Organization and cellular arrangement of two neurogenic regions in the adult ferret (Mustela putorius furo) brain

In the adult mammalian brain, two neurogenic regions have been characterized, the subventricular zone (SVZ) of the lateral ventricle (LV) and the subgranular zone (SGZ) of the dentate gyrus (DG). Despite remarkable knowledge of rodents, the detailed arrangement of neurogenic regions in most mammals is poorly understood. In this study, we used immunohistochemistry and cell type‐specific antibodies to investigate the organization of two germinal regions in the adult ferret, which belongs to the order Carnivora and is widely used as a model animal with a gyrencephalic brain. From the SVZ to the olfactory bulb, doublecortin‐positive cells tended to organize in chain‐like clusters, which are surrounded by a meshwork of astrocytes. This structure is homologous to the rostral migratory stream (RMS) described in other species. Different from rodents, the horizontal limb of the RMS emerges directly from the LV, and the anterior region of the LV extends rostrally and reached the olfactory bulb. In the DG, glial fibrillary acidic protein‐positive cells with long radial processes as well as doublecortin‐positive cells are oriented in the SGZ. In both regions, doublecortin‐positive cells showed characteristic morphology and were positive for polysialylated‐neural cell adhesion molecule, beta‐III tubulin, and lamin B1 (intense staining). Proliferating cells were detected in both regions using antibodies against proliferating cell nuclear antigen and phospho‐histone H3. These observations demonstrate that the two neurogenic regions in ferrets have a similar cellular composition as those of other mammalian species despite anatomical differences in the brain. J. Comp. Neurol. 522:1818–1838, 2014. © 2013 Wiley Periodicals, Inc.     

t(X;14)(p11.4;q32.33) is recurrent in marginal zone lymphoma and up-regulates GPR34

Genetic events underlying pathogenesis of nodal and extranodal marginal zone lymphoma are not completely understood. We report here a novel t(X;14)(p11.4;q32.33) identified in 4 lymphoma cases: 2 with a mucosa-associated lymphoid tissue lymphoma, one with a nodal marginal zone lymphoma and one with gastric diffuse large B-cell lymphoma. In all cases, lymphoma evolved from a previous auto-immune disorder. Fluorescence in situ hybridization and molecular studies showed that t(X;14), which is mediated by immunoglobulin heavy chain locus, targets the GPR34 gene at Xp11.4. Upregulation of GPR34 mRNA and aberrant expression of GPR34 protein has been demonstrated in 3 presented cases by quantitative real-time polymerase chain reaction and immunohistochemistry, respectively. GPR34 belongs to the largest family of cell surface molecules involved in signal transmission that play important roles in many physiological and pathological processes, including tumorigenesis. Although functional consequences of t(X;14) have not been identified, our studies suggest that up-regulated GPR34 activate neither nuclear factor-κB nor ELK-related tyrosine kinase.     

Identification of the slow conduction zone in a macroreentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia using electroanatomic mapping

Identification of the Slow Conduction Zone in a Macroreentry. Background: Although idiopathic left ventricular tachycardia (ILVT) has been shown to possess a slow conduction zone (SCZ), the details of the electrophysiological and anatomic aspects are still not well understood. Objective: We hypothesized that the SCZ can be identified using a 3‐dimensional electroanatomic (EA) mapping system. Methods : Ten patients with ILVT were mapped using a 3‐dimensional electroanatomic (EA) mapping system. After a 3‐dimensional endocardial geometry of the left ventricular was created, the conduction system with left Purkinje potential (PP) and the SCZ with diastolic potential (DP) in LV were mapped during sinus rhythm (SR) and ventricular tachycardia (VT) and were tagged as special landmarks in the geometry. The electrophysiological and anatomic aspects of it were investigated. Results: EA mapping during SR and VT was successfully performed in 7 patients, during VT in 3 patients. The SCZ with DPs located at the inferoposterior septum was found in 7 patients during SR and all patients during VT. The length of the SCZ was 25.2 ± 2.3 mm with conduction velocity 0.08 ± 0.01 m/s. No differences in these parameters were found between patients during SR and VT (P > 0.05). An area with PP was found within the posterior septum. A crossover junction area with DP and PP was found in 7 patients during SR and VT. This area with DP and PP during SR coincided or were in proximity to such area during VT and radiofrequency ablation targeting the site within the area abolished VT in all patients. Conclusion: The ILVT substrate within the junction area of the SCZ and the posterior fascicular can be identified and can be used to guide the ablation of ILVT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 840‐845, August 2012)     

Relaxin‐3 innervation of the intergeniculate leaflet of the rat thalamus – neuronal tract‐tracing and in vitro electrophysiological studies

Behavioural state is controlled by a range of neural systems that are sensitive to internal and external stimuli. The relaxin‐3 and relaxin family peptide receptor 3 (RXFP3) system has emerged as a putative ascending arousal network with putative involvement in regulation of stress responses, neuroendocrine control, feeding and metabolism, circadian activity and cognition. Relaxin‐3/γ‐aminobutyric acid neuron populations have been identified in the nucleus incertus, pontine raphe nucleus, periaqueductal grey (PAG) and an area dorsal to the substantia nigra. Relaxin‐3‐positive fibres/terminals densely innervate arousal‐related structures in the brainstem, hypothalamus and limbic forebrain, but the functional significance of the heterogeneous relaxin‐3 neuron distribution and its inputs to specific brain areas are unclear. Therefore, in this study, we used neuronal tract‐tracing and immunofluorescence staining to explore the source of the dense relaxin‐3 innervation of the intergeniculate leaflet (IGL) of the thalamus, a component of the neural circadian timing system. Confocal microscopy analysis revealed that relaxin‐3‐positive neurons retrogradely labelled from the IGL were predominantly present in the PAG and these neurons expressed corticotropin‐releasing factor receptor‐like immunoreactivity. Subsequently, whole‐cell patch‐clamp recordings revealed heterogeneous effects of RXFP3 activation in the IGL by the RXFP3 agonist, relaxin‐3 B‐chain/insulin‐like peptide‐5 A‐chain (R3/I5). Identified, neuropeptide Y‐positive IGL neurons, known to influence suprachiasmatic nucleus activity, were excited by R3/I5, whereas neurons of unidentified neurotransmitter content were either depolarized or displayed a decrease in action potential firing and/or membrane potential hyperpolarization. Our data identify a PAG to IGL relaxin‐3/RXFP3 pathway that might convey stress‐related information to key elements of the circadian system and influence behavioural state rhythmicity.     

The missing link between action and cognition

The study of the neural correlates of motor behaviour at the systems level has received increasing consideration in recent years. One emerging observation from this research is that neural regions typically associated with cognitive operations may also be recruited during the performance of motor tasks. This apparent convergence between action and cognition - domains that have most often been studied in isolation - becomes especially apparent when examining new complex motor skills such as those involving sequencing or coordination, and when taking into account external (environment-related) factors such as feedback availability and internal (performer-related) factors such as pathology. Neurally, overlap between action and cognition is prominent in frontal lobe areas linked to response selection and monitoring. Complex motor tasks are particularly suited to reveal the crucial link between action and cognition and the generic brain areas at the interface between these domains.     

Immunohistochemical changes related to ageing in the mouse hippocampus and subventricular zone

We investigated mainly immunohistochemical changes of nestin (a marker of neuroepithelial stem cells) and Ki-67 (a marker of proliferating cells) proteins related to ageing in the mouse hippocampus and subventricular zone (SVZ) using young adult (8 weeks old) and middle-aged (40 weeks old) mice. In the present study, no significant changes in neurons and astrocytes of the hippocampal CA1 sector were found in a middle-aged male ICR mice without severe senile weakness, as compared with young adult animals. In contrast, a significant change in the number of microglia was found in the hippocampal CA1 sector of the middle-aged mice. Furthermore, no significant changes in the number of nestin- and Ki-67-positive cells were observed in the hippocampal CA1 sector of the middle-aged mice. On the other hand, decreases in the number of nestin- and Ki-67-immunopositive cells were observed in the SVZ of the middle-aged mice. Furthermore, a migration of nestin- and Ki-67-immunoreactive cells in the corpus callosum was not observed in the SVZ of the middle-aged mice. In the dentate gyrus, significant decreases in the number of Ki-67-immunopositive cells were observed in the middle-aged mice. Our study also showed that nestin immunoreactivity was observed in both Ki-67-postive cells and astrocytes in the SVZ of young adult mice. These findings emphasize the need to recognize ageing as important factors in studies of microglia, which may help to clarify the role of glial cell structure and function during ageing processes. Furthermore, the present findings suggest that ageing processes may decrease neurogenesis in the corpus callosum, SVZ and dentate gyrus. Thus our present findings provide valuable information for the neurogenesis during ageing processes.