[The central cholinergic stimulation in sinoaortic denervation. Effect of intracerebroventricular administration of cholinomimetic agents].

It was decided to made a pharmacological study of the cholinergic participation in the sinoaortic denervation experimental model by analyzing the cardiovascular effects of several muscarinic agonists and the anticholinesterase neostigmine administered either by intravenous via or by the intracerebroventricular via. The activity of the enzyme acetylcholinesterase was also evaluated in diverse structures of the central nervous system after the intracerebral administration of neostigmine. Sinoaortic denervation increases the pressor response to the i.c.v. administration of the agonist bethanechol and of the anticholinesterase neostigmine but it diminishes the bradycardic effect. However it would not alter the cardiovascular responses to the i.v. injection of the agonist oxotremorine and to the i c v. administration of the agonist McNeil-A-343. After the i c v. administration of neostigmine, the enzymatic activity oscillated among 24%-30% in hypothalamic structures and among 42%-52% in the remaining tissues, without differences between the rats with sham operation and those with sinoaortic denervation. The results suggest that M, muscarinic receptor subtype would not be involved in the cardiovascular effects of the central cholinergic stimulation On the other hand, it would support the idea of an involvement of muscarinic receptors in the observed changes. Because the used route of administration of neostigmine, a greater degree of inhibition of the hypothalamic acetylcholinesterase is observed, suggesting then that the hypothalamic structures could be involved in the cardiovascular effects induced by the intracerebral administration of the anticholinesterase.