Efecto del agua del embalse de la vega en la lipoperoxidación y los niveles de la acetilcolinesterasa en el hígado y el músculo de Xiphophorus helleri

The discharge of pollutants by industries represents a serious water contamination problem because the contaminants reduce the quality of freshwater and are hazards to the fish population. The Ameca river, located in the Pacific slope of western México is characterized by the presence of springs and a reservoir (De La Vega reservoir). This reservoir receives sewage from the sugar industry. The measurable biological response of an organism to environmental contamination has been termed a biomarker response. The aim of the present study was to investigate the physicochemical characteristics of De La Vega water and the toxic effect of this water. Bioassays were performed in Xiphophorus helleri to determine the effects of a short-term exposure (96 h) to water of De La Vega reservoir on two biomarkers: acetylcholinesterase (AchE) and lipid peroxidation (LP). After acclimatization, the fish were divided into three groups and each group (n=8) was exposed to water of each site, N, C, and S, respectively and the control group (n=8) was maintained in reconditioned water that served as control. In the reservoir there was possible to detect marked fluctuations in the physicochemical factors both with vertical gradients and seasonal fluctuations as occurred with dissolved oxygen, conductivity, turbidity, nitrates and nitrites, on site S. Acetylcholinesterase activity was inhibited in the liver and muscle of exposed fish. There was a 86, 88 and 89 % inhibition of AchE activity in the liver, at N, C and S sites, respectively, after 96 h exposure to reservoir waters compared to control values but the highest AchE inhibition was observed in muscle. Fish exposed to reservoir water also demonstrated a significant increase in LP measured as the amount of TBARS as compared to controls. Water treatment led to 1.5, 2.5 and 4 fold in increase in LP liver and in muscle 2, 1.5 and 3.5 fold corresponding to N, C and S, respectively. Also, the conjugated dienes showed an increase. The water exposure caused a 100 % increase in the level of conjugated dienes in the liver and muscle homogenates. The results reported here indicate that fish subjected to a exposure of combined contaminants of De La Vega water are vulnerable to the toxic effect of them. Although X. helleri is a tolerant species, exposure to levels of pollutants may lead to the impairment of the reproductive activities and changes in either the population size and structure of this species.