Long-term sequelae of soman exposure: hormonal rhythms two weeks postexposure to a single dose

Two weeks following a single exposure to either soman (100 micrograms/kg, sc) or saline, rats were sacrificed at 2-hr intervals over a 26-hr period. Trunk blood was collected and plasma was stored until assayed for corticosterone, prolactin, growth hormone, adrenocorticotropin, beta-endorphin, and beta-lipotropin. Rats surviving for 2 weeks following soman appeared well groomed and were gaining weight at a rate similar to saline-treated rats at the time of termination. Thus, they appeared to have recovered from the initial physiological effects of soman exposure. However, substantial differences in plasma levels of most hormones were seen in comparing soman- vs saline-treated rats. Levels of prolactin were suppressed at all time points in soman-treated rats. Growth hormone secretion was also suppressed and the normal episodic peaks of growth hormone were missing in soman-treated rats. Both soman- and saline-treated rats displayed circadian rhythms in levels of plasma corticosterone, but the usual late afternoon rise in plasma corticosterone levels was shifted to earlier time points in the soman-treated rats. Levels of beta-endorphin and beta-LPH were slightly but significantly suppressed in soman-treated rats at almost all time points. Levels of adrenocorticotropin were similar in control and soman-treated rats. The results of this experiment demonstrate that a single exposure to soman may have long-lasting effects on neuroendocrine function.