Cyto- and genotoxic profile of groundwater used as drinking water supply before and after disinfection.

The assessment of the toxicological properties of raw groundwater may be useful to predict the type and quality of tap water. Contaminants in groundwater are known to be able to affect the disinfection process, resulting in the formation of substances that are cytotoxic and/or genotoxic. Though the European directive (98/83/EC, which establishes maximum levels for contaminants in raw water (RW)) provides threshold levels for acute exposure to toxic compounds, the law does not take into account chronic exposure at low doses of pollutants present in complex mixture. The purpose of this study was to evaluate the cyto- and genotoxic load in the groundwater of two water treatment plants in Northern Italy. Water samples induced cytotoxic effects, mainly observed when human cells were treated with RW. Moreover, results indicated that the disinfection process reduced cell toxicity, independent of the biocidal used. The induction of genotoxic effects was found, in particular, when the micronucleus assay was carried out on raw groundwater. These results suggest that it is important to include bio-toxicological assays as additional parameters in water quality monitoring programs, as their use would allow the evaluation of the potential risk of groundwater for humans.

Leptin inhibits steroid biosynthesis by human granulosa-lutein cells.

Absence of leptin secretion compromises reproductive function and fertility in the ob/ob mouse which, when given leptin, shows a rise in serum LH levels and becomes fertile. Recently, the long and active isoform of the leptin receptor was detected in the ovary, indicating that leptin may also show direct gonad-related activity. To examine this, we studied the effect of graded doses of human leptin on estradiol (E2) and progesterone (P4) concentrations in the culture media of human granulosa-lutein cells obtained from follicular fluid of women undergoing in vitro fertilization. We also evaluated the mRNA expression of steroidogenic acute regulatory protein (StAR), aromatase, and cytochrome P450 17alpha (CYP17) in these cells at baseline and after exposure to leptin. Estradiol levels were significantly decreased in the media 24 hours after incubation of the cells with increasing hLeptin concentrations (10(-11) - 10(-7) mol/l). The maximal 30% decrease in E2 production was caused by the 10(-9) mol/l hLeptin concentration; however, P4 levels in the media were not influenced by leptin. Exposure of granulosa-lutein cells to 10(-9) mol/l hLeptin did not produce any measurable changes on StAR, aromatase, or CYP17 mRNA expression. When hLeptin (10(-9) mol/l) was co-incubated with increasing concentrations of hCG (1.25 - 10 mlU/ml), IGF-II (15-60 ng/ml) or 1-6 desaminated IGF-II (deslGF-II; 15-60 ng/ml), it did not modify the elevation of E2 concentrations caused by each of the different stimuli. We conclude that leptin suppresses E2 secretion by human granulosa-lutein cells but does not impair the stimulatory effects of hCG and IGFs on these cells. Leptin may play a minor, but direct regulatory role on unstimulated human ovarian steroidogenesis by interfering with either the translational or post-translational steps of the baseline CYP17 and/or aromatase synthesis and/or the activation of the enzymes.

Interactions of leptin and thyrotropin 24-hour secretory profiles in short normal children.

Thyroid hormones and leptin have effects on similar aspects of body homeostasis, such as energy expenditure, thermogenesis, and metabolic efficiency. Thus, the cross-talk between the thyrostat and the lipostat might play a crucial role in the maintenance of body homeostasis. To investigate the relationship between the hypothalamic-pituitary-thyroid (HPT) axis and leptin under physiological conditions, we evaluated the pulsatility and circadian rhythmicity and time-cross-correlated the 24-h secretory patterns of leptin and TSH in 12 short normal prepubertal children (6 girls and 6 boys). In both male and female subjects, leptin was secreted in a pulsatile and circadian fashion, with a nocturnal leptin surge that was more pronounced in males than in females. Mean 24-h leptin levels and total area under the curve were significantly higher in girls than in boys. This was mainly due to the nighttime mean leptin levels and total area under the curve, which were higher than those in boys. The cross-correlated 24-h leptin and TSH levels revealed significant positive and negative correlations. The positive one, of leptin over TSH, suggests a positive feedback regulation by leptin on the HPT axis, which might play an important role in triggering the neuroendocrine response to starvation, including decreased thyroid hormone levels. The negative correlation, of TSH over leptin, could explain the compensatory changes in adipocyte metabolism, and indirectly in circulating leptin levels, in response to alterations in thyroid status. In conclusion, we suggest that under baseline physiological conditions, the HPT axis has a prevailing inhibitory effect on leptin secretion, whereas leptin has a prevailing positive effect on the HPT axis. The sexual dimorphism in leptin levels does not seem to influence in a major way the interactions between the HPT axis and leptin.

Corticotropin-releasing hormone (CRH) inhibits steroid biosynthesis by cultured human granulosa-lutein cells in a CRH and interleukin-1 receptor-mediated fashion.

The presence of immunoreactive CRH was recently demonstrated in human ovaries. CRH immunoreactivity was localized by immunohistochemistry in the cytoplasm of thecal cells surrounding the ovarian follicles, in luteinized cells of the stroma, and in large granulosa-derived luteinized cells of developing corpora lutea. Also, CRH and its receptors were identified in Leydig cells of the testis where CRH was shown to inhibit testosterone biosynthesis. To examine the role of CRH in the ovary, we studied its effect on estradiol (E2) and progesterone (P4) release by human granulosa cells obtained from women undergoing in vitro fertilization for male factor infertility or uni- or bilateral tubal impatency. In all subjects, superovulation was induced by treatment with gonadotropins. The effects of graded doses of ovine CRH (10[-11]-10[-6] mol/liter) were evaluated in the conditioned medium obtained after 24 h incubation of the cells. All CRH concentrations employed except for the lowest one (10[-11] mol/liter) caused a significant decrease of media E2 and P4 levels. Maximal inhibition for both E2 and P4 production was obtained by 10[-6] mol/liter CRH concentration, which decreased hormone production by 39% and 34%, respectively. The alpha-helical CRH9-41 antagonist at 10(-6) and 10(-7) mol/liter blocked the suppressive effect of 10(-9) mol/liter CRH on both E2 and P4 secretion, while it had no effect when added to the culture media without CRH. Since interleukin (IL-1)-1 mediates certain actions of CRH on leukocytes, we examined whether the CRH effect on ovarian steroidogenesis was IL-1-mediated. Interleukin-1 receptor antagonist at 10(-7) and 10(-6) mol/liter blocked the inhibitory effects of CRH on E2 and P4 secretion, while it had no effect in the absence of CRH. In conclusion, CRH exerts a CRH- and IL-1 receptor-mediated inhibitory effect on ovarian steroidogenesis and might be actively involved in the still enigmatic processes of follicular atresia and luteolysis.