Maternal exposure to hexachlorophene targets intermediate-stage progenitor cells in the hippocampal neurogenesis involving myelin vacuolation of cholinergic and glutamatergic inputs in mice.

Hexachlorophene (HCP) has been shown to induce myelin vacuolation due to intramyelinic edema of the nerve fibers in animal neural tissue. We investigated the maternal exposure effect of HCP on hippocampal neurogenesis in the offspring of pregnant mice supplemented with 0 (control), 33 or 100 ppm HCP in diet from gestational day 6 to day 21 after delivery. On postnatal day (PND) 21, offspring as examined in males exhibited decreased granule cell lineage populations expressing paired box 6, sex-determining region Y-box 2 and eomesodermin in the hippocampal subgranular zone (SGZ) accompanied by myelin vacuolation involving white matter tracts of the hippocampal fimbria at ≥ 33 ppm. However, SGZ cellular populations expressing brain lipid binding protein and doublecortin were unchanged at any dose. Transcript expression of cholinergic receptor genes, Chrna4 and Chrnb2, and glutamate receptor genes, Grm1 and Grin2d, examined at 100 ppm, decreased in the dentate gyrus. HCP exposure did not alter the number of proliferating or apoptotic cells in the SGZ, or reelin- or calcium-binding protein-expressing γ-aminobutyric acid (GABA)ergic interneurons in the dentate hilus, on PND 21 and PND 77. All neurogenesis-related changes observed in HCP-exposed offspring on PND 21 disappeared on PND 77, suggesting that maternal HCP exposure at ≥ 33 ppm reversibly decreased type 2 intermediate-stage progenitor cells in the hippocampal neurogenesis. Myelin vacuolation might be responsible for changes in neurogenesis possibly by reducing nerve conduction velocity of cholinergic inputs from the septal-hippocampal pathway to granule cell lineages and/or GABAergic interneurons, and of glutamatergic inputs to granule cell lineages.

Maternal exposure to hexachlorophene targets intermediate-stage progenitor cells of the hippocampal neurogenesis in rat offspring via dysfunction of cholinergic inputs by myelin vacuolation.

Hexachlorophene (HCP) is known to induce myelin vacuolation corresponding to intramyelinic edema of nerve fibers in the central and peripheral nervous system in animals. This study investigated the effect of maternal exposure to HCP on hippocampal neurogenesis in rat offspring using pregnant rats supplemented with 0 (controls), 100, or 300 ppm HCP in the diet from gestational day 6 to day 21 after delivery. On postnatal day (PND) 21, the numbers of T box brain 2(+) progenitor cells and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling(+) apoptotic cells in the hippocampal subgranular zone (SGZ) decreased in female offspring at 300 ppm, which was accompanied by myelin vacuolation and punctate tubulin beta-3 chain staining of nerve fibers in the hippocampal fimbria. In addition, transcript levels of the cholinergic receptor, nicotinic beta 2 (Chrnb2) and B-cell CLL/lymphoma 2 (Bcl2) decreased in the dentate gyrus. HCP-exposure did not alter the numbers of SGZ proliferating cells and reelin- or calcium-binding protein-expressing γ-aminobutyric acid (GABA)-ergic interneuron subpopulations in the dentate hilus on PND 21 and PND 77. Although some myelin vacuolation remained, all other changes observed in HCP-exposed offspring on PND 21 disappeared on PND 77. These results suggest that maternal HCP exposure reversibly decreases type-2b intermediate-stage progenitor cells via the mitochondrial apoptotic pathway in offspring hippocampal neurogenesis at 300 ppm HCP. Neurogenesis may be affected by dysfunction of cholinergic inputs into granule cell lineages and/or GABAergic interneurons as indicated by decreased transcript levels of Chrnb2 and numbers of Chrnb2(+) interneurons caused by myelin vacuolation in the septal-hippocampal pathway.

Promoter-region hypermethylation and expression downregulation of Yy1 (Yin yang 1) in preneoplastic liver lesions in a thioacetamide rat hepatocarcinogenesis model.

Thioacetamide (TAA) has been used to develop a rodent model for hepatocarcinogenesis. To determine the genes with epigenetic modifications in early hepatocarcinogenesis, we did a genome-wide scan for hypermethylated promoter regions using CpG island microarrays in TAA-promoted rat liver tissue. Eight genes were selected based on the microarray profile; of these, Yy1 and Wdr45b were confirmed to be hypermethylated by methylation-specific polymerase chain reaction (PCR) and pyrosequencing and downregulated by real-time reverse transcription PCR. Non-neoplastic liver cells had nuclear Yy1 immunoreactivity, while preneoplastic foci with glutathione S-transferase placental form (GST-P) immunoreactivity had decreased Yy1 immunoreactivity. The incidence of these foci was proportional to the dose of TAA administered. Co-expression analysis of gene products downstream of Yy1 revealed increased nuclear phospho-c-Myc(+) foci as well as nuclear and cytoplasmic p21(Cip1+) foci in Yy1(-) or GST-P(+) foci in response to TAA-promotion dose. Although the absolute number of cells was low, the incidence of death receptor 5(-) foci was increased in Yy1(-) foci in proportion to the TAA dose. Yy1(-)/GST-P(+) foci revealed a higher number of proliferating cell nuclear antigen (PCNA)-immunoreactive cells than Yy1(+)/GST-P(+) foci, while cleaved caspase-3(+) cells were unchanged between Yy1(-)/GST-P(+) and Yy1(+)/GST-P(+) foci. In the case of Wdr45b, most GST-P(+) foci were Wdr45b(-) and were not increased by TAA promotion. These results suggest involvement of Yy1 in the epigenetic gene regulation at the early stages of TAA promoted cell proliferation and concomitant cell cycle arrest in preneoplastic lesions.

Higher serum vitamin D concentrations are associated with longer leukocyte telomere length in women.

BACKGROUND: Vitamin D is a potent inhibitor of the proinflammatory response and thereby diminishes turnover of leukocytes. Leukocyte telomere length (LTL) is a predictor of aging-related disease and decreases with each cell cycle and increased inflammation. OBJECTIVE: The objective of the study was to examine whether vitamin D concentrations would attenuate the rate of telomere attrition in leukocytes, such that higher vitamin D concentrations would be associated with longer LTL. DESIGN: Serum vitamin D concentrations were measured in 2160 women aged 18-79 y (mean age: 49.4) from a large population-based cohort of twins. LTL was measured by using the Southern blot method. RESULTS: Age was negatively correlated with LTL (r = -0.40, P < 0.0001). Serum vitamin D concentrations were positively associated with LTL (r = 0.07, P = 0.0010), and this relation persisted after adjustment for age (r = 0.09, P < 0.0001) and other covariates (age, season of vitamin D measurement, menopausal status, use of hormone replacement therapy, and physical activity; P for trend across tertiles = 0.003). The difference in LTL between the highest and lowest tertiles of vitamin D was 107 base pairs (P = 0.0009), which is equivalent to 5.0 y of telomeric aging. This difference was further accentuated by increased concentrations of C-reactive protein, which is a measure of systemic inflammation. CONCLUSION: Our findings suggest that higher vitamin D concentrations, which are easily modifiable through nutritional supplementation, are associated with longer LTL, which underscores the potentially beneficial effects of this hormone on aging and age-related diseases.

Potassium chloride supplementation diminishes platelet reactivity in humans.

The prevalence of occlusive stroke is inversely correlated with potassium intake. We explored the hypothesis that a high potassium intake attenuates platelet reactivity, as expressed in ADP-evoked platelet aggregation. We studied healthy men (n=31) and women (n=42), blacks (n=33) and whites (n=40). In this cohort, we supplemented the habitual intake of 17 men and 21 women with 60 mmol KCl/70 kg body weight per day for 3 days and maintained 14 men and 21 women on their habitual intake. We then compared the change in ADP concentration causing 50% of the maximal initial rate (EC50) of platelet aggregation in the potassium-supplemented versus control groups. Potassium supplementation attenuated platelet reactivity, expressed by an increase in EC50 of platelet aggregation (P=0.0005), which was primarily attributable to an increase in EC50 in whites (P=0.0004). Urinary potassium excretion was significantly lower in blacks than in whites under basal conditions and after potassium supplementation. We conclude that potassium supplementation diminishes platelet reactivity, a phenomenon that provides a link between platelet biology and occlusive stroke.

Studies for the emetic mechanisms of ipecac syrup (TJN-119) and its active components in ferrets: involvement of 5-hydroxytryptamine receptors.

Ipecac syrup, prepared from a galentical ipecac, contains the nauseant alkaloids cephaeline and emetine. The involvement of receptors and serotonin- and dopamine-metabolizing enzymes in the emesis induced by ipecac syrup and these components was investigated. 1) In ferrets, the selective 5-HT3-receptor antagonist ondansetron (0.5 mg/kg, p.o.) prevented each emesis induced by TJN-119 (0.5 mL/kg, p.o.), cephaeline (0.5 mg/kg, p.o.) and emetine (5.0 mg/kg, p.o.), but the intraperitoneal administration of the selective dopamine D2-receptor antagonist sulpiride failed to significantly suppress the TJN-119, cephaeline and emetine-induced emesis at a dose of 0.1 mg/kg that blocked apomorphine-induced emesis. 2) In the receptor binding assays, cephaeline and emetine had a distinct affinity to 5-HT4 receptor, but no or weak affinity to 5-HT1A, 5-HT3, nicotine, M3, beta1, NK1, and D2 receptors. 3) Cephaeline and emetine did not affect activities of metabolic enzymes of 5-HT and dopamine (MAO-A, MAO-B, tryptophan 5-hydroxylase and tyrosine hydroxylase) in vitro. These results suggest that 5-HT3 receptor plays an important role in the emetic action of TJN-119, cephaeline and emetine, and the 5-HT4 receptor may be involved in their mechanisms.

Absorption, distribution and excretion of 3H-labeled cephaeline- and emetine-spiked ipecac syrup in rats.

The maximum plasma radioactivity levels of tritium (3H)-labeled cephaeline, (24.3, 28.7 and 40.6 ng eq./mL) were reached at 2.00-3.33 hours following oral dosing of ipecac syrup. The maximum plasma radioactivity levels of 3H-emetine (2.71, 6.47 and 9.62 ng eq./mL) were reached at 1.08-2.33 hours following ipecac syrup administration. The Cmax values of 3H-cephaeline were followed by a biexponential decrease with half-lives t 1/2(lambda z) of 3.45-9.40 hours. On the other hand, the t 1/2 (lambda z)of 3H-emetine were 65.4-163 hours, which revealed a biexponential decrease. The radioactivity of both tritium-labeled compounds was distrbuted maximally in most tissues at 24 hours. For 3H-cephaeline, the maximum radioactivity levels in tissues were approximately 100-150 times greater than in plasma. For 3H-emetine, the radioactivity levels in tissues were approximately 1000-3000 times greater than in plasma. Tissue radioactivity levels decreased at a substantially slower rate than that observed in plasma. Tissue radioactivity of 3H-emetine decreased more slowly than that of 3H-cephaeline. For 3H-cephaeline, the cumulative biliary excretion of radioactivity was 57.5% at 48 hours. The cumulative urinary and fecal excretion of radioactivity in these rats was 16.5% and 29.1%, respectively, of the dose at 48 hours following dosing. For 3H-emetine, the cumulative biliary excretion of radioactivity was 12.5% at 48 hours. The cumulative urinary and fecal excretion of radioactivity was 9.4% and 34.1%, respectively, of the administered dose at 48 hours. The radioactivity level of 3H-emetine remaining in the carcasses at 48 hours was equivalent to approximately 50% of the dose. A portion of each tritium-labeled compound was subjected to entero-hepatic circulation. Thus, the absorption rate of 3H-cephaeline and 3H-emetine was estimated to be approximately 70% on the basis of the data obtained from excretion studies. There was no difference in the absorption process between these two compounds. However, the difference was admitted in the biliary clearance, which is the main excretion route of both compounds. Delayed excretion of 3H-emetine may be primarily due to its resorption as related to entero-hepatic circulation and tissue retention. This study has determined the absorption, distribution and excretion of 3H-cephaeline and 3H-emetine in rats.

Biotransformation of the ipecac alkaloids cephaeline and emetine from ipecac syrup in rats.

The metabolism of cephaeline and emetine, which are the primary active components of ipecac syrup, were investigated in rats. Cephaeline-6'-O-glucuronide was found to be a biliary metabolite of cephaeline. Cephaeline (6'-O-demethylemetine) and 9-O-demethylemetine were observed to be enzyme-hydrolyzed biliary metabolites of emetine. Cephaeline was conjugated to glucuronide, while emetine was demethylated to cephaeline and 9-0-demethylemetine, and may be conjugated to glucuronides afterwards. Urine, feces and bile were collected from rats within 48 hours following the administration of ipecac syrup containing tritium (3H)--labeled cephaeline or emetine. Metabolites were separated and quantified by thin layer chromatography (TLC) or high-performance liquid chromatography (HPLC). Biliary and urinary excretion rates of 3H-cephaeline were 57.5% and 16.5% of the dose, respectively. Cephaeline-6'-O-glucuronide was comprised 79.5% of biliary radioactivity and 84.3% of urinary radioactivity. Unchanged cephaeline was detected in 42.4% of the dose in feces. Biliary excretion rate of 3H-emetine was 6.9% of the dose. Emetine, cephaeline and 9-0-demethylemetine comprised 5.8%, 43.2% and 13.6% in hydrolyzed bile, respectively. There were no emetine-derived metabolites in urine or feces. The occurrence of unchanged emetine was 6.8% and 19.7% of the dose in urine and feces, respectively.