The effects of mecholyl and atropine on the muscarinic receptors in rat small intestine after long-term atropine administration in vivo

Rats were given atropine (AT) in 10 mg/kg doses daily during 14, 28 or 64 days. Another group of rats had AT withdrawn for 7 days after 64 days of its daily administration. Then the affinity of beta-methylacetylcholine (Mecholyl - MECH) and pA2AT for the muscarinic receptors was determined in the isolated small intestine by the method of Ariëns. No changes were observed in the pD2 value. The pA2 index increased in the rats receiving AT during 64 days and in those after AT withdrawal for 7 days. The results suggest a stronger effect of AT action after its long-term administration and withdrawal which may be due to its higher affinity to the receptors, as demonstrated, and also to an increase in the number of receptor sites, which is likely possibility.

Effects of intrahypothalamic injections of kainic acid on the behaviour of rats

The effects of bilateral microinjections of kainic acid 1.0 microgram and 2.5 micrograms into the hypothalamus on the behaviour of rats were studied controlling this behaviour during 2 weeks by the method of Lat. Moreover, the exploratory activity and irritability of the animals were assessed during that time period. After 2 weeks the activity of acetyltransferase and the level of GABA were determined in rat brain. Bilateral injections of kainic acid produced only slight changes in rat behaviour, no changes in the activity of acetyltransferase in the hypothalamus, but raised significantly the level of GABA in this structure and in the thalamus. The results of these investigations point out indirectly that the hypothalamus contains no greater number of cell bodies of cholinergic neurons but it may contain cholinergic and GABA-ergic axons which are not destroyed by kainic acid.

Choline acetyltransferase and acetylcholinesterase activities in mice brain during the antagonistic action of antidepressant drugs and Ro 4--1284

Choline acetyltransferase (Ach-T) and acetylcholinesterase (Ach-E) activities in mice brain during the reverse action by imipramine, pheniprazine and pargyline to the syndrome elicited by intraperitoneal administration of Ro 4--1284 were investigated. A single dose of imipramine did not reverse reserpine-like syndrome whereas inhibited Ach-E activity and increased Ach-T activity at the same time. The reversal of reserpine-like syndrome by administration of pargyline, pheniprazine or chronic administration of imipramine was accompanied by no changes in Ach-E and Ach-T activities.

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.

Acetylcholine content in the brain and heart of developing rats

Acetylcholine content in the brain and heart of developing rats. Acta Physiol. Pol. 1975, 26 (1): 41-44. The content of acetylcholine was determined in four parts of the brain and in the heart of developing rats. It was found that changes in acetylcholine level were not parallel in the examined brain stuctures and in the heart in the time period from birth to 18 months of age of the rats.