Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB012

Poster Communications

Chronic exposure to chlorpyrifos changes cardiac morphometry in rats.

V. S. MINASSA1, A. V. Aitken1, T. J. Batista1, I. S. Felippe1,2, K. N. Sampaio1


Previous studies from our group showed that acute exposure to chlorpyrifos (CPF), an organophosphorus (OP) compound, impairs cardiovascular reflexes in rats (Cunha et al., 2018). Some evidence suggests that low level chronic exposure to OP compounds induces cardiac hypertrophy (Calore et la., 2007). However, whether long term exposure to CPF affects cardiac morphometry in rats remains unexplored. Male Wistar rats were intraperitoneally injected with CPF for 1 month (3 times/week), at the following doses: 7 mg/kg (CPF 7; n=25) and 10 mg/kg (CPF 10, n=19). A control group received saline (NaCl, 0.9%) for the same period (SAL, n=21). The study followed the recommendations of the Brazilian National Council for Animal Experimentation and was approved (approval number 20/2016) by the University Committee for Animals Ethical Use (CEUA-UFES). After treatment, animals were euthanized by decapitation, and hearts and blood samples collected for measurement of plasma butyrylcholinesterase (BuChE) activity to confirm OP exposure. As evidence has shown that anaesthesia may interfere with BuChE activity (Nana et al., 1977), decapitation was conducted by a well experienced-trained researcher, without the use of anaesthetics. After removing the hearts, left ventricles (LV) were separated and both wet and dry weight documented (SAL, n=11, CPF 7, n=15 and CPF 10, n=11) and ventricular mass normalized to body weight (LV/BW). Some ventricular tissue (SAL, n= 10, CPF 7, n=10 and CPF 10, n=8) was sectioned and stained with hematoxylin-eosin or picrosirius red to determine the smaller diameter and collagen content, respectively. Images were captured with a video camera (AxioCam ERc 5s, Carl Zeiss) coupled to an optical microscope (Olympus AX70, Olympus Corporation) under 400X magnification. All histologic analysis was performed using ImageJ software (v.1.43u, National Institutes of Health). Data were analysed by ANOVA followed by Dunnett's post hoc test and expressed as mean ± error standard of mean (EPM). No statistical difference was observed for wet (F(2,32)= 0.87; P= 0.43) or dry (F(2,32)= 0.55; P= 0.58) left ventricular mass when standardises with body weight, among all groups tested. On the other hand, myocytes smaller diameter and percentage of collagen content was significantly increased in CPF 10 group compared to SAL animals (P<0.05). BuChE activity was significantly decreased in all CPF treated animals when compared with SAL group (P<0.05). Our data shows that despite the absence of changes in LV/BW ratio, CPF treatment altered cardiac morphometry in the animals exposed to OP. These results may have important clinical implications for laborers, such as farmers, frequently exposed to these compounds.

Where applicable, experiments conform with Society ethical requirements