Bull. Environ. Contam. Toxicol. (1991) 47:455-458 9 1991 Springer-Verlag New York Inc. ~Environmental Contamination iand Toxicology Neurobehavioral Changes in Freshwater Fish Channa punctatus Exposed to Fenitrothion Murali Dhar Ram and Krishna Gopal Industrial Toxicology Research Centre, Post Box No. 80, Mahatma Gandhi Marg, Lucknow-226 001, India Recently a vast number of pesticides have been liberally used in agriculture to combat the pest menace to procure the higher yield from the crops. These pesticides indiscriminately affect ~he nontarget organisms such as fishes and prawns which are of great economic significance to common man (Butler 1965). Fenitrothion is an organophosphate pesticide extensively used in agriculture for crop protection. Fenitrothion has induced remarkable changes in the tissues of exposed fishes followed by depletion of succinate dehydrogenase and increase of lactate dehydrogenase activity (Koundiya and Ramamurthi 1978). Neuro- transmitters such as acetylcholine (Ach) catecholamine 5-hydroxy- ~ryptamine (5-HT) and aminoacids are closely associated with functional activities in the central nervous system (Goodman et al. 1980). MATERIALS AND METHODS Channa punctatus (Bloch) I0-15 gm were collected from local resources and acclimated to standard laboratory conditions(Gopal and Mishra, 1988). Toxicity tests were conducted in wide mouth- ed jars containing 20 L of tapwater with following characterist- ics: temperature 26+-2~ pH 6.9-7.2, alkalinity 95-100 gm/L as CaCO 3 and hardness 118-122 mg/L as CaCO 3. Fenitrotbion dissolved in alcohol was added to water containing test fishes to attain the desired concentration (0.4 rag/L) for 96 hr. Parallel group of control fish was also maintained under identical conditions. Brains of 5 fish from treated as well as control were removed quickly and deep frozen at (0~ Parts of the brains were dissected out into 3 regions on ice cold glass plate and homo- genized in N-butanol. Norepinephrine (NE), Dopamine (DA) were extracted in 0.I M phosphate buffer and 5-hydroxytryptamine (5-HT) in heptane. Fluoroscence of NE was measured at 385 *SerLd r e p r i n t request to Dr.Krishna Gopal at the above address 455