S.B. Jones S.K. Brewer E. E. Little S.L. Beauvais 2000 <p><span>Relations between neurotoxicants and changes in physiological parameters and behavior were investigated in larval rainbow trout (RBT; </span><i>Oncorhynchus mykiss</i><span>) exposed to sublethal concentrations of two organophosphate pesticides (OPs). Fish were exposed to diazinon and malathion in static-renewal experiments. After exposures for 24, 96, or 96 h, followed by 48 h of recovery, individual RBT were videotaped to assess locomotory behaviors. Brain tissue from the same fish was assayed for the physiological endpoints, cholinesterase (ChE) activity, muscarinic cholinergic receptor (MChR) number (B</span>_max<span>), and MChR affinity (K</span>_D<span>). Cholinesterase activity decreased significantly with increasing concentrations of both diazinon and malathion and differed significantly among exposure durations, with 24- and 96-h means less than 48-h recovery means. Decreases in B</span>_max<span> with OP concentration were not significant for either chemical, and K</span>_D<span>was unaffected. Changes in swimming speed and distance were significantly correlated with changes in ChE activity for both chemicals; rate of turning was significantly correlated with ChE activity in malathion exposures. These results suggest that correlations between physiological and behavioral changes previously seen in mammals also occur in fish.</span></p> application/pdf 10.1002/etc.5620190722 en Wiley Physiological measures of neurotoxicity of diazinon and malathion to larval rainbow trout (<i>Oncorhynchus mykiss</i>) and their correlation with behavioral measures article