Disruption of normal adipocyte development and function by methyl- and propyl- paraben exposure.

Methyl- and propyl- parabens are generally regarded as safe by the U.S Food and Drug Administration and as such are commonly used in personal care products. These parabens have been associated with increased white adipogenesis in vitro and methyl paraben also increased the white adipose mass of mice. Given brown adipose also plays a role in energy balance, we sought to evaluate whether the effects of methyl- and propyl- parabens on white adipocytes extended to brown adipocytes. We challenged white and brown pre-adipocytes at low doses of both parabens (up to 1 µM) during the differentiation process and examined adipogenesis with the ORO assay. The impact of each paraben on glucose uptake and lipolytic activity of adipocytes were measured with a fluorescent glucose analog and enzymatically, respectively. Methyl- and propyl- parabens increased adipogenesis of 3T3-L1 white adipocytes but not brown adipocytes. In white adipocytes, methyl paraben increased glucose uptake and both parabens reduced basal lipolysis. However, in brown adipocytes, parabens had no effect on basal lipolysis and instead attenuated isoproterenol induced lipolysis. These data indicate that methyl- and propyl- parabens target the differentiation and metabolic processes of multiple types of adipocytes in a cell autonomous manner.

The association between p,p'-DDE levels and left ventricular mass is mainly mediated by obesity.

BACKGROUND AND OBJECTIVES: The pesticide metabolite p,p'-DDE has been associated with left ventricular (LV) mass and known risk factors for LV hypertrophy in humans and in experimental models. We hypothesized that the associations of p,p'-DDE with LV hypertrophy risk factors, namely elevated glucose, adiposity and hypertension, mediate the association of p,p'-DDE with LV mass. METHODS: p,p'-DDE was measured in plasma from 70-year-old subjects (n = 988) of the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS). When these subjects were 70-, 75- and 80- years old, LV characteristics were measured by echocardiography, while fasting glucose, body mass index (BMI) and blood pressure were assessed with standard clinical techniques. RESULTS: We found that p,p'-DDE levels were associated with increased fasting glucose, BMI, hypertension and LV mass in separate models adjusted for sex. Structural equation modeling revealed that the association between p,p'-DDE and LV mass was almost entirely mediated by BMI (70%), and also by hypertension (19%). CONCLUSION: The obesogenic effect of p,p'-DDE is a major determinant responsible for the association of p,p'-DDE with LV mass.

The impact of prenatal parental tobacco smoking on risk of diabetes mellitus in middle-aged women.

Growing evidence indicates that parental smoking is associated with risk of offspring obesity. The purpose of this study was to identify whether parental tobacco smoking during gestation was associated with risk of diabetes mellitus. This is a prospective study of 44- to 54-year-old daughters (n = 1801) born in the Child Health and Development Studies pregnancy cohort between 1959 and 1967. Their mothers resided near Oakland California, were members of the Kaiser Foundation Health Plan and reported parental tobacco smoking during an early pregnancy interview. Daughters reported physician diagnoses of diabetes mellitus and provided blood samples for hemoglobin A1C measurement. Prenatal maternal smoking had a stronger association with daughters' diabetes mellitus risk than prenatal paternal smoking, and the former persisted after adjustment for parental race, diabetes and employment (aRR = 2.4 [95% confidence intervals 1.4-4.1] P < 0.01 and aRR = 1.7 [95% confidence intervals 1.0-3.0] P = 0.05, respectively). Estimates of the effect of parental smoking were unchanged when further adjusted by daughters' birth weight or current body mass index (BMI). Maternal smoking was also significantly associated with self-reported type 2 diabetes diagnosis (2.3 [95% confidence intervals 1.0-5.0] P < 0.05). Having parents who smoked during pregnancy was associated with an increased risk of diabetes mellitus among adult daughters, independent of known risk factors, providing further evidence that prenatal environmental chemical exposures independent of birth weight and current BMI may contribute to adult diabetes mellitus. While other studies seek to confirm our results, caution toward tobacco smoking by or proximal to pregnant women is warranted in diabetes mellitus prevention efforts.

Enhancement of the anticonvulsant effect of fluoxetine following blockade of 5-HT1A receptors.

Serotonin reuptake inhibitors, such as fluoxetine, have been shown to exert anticonvulsant effects in several animal models of epilepsy. In view of recent studies showing that 5-HT1A receptor antagonists (somatodendritic autoreceptor antagonists) enhance the increase in extracellular 5-hydroxytryptamine (5-HT, serotonin) produced by serotonin reuptake inhibitors, it was of interest to determine if these antagonists also enhance the anticonvulsant effect of fluoxetine in Genetically Epilepsy-Prone Rats (GEPRs). The 5-HT1A receptor antagonists (-)-pindolol and LY 206130 (1-[1-H-indol-4-yloxy]-3-[cyclohexylamino]-2-propanol maleate) were examined in the present study and both enhanced the anticonvulsant action of fluoxetine in severe seizure GEPRs (GEPR-9s). The latter effect of LY 206130 was found to be dose- and 5-HT-dependent. These findings provide further evidence that the increase in extracellular serotonin observed after administering fluoxetine in combination with a 5-HT1A receptor antagonist is physiologically important and that the anticonvulsant effect of fluoxetine in the GEPR is mediated through an increase in extracellular 5-HT.

Hyperthermia induces resistance to ultraviolet light B in primary and immortalized epidermal keratinocytes.

Environmental exposure to UVB (290-320 nm) wavelengths of the solar spectrum causes major damage, including carcinogenesis, in the skin. Therefore, cellular responses that protect against UVB damage are of particular interest in cutaneous epithelial cells. In cultured keratinocytes, mild hyperthermia generates a classical stress response with acquired thermotolerance and elevated stress protein synthesis (E. V. Maytin, J. Biol. Chem., 267: 23189-23196, 1992). To test the ability of this stress response to protect against UVB damage, monolayers of primary murine keratinocytes or BALB/MK keratinocytes were heated at 42 degrees C for 1 h and then exposed to UVB at 6 h (typical dose, 40 mJ/cm2). Survival was assessed by fluorescein diacetate/ethidium bromide vital dye uptake and video microscopy. With heat-conditioning prior to UVB, a significant increase in both the percentage viability (2- to 3-fold) and in the absolute number of living (fluorescein diacetate-positive) cells was measurable at 24-48 h. Steady-state incorporation into [3H]DNA and 35S-protein, while suppressed immediately after UVB, showed greater recovery in heat-conditioned cultures compared to sham-conditioned cultures at 48 h. Increased metabolic activity was accompanied by increased proliferative potential since colonies of BALB/MK cells observed at 72 h were larger, more numerous, and more active in the uptake of 5-bromo-2'-deoxyuridine in heat-conditioned cultures. A time course for the development of UVB resistance showed maximal protection when heat and UVB were spaced approximately 6 h apart. Hyperthermic conditioning could induce UVB protection in nonproliferating cells, indicating that cell cycle arrest was not primarily responsible for the UVB-protective effect. In summary, hyperthermia induces a mechanism in epithelial cells which can ameliorate damage from UVB.