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Medullary Nuclei (medullary + nucleus)
Selected AbstractsAnatomic distribution of apoptosis in medulla oblongata of infants and adultsJOURNAL OF ANATOMY, Issue 2 2008A. Porzionato Abstract The aim of the study was to evaluate the distribution of apoptosis in the medullary nuclei of infants and adults who died of hypoxic-ischaemic injury. Apoptosis was studied by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) in brainstems from 22 adults (7 subjects who died of opiate intoxication, 15 who died of other hypoxic-ischaemic injury) and 10 infants. The nuclei examined included the hypoglossal, dorsal motor nucleus of the vagus, nucleus tractus solitarii, nucleus of the spinal trigeminal tract, cuneate, vestibular and inferior olivary nuclei. A morphometric analysis with the optical disector method was performed to calculate the mean percentages (± standard deviation) of TUNEL-positive neuronal and glial cells for the sample populations. Opiate deaths did not have higher apoptotic indices than other adult hypoxic-ischaemic deaths. Statistically significant differences between adults and infants were found in the neuronal apoptotic indices of the cuneate (28.2 ± 16.3% vs. 6.9 ± 8.7%), vestibular (24.7 ± 15.0% vs. 11.3 ± 11.4%), nucleus tractus solitarii (11.2 ± 11.2% vs. 2.3 ± 2.4%), dorsal motor nucleus of the vagus (6.8 ± 8.5% vs. 0.1 ± 0.2%) and hypoglossal (6.6 ± 5.7% vs. 0.1 ± 0.2%), indicating higher resistance of the neuronal populations of these infant medullary nuclei to terminal hypoxic-ischaemic injury or post-mortem changes. Differences in neuronal apoptotic index were also statistically significant among nuclei, suggesting differential characteristics of survival. Nuclei with higher neuronal apoptotic indices were the cuneate, vestibular and nucleus of the spinal trigeminal tract, which are located in the lateral medullary tegmentum and share the same vascular supply from the posterior inferior cerebellar artery. [source] Noradrenergic Nuclei that Receive Sensory Input During Mating and Project to the Ventromedial Hypothalamus Play a Role in Mating-Induced Pseudopregnancy in the Female RatJOURNAL OF NEUROENDOCRINOLOGY, Issue 10 2010L. E. Northrop In female rats, vaginal-cervical stimulation (VCS) received during mating induces bicircadian prolactin surges that are required for the maintenance of pregnancy or pseudopregnancy (PSP). The neural circuits that transmit VCS inputs to the brain have not been fully described, although mating stimulation is known to activate medullary noradrenergic cell groups that project to the forebrain. In response to VCS, these neurones release noradrenaline within the ventrolateral division of the ventromedial hypothalamus (VMHvl) and the posterodorsal medial amygdala (MePD), two forebrain sites that are implicated in the initiation of PSP. Noradrenaline receptor activation within the VMHvl is both necessary and sufficient for PSP induction, suggesting that noradrenaline acting within the VMHvl is particularly important in mediating the effects of VCS towards the establishment of PSP. We therefore investigated whether or not endogenous, VCS-induced noradrenaline release within the VMHvl is involved in PSP induction in the rat. Before the receipt of sufficient mating stimulation to induce PSP, a retrograde neurotoxin, dopamine-,-hydroxylase-saporin (DBH-SAP), was infused bilaterally into the either the VMHvl or the MePD to selectively destroy afferent noradrenergic nuclei in the brainstem. DBH-SAP infusions into the VMHvl lesioned mating-responsive noradrenergic neurones in A1 and A2 medullary nuclei and reduced the incidence of PSP by 50%. Infusions of DBH-SAP into the MePD had no effect on the subsequent induction of PSP. These results suggest that VCS is conveyed to mating-responsive forebrain areas by brainstem noradrenergic neurones, and that the activity of noradrenergic cells projecting to the VMHvl is involved in the induction of PSP. [source] Developmental changes in cell proliferation in the auditory midbrain of the bullfrog, Rana catesbeianaDEVELOPMENTAL NEUROBIOLOGY, Issue 11 2006Andrea Megela Simmons Abstract We examined patterns of cell proliferation in the auditory midbrain (torus semicircularis) of the bullfrog, Rana catesbeiana, over larval and early postmetamorphic development, by visualizing incorporation of 5-bromo-2,-deoxyuridine (BrdU) in cycling cells. At all developmental stages, BrdU-labeled cells were concentrated around the optic ventricle. BrdU-labeled cells also appeared within the torus semicircularis itself, in a stage-specific manner. The mitotic index, quantified as the percent of BrdU-positive cells outside the ventricular zone per total cells available for label, varied over larval development. Mitotic index was low in hatchling, early larval, and late larval stages, and increased significantly in deaf period, metamorphic climax, and froglet stages. Cell proliferation was higher in metamorphic climax than at other stages, suggesting increased cell proliferation in preparation for the transition from an aquatic to an amphibious existence. The change in mitotic index over development did not parallel the change in the total numbers of cells available for label. BrdU incorporation was additionally quantified by dot-blot assay, showing that BrdU is available for label up to 72 h postinjection. The pattern of change in cell proliferation in the torus semicircularis differs from that in the auditory medulla (dorsal medullary nucleus and superior olivary nucleus), suggesting that cell proliferation in these distinct auditory nuclei is mediated by different underlying mechanisms. © 2006 Wiley Periodicals, Inc. J Neurobiol 66: 1212,1224, 2006 [source] | ||||||||||