Study of the participation of the dopaminergic transmission system in the effects of two newly synthesized barbiturates.

The effects of two newly synthesized barbiturates--HB-7 (2-hydroxylamino-5-ethyl-5-sec. pentylbarbituric acid) and HB-2 (2-hydroxylamino-5-ethyl-5-propylbarbituric acid--on models of apomorphine stereotypy and haloperidol catalepsy were investigated in experiments on male rats and mice. The test drugs used were phenobarbital (PB)--in stereotypy and catalepsy, and diphenylhydantoin (DPH)--in catalepsy. HB-7 changes the stereotypy considerably: it developed faster and disappeared faster than in the control group. Phenobarbital had a weaker effect on the intensity and duration of the stereotypy. Catalepsy was induced with haloperidol in doses of 1 and 2 mg/kg. HB-7 and HB-2 weakened haloperidol catalepsy, compared with PB and DPH. The faster occurrence of apomorphine stereotypy and the weakening of the haloperidol-induced catalepsy under the effect of the two hydroxyl-amine derivatives of barbituric acid suggest an effect on the cerebral dopaminergic transmission. This effect may be mediated through the effect of HB-7 on DA-ergic transmission or through the GABA-ergic transmission in the brain structures responsible for these behavioural reactions.