Brain concentrations of phenobarbital and behavioral activation or depression.

Brain concentrations of phenobarbital and its effects on locomotor activity and lever responding for food reinforcement were determined at several intervals following injections into C57BL/6J mice. Phenobarbital either elevated or depressed both types of behavior depending on dose and time after injection. Excitation was noted at times and doses when brain concentration was 9 micrograms-11.5 micrograms/g tissue. Depression was initially noted at approximately 20 micrograms/g tissue. Lever responding was altered when brain concentrations of the drug were lower than those associated with corresponding effects on locomotor activity. Excitatory and depressive effects were most extensive when basal response rates were moderate or high respectively. Hence, whether phenobarbital is excitatory or depressive depends on a complex interaction of brain concentration, rate of ongoing behavior and the stimulus conditions maintaining the behavior.

Neurochemical and behavioral effects of diet related perinatal folic acid restriction.

Some effects of restricting dietary folic acid during the perinatal period on tissue folate and S-adenosyl-L-methionine (SAM) concentrations and on behavior were examined in 35-day-old DBA/2J mice. In one study dams were started on diets containing no folate (FO), 1.1 mg of folic acid/kg diet (F1.1) or 9.9 mg of folic acid/kg diet (F9.9) on the day of parturition. In a second study some mice were started on the FO or F9.9 diets 6-7 days prior to parturition and some remained on lab chow (LC). The dams and their pups remained on their assigned diets until offspring were killed for biochemical assays. The major findings of the 2 studies are: (1) that eliminating folic acid from diets of dams and developing pups from birth or 1 week prior to birth causes a reduction of folate in brain tissue; (2) that reduction in brain tissue is not as severe as that of liver; (3) that initiating the folate free diet 1 week prior to birth caused reductions in body, liver, and brain weights and in activity levels of surviving offspring; and (4) that offspring of dams started on either the FO or F9.9 diet one week prior to parturition are less viable and have lower levels of SAM in brain tissue than animals reared on the LC diets.