Clinical Neuroscience

[POSTNATAL EXPRESSION PATTERN OF DOUBLECORTIN (DCX) IN SOME AREAS OF THE DEVELOPING BRAIN OF MOUSE]

TAKÁCS József, ROBERTA Zaninetti, VÍG Julianna, VASTAGH Csaba, HÁMORI József

MARCH 20, 2007

Clinical Neuroscience - 2007;60(03-04)

[We have investigated the spatio-temporal expression pattern of doublecortin (DCX) protein from postnatal day (P) 2 to postnatal day (P) 22 in the brain of developing mouse. We compared the expression of DCX in the rostral migratory stream (RMS) and dentate gyrus of the hippocampus (DG). Weak expression of DCX was detected in the RMS at P5, it became gradually stronger during the second postnatal week and reached its strongest expression by P18-P22. Moderate DCX immunostaining was present in the DG at P11, its marked expression - characteristic of newly generated neurons in the adult DG - appeared only after P22. Morphological and functional maturation was different in the RMS and DG, continuous neurogenesis appeared earlier in the RMS than in the DG.]

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Clinical Neuroscience

[Editor’s note]

RAJNA Péter

Clinical Neuroscience

[SALSOLINOL AND THE PERIPHERAL SYMPATHETIC ACTIVITY: THE EFFECTS OF HYPOPHYSECTOMY, ADRENALECTOMY AND ADRENAL MEDULLECTOMY]

SZÉKÁCS Dániel, BODNÁR Ibolya, NAGY M. György, FEKETE I.K. Márton

[The endogenous isoquinoline salsolinol (SALS) is a recently identified prolactin (PRL) releasing factor, a selective and potent stimulator of PRL secretion both in vivo and in vitro. SALS decreased the peripheral tissue dopamine (DA) level dose dependently, consequently increased the NE/DA ratio, indicating reduced release of newly formed norepinephrine (NE) from sympathetic terminals. The aim of our study was to investigate the effect of adrenal medullectomy (MEDX), adrenalectomy (ADX) and hypophysectomy (HYPOX) on the action of SALS on the PRL secretion, and on the catecholamine concentration of the selected sympathetically innervated peripheral tissues (atrium, spleen, etc). The experiments were done in male rats of 200-300 g body weight kept in air conditioned room with regular lighting. We used high-pressure liquid chromatography with electrochemical detection (HPLC-EC) for measurement of NE and DA concentrations, and radioimmunoassay for prolactin measurement. In MEDX as well as in ADX rats, SALS (25 mg/kg i.p.) was able to reduce DA level and increase the NE/DA ratio. The changes of prolactin secretion (increase by SALS) were not affected either by ADX or MEDX. Therefore the presence of the adrenal gland is not required for the changes of prolactin secretion, nor for the reduction of peripheral sympathetic activity induced by SALS. Investigating the possible effect of pituitary hormones on the peripheral sympathetic system, the action of SALS has been tested in HYPOX rats. We have found that the effect of SALS on peripheral sympathetic terminals is not affected by HYPOX, consequently the role of pituitary hormones in the effect of SALS on the peripheral catecholamine metabolism may be excluded.]

Clinical Neuroscience

[THE GHRELIN SYSTEM: PHYSIOPATHOLOGICAL INVOLVEMENT IN THE CONTROL OF BODY GROWTH AND ENERGY METABOLISM]

JACQUES Epelbaum

[This short review will summarize some recent findings on the physiopathology of the endogenous ghrelin/obestatin system by focussing on experimental studies aiming at blocking the effects of endogenous ghrelin and clinical studies investigating genotype/phenotype correlations concerning the genes encoding for ghrelin and its cognate receptor.]

Clinical Neuroscience

[IMMOBILIZATION INDUCED FOS EXPRESSION IN THE MEDIAL AND LATERAL HYPOTHALAMIC AREAS: A LIMITED RESPONSE OF HYPOCRETIN NEURONS]

KISS Alexander

[Induction of Fos, a proto-oncogene c-fos protein product, was immunohistochemically examined in the rat hypothalamic neurons 3 h after a single (1×120 min) or repeated (7×120 min) immobilization (IMO) stress. The aim of the present study was to reveal a possible parallelism in the cell activation between the medial and lateral hypothalamic neurons, especially between the stress responsive neurons in the hypothalamic paraventricular nucleus (PVN) and hypocretin (Hcrt) synthesizing neurons, i.e. suspected stress active neurons of the lateral hypothalamus. After IMO, the animals were perfused and their brains processed with immunohistochemistry for Fos or Fos/Hcrt proteins. Acute IMO elicited extensive Fos expression in both the examined areas. Excessive Fos expression was mainly seen in the PVN, while Hcrt neurons failed to show a broad response (appr. 5%) to single IMO. Clear occurrence of Fos signal was also seen in both hypothalamic areas of IMO-habituated rats. However, in these animals, in both areas examined, the number of Fos neurons was considerably suppressed, including the PVN. These results indicate that IMO is able to evoke a concurrent activation of Fos in many medial and lateral hypothalamic neurons. However, the scanty response of Hcrt neurons to acute IMO does not allow to assort them to a distinct IMO stress-responsive neuronal phenotypes of the brain.]

Clinical Neuroscience

[CENTRAL ATRIAL NATRIURETIC PEPTIDE IN DEHYDRATION]

BAHNER Udo, GEIGER Helmut, PALKOVITS Miklós, LENKEI Zsolt, LUFT C. Friedrich, HEIDLAND August

[To test the effect of dehydration on brain atrial natriuretic peptide (ANP) concentrations in areas important to salt appetite, water balance and cardiovascular regulation, we subjected rats to dehydration and rehydration and measured ANP concentration in 18 brain areas, as well as all relevant peripheral parameters. Water deprivation decreased body weight, blood pressure, urine volume, and plasma ANP, while it increased urine and plasma osmolality, angiotensin II, and vasopressin. ANP greatly increased in 17 and 18 brain areas (all cut cerebral cortex) by 24 h. Rehydration for 12 h corrected all changes evoked by dehydration, including elevated ANP levels in brain. We conclude that chronic dehydration results in increased ANP in brain areas important to salt appetite and water balance. These results support a role for ANP as a neuroregulatory substance that participates in salt and water balance.]

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[Regional cues and phenotypic responses during the ontogeny and postnatal development of splenic vasculatur]

BALOGH Péter

[Among structured peripheral lymphoid tissues in man and rodents, the spleen demonstrates the most extensive flexibility in functional activities, which is coupled with considerable tissue architecture adjustments during ontogeny and immune reactions. The sequential conversion of a primary lymphohemopoietic tissue into a major peripheral lymphoid organ (while participating in the post-myeloid period of primary B-lymphopoiesis and retaining the potential for myelopoiesis) is accompanied with the ordered segregation involving various non-hemopoietic components of architecture, including the endothelia of blood vessels. In this report we will survey the functional and structural aspects of heterogeneous endothelial cells lining the various splenic vascular beds, comprising the complex circulatory network of the spleen. These features will be correlated with the characteristics of those regulatory mechanisms that have recently been demonstrated to be responsible for the establishment and maintenance of the endothelial divergence during splenic vascular development, including crucial transcription factors, morphogenic regulatory ligands and receptors of the tumor necrosis factor/lymphotoxin (TNF/LT) family and others. The influence of these regulatory elements in mice appears to be highly restricted in terms of regional involvement of the vasculature, with cellular alterations of the marginal sinus representing the most frequently affected region. This complexity highlights the importance of this tissue region in both the formation of splenic vasculature and a possible source for white pulp stromal elements as well as its function as a major gateway for lymphocyte traffic.]

Clinical Neuroscience

[ACTIVATED SOMATOSTATIN TYPE 2 RECEPTORS TRAFFIC IN VIVO FROM DENDRITES TO THE TRANS-GOLGI NETWORK]

CSABA Zsolt, PASCAL Dournaud

[Background and purpose - Understanding the trafficking of G-protein-coupled receptors is of particular importance. In the central nervous system, although some Gprotein- coupled receptors were reported to internalize in vivo, little is known about their trafficking downstream of the endocytic event. Methods - The distribution of the major somatostatin receptor subtype, the sst2, was monitored in the hippocampus using immunofluorescence from 10 minutes to seven days after in vivo injection of the receptor agonist octreotide. Results - From 10 min to 3 h after agonist injection, intensity of receptor immunoreactivity gradually decreased in the molecular layer of dentate gyrus and in the strata oriens and radiatum of CA1. Concomitantly, in the granular and pyramidal layers, small spherical immunofluorescent particles became apparent in perikarya, shortly after agonist stimulation (i.e. 30 min, 60 min). After longer survival times (i.e. 3 h, 6 h, 24 h), immunolabeling was confined to larger, intensely-stained intracytoplasmic vesicles. From 48 h to 7 d after agonist injection, distribution and intensity of sst2 receptor immunoreactivity became similar to that of control animals. The sst2 receptor labeling extensively colocalized with TGN38 and syntaxin 6 after OCT injection. Colocalization with trans-Golgi markers was observed as soon as 1 h after OCT injection and still present 24 h after. By contrast, colocalization with the endoplasmic reticulum marker PDI and the cis-Golgi marker GM130 was never observed. Conclusions - Our results suggest that upon agonist stimulation, dendritic receptors are retrogradely transported to a trans-Golgi network domain enriched in the t-SNARE syntaxin-6 and TGN38 proteins before recycling.]

Clinical Neuroscience

[EFFECTS OF KETAMINE ON THE DEVELOPING CENTRAL NERVOUS SYSTEM]

VUTSKITS László, GASCON Eduardo, KISS Zoltán József

[Ketamine is a widely used drug in pediatric anesthesia practice, acting primarily through the blockade of the Nmethyl- D-aspartate (NMDA) type of glutamate receptors. A growing body of laboratory evidence, accumulated during the past few years, suggests that this drug could have potential adverse effects on the developing central nervous system. The goal of this short review is to give a brief synopsis of experimental work indicating ketamine-induced developmental neurotoxicity as well as to discuss potential limitations concerning extrapolation of these studies to clinical practice.]