Besides extrapyramidal motor disorders, disturbances in breathing form an important part of the Parkinson’s disease (PD) syndrome. Respiratory disturbances include alternations in respiratory pattern, pulmonary ventilation and a dysfunction of upper-airway muscles. We investigated whether the animal model of Parkinson’s disease created by unilateral injection of 6-hydroxydopamine (6-OHDA) into the striatum induced changes in neural respiratory activity to the diaphragm and upper-airways muscles and the respiratory response to hypoxia. The respiratory effects and response to intermittent hypoxia were studied in animals after unilateral infusion of 24 µg 6-OHDA (4 µg/1µl) or 6 µl of vehiculum into the striatum. Two weeks following the infusion the rats were anesthetized, subjected to bilateral midcervical vagotomy, paralyzed and artificially ventilated. Relation between activity of the phrenic and hypoglossal nerves was analyzed during normoxic ventilation and during acute intermittent hypoxia, composed of five episodes of 11% hypoxia introduced every 3 minutes, in the control and 6-OHDA lesioned animals. Amplitude, frequency of integrated phrenic and hypoglossal nerve activity and minute phrenic and hypoglossal activity were calculated. The results showed that unilateral nigrostriatal dopaminergic destruction in the 6-OHDA model of Parkinson’s disease did not evoke an alternation of the respiratory pattern of the phrenic and hypoglossal activity in anesthetized, normoxic rats. The difference between the control and 6-OHDA lesioned animals appeared when respiratory drive increased due to hypoxia. While the magnitude of the phrenic response to each episode of hypoxia was almost unchanged in the lesioned vs. control animals, the hypoglossal hypoxic response attained significantly higher levels in 6-OHDA lesioned rats. The biphasic response to hypoxia was maintained, however, a decline of the hypoglossal hypoxic response was more emphasized in the PD model. Changes in the respiratory frequency due to hypoxia were comparable in both groups of rats. In conclusions this study reveals that central dopamine depletion elicited by unilateral infusion of 6-OHDA into the nigrostriatal region develops a modification of the respiratory hypoxic response and intensifies an asymmetry of the phrenic and hypoglossal nerve activity. Uneven hypoxic drive to the diaphragm and the muscles of upper respiratory tract is a probable cause of this modification and might be a source of respiratory disturbances in the Parkinson’s disease
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.