Cholinergic and behavioral neurotoxicity of carbaryl and cadmium to larvalrainbow trout (Oncorhynchus mykiss)

Pesticides and heavy metals are common environmental contaminants that can cause neurotoxicity to aquatic organisms, impairing reproduction and surviv al. Neurotoxic effects of cadmium and carbaryl exposures were estimated in larval rainbow trout (RBT; Oncorhynchus mykiss) using changes in physiologi cal endpoints and correlations with behavioral responses. Following exposur es, RBT were videotaped to assess swimming speed. Brain tissue was used to measure cholinesterase (ChE) activity, muscarinic cholinergic receptor (MCh R) number, and MChR affinity, ChE activity decreased with increasing concen trations of carbaryl but not of cadmium, MChR were not affected by exposure to either carbaryl or cadmium, Swimming speed correlated with ChE activity in carbaryl-exposed RBT, but no correlation occurred in cadmium-exposed fi sh, Thus, carbaryl exposure resulted in neurotoxicity reflected by changes in physiological and behavioral parameters measured, while cadmium exposure did not, Correlations between behavior and physiology provide a useful ass essment of neurotoxicity. (C) 2001 Academic Press.