The influence of antidepressive drugs on the level of acetylcholine and on the acetylcholinesterase activity in the brain of rats.

Rats were treated ip with MAO inhibitos (MAO-I): nialamid (NL), pivalylbenzylhydrazine, tranylcypromine, pheniprazine (Ph) or pargyline, and the leve of total, free and bound acetylcholine (Ach) as well as the acetylcholinesterase (Ach-E) activity were estimated in four parts of rats brain 2 or 16 hr after the treatment. These parameters were estimated also after the treatment with tricyclic antidepressants: desmethylimipramine (DMI), amitriptyline, or protriptiline, and in the conditions of the reversal of reserpine-like syndrom. MAO-I, 2 hr after their application and the reversal of reserpine like-syndrom have not changed the level of measured fractions of Ach in parts of the brain. DMI increased the level of all Ach fractions in the striatum. NL caused the decrease of bound Ach level in all parts of the brain with no changes of free Ach level, 16 hr after the treatment. Ph, 16 hr after the treatment, decrease both fractions of ACh only in the cortex. All studied drugs affected evidently ACh-E activity in various parts of brain. It is concluded that:1) Cholinergic mechanisms in the rat brain are involved in the central action of DMI and of some MAO-I., 3) Cholinergic function of the brain may be modulated by the adrenergic activity, 2) Individual parts of the brain have different susceptibility to the influence of different MAO-I on the ACh-E activity.