The distribution of the projection from the hippocampal formation to the nucleus accumbens in the rat: an anterograde- and retrograde-horseradish peroxidase study

We have investigated the distribution and organization of the projection from the hippocampal formation to the nucleus accumbens in the rat. In the first experiments, horseradish peroxidase was injected into the fimbria fornicis. This procedure resulted in massive anterograde labelling of fornix fibers, and enabled the hippocampo--accumbens projection to be charted in detail. Labelled fornix fibers are distributed to the entire length of the nucleus accumbens and do not spread lateral to the anterior limb of the anterior commissure, that is, the projection is limited to the medial nucleus accumbens. Terminal labelling is particularly dense in a caudal dorsomedial sector of accumbens immediately adjacent to the septum. In the second part of the study, horseradish peroxidase was microelectrophoretically injected into the nucleus accumbens, in order to confirm the findings from the anterograde experiments. When the deposit was localized within the fornix distribution field, as indicated by the first experiment, retrogradely-labelled cells were observed in the subiculum, prosubiculum, and to a lesser extent, in hippocampal field CAI. When the deposit was located outside of the fornix distribution field, no hippocampal labelling was noted. The topography of the projection, suggested by the retrograde labelling experiments, is discussed. The findings confirm earlier reports of such a projection from the hippocampal formation to the nucleus accumbens, and with the use of a relatively novel anterograde-horseradish peroxidase technique, provide a picture of fiber labelling representing the entire field of origin of the fornix system. The striatal projection field of this pathway is discussed in relation to other striatal afferents, with particular emphasis on limbic afferentation of the striatum. Finally, the so-called 'hippocampal district' of striatum is discussed with respect to its neurotransmitter composition, as well as its functional importance regarding limbic system influence on central motor mechanisms.     

The amygdalostriatal projection in the rat—an anatomical study by anterograde and retrograde tracing methods

Tritiated leucine and proline injected into the amygdaloid complex was found to label a voluminous amygdalostriatal fiber system which is distributed to all parts of the striatum except an antero-dorsolateral striatal sector. The connection is established by way of the longitudinal association bundle as well as the stria terminalis, and includes a modest (10–15%), symmetrically distributed contralateral component conveyed by the anterior commissure. Both autoradiographic findings and subsequent observations in retrograde cell-labelling (horseradish peroxidase) material indicate that the amygdalostriatal projection originates mainly from the nucleus basalis lateralis amygdalae, in much lesser volume from the nucleus basalis medialis, and minimally from the nucleus lateralis amygdalae; no other contributing amygdaloid cell group could be identified.A comparison of the present findings with earlier reports indicates that the amygdalostriatal projection widely overlaps the striatal projections from the ventral tegmental area, the mesencephalic raphe nuclei and the prefrontal cortex. Like the amygdalostriatal projection, these striatal afferents largely or entirely avoid the antero-dorsolateral striatal quadrant, which thus appears to be the striatal region most sparsely innervated by afferents originating from structures within the circuitry of the limbic system. Findings in additional autoradiographic material identify this relatively non-limbic striatal quadrant as the main region of distribution of the corticostriatal projection from the sensorimotor cortex.     

Extra-hypothalamic afferent inputs to the supraoptic nucleus area of the rat as determined by retrograde and anterograde tracing techniques

To detect neuronal cell bodies whose axon projects to the hypothalamic supraoptic nucleus, small volumes (10-50 nl) of 30% horseradish peroxidase or 2% fast blue solutions were pressure-injected into the area of one supraoptic nucleus of rats. Both dorsal and ventral approaches to the nucleus were used. In animals where the injection site extended beyond the limits of the supraoptic nucleus, retrogradely labelled cell bodies were found in many areas of the brain, mainly in the septum, the nucleus of the diagonal band of Broca and ventral subiculum in the limbic system; the dorsal raphe nucleus, the locus coeruleus, the nucleus of the dorsal tegmentum, the dorsal parabrachial nucleus, the nucleus of the solitary tract and the catecholaminergic A1 region in the brain stem; in the subfornical organ and the organum vasculosum of the lamina terminalis, as well as in the median preoptic nucleus. In contrast, when the site of injection was apparently restricted to the supraoptic nucleus, labelling was only clearcut in the two circumventricular organs, the median preoptic nucleus, the nucleus of the solitary tract and the A1 region. Injections of wheat germ agglutinin coupled with horseradish peroxidase (60-80 nl of a 2.5% solution) made in the septum and in the ventral subiculum anterogradely labelled fibers coursing in an area immediately adjacent to the supraoptic nucleus but not within it. In contrast, labelling within the nucleus was found following anterograde transport of tracer deposited in the A1 region and in an area that includes the nucleus of the solitary tract. Neurones located in the perinuclear area were densely labelled by small injections into the supraoptic nucleus; they may represent a relay station for some afferent inputs to the supraoptic nucleus. These results suggest that the supraoptic nucleus is influenced by the same brain areas which project to its companion within the magnocellular system, the paraventricular nucleus.     

Immunocytochemical localization of a granuliberin-like peptide in Rana pipiens brain

The histamine-releasing peptide “granuliberin”, originally isolated from the skin of Rana rugosa, was localized by immunofluorescence within nerve cell bodies and fibers in the brain of Rana pipiens. The granuliberin-positive neurons were characterized ultrastructurally by electron microscopic observation of ultrathin sections stained either with immunoperoxidase or with conventional stains. Granuliberin-positive nerve cell bodies were seen throughout the hypothalamus, from the suprachiasmatic area rostrally to the full length of the periinfundibular grey matter caudally. Similarly positive nerve fibers were localized in the hypothalamus radiating upwards to the optic vesicles in the midbrain, extending through the preoptic area into the subpallium in the forebrain, and throughout the white matter surrounding the floor and lateral walls of the fourth ventricle in the brainstem. The granuliberin-positive nerve cells showed the presence of variable numbers of small cytoplasmic neurosecretory granules. Possessing an electron dense elongated core, and measuring 250–350 nm in their largest diameter. The functional significance of a granuliberin-like peptide in neurons of the frog brain is not known.     

Detection of radiolabelled bone marrow cells bearing surface ace immunoglobulins by combined autoradiography and immunoperoxidase

A method is described for the simultaneous detection of radiolabelled bone marrow cells bearing surface immunoglobulins by combined autoradiography and immunoperoxidase. Bone marrow cells from normal CBA mice prelabelled in vivo with ¹²⁵IUDR or exposed in vitro to [³H]thymidine were incubated with rabbit anti-mouse immunoglobulins under capping conditions, washed, cytocentrifuged and treated with methanol and hydrogen peroxide to destroy endogenous peroxidase. Cells were then covered with peroxidase-conjugated goat anti-rabbit immunoglobulins, washed, treated with diaminobenzidine a and hydrogen peroxide and finally covered with autoradiographic stripping film and exposed for different times. Peroxidase-positive cells were typically capped and those radiolabelled had autoradiographic silver grains overlying the nucleus.     

The regional distribution and cellular localization of iron in the rat brain

The regional distribution and cellular localization of iron throughout the rat brain was determined with iron histochemistry. Densitometry was used to measure the intensity of stain of 51 iron-concentrating sites. Among the areas of highest iron content are the circumventricular organs, islands of Calleja, globus pallidus, ventral pallidum, substantia nigra pars reticulata, interpeduncular nucleus, dentate nucleus, and interpositus nucleus. Iron occurs most commonly in oligodendrocytes and in the fibrous network of the neuropil, but is also found in the interstitial spaces of circumventricular organs and in the tanycytes of the organum vasculosum of the lamina terminalis, median eminence, and walls of the third ventricle. In diverse areas throughout the brain—among them, the islands of Calleja, dentate gyrus of the hippocampal formation, lateral septal nucleus, and central amygdala—iron is found in association with the perikarya and neuronal processes of nerve cells.The overlapping distribution patterns of iron and γ-aminobutyric acid, enkephalin, and luteinizing hormone-releasing hormone suggest that the distribution of iron is related to its association with the metabolism of one or more neurotransmitters or neuroactive compounds.     

DAB2IP基因沉默引起膀胱癌细胞辐射耐受与化疗抵抗

目的 观察DAB2IP基因对膀胱癌细胞放化疗敏感性的影响.方法 RNA干扰建立DAB2IP表达抑制的膀胱癌细胞,克隆形成实验比较不同DAB2IP表达的细胞对射线放射敏感性的差异,噻唑蓝方法检测不同DAB2IP表达的细胞对常用化疗药物敏感性的变化.结果 DAB2IP基因沉默造成细胞对射线与化疗药物均出现耐受.结论 DAB2IP可能用作预测膀胱癌患者放射或化学治疗预后的分子标志物.     

Application of Pop-off Method to Bone Marrow and Peripheral Blood Specimens for Purposes of Electron Microscopy

In this paper, we describe a pop-off method applicable to the hematological field. Bone marrow or peripheral blood specimens from patients were placed on a clean glass slide and fixed immediately in 2% glutaraldehyde solution for 10 minutes. For the DAB reaction, the slide was immersed in the DAB reagent for 30 minutes, and post fixed with 1 % OsO₄ solution for 1 hour. Specimens on the slide were washed with buffer solution, dehydrated and polymerized directly on the slide. A gelatin capsule filled with Epon mixed monomer was then reversed over the specimen. After polymerization was completed, the specimen was popped off from the slide to the capsule and trimmed carefully to prepare for ultrathin sectioning. This method allows the entire sequence of tissue preparation to be carried out on the slide, from fixation to embedding, and even, especially in scanty specimens, including the DAB reaction. Electron microscopic findings in specimens prepared by this technique show excellent preservation and the absence of specific artifacts.     

Involvement of epigenetics and microRNA-29b in the urethane induced inception and establishment of mouse lung tumors

Epigenetic changes are correlated with tumor development showing aberrations in DNA methylation and histone modifications. To find the early changes, we evaluated the epigenetic events from early to late stage of the urethane induced lung tumor development in mouse model and tried to correlate the molecular events with the progression of tumor. We addressed the hypothesis by examining the tumor development, status of DNMTs, HDACs and MBDs, DNA methylation and expression of microRNA-29b during 1 to 36 weeks after urethane exposure that included the period before and after the tumor appearance. Tumors did not appear after 1 or 4 weeks but well defined tumors appeared after 12 weeks and larger tumors appeared at 36 weeks which was prevented by IP6. DNMT1, DNMT3a and DNMT3b were upregulated after urethane exposure at the time of no tumor till the tumor developed and showed its upregulated functional activity. DNMTs are shown to be the targets of microRNA-29b and we showed that microRNA-29b was downregulated in the line of DNMT upregulation. HDAC, the histone modifier, also showed progressive upregulation. Periodic increase in methyl binding proteins, MBD2, supported the expression of gene silencing pathways in terms of the downregulation of tumor suppressor genes, p16 and MLH1. All these molecular alterations were protected in the presence of IP6. Our results showed that the key steps of epigenetics, DNMTs, mir29b, and HDAC1, are altered both before and after the development of tumors.