Abstract
We investigated the behavioral correlates of the activity of serotonergic and non-serotonergic neurons in the nucleus raphe pallidus (NRP) and nucleus raphe obscurus (NRO) of unanesthetized and unrestrained cats. The animals were implanted with electrodes for recording single unit activity, parietal oscillographic activity, and splenius, digastric and masseter electromyographic activities. They were tested along the waking-sleep cycle, during sensory stimulation and during drinking behavior. The discharge of the serotonergic neurons decreased progressively from quiet waking to slow wave sleep and to fast wave sleep. Ten different patterns of relative discharge across the three states were observed for the non-serotonergic neurons. Several non-serotonergic neurons showed cyclic discharge fluctuations related to respiration during one, two or all three states. While serotonergic neurons were usually unresponsive to the sensory stimuli used, many non-serotonergic neurons responded to these stimuli. Several non-serotonergic neurons showed a phasic relationship with splenius muscle activity during auditory stimulation. One serotonergic neuron showed a tonic relationship with digastric muscle activity during drinking behavior. A few non-serotonergic neurons exhibited a tonic relationship with digastric and/or masseter muscle activity during this behavior. Many non-serotonergic neurons exhibited a phasic relationship with these muscle activities, also during this behavior. These results suggest that the serotonergic neurons in the NRP and NRO constitute a relatively homogeneous population from a functional point of view, while the non-serotonergic neurons form groups with considerable functional specificity. The data support the idea that the NRP and NRO are implicated in the control of somatic motor output.
Highlights
The two most caudal raphe nuclei, the nucleus pallidus (NRP) and nucleus obscurus (NRO), have been implicated in the control of somatic motor and visceral motor-secretory functions
We investigated the behavioral correlates of the activity of serotonergic and non-serotonergic neurons in the nucleus raphe pallidus (NRP) and nucleus raphe obscurus (NRO) of unanesthetized and unrestrained cats
These results suggest that the serotonergic neurons in the NRP and NRO constitute a relatively homogeneous population from a functional point of view, while the non-serotonergic neurons form groups with considerable functional specificity
Summary
The two most caudal raphe nuclei, the nucleus pallidus (NRP) and nucleus obscurus (NRO), have been implicated in the control of somatic motor and visceral motor-secretory functions. The major projections of these nuclei are directed at the somatic motor/premotor and the visceral motor-secretory/premotor-secretory nuclei of the brainstem and spinal cord. Increased NRP or NRO activity induced by electrical or chemical stimulation facilitates trigeminal motoneurons [18], facilitates or depresses phrenic motoneurons [19,20,21], facilitates lumbar motoneurons [22,23], facilitates motor and secretory gastric preganglionic neurons in the dorsal motor nucleus of the vagus [12,24], and facilitates or depresses sympathetic preganglionic neurons to the heart and vessels [25, 26]
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Schedule a callMore From: Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
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