (IL), and neuro-(NP) hypophyseal lobes demonstrated prominent hypercytolipidemia in db/db mutants relative to controls. Prominent cytolipidemia was localized within well-granulated basophilic gonadotrophs and within IL and NP pituicytes. Vasolipidemia and interstitial cytoadiposity were prominent throughout all db/db pituitary lobes. Thus, disturbances associated with pituitary hypercytolipidemia are functional components of the expressed diabetes-associated hypogonadal syndrome in db/db mutants. Progressive alterations in hypophyseal cytoarchitecture are correlated with suppression of pituitary metabolic and endocrine indices, alterations that contribute to functional disruption of the pituitary-hypogonadal axis in C57BL/KsJ-db/db mice.

Estrogenic restoration of functional pancreatic islet cytoarchitecture in diabetes (db/db) mutant C57BL/KsJ mice: relationship to estradiol localization, systemic glycemia, and persistent hyperinsulinemia

The diabetes (db/db) genotype mutation induces a hyperglycemic-hyperinsulinemic endometabolic state in C57BL/KsJ mice, manifesting a type 2 NIDDM diabetes-obesity syndrome (DOS) in this hyperphagic, leptin receptor (lf) defective model. The severity of the DOS induced by the single gene, homozygous-recessive mutation may be therapeutically moderated by gonadal steroids and pre-steroidal metabolites. The current studies define the estradiol (E2)-modulated phenotypic, systemic, cytochemical, and cellular metabolic responses to db/db mutation expression as compared to littermate control (+/?) indices. The db/db mutation induced dramatic age- and DOS severity-related increases in body weights, blood glucose, and serum insulin concentrations relative to +/? indices between 4-week-old (i.e., initial onset stage of DOS phenotype) and 16-week-old (i.e., chronic stage of DOS) groups. Chronic, low-dose (0.1 microg/3.5 days) E2 treatment (E2-HRx) significantly reduced the obesity mass and blood glucose levels of db/db mutants relative to oil-HRx groups. Similarly, E2-HRx maintained pancreatic glucose utilization rates and pancreatic tissue weights in db/db mutants to near +/? indices. Concurrent amelioration of db/db-enhanced pancreatic lipogenesis and islet hypercytolipidemia occurred following E2-HRx. Pancreatic islet lipo-deposition was markedly reduced in db/db mutants following E2-HRx, and the restoration of islet size and cellular insulin concentrations correlated with beta-cell cytoplasmic regranulation of insulin secretory vesicles. In chronic E2-HRx db/db groups, autoradiographic localization of (3)H-E2 was demonstrated in the nuclear compartments of regranulated, nonhypertrophic islet cell populations, including insulin-containing beta-cells. In chronic E2-HRx db/db mutants, beta-cell insulin granulation was prominent in mildly hypertrophic pancreatic islets, with cytodistribution patterns and concentrations comparable to normal +/? indices. In contrast, E2-HRx maintained the systemic hyperinsulinemia characteristic of oil-HRx db/db mutants. The results of these studies indicate that the severity of the type 2 NIDDM endometabolic syndrome induced by the db/db genotypic mutation may be influenced by E2-HRx, including reduction of the islet hypercytolipidemia and hypertrophic atrophy which are indicators of impending pancreatic involution in this mutant model. The hypercytolipidemia-induced demise of beta-cell cytoarchitecture was reduced by E2-HRx, including the reestablishment of islet beta-cell cytogranulation. These data suggest that the severity of genomic db/db-mutation expression may be modified by E2-HRx, with the gonadal steroid probably acting as a nuclear-specific stimulatory transcriptional modulator of cellular glucometabolic cascades in the absence of leptin-directed homeostatic influences.

Estrogenic stimulation of ovarian follicular maturation in diabetes (db/db) mutant mice: restoration of euglycemia prevents hyperlipidemic cytoatrophy

The diabetes (db/db) mutation (leptin-receptor defect) induces a hyperglycemic-hyperinsulinemic endometabolic environment that promotes hypercytolipidemic ovarian involution in C57BL/KsJ mice, resulting in reproductive sterility and eventual organoatrophy. The effectiveness of low-dose (1.0 microg/sc/3.5 day intervals), 17- beta-estradiol therapy (E2-HRx), initiated prior to expression of the overt diabetes-obesity syndrome (DOS), on preventing female ovarian follicular cytolipid atrophy was evaluated by analysis of cytochemical, endocrine, and tissue lipo-metabolic indices relative to oil-vehicle treated control (+/?) and (db/db) groups. Chronic low-dose E2-HRx moderated DOS-induced trends in (db/db) groups, maintaining lowered body weights, and systemic euglycemia while stimulating ovarian weight indices. E2-HRx prevented the dramatic hypercytolipidemic condition associated with ovarian follicular involution in (db/db) mice, as evidenced by progressive viable follicular maturation, cytomorphometric analysis of tertiary follicular development, and pre-luteinization indices with diminished follicular atresia rates. The coincident stimulation of tissue lipoprotein lipase and acetyl CoA carboxylase activities in (db/db) ovarian compartments, under persistent hyperinsulinemic influences, indicated that E2-HRx effectively moderated both the structural and hyperlipometabolic consequences of DOS from promoting (db/db)-associated reproductive organoatrophy. Thus, the patho-reproductive alterations induced by the (db/db) mutation can be moderated through low-dose steroidal therapy, the efficacy of which is suspected to occur by steroid-specific nuclear transcription or post-insulin receptor modulation of gluco-metabolic cascades in reproductive target cells.

Cytolipotoxicity-induced involution of the female reproductive tract following expression of obese (ob/ob) and diabetes (db/db) genotype mutations: progressive, hyperlipidemic transformation into adipocytic tissues

Both diabetes (db/db) and obese (ob/ob) single gene mutations induce a progressive, hyperglycemic-hyperinsulinemic endometabolic environment which promotes hypercytolipidemic, utero-ovarian involution in C57BL/KsJ mice. The progressive expression of the induced diabetes-obesity syndrome (DOS) results in female reproductive sterility and eventual organoatrophy. In order to define the intra-cytoplasmic alterations induced by the progressive cytolipidemia on cellular vitality, utero-ovarian tissue samples were collected from both control (+/?) and littermate-matched ob/ob or db/db C57BL/KsJ mice at either 4 weeks (initial-onset DOS phase), 8 weeks (progressive, overt DOS phase), or 16 weeks (chronic-DOS phase) of age for cytolipid distribution analysis. All db/db and ob/ob mutant groups exhibited phenotypic obesity and systemic hyperglycemia-hyperinsulinemia relative to age-matched littermate +/? groups. In all db/db and ob/ob age groups, a progressive hypercytolipidemia was noted relative to +/? groups. When analyzed for lipid channeling, a progressive perinuclear mapping pattern of cytolipid distribution was noted. The primary locus of initial db/db and ob/ob cytolipid deposition was localized to the baso-polar regions in endometrial epithelia samples, or to the interstitium-thecal layer border of ovarian follicular compartments, during the initial-onset DOS phase. Progressively, intra-cytoplasmic lipid mobilization promoted a consistent perinuclear channeling of lipid vacuoles, ultimately isolating nuclear loci from the peripherally displaced cytoplasmic organelles within uterine epithelial layers. In db/db and ob/ob ovarian tissue samples, a progressive, gradient-related lipid infiltration of interstitial, thecal and, ultimately, granulosa cell layers promoted an enhanced rate of follicular-lipidemic atresia relative to +/? groups. In each tissue layer, the cytolipidemia promoted a dramatic perinuclear lipid-isolation barrier from intra-cytoplasmic organelle domains. With age-related exacerbation of the DOS syndrome, cytoplasmic nuclear-organelle displacement and lipoisolation resulted in cellular atresia, promoting the eventual utero-ovarian organoatrophy which characterized the chronic-DOS phase in db/db and ob/ob C57BL/KsJ mutants. These results indicate that the cytoinvolution associated with reproductive tract atrophy in these genetically mutant, diabetic-obese models is promoted by the disruption of the normal cytoarchitecture of utero-ovarian tissue layers induced by the progressive lipid sequestration, accumulation and ultimate isolation-induced disruption of intra-cellular organelle compartmentalization.

Diabetes (db/db) mutation-induced female reproductive tract hypercytolipidemia: estrogenic restoration of utero-ovarian indices

The diabetes (db/db) mutation (leptin-receptor defect) induces a hyperglycemic-hyperinsulinemic endometabolic environment that promotes hypercytolipidemic, utero-ovarian involution in C57BL/KsJ mice, resulting in reproductive sterility and eventual organoatrophy. The effectiveness of low-dose, 17-B-estradiol therapy (E2-HRx), initiated prior to the genetic expression of the overt diabetes-obesity syndrome (DOS) on preventing female reproductive tract involution was evaluated by analysis of cytochemical, endocrine and tissue lipo-metabolic indices relative to oil (O)-vehicle treated (HRx) control (+/?) and (db/db) groups. All HRx treatments started at 4 weeks of age (i.e., pre-overt DOS stage) and continued through 16 weeks of age (i.e., chronic DOS expression) when tissue parameters were evaluated. The DOS promoted a dramatic increase in phenotypic obesity, hyperglycemia and hyperinsulinemia in (db/db) groups, relative to (+/?) indices, throughout the experimental period. In contrast, utero-ovarian weights were dramatically reduced in (db/db) groups relative to (+/?). Chronic low-dose E2-HRx moderated these DOS-induced trends in (db/db) groups, maintaining lowered body weights and normoglycemic parameters while stimulating utero-ovarian weight indices. In addition, E2-HRx prevented the dramatic hypercytolipidemic condition which promotes utero-ovarian involution in (db/db) mice as evidenced by the maintenance of normal reproductive cytoarchitecture. The concurrent moderation of tissue lipase activity and stimulated glucose uptake rates by (db/db) utero-ovarian compartments, under persistent hyperinsulinemic influences, indicated that E2-HRx effectively reduced both the structural and endometabolic consequences of the DOS from promoting (db/db)-associated reproductive organoatrophy. These results indicate that the pathophysiological alterations induced by the (db/db) mutation may be ameliorated through low-dose steroidal therapy, the efficacy of which is suspected to occur via membrane metabolic cascade induction mechanisms or by direct nuclear transcription modulation in reproductive target cells. The subsequent re-establishment of insulin-coupled glucose utilization and suppressed caloric shunting towards lipogenesis promotes the normalization of utero-ovarian structural and metabolic homeostasis in C57BL/KsJ-db/db mutants.

Ovarian hypercytolipidemia induced by obese (ob/ob) and diabetes (db/db) mutations: basis of female reproductive tract involution II

The diabetes (db/db) and obese (ob/ob) genotype mutations induce a progressive, hypercytolipidemic condition within the ovarian compartments of the female reproductive tract that results in sterility and premature organ involution in C57BL/KsJ mice. The current studies focus on the ultrastructural changes that occur within the ovarian interstitial, thecal, and follicular granulosa cell layers during the progressive expression of these mutations which promote tissue cytolipidemia-induced organoinvolution. Control (normal: +/?), diabetes (db/db), and obese (ob/ob) genotype groups were prepared for high resolution light (HRLM) and transmission electron microscopic (TEM) analysis of ovarian tissue samples collected from 4 (young)- to 20 (aged)-week-old mice, allowing for the progressive influences of the mutational aberrations on tissue structure to be evaluated. Compared to controls, both (ob/ob) and (db/db) mutations induced a dramatic increase in ovarian interstitial, thecal and follicular granulosa cytolipid vacuole accumulations, which increased in density between 4 and 20 weeks of age. Initially, lipid vacuoles aggregated in the interstitial and thecal regions of ovarian follicles in response to the hyperglycemic-hypertriglyceridemic metabolic conditions typical of both (ob/ob) and (db/db) groups. Progressive cytoplasmic movement of the lipid pools established a perinuclear isolation from associated cytoplasmic organelles. Progressive lipid accumulations forced cytoplasmic organelles to peripheral cell compartments and altered the follicular cell profile towards that of adipocyte-like entities relative to controls. The progressive hypercytolipidemia-induced alterations in cell structure disrupted normal tissue continuity, which culminated in premature ovarian organo-involution and female reproductive sterility.

Hypophyseal lipoapoptosis: diabetes (db/db) mutation-associated cytolipidemia promotes pituitary cellular disruption and dysfunction

Expression of the diabetes (db/db) mutation in C57BL/KsJ mice suppresses the female pituitary-gonadal axis via progressive cytolipidemic disruption of hypophyseal gonadotropin release, culminating in premature involution of the reproductive tract and manifest infertility. The current studies define the systemic, endocrine, cytochemical and structural apoptotic changes that result from pituitary hypercytolipidemia induced by db/db mutation expression in this Type II diabetes-obesity syndrome (DOS) model. Adult female C57BL/KsJ control (+/? genotype) and db/db littermates were monitored for systemic and cellular alterations in LH-, FSH- and gonadal steroid-secretion, and coincident pituitary apoptosis, as indexed by TUNEL labeled 3' nuclear DNA-fragmentation, associated with cytolipid depositions. Obesity, hyperglycemia and hyperinsulinemia characterized all db/db-mutants relative to +/? groups. Serum progesterone (P) and estradiol (E2) concentrations were suppressed in db/db mutants coincident with decreased plasma LH and FSH concentrations relative to +/? values. Cytochemical analysis of anterior (AP) pituitary cell subtypes indicated that db/db mutants demonstrated prominent hypercytolipidemia relative to +/? pituitary cytoarchitecture. Cytolipidemic vacuoles were localized within protein vesiculated db/db hypophyseal basophilic and acidophilic cell populations. Hypophyseal cytoadiposity in db/db AP cells was co-localized with prominent cellular apoptotic TUNEL labeling of nuclear 3'-DNA fragments in cells demonstrating vesicular depopulation and cytolytic vacuolization. These data represent the first demonstration of co-localized hypercytolipidemic and cytoapoptotic disruptive events occurring concurrently in a hypopituitary-hypogonadal syndrome model following expression of the Type II (NIDDM) diabetes-obesity syndrome in db/db-mutants. The coincident and progressive vascular-, interstitial- and cyto-lipidemic alterations in hypophyseal cytoarchitecture correlated with the concurrent apoptotic disruption of pituitary endocrine cytoarchitecture and supressed gonadal steroid synthesis, influences which collectively contribute to the premature involution of the pituitary-gonadal axis in C57BL/KsJ- db/db mice.