Clinical Neuroscience

[Dedication]

PALKOVITS Miklós

MARCH 20, 2007

Clinical Neuroscience - 2007;60(03-04)

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Clinical Neuroscience

[Editor’s note]

RAJNA Péter

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

[CHARACTERIZATION OF SPECIFIC SUCCINATE BINDING SITE IN BRAIN SYNAPTIC MEMBRANES]

MOLNÁR Tünde, KÚTINÉ Fekete Erzsébet, KARDOS Julianna, PALKOVITS Miklós

[A synaptic receptor for gamma-hydroxybutyric acid (GHB) - a naturally occuring metabolite of succinic acid1 - interacting succinate has been disclosed in rat and human nucleus accumbens (NA) subcellular fractions2, but the molecular properties of this recognition site were not characterised. To address the presumed recognition site for succinate, the pharmacological profile of [3H]succinate binding to synaptic membranes prepared from rat forebrain and human NA samples has been investigated. Specific [3H]succinate binding sites in the human NA synaptic membrane fraction showed a strong pH-dependence and were characterized by binding of succinate (IC50,SUCC=2.9±0.6 µM), GHB (IC50,GHB=2.1±1.3 µM) and gap junction blocker carbenoxolone (IC50,CBX=7.1±5.8 µM). A similar [3H]succinate binding profile was found in rat forebrain synaptic membrane fractions. We conclude the existence of a pHo-dependent synaptic membrane binding site for the intermediary metabolite succinate. The pharmacological properties of this recognition site may possibly suggest the existence of a hemichannel-like target protein for succinate.]

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

[PROTECTIVE ACTION OF SNAKE VENOM NAJA NAJA OXIANA AT SPINAL CORD HEMISECTION]

SILVA S. Abrahamyan, IRINA B. Meliksetyan, VERGINE A. Chavushyan, MERY L. Aloyan, JOHN S. Sarkissian

[Based on data accumulated regarding the neuroprotective action of Proline-Rich-Peptide-1 (PRP-1, a fragment of neurophysin vasopressin associated hypothalamic glycoprotein consisting of 15 amino acid residues) on neurons survival and axons regeneration and taking into the account that LVV-Hemorphin-7 (LVV-H7, an opioid peptide, widely distributed in different cell types of various tissues of intact rats, including those of the nervous and immune systems) derived from the proteolitic processing of hemoglobin in response to adverse environmental and physiological conditions, possesses the anti-stressor properties, we used histochemistry, immunohistochemistry and electrophysiology to investigate the putative neuroprotective action of Central Asian Cobra Naja naja oxiana snake venom (NOX) on trauma-injured rats. ABC immunohistochemical method and histochemical method on detection of Ca2+- dependent acid phosphatase activity were used for the morpho-functional study. By recording the electrical activity of the signals from the single neurons in and below the SC injury place, NOX venom has been shown to result in the complete restoration of hypothalamic-spinal projections originated from ipsi- and contra-lateral PVN and SON to neurons of SC lumbar part. NOX prevented the scar formation, well observed two months after SC injury in the control rats, resulted in the regeneration of nerve fibers growing through the trauma region, survival of the PRP-1- and LVV-H7-immunoreactive (Ir) neurons, and increase of the PRP-1- and LVV-H7-Ir nerve fibers and astrocytes in the SC lesion region. NOX was suggested to exert the neuroprotective effect, involving the PRP-1 and LVV-H7 in the underlying mechanism of neuronal recovery.]

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