The sources of noradrenergic (NA) innervation to the hypoglossal nucleus (nXII) in the rat were investigated with double-labeling histochemical/immunocytochemical and lesion/degeneration techniques. Following injection of wheat germ-agglutinin conjugated to horseradish peroxidase into nXII, brain stem sections were reacted with tetramethylbenzidine, stabilized, and incubated in antiserum to tyrosine hydroxylase (TH). Double-labeled neurons were observed in three pontine sites bilaterally, although mainly ipsilaterally, that included the nucleus subceruleus (nSC; 68.75%) and the A7 (21.09%) and A5 (10.15%) cell groups. Confirmation of the above results and identification of the course taken by descending NA-nXII projections was accomplished by lesioning the rostral pons, the nSC, or the medullary catecholamine bundle (MB), the suspected route by which NA afferents reach nXII. Quantitative estimates of the reduction of TH immunoreactivity on the lesioned compared to nonlesioned side of nXII were made densitometrically. In each case, TH immunostaining was significantly decreased (75%) in the ipsilateral caudoventromedial district of nXII, the predominant target area of NA input. The results from this study establish that multiple NA sources in the pons project to nXII in the rat, the majority of NA-nXII afferents are derived from the nSC, and descending NA-nXII projections course in the MB. These data are discussed relative to tongue control.
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http://dx.doi.org/10.1016/0361-9230(92)90168-w | DOI Listing |
Unlabelled: The locus coeruleus (LC) is the primary source of noradrenaline (NA) in brain and its activity is essential for learning, memory, stress, arousal, and mood. LC-NA neuron activity varies over the sleep-wake cycle, with higher activity during wakefulness, correlating with increased CSF NA levels. Whether spontaneous and burst firing of LC-NA neurons during active and inactive periods is controlled by mechanisms independent of wakefulness and natural sleep, is currently unknown.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Bioengineering, University of Washington, Seattle, WA, USA.
Dysregulation in aversive contextual processing is believed to affect several forms of psychopathology, including post-traumatic stress disorder (PTSD). The dentate gyrus (DG) is an important brain region in contextual discrimination and disambiguation of new experiences from prior memories. The DG also receives dense projections from the locus coeruleus (LC), the primary source of norepinephrine (NE) in the mammalian brain, which is active during stressful events.
View Article and Find Full Text PDFAging Cell
November 2024
Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea.
Alzheimer's disease (AD) is marked by the presence of intraneuronal neurofibrillary tangles (NFTs), which are primarily composed of hyperphosphorylated tau protein. The locus coeruleus (LC), the brain's main source of norepinephrine (NE), is one of the earliest regions to develop NFTs and experience neurodegeneration in AD. While LC-derived NE plays beneficial roles in cognition, emotion, locomotion, and the sleep-wake cycle, its impact on tau pathology is unclear.
View Article and Find Full Text PDFPeptides
December 2024
Department of Pathophysiology, Faculty of Medicine, University of Szeged, Hungary.
Corticotropin-releasing factor (CRF) activates the hypothalamic-pituitary-adrenal (HPA) axis and stimulates the noradrenergic neurotransmission, both processes being implicated in the pathogenesis of anxiety and depression, but the intimate site and mechanism of interaction of CRF and CRF-related peptides, named urocortins (UCN1, UCN2, UCN3), with noradrenaline (NA) was not fully elucidated yet. Therefore, the aim of the present study was to investigate the actions of CRF and urocortins on the NA released from the rat locus coeruleus (LC), the primary source of NA in the brain, and the participation of CRF receptors (CRF1 and CRF2) in these actions. In order to do so, male Wistar rats were used, their LC were isolated and dissected, and the LC slices were incubated with tritium-labelled NA, superfused and stimulated electrically.
View Article and Find Full Text PDFDysregulation in aversive contextual processing is believed to affect several forms of psychopathology, including post-traumatic stress disorder (PTSD). The dentate gyrus (DG) is an important brain region in contextual discrimination and disambiguation of new experiences from prior memories. The DG also receives dense projections from the locus coeruleus (LC), the primary source of norepinephrine (NE) in the mammalian brain, which is active during stressful events.
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