1. The effects of phenol and phenyl glucuronide on the responses of normal rat brain adenyl cyclase to noradrenaline and dopamine have been investigated. Neurotransmitter responses have also been examined in brains from uraemic and normal rats.
2. A depressive effect of phenol on the adenosine 3′: 5′-cyclic monophosphate response of the neostriatum to dopamine was shown to be completely abolished if the toxin was present in the conjugated form; the response of the cortex to noradrenaline was stimulated by the presence of phenyl glucuronide, even though the unconjugated form had no effect.
3. The uraemic state in the rat also resulted in a depression of the neostriatum response to dopamine, yet an enhancement of the cortical response to noradrenaline.
4. The action of phenols on the brain is relevant to hepatic and uraemic coma.