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1. Three groups of six pregnant albino mice at the third stage of gestation were given chlordane 1 or 2.5 mg/kg body weight or olive oil 10 ml/kg. They were dosed orally for seven consecutive days.2. Ten young mice, regardless of sex, were randomly selected from the progeny of each group of treated mothers and tested for conditioned avoidance response, electroshock seizure threshold, and open-field performance.3. Offspring of chlordane-treated mice made fewer conditioned avoidance responses than the controls on each day of training.4. Electroshock seizure threshold was raised.5. In the open-field test, progeny of mothers receiving the larger dose were more active than controls. A dose x days interaction indicated a complex response of the chlordane-treated mice to experience in the open-field.6. The significance of these findings is discussed.

Administration of phenobarbital to rats in a dosage schedule previously demonstrated to increase hepatocellular binding of thyroxine results in increased hormonal turnover, due both to increased deiodination and to fecal disposition of thyroxine iodine. The rate of biliary excretion of thyroxine iodine is roughly proportional to the hepatic content of exchangeable thyroxine. The enhanced peripheral disposition of thyroxine appears to lead to increased thyroidal function, as measured by isotopic iodine studies, and the maintenance of a normal nonradioactive serum PBI. On the other hand, thyroidectomized animals maintained on a constant replacement dose of L-thyroxine and treated with phenobarbital exhibit a marked fall in serum PBI. These findings suggest that increased thyroxine flux in phenobarbital-treated animals is secondary to primary stimulation of hepatocellular binding. Exchangeable intracellular thyroxine may thus be an important determinant of hormone turnover and, possibly, of hormonal action.