Hypercytolipidemia-Induced Nuclear Lipoapoptosis: Cytochemical Analysis and Integrated Review of Hypogonadal, Diabetes-Obesity Syndrome-Induced Female Reproductive Axis Disruption

Abstract

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.

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

“…The ensuing nuclear isolation, chemical disruption and structural dissolution collectively promote the subsequent apoptotic, autolytic demise of cellular organization and structural viability [15], which results in premature cytoatrophy within the affected tissues. The previously noted therapeutic effectiveness of various lipolytic agents [26-28] towards the restoration and maintenance of reproductive tract cytoarchitecture in hypogonadal genotype mutants supports the concept that lipoapoptosis, representing a lipometabolic disruption of cytointegrity within affected db/db cells, effectively compromises reproductive efficiency in experimental models or humans which suffer from Type 2 (NIDDM) diabetes- and obesity-related, hyperlipidemic metabolic (X) syndrome-induced, reproductive dysfunction [24]. …”

“…Collected mid-cornua uterine tissue samples were cleaned, blotted, blocked and embedded in either paraffin or plastic using conventional techniques [2]. All tissue samples were subsequently sectioned and stained with a toluidine blue-basic fuchsin mixture for polychromatic identification [24,25] of cellular lipid pools by HRLM or with osmium tetroxide [2] prior to examination by TEM.…”

“…The resulting reproductive incompetence is characterized by reproductive acyclicity [13,14], compromised ovarian follicular development [14], depressed ovarian steroid hormone synthesis [17], depressed sensitivity and responsivity to endocrine stimulated cellular metabolism [18-20] and enhanced utero-epithelial atrophy [2]. The affected endometrial architecture is characterized by an enormous increase in intra-and inter-cellular lipid depositions [2,13], resulting from the interstitial perivascular escape and imbibition of elevated systemic triglyceride and free fatty acid moities [21,22] which characterize the overt diabetes (Type 2) metabolic (X) syndrome [23,24]. Ultimately, exposure to the chronic influences of the non-homeostatic metabolic condition induces a lipoatrophy syndrome [12-14], characterized by the progressive accumulation of cytolipid inclusions [2], organelle dissolution [2], nuclear compartment isolation [15], suppressed cellular oxidative metabolism [13], and cyto-atrophy [9,13,14,17].…”

“…Recent reports have indicated that the expression of the diabetes (db/db) mutation in C57BL/KsJ mice compromises reproductive tract maturation by promoting hypercytolipidemia within the endometrial epithelial (EE) layer [2] that is characterized by a progressive lipid-isolation of the cell nuclei from surrounding cytoplasmic organelle compartments [15]. The expanding endometrial cytolipid volume in db/db mutants has been associated with disrupted nuclear chromatin (DNA) structural integrity and pycnosis-associated degeneration [24]. However, the co-incident expression of metabolic hypercytolipidemia and structural nuclear dissolution, as indexed by 3'-DNA fragmentation [24] within apoptotic nuclei, remains to be demonstrated.…”

“…The expanding endometrial cytolipid volume in db/db mutants has been associated with disrupted nuclear chromatin (DNA) structural integrity and pycnosis-associated degeneration [24]. However, the co-incident expression of metabolic hypercytolipidemia and structural nuclear dissolution, as indexed by 3'-DNA fragmentation [24] within apoptotic nuclei, remains to be demonstrated. The present studies were designed to evaluate the co-incident cytochemical and ultrastructural alterations which promote premature, progressive lipoapoptotic nuclear degeneration within the endometrial epithelial tissue layer of the obese, hyperglycemic, hyperlipidemic and hypogonadal (infertile) db/db-mutant reproductive tract.…”