You are here:
Effect of Chlorotriazine Pesticides on Gonadotrophin Releasing Hormone in the Neuronal GT1-7 Cell Line and Hypothalamic Explants
Citation:
Zorilla, L. M. AND T. E. STOKER. Effect of Chlorotriazine Pesticides on Gonadotrophin Releasing Hormone in the Neuronal GT1-7 Cell Line and Hypothalamic Explants . Presented at Society for the Study of Redroduction, 42nd Annual Meeting, Pittsburgh, PA, July 18 - 22, 2009.
Impact/Purpose:
To be presented at Society for the Study of Reproduction, 42th Annual Meeting
Description:
Gonadotrophin releasing hormone (GnRH) stimulates the release of pituitary luteinizing hormone (LH) and follicle stimulating hormone. These pituitary hormones are necessary for normal reproductive function in both males and females. It is well recognized that disruption of normal GnRH release will result in adverse reproductive health effects. Chlorotriazines are a group of chemicals used extensively to control broadleaf and grassy weeds in corn, sorghum, sugarcane, cotton and other crops worldwide. Previous studies in our laboratory have demonstrated a number of environmental chemicals disrupt estrous cyclicity by decreasing the ovulatory surge of LH through suppression of GnRH. The exact neuronal target site of this hypothalamic insult is unknown. In the current study we examined the effects of the chlorotriazine, atrazine (ATR), and its metabolites on the hypothalamus, utilizing medial basal hypothalamic (MBH) explants and the GT1-7 cell line to identify direct effects on the GnRH neurons themselves and on intact hypothalamic tissue (representative of a more complex neuronal network that regulates GnRH pulsatility). GT1-7 cells were grown to 85-90% confluency and then added to Cytodex beads. Cells were rocked for 1 hour and then incubated for 72 hours to allow GT1-7 cells to attach to the beads. Atrazine or its primary metabolite, diaminochlorotriazine (DACT; 0, 1, 10 and 100 μM) were added to the cell media and incubated for 24 hours. Cells were then perfused at a flow rate of 0.125 ml/min at 37ºC. Media was collected every 5 minutes for 5.5 hours and stored at -80°C until GnRH was measured by ELISA. MBH tissue was collected from 14 day old female Wistar rats and placed in perifusion chambers. Media was collected every 7.5 minutes for 4 hours and stored at -80°C until analyzed for GnRH. In the GT1-7 cell experiments, 100 mM ATR and DACT decreased baseline GnRH, secretion frequency and pulse amplitude. MBH pulsatility was affected by 10 and 100 mM ATR and 100 mM DACT as indicated by a decreased baseline, pulse frequency and pulse amplitude of GnRH. No cytotoxic effects were observed at these doses. These data suggest that the chlorotriazines have a direct effect on both the GnRH secreting neuron (GT1-7) and the MBH. Further studies are underway to examine the effects of the intermediate metabolites of ATR. This abstract does not necessarily reflect US EPA policy.