Toxic effects of sarin in rats at three months following single or repeated low-level inhalation exposure

Male albino Wistar rats were once or repeatedly exposed to three various lo w concentrations of sarin for 60 min. in the inhalation chamber. The clinic al status of control as well as sarin-poisoned rats was tested 3 months aft er exposure to sarin using biochemical, haematological, neurophysiological, behavioural and immunotoxicological methods. While biochemical and haemato logical parameters, including the activities of cholinesterases in erythroc ytes, plasma and various organs (brain, diaphragm), did not differ from the control values regardless of the sarin concentration used, few signs of sa rin-induced neurotoxicity and immunotoxicity in sarin-poisoned rats were de monstrated. This was especially true when the single exposure of rats to no n-convulsive symptomatic concentration and repeated exposure of rats to cli nically asymptomatic concentration of sarin was used. In rats repeatedly po isoned with clinically asymptomatic concentrations of sarin, the alteration of the gait characterized by ataxia, the increase in the stereotyped behav iour, the increase in the excitability of the central nervous system follow ing the administration of the convulsive drug pentamethylenetetrazol were o bserved. In rats poisoned with non-convulsive symptomatic concentration of sarin, the subtle supression of spontaneous, as well as lipopolysaccharides -stimulated, proliferation of spleen lymphocytes and the bactericidal activ ity of peritoneal macrophages was primarily observed besides the signs of n eurotoxicity. Our findings confirm that both nonconvulsive symptomatic and clinically asymptomatic concentrations of sarin can only cause very few, su btle long-term signs of neurotoxicity and immunotoxicity in sarin-poisoned rats when the rats were exposed to asymptomatic sarin concentrations repeat edly.