No abstract

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) induces aberrant release of gonadotropins, FSH, and LH and blocks ovulation during induced ovarian follicular development in rats by an unknown mechanism. In the current study, TCDD (0, 8, or 32 microg/kg orally) was administered to immature female Sprague-Dawley rats, and synchronous follicular development was induced 24 h later with equine chorionic gonadotropin (eCG, 5 IU s.c.). Both doses of TCDD induced a significant premature increase in serum FSH and LH (P < 0.05) at 12 h post-eCG. This premature gonadotropin surge was facilitated by the administration of a long-acting estradiol (estradiol cypionate, 0.01, 0.1, and 0.5 mg/kg s.c.), whereas the progesterone and cortisol receptor antagonist RU486 (0, 1, and 10 mg/kg s.c.) potentiated the premature release of FSH and LH following TCDD as well. Pentobarbital (32 mg/kg i.p.) administered at 6 or 9 h, but not 0 h, post-eCG ablated the ability of TCDD to stimulate the release of FSH and LH in vivo. TCDD had no significant effect on GnRH accumulation in vitro from immortalized GnRH neuronal (GT1-7) cells and failed to alter the cell number. Transfection of these cells with a rat GnRH promoter-reporter construct revealed no significant acute effect of TCDD on GnRH promoter activity. Aryl hydrocarbon receptor mRNA was not detected in the GT1-7 cells by reverse transcription polymerase chain reaction. TCDD appears to stimulate premature gonadotropin release in the gonadotropin-primed immature rat by interacting with an estradiol- and pentobarbital-sensitive neural signal for GnRH release but not by acting upon the GnRH neuron directly.

No abstract

Subjective cognitive decline (SCD) is considered the earliest preclinical stage of Alzheimer’s disease (AD) that precedes mild cognitive impairment (MCI). Effective and accurate diagnosis of SCD is crucial for early detection of and timely intervention in AD. In this study, brain functional connectome (i.e., functional connections and graph theory metrics) based on the resting-state functional magnetic resonance imaging (rs-fMRI) provided multiple information about brain networks and has been used to distinguish individuals with SCD from normal controls (NCs). The consensus connections and the discriminative nodal graph metrics selected by group least absolute shrinkage and selection operator (LASSO) mainly distributed in the prefrontal and frontal cortices and the subcortical regions corresponded to default mode network (DMN) and frontoparietal task control network. Nodal efficiency and nodal shortest path showed the most significant discriminative ability among the selected nodal graph metrics. Furthermore, the comparison results of topological attributes suggested that the brain network integration function was weakened and network segregation function was enhanced in SCD patients. Moreover, the combination of brain connectome information based on multiple kernel-support vector machine (MK-SVM) achieved the best classification performance with 83.33% accuracy, 90.00% sensitivity, and an area under the curve (AUC) of 0.927. The findings of this study provided a new perspective to combine machine learning methods with exploration of brain pathophysiological mechanisms in SCD and offered potential neuroimaging biomarkers for diagnosis of early-stage AD.

Ovulation has been noted for some time to bear a remarkable similarity to an inflammatory response. One of the principal components that is activated and helps mediate the events during an inflammatory response is the kinin system. Therefore, the purpose of the present study was to examine whether this system could be similarly activated and involved in the cascade of events that leads to ovulation. To answer this question, immature 23-day-old female rats were primed with eCG (10 IU) and ovulation was induced by administration of hCG (10 IU) 48 h later. Groups of rats were killed at 0 h, 10 h, 20 h, and 30 h after hCG for determination of ovulation, ovarian steroid levels, and changes in the levels of kinin system components. Plasma total kininogen levels did not change during the entire period studied. In contrast, ovarian total kininogen levels rose from 0 h to reach a peak at 10 h--a time immediately preceding the beginning of ovulation--after which the levels fell at 20 h, only to rise again at 30 h. Three species of kininogens, high molecular weight (HMW), low molecular weight (LMW), and T-kininogen, were shown to be present in the ovary. T-kininogen was the major kininogen present in the ovary, accounting for 60-92% of the total kininogen at any given time point during the ovulatory process. HMW kininogen levels accounted for only 1.2% of the total ovarian kininogen.(ABSTRACT TRUNCATED AT 250 WORDS)