ENDOCRINE DISTURBANCES INDUCED BY LOW-DOSE ORGANOPHOSPHATE EXPOSURE IN MALE WISTAR RATS

Background. Organophosphate exposure induces many endocrine effects. Aim. In this study we observed the effects of acute stress induced by cholinesterase inhibition on the main hormonal axes. Materials and Methods. We included thirteen weanling Wistar rats that were subjected to organophosphate exposure. They were first tested for baseline levels of butyrylcholinesterase, cortisol, free triiodothyronine, thyroxine, thyroid-stimulating hormone and prolactin. Secondly, chlorpyrifos was administered. Next samples were taken to determine the level of all the above-mentioned parameters. Results. Butyrylcholinesterase was significantly decreased after exposure (p<0.001). Cortisol levels were significantly higher after clorpyrifos administration (358.75 +/- 43 vs. 241.2 +/- 35 nmoL/L)(p<0.01). Although prolactin had a growing trend (450.25 +/- 24.65 vs. 423 +/- 43.4 uI/mL), the results were not statistically significant. Both free triiodothyronine and thyroxine were significantly higher after exposure. Surprisingly, thyroid-stimulating hormone level almost doubled after exposure with high statistical significance (p<0.001), suggesting a central stimulation of thyroid axis. Butyrylcholinesterase level was proportional with thyroid-stimulating hormone level (p=0.02) and thyroxine level was inversely correlated to the cortisol level (p=0.01). Acute cholinesterase inhibition may induce high levels of cortisol, free triiodothyronine, thyroxine and thyroid-stimulating hormone. From our knowledge this is the first study dedicated to the assessment of acute changes of hormonal status in weanling animals after low-dose organophosphate exposure. Conclusion. Acute cholinesterase inhibition may cause acute phase hormonal disturbances specific to shocked patients.