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Retrograde Labelling (retrograde + labelling)
Selected AbstractsImpact of Sim1 gene dosage on the development of the paraventricular and supraoptic nuclei of the hypothalamusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2009Sabine Michaėlle Duplan Abstract The bHLH-PAS transcription SIM1 is required for the development of all neurons of the paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus. Mice with a loss of Sim1 die within a few days of birth, presumably because of the lack of a PVN and SON. In contrast, mice with a decrease of Sim1 survive, are hyperphagic and become obese. The mechanism by which Sim1 controls food intake remains unclear. Here we show that the development of specific PVN and SON cell types is sensitive to Sim1 gene dosage. Sim1 haploinsufficiency reduces the number of vasopressin (AVP)- and oxytocin-producing cells in the PVN by about 50 and 80%, respectively, but does not affect the development of Crh, Trh and Ss neurons. A decrease of AVP-producing cells increases the sensitivity of Sim1 heterozygous mice to chronic dehydration. Moreover, retrograde labelling showed a 70% reduction of PVN neurons projecting to the dorsal vagal complex, raising the possibility that a decrease of these axons contributes to the hyperphagia of Sim1+/, mice. Sim1 haploinsufficiency is thus associated with a decrease of several PVN/SON cell types, which has the potential of affecting distinct homeostatic processes. [source] The subcellular localization of GABAB receptor subunits in the rat substantia nigraEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2003Justin Boyes Abstract The inhibitory effects of GABA within the substantia nigra (SN) are mediated in part by metabotropic GABAB receptors. To better understand the mechanisms underlying these effects, we have examined the subcellular localization of the GABAB receptor subunits, GABAB1 and GABAB2, in SN neurons and afferents using pre-embedding immunocytochemistry combined with anterograde or retrograde labelling. In both the SN pars compacta (SNc) and pars reticulata (SNr), GABAB1 and GABAB2 showed overlapping, but distinct, patterns of immunolabelling. GABAB1 was more strongly expressed by putative dopaminergic neurons in the SNc than by SNr projection neurons, whereas GABAB2 was mainly expressed in the neuropil of both regions. Immunogold labelling for GABAB1 and GABAB2 was localized in presynaptic and postsynaptic elements throughout the SN. The majority of labelling was intracellular or was associated with extrasynaptic sites on the plasma membrane. In addition, labelling for both subunits was found on the presynaptic and postsynaptic membranes at symmetric, putative GABAergic synapses, including those formed by anterogradely labelled striatonigral and pallidonigral terminals. Labelling was also observed on the presynaptic membrane and at the edge of the postsynaptic density at asymmetric, putative excitatory synapses. Double immunolabelling, using the vesicular glutamate transporter 2, revealed the glutamatergic nature of many of the immunogold-labelled asymmetric synapses. The widespread distribution of GABAB subunits in the SNc and SNr suggests that GABAB -mediated effects in these regions are likely to be more complex than previously described, involving presynaptic autoreceptors and heteroreceptors, and postsynaptic receptors on different populations of SN neurons. [source] Prefrontal and agranular cingulate projections to the dorsal premotor areas F2 and F7 in the macaque monkeyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003Giuseppe Luppino Abstract The superior sector of Brodmann area 6 (dorsal premotor cortex, PMd) of the macaque monkey consists of a rostral and a caudal architectonic area referred to as F7 and F2, respectively. The aim of this study was to define the origin of prefrontal and agranular cingulate afferents to F7 and F2, in the light of functional and hodological evidence showing that these areas do not appear to be functionally homogeneous. Different sectors of F7 and F2 were injected with neural tracers in seven monkeys and the retrograde labelling was qualitatively and quantitatively analysed. The dorsorostral part of F7 (supplementary eye field, F7-SEF) was found to be a target of strong afferents from the frontal eye field (FEF), from the dorsolateral prefrontal regions located dorsally (DLPFd) and ventrally (DLPFv) to the principal sulcus and from cingulate areas 24a, 24b and 24c. In contrast, the remaining part of F7 (F7-non SEF) is only a target of the strong afferents from DLPFd. Finally, the ventrorostral part of F2 (F2vr), but not the F2 sector located around the superior precentral dimple (F2d), receives a minor, but significant, input from DLPFd and a relatively strong input from the cingulate gyrus (areas 24a and 24b) and area 24d. Present data provide strong hodological support in favour of the idea that areas F7 and F2 are formed by two functionally distinct sectors. [source] Circulating Angiotensin II Activates Neurones in Circumventricular Organs of the Lamina Terminalis That Project to the Bed Nucleus of the Stria TerminalisJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2003N. Sunn Abstract The aim of this study was to determine, in conscious rats, whether elevated concentrations of circulating angiotensin II activate neurones in both the subfornical organ and organum vasculosum of the lamina terminalis (OVLT) that project to the bed nucleus of the stria terminalis (BNST). The strategy employed was to colocalize retrogradely transported cholera toxin B subunit (CTB) from the BNST, with elevated levels of Fos protein in response to angiotensin II. Circulating angiotensin II concentrations were increased by either intravenous infusion of angiotensin II or subcutaneous injection of isoproterenol. Neurones exhibiting Fos in response to angiotensin II were present in the subfornical organ, predominantly in its central core but with some also seen in its peripheral aspect, the dorsal and lateral margins of the OVLT, the supraoptic nucleus and the parvo- and magnocellular divisions of the paraventricular nucleus. Fos-labelling was not apparent in control rats infused with isotonic saline intravenously or injected with either CTB or CTB conjugated to gold particles (CTB-gold) only. Of the neurones in the subfornical organ that were shown by retrograde labelling to project to BNST, approximately 50% expressed Fos in response to isoproterenol. This stimulus also increased Fos in 33% of neurones in the OVLT that project to BNST. Double-labelled neurones were concentrated in the central core of the subfornical organ and lateral margins of the OVLT in response to increased circulating angiotensin II resulting from isoproterenol treatment. These data support a role for circulating angiotensin II acting either directly or indirectly on neurones in subfornical organ and OVLT that project to the BNST and provide further evidence of functional regionalization within the subfornical organ and the OVLT. The function of these pathways is yet to be determined; however, a role in body fluid homeostasis is possible. [source] Retrograde tracing of enteric neuronal pathwaysNEUROGASTROENTEROLOGY & MOTILITY, Issue 1 2001S. J. H. Brookes Neuroanatomical tracing techniques, and retrograde labelling in particular, are widely used tools for the analysis of neuronal pathways in the central and peripheral nervous system. Over the last 10 years, these techniques have been used extensively to identify enteric neuronal pathways. In combination with multiple-labelling immunohistochemistry, quantitative data about the projections and neurochemical profile of many functional classes of cells have been acquired. These data have revealed a high degree of organization of the neuronal plexuses, even though the different classes of nerve cell bodies appear to be randomly assorted in ganglia. Each class of neurone has a predictable target, length and polarity of axonal projection, a particular combination of neurochemicals in its cell body and distinctive morphological characteristics. The combination of retrograde labelling with targeted intracellular recording has made it possible to target small populations of cells that would rarely be sampled during random impalements. These neuroanatomical techniques have also been applied successfully to human tissue and are gradually unravelling the complexity of the human enteric nervous system. [source] Synchronization of enteric neuronal firing during the murine colonic MMCTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Nick J. Spencer DiI (1,1,didodecyl-3,3,3,,3,-tetramethylindocarbecyanine perchlorate) retrograde labelling and intracellular electrophysiological techniques were used to investigate the mechanisms underlying the generation of spontaneously occurring colonic migrating myoelectric complexes (colonic MMCs) in mice. In isolated, intact, whole colonic preparations, simultaneous intracellular electrical recordings were made from pairs of circular muscle (CM) cells during colonic MMC activity in the presence of nifedipine (1,2 ,m). During the intervals between colonic MMCs, spontaneous inhibitory junction potentials (IJPs) were always present. The amplitudes of spontaneous IJPs were highly variable (range 1,20 mV) and occurred asynchronously in the two CM cells, when separated by 1 mm in the longitudinal axis. Colonic MMCs occurred every 151 ± 7 s in the CM and consisted of a repetitive discharge of cholinergic rapid oscillations in membrane potential (range: 1,20 mV) that were superimposed on a slow membrane depolarization (mean amplitude: 9.6 ± 0.5 mV; half-duration: 25.9 ± 0.7 s). During the rising (depolarizing) phase of each colonic MMC, cholinergic rapid oscillations occurred simultaneously in both CM cells, even when the two electrodes were separated by up to 15 mm along the longitudinal axis of the colon. Smaller amplitude oscillations (< 5 mV) showed poor temporal correlation between two CM cells, even at short electrode separation distances (i.e. < 1 mm in the longitudinal axis). When the two electrodes were separated by 20 mm, all cholinergic rapid oscillations and IJPs in the CM (regardless of amplitude) were rarely, if ever, coordinated in time during the colonic MMC. Cholinergic rapid oscillations were blocked by atropine (1 ,m) or tetrodotoxin (1 ,m). Slow waves were never recorded from any CM cells. DiI labelling showed that the maximum projection length of CM motor neurones and interneurones along the bowel was 2.8 mm and 13 mm, respectively. When recordings were made adjacent to either oral or anal cut ends of the colon, the inhibitory or excitatory phases of the colonic MMC were absent, respectively. In summary, during the colonic MMC, cholinergic rapid oscillations of similar amplitudes occur simultaneously in two CM cells separated by large distances (up to 15 mm). As this distance was found to be far greater than the projection length of any single CM motor neurone, we suggest that the generation of each discrete cholinergic rapid oscillation represents a discreet cholinergic excitatory junction potential (EJP) that involves the synaptic activation of many cholinergic motor neurones simultaneously, by synchronous firing in many myenteric interneurones. Our data also suggest that ascending excitatory and descending inhibitory nerve pathways interact and reinforce each other. [source] | |||||||||||||