Meperidine-promethazine combination and learning function of mice and of their progeny.
Twenty mice aged three to four months and trained to find food in a six compartment maze after a 24 hour fast, were divided into two equal groups. For just over one month the group which had received intraperitoneal meperidine 3 microgram.g-1 and promethazine 1.66 microgram.g-1 performed significantly slower than the group which had received intraperitoneal physiological saline. Because of this marked effect, it was decided to investigate the action of the drug combination on brain development and to assess whether it produced permanent retardation in learning function. The dams of a second group of 12 mice were, therefore, given either the same dose of drug combination or saline. At the age of seven weeks, the six pups born to dams which had received intramuscular saline and the six born to dams which were given intramuscular promethazine with meperidine performed equally well in a series of tests conducted in a T maze and in the six compartment maze after a 24 hour fast. In the T maze they had to distinguish between the presence of food provided in diminishing amounts or no food. In the six compartment maze they were tested with multiple maze pattern sequences. Meperidine and promethazine given during early labor does not permanently affect the learning function of the progeny of mice.