Acute and chronic effects of pentobarbital on 5-hydroxytryptamine in mouse brain

• 1.

  1. The influence of acute and chronic administration of pentobarbital on the brain 5-hydroxytryptamine systems was investigated in mice.

• 2.

  2. Treatment of the animals with sodium pentobarbital, 75 mg/kg, i.p., resulted in an increase of 5-hydroxytryptamine and a decrease of 5-hydroxyindoleacetic acid levels.

• 3.

  3. Acute pentobarbital treatment also caused the reduction of 5-hydroxytryptamine turnover without an equivalent decrease in 5-hydroxytryptamine synthesis. However, the 5-hydroxytryptamine synthesis was significantly decreased in animals which have developed tolerance to pentobarbital.

• 4.

  4. The pretreatment of animals with p̱-chlorophenylalanine attenuated the development of tolerance to pentobarbital without altering the response of the animal to acute administration pentobarbital.

• 5.

  5. On the other hand, no significant change was observed in 5-hydroxytryptamine systems in pentobarbital-withdrawal groups.

• 6.

  6. These results strongly suggest that functional states of brain serotonergic systems may be involved in barbiturate action.