An acute dose of monosodium L-glutamate causes decreased fecundity and enhanced loss of the cestode Hymenolepis diminuta from rats.

A method for the rapid quantitative analysis of eggs in the feces of rats infested with Hymenolepis diminuta is described. In one experiment, eggs in the feces of individual rats were monitored for 8 days. Rats were provided with 1 ml saline vehicle or with 0.1 or 1 g monosodium glutamate (MSG) by stomach tube and egg production was monitored. Egg production decreased in saline vehicle-treated rats, but the decrease was significantly greater in the group treated with 1 g MSG. There was no significant change in fecal mass output from rats with different treatments. The number of worms harbored by rats treated with 1 g MSG was significantly lower than those of saline control-treated rats. In another experiment, neither anesthesia alone nor anesthesia with 1 g sucrose significantly reduced egg output as compared with that observed in untreated rats. Therefore, MSG has a significant negative effect on both the fecundity of H. diminuta and the numbers of worms harbored by rats.