Toxicity and toxicokinetics of carbaryl in chickens and rats: A comparative study

Abstract

Carbaryl, a carbamate insecticide, exerts its toxic effect in animals by inhibiting the activity of neural acetylcholinesterase. Differences in sensitivity of this enzyme to inhibition were studied after intraperitoneal administration to chickens and rats. A dose of 900 mg/kg to chickens and 70 mg/kg to rats caused equivalent inhibition of brain cholinesterase activities (57% +/- 6 and 47% +/- 4, respectively) 60 min after administration, which was the time of maximal cholinergic signs. Signs of toxicity (salivation, respiratory distress, muscle tremors and weakness) were more pronounced in rats than in chickens when brain acetylcholinesterase was inhibited to the same extent in both species. Carboxylesterase activities in brain, liver, and plasma were also inhibited 60 min after administration of carbaryl to chickens and rats. Activities of enzymes associated with hepatic microsomes were unaffected. Specific activities of brain esterases, including acetylcholinesterase, carboxylesterase and neurotoxic esterase, were higher in untreated chickens than in untreated rats. Specific activities of liver esterases (carboxylesterase, A-esterase) were, however, 4- and 10-fold lower in untreated chickens than in untreated rats. Total clearance of carbaryl in the chicken, determined after intravenous administration of 5 mg/kg, was 0.26 +/- 0.02 l/kg/min. This value is 5.7 times higher than that reported for the rat, indicating that the relatively lower activities of esterases in the liver of chickens did not affect the clearance of this chemical in the avian species.

Subchronic neurotoxicity of chlorpyrifos, carbaryl, and their combination in rats

“…Previous studies demonstrated that AChE activity in the rats was significantly inhibited by chlorpyrifos but no activity inhibited by carbaryl after exposure to these pesticides separately (Ehrich et al,; Sachana et al,), which was similar to the results observed in our current study. The inhibition of AChE in the rats treated with middle‐ and high‐dose of the mixture of chlorpyrifos and carbaryl was similar to that induced by chlorpyrifos alone and no AChE activity inhibition by carbaryl alone was found.…”

Effect of Diplodiatoxin (Stenocarpella maydis) on Some Enzymatic Profiles in Male and Female Rats

“…The phosphorylation reaction is responsible for the inhibition of AChE, which causes neurotoxicity. An inhibition of brain AChE similar to that in the present study was reported in rats treated with MCP (Janardhan and Sisodia, 1990), carbaryl (Ehrich et al, 1992), and permethrin (Bandyopadhyay, 1982). It has been reported that diplodiatoxin causes mycotoxic peripheral myelinopathy and hepatitis in monkeys (Fincham et al, 1991).…”

Impact of Chemical Proportions on the Acute Neurotoxicity of a Mixture of Seven Carbamates in Preweanling and Adult Rats

“…carboxylesterases produced by carbaryl, carbofuran, methomyl, oxamyl, and propoxur (e.g., Barata et al, 2004;Costa and Murphy, 1983;Ehrich et al, 1992;Fossi et al, 1992;Gupta and Dettbarn, 1993;Kadel, 1989, 1990;Parker and Goldstein, 2000). This binding is biologically significant in that coadministration of carboxylesterase inhibitors potentiates the toxicity of carbofuran, oxamyl, and propoxur (Costa and Murphy, 1983;Gupta and Dettbarn, 1993;Kadel, 1989, 1990;Parker and Goldstein, 2000).…”