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

Nimbin analogs stimulate glucose uptake and glycogen storage in the insulin signalling cascade by enhancing the IRTK, PI3K and Glut-4 mechanism in myotubes

BACKGROUND

Diabetes Mellitus is a metabolic disorder characterized by insulin dysfunction or failure of the pancreatic β-cells to produce insulin resulting in hyperglycemia. Adverse effects of hyperglycemic conditions continue to be common, reducing treatment adherence. Intensified therapies are required for the constant loss of endogenous islet reserve.

AIM

This study aimed to evaluate the effect of Nimbin semi-natural analogs (N2, N5, N7, and N8) from A. indica on high glucose-induced ROS and apoptosis with insulin resistance in L6 myotubes evaluated along with Wortmannin and Genistein inhibitors and the expression of key genes in the insulin signalling pathway.

MATERIALS AND METHODS

The analogs were screened for anti-oxidant and anti-diabetic activity using cell-free assays; The ability of analogs to suppress ROS and prevent apoptosis induced by High glucose and uptake glucose and glycogen storage in L6 myotubes was evaluated using DCFH-DA, AO-PI and 2NBDG staining. Further, the glucose uptake was performed in the presence of Insulin Receptor Tyrosine Kinase (IRTK) inhibitors, and the expression of key genes PI3K, Glut-4, GS and IRTK in the insulin signalling pathway were evaluated.

KEY FINDINGS

The Nimbin analogs were not toxic to the L6 cells, and the analogs could scavenge ROS and suppress cellular damage induced due to high glucose. Enhanced glucose uptake was observed in N2, N5 and N7 compared to N8. The maximum activity of optimum concentration was found to be 100 μM. The N2, N5 and N7 showed an increase in IRTK, which is equivalent to insulin at a concentration of 100 µM. The IRTK inhibitor with Genistein (50 µM) confirmed the presence of IRTK-dependent glucose transport activation; it also supports the expression of key genes PI3K, Glut-4, GS and IRTK. As a result of PI3K activation, N2, N5, and N7 exhibited the insulin-mimetic effect by enhancing glucose uptake and glycogen conversion regulating glucose metabolism.

SIGNIFICANCE

N2, N5 and N7 could therapeutically benefit against insulin resistance by glucose metabolism modulation, insulin secretion, β-cell stimulation, inhibition of gluconeogenic enzymes and ROS protection.

Evidence-based hormonal, mutational, and endocrine-disrupting chemical-induced zebrafish as an alternative model to study PCOS condition similar to mammalian PCOS model

Polycystic ovarian syndrome (PCOS) causes swollen ovaries in women at reproductive age due to hormonal disorder with small cysts on the outer edges. The cause of the disorder is still yet to be found. Multiple factors have increased PCOS prevalence, hyperandrogenism, oxidative stress, inflammation, and insulin resistance. Various animal PCOS models have been developed to imitate the pathophysiology of PCOS in humans. Zebrafish is one of the most versatile animal experimental models because of the transparency of the embryos, small size, and rapid growth. The zebrafish similarity to higher vertebrates made it a useful non-mammalian model for PCOS drug testing and screening. This review provides an insight into the usage of zebrafish, a non-mammalian model for PCOS, as an opportunity for evaluating future initiatives in such a research domain.

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.

Effects of resveratrol on ovarian response to controlled ovarian hyperstimulation in ob/ob mice

OBJECTIVE

To evaluate antidiabetic and anti-inflammatory effects of resveratrol on the ovarian response to controlled ovarian hyperstimulation (COH) in obesity-related infertility.

DESIGN

Experimental.

SETTING

University laboratory.

ANIMAL(S)

Sixteen female ob/ob mice and 16 female C57BL/6J mice undergoing COH.

INTERVENTION(S)

Wild-type placebo group; wild-type resveratrol group; ob/ob mice placebo group; ob/ob mice resveratrol group. Resveratrol 3.75 mg/kg daily for 20 days and undergoing COH protocol.

MAIN OUTCOME MEASURE(S)

Body and reproductive system weight, food intake, fasting blood glucose, plasma insulin and T levels, and Homeostatic Index of Insulin Resistance; interleukin-6 and tumor necrosis factor-α levels in adipose tissue by Western blot; assessment of quality and quantity of oocytes retrieved; and quantitative analysis of ovarian follicles.

RESULT(S)

Plasma insulin and T levels decreased and Homeostatic Index of Insulin Resistance improved in ob/ob mice treated with resveratrol. Interleukin-6 and tumor necrosis factor-α levels were significantly reverted back to near normalcy after resveratrol treatment in obese mice. Administration of resveratrol resulted in a significantly higher number of oocytes collected in wild-type mice. The number of primary, growing, preovulatory, and atretic follicles was found to be decreased in the group of obese mice treated with resveratrol when compared with the obese control group.

CONCLUSION(S)

Resveratrol administration could exert benefits against loss of ovarian follicles, and these actions may be mediated, at least in part, via anti-inflammatory, insulin-sensitizing, and antihyperandrogenism effects. These observations further validate the therapeutic potential of resveratrol to preserve ovarian reserve in conditions associated with obesity. Our results suggest the possible clinical use of resveratrol to enhance the ovarian response to COH in normal-weight females.

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.

Rodent models for human polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most frequent female endocrine disorder, affecting 5%-10% of women, causing infertility due to dysfunctional follicular maturation and ovulation, distinctive multicystic ovaries and hyperandrogenism, together with metabolic abnormalities including obesity, hyperinsulinism, an increased risk of type 2 diabetes, and cardiovascular disease. The etiology of PCOS is unclear, and decisive clinical studies are limited by ethical and logistic constraints. Consequently treatment is palliative rather than curative and focuses on symptomatic approaches. Hence, a suitable animal model could provide a valuable means with which to study the pathogenesis of the characteristic reproductive and metabolic abnormalities and thereby identify novel and more effective treatments. So far there is no consensus on the best experimental animal model, which should ideally reproduce the key features associated with human PCOS. The prenatally androgenized rhesus monkey displays many characteristics of the human condition, including hyperandrogenism, anovulation, polycystic ovaries, increased adiposity, and insulin insensitivity. However, the high cost of nonhuman primate studies limits the practical utility of these large-animal models. Rodent models, on the other hand, are inexpensive, provide well-characterized and stable genetic backgrounds readily accessible for targeted genetic manipulation, and shorter reproductive life spans and generation times. Recent rodent models display both reproductive and metabolic disturbances associated with human PCOS. This review aimed to evaluate the rodent models reported to identify the advantages and disadvantages of the distinct rodent models used to investigate this complex endocrine disorder.

Lipid homeostasis, lipotoxicity and the metabolic syndrome

In the 20th century industrialized nations have become afflicted with an unprecedented pandemic of increased adiposity. In the United States, the epicenter of the epidemic, over 2/3 of the population, is overweight and 1 of every 6 Americans carries the diagnosis of metabolic syndrome. Although genes determine susceptibility to environmental factors, the epidemic is clearly due to increased consumption of calorie-dense, highly lipogenic foods, coupled with a marked decrease in physical exertion resulting from modern technologies. If this lifestyle continues, morbid consequences are virtually inevitable. They include type II diabetes and a cluster of disorders known as "the metabolic syndrome" usually appearing in middle age. The morbid consequences of the chronic caloric surplus are buffered before middle age by the partitioning of these calories as fat in the adipocyte compartment which is specifically designed to store triglycerides. Leptin has been proposed as the major hormonal regulator of the partitioning of surplus calories. However, multiple factors can determine the storage capacity of the fat tissue and when it is exceeded ectopic lipid deposition begins. The organs affected in metabolic syndrome include skeletal muscle, liver, heart and pancreas, which are now known to contain abnormal levels of triglycerides. While neutral fat is probably harmless, it is an index of ectopic lipid overload. Fatty acid derivatives can interfere with the function of the cell and ultimately lead to its demise through lipoapoptosis, the consequences of which are gradual organ failure.

Reduction in corpora lutea number in obese melanocortin-4-receptor-deficient mice

Obese melanocortin-4-receptor-deficient (MC4R-/-) male mice are reported to have erectile dysfunction, while homozygous MC4R-/- female mice are apparently fertile. A recently established obese mouse strain, carrying an inactivating mutation in the MC4R gene, revealed difficulties in breeding for the homozygous female mice. This prompted us to determine the presence of follicles and corpora lutea (CL) in ovaries of MC4R-/- mice aged 3-6 months in comparison to wild type (MC4R+/+) littermates. Serial sections of formaldehyde-fixed ovaries of mice with vaginal signs of estrus and metestrus were assessed for the number of healthy and regressing follicles and CL. The number of CL, as an estimate for the ovulation rate, decreased to zero during aging in MC4R-/- mice. The number of small- (diameter 100-200 micrometer) and large-sized follicles namely antral follicles (diameter >200 micrometer) were slightly increased in MC4R-/- compared to MC4R+/+ mice. Greater differences were found in very large to cystic follicles, which were more numerous in MC4R-/- mice. The number of regressing antral follicles was higher in the MC4R-/- group compared to the MC4R+/+ group. This was associated with a wide range in the number of collapsed zonae pellucidae as the last remnants of regressed follicles. A conspicuous hypertrophy of the interstitial cells was noted in 6-month-old MC4R-/- mice. In conclusion, cystic follicles and the reduction in CL number point to a decreased ovulation rate in obese MC4R-/- mice.

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.

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.

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 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.