Dithiocarbamate fungicides decrease histochemical reactivity of cholinesterases in the gut wall of the rat.

The toxicity of dithiocarbamate fungicides is poorly known, especially in the autonomic nervous system. Male Wistar rats were given tetraethylthiuramdisulfide (DSF), maneb, and zineb as a suspension in saline i.p. 200 mg/kg daily for 4 d. Rats received a similar dose of ethylenethiourea (ETU) as a solution in saline i.p., and the control rats received a corresponding volume of saline i.p. After decapitation, pieces of ileum were taken, and the enzyme histochemical reactivity for the acetylcholinesterase (AChE) and for the nonspecific cholinesterase (nsChE) in the ilea of the treated and control animals was studied. The reaction intensities in the samples were estimated by eye using a scale from 0 (no reaction product) to 3+ (maximal reaction). DSF was used as an internal standard. Controls showed the maximal reaction for the AChE and for the nsChE. Maneb, ETU and zineb showed consistent decrease in the reactivity for the AChE (+ +) and for the nsChE (+ +). The decrease by DSF of the reactions for both the AChE (+) as well as for the nsChE(+) was even more pronounced indicating a possible nerve damage to the cholinergic innervation of rat intestine. Kinetic differences may explain the divergent effects between the agents studied.