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TIME-DEPENDENT EFFECTS OF ACUTE CHLORPYRIFOS ADMINISTRATION ON SPATIAL DELAYED ALTERNATION AND CHOLINERGIC NEUROCHEMISTRY IN WEANLING RATS
Citation:
Stanton, M., W. Mundy, T. Ward, V. Dulchinos, AND C. Barry. TIME-DEPENDENT EFFECTS OF ACUTE CHLORPYRIFOS ADMINISTRATION ON SPATIAL DELAYED ALTERNATION AND CHOLINERGIC NEUROCHEMISTRY IN WEANLING RATS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/529 (NTIS PB95148912), 1994.
Description:
On postnatal day 21 (PND21), Long-Evans rat pups received a single subcutaneous injection of either 0 (corn oil), 90, 120, or 240 mg/kg chlorpyrifos and were then tested for T-maze delayed alternation on PND23 or 26. cetylcholinesterase (ACHE) activity and muscarinic receptor density [ie., quinuclidinyl benzilate (QNB) binding) were determined in hippocampus and cortex of brains taken from pups 15 hours after the end of behavioral testing (ie., the morning of PND24, and 27). ups exposed to the 240 mg/kg dose of chlorpyrifos showed signs of overt toxicity that precluded behavioral testing. xposure to the 120 mg/kg dose produced a selective memory impairment (ie. , a deficit in delayed alternation but not position discrimination) relative to the 90 mg/kg and vehicle groups. his impairment was transient, however, as it appeared on PND23 and was absent by PND26. ND21 exposure to chlorpyrifos produced dose-related inhibition and recovery of brain ACHE over the PND24-27 age 3 range. A similar pattern was observed in hippocampus. Binding f 3H]QNB as reduced in frontal cortex on PND27 only at the 240 mg/kg dose. No significant effects were observed in the hippocampus. These results suggest that the neurochemical effects of acute chlorpyrifos administration are more transient, and the ehavioral ffects re maller than what has been reported in adult rats.