| The aim of this dissertation was to determine whether the newly described neuroanatomical pathway involving the pontine structure called the intertrigeminal region (ITR), has a physiological role in mediating or modulating both reflex and sleep-related apneas.;To explore the ITR impact on reflex apneas, we elicited vagal reflex apnea by intravenuously injected serotonin (5-HT) in anesthetized rats, which produced apneas lasting 3 s. Microinjections of L-glutamate into the ITR produced immediate apneas ranging from 2.5--6 s, while microinjections of a glutamate receptor antagonist, kynurenic acid, blocked the glutamate effect. After kynurenic acid application, subsequent administration of 5-HT produced apneas of much longer duration (8 s). We concluded that a physiological role for the ITR in respiration is to attenuate vagally-induced reflex apneas.;Further, we hypothesized that reflex and sleep-related apneas may share a common central mechanism and wanted to determine whether the ITR has an impact on spontaneous sleep-related apneas in rat. To test this hypothesis, rats were surgically implanted with electroencephalographic (EEG) and electromyographic (EMG) electrodes for monitoring of sleep-wake states and were placed into a plethysmographic chamber for monitoring of respiration. We recorded respiration, EEG and EMG in control animals, as well as in animals with lesioned ITR. Again, L-glutamate microinjections were used to identify the ITR apneic sites that were subsequently lesioned by injecting ibotenic acid. ITR lesions produced no effect on mean respiratory pattern during any sleep-wake state, when compared to baseline recordings. On the other hand, apnea frequency increased following ITR lesion during non-rapid eye movement sleep two, seven and especially fourteen days after the lesion. This study demonstrated that unilateral lesion of the ITR region, increases sleep apnea expression in freely moving rats over a two-week period.;Together, these observations are in agreement with the general modulatory role of pontine structures in various activities, including respiration. |
