The influence of cholinergic drugs on EEG of the brain of the castrated rabbit males

Aim. We investigated the influence of various cholinoceptive drugs on spontaneous activity of a brain at the intact rabbit and in the conditions of deficit of gonadal hormones, and also studied of reciprocal influence of cholinergic drugs on changes of character of a range of EEG at the intact and castrated rabbits.

Methods. Our researches were carried out on 32 rabbit males of breed the Chinchilla. Bipolar nichrome electrodes implanted to rabbits by stereotactic operaition into a caudate nucleus, a hippocampus and a reticular formation of a mesencephalon and also cortical monopolar chlorsilver electrodes with a diameter of 1 mm - to the optic and frontal area of cortex. Registration of EEG carried out in a shielded chamber with use of the electroencephalograph-analyzer EEGA-21/26 “Encephalan-131-03”. The averaged EEG range power was analyzed with a 60 s recording epoch. In 3 weeks after implantation of electrodes we studied the influence a number of cholinergic drugs on spontaneous EEG: M-cholinolytic metamizyl (1 mg/kg i.p.), N-cholinolytic gangleronum (5 mg/kg i.p.), inhibitor of acetylcholinesterase (AChE) galantamine (0.5 mg/kg i.p.). Registration was carried out in 1, 2 and 3 hours after an injection. Under the combined investigation of preparation galantamine was entered in 20 minutes after an injection of cholinolytics. Then, we carried out removal of a testis at rabbits — males under etherization. The spontaneous electric activity of a brain of that rabbits and influence of cholinergic drugs was registered in 30 days after operation of bilateral gonadectomy.

Result. The gonadectomy of Chinchilla rabbits causes the deceleration of EEG range power twice in comparison with intact animals in a chronic experiment. The analysis of influence of cholinoceptive substances on EEG showed that the most sensitive to the change of balance between M- and N-cholinoreceptors are cerebral cortex and caudate nucleus. The intensity of the activating effect accompanying blockade of M-cholinoreceptors is higher in cortical structures, than in subcortical nuclei in all animals. The reaction of caudate nucleus to the blockade of M-cholinoreceptors is the most sensitive among subcortical nuclei. It “answers” with increase in EEG range power. The blockade of N-cholinoreceptors in this structure after insignificant potentiating is followed by decrease of EEG range power. The activity of hippocampus is least dependent on the level of androgens in organism.

Conclusions. The analysis of influence of cholinoceptive substances on spontaneous activity of a brain showed that the most sensitive to change of balance between M-cholinoreceptors and H-cholinoreceptors were a cerebral cortex and a caudate nucleus. As at the intact as the castrated animals the expressiveness of the activating effect accompanying blockade of M-cholinoreceptors is higher in cortical structures than in subcortical nuclei.