Clinical Neuroscience

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

JACQUES Epelbaum

MARCH 20, 2007

Clinical Neuroscience - 2007;60(03-04)

[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.]

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Clinical Neuroscience

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

ABRAHAMYAN S. Silva, MELIKSETYAN B. Irina, CHAVUSHYAN A. Vergine, ALOYAN L. Mery, SARKISSIAN S. John

[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.]

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.]

Clinical Neuroscience

[OXYGEN-GLUCOSE DEPRIVATION-INDUCED CHANGES IN ORGANOTYPIC CULTURES OF THE RAT HIPPOCAMPUS]

BALI Balázs, NAGY Zoltán, KOVÁCS J. Krisztina

[Introduction - (-)Deprenyl is an irreversible inhibitor of type B monoamine oxidase (MAO-B), which is now used for treatment of Parkinson’s or Alzheimer’s diseases. Evidence suggests that the neuroprotective effect of deprenyl may not be related exclusively to the inhibition of the enzyme MAO-B. Methods - To test the impact of deprenyl on ischemiainduced changes in vitro, we followed the time course of propidium iodide (PI) uptake as an indicator of neuronal cell death as well as the expression of apoptotic factors in organotypic hippocampal slice cultures exposed to oxygen- glucose deprivation (OGD) for 45 min. Results - The first signs of neuronal death were detected 2 hours after OGD and were extended to all subfields of the hippocampus by 24 hours post-injury. Presence of deprenyl (10-9 M) significantly delayed the cell death induced by the insult. Exposure of control cultures to deprenyl significantly increased the abundance of Bcl-2 and Bcl-xl mRNAs as revealed by RT-PCR. OGD resulted in an elevation of anti-apoptotic factors, while the expression of pro-apoptotic bax remained unchanged. Conclusion - These data suggest that deprenyl is neuroprotective in an in vitro model of ischemia. Although deprenyl upregulates the expression of Bcl-2 under basal conditions, its effect on anti-apoptotic factors is not significantly manifested during OGD.]

Clinical Neuroscience

[EFFECT OF LOCAL (INTRACEREBRAL AND INTRACEREBROVENTRICULAR) ADMINISTRATION OF TYROSINE HYDROXYLASE INHIBITOR ON THE NEUROENDOCRINE DOPAMINERGIC NEURONS AND PROLACTIN RELEASE]

BODNÁR Ibolya, HECHTL Dániel, SZÉKÁCS Dániel, OLÁH Márk, NAGY M. György

[Background and purpose - Hypothalamic dopamine (DA), the physiological regulator of pituitary prolactin (PRL) secretion, is synthesized in the neuroendocrine DAergic neurons that projects to the median eminence and the neurointermediate lobe of the pituitary gland. The rate-limiting step of DA biosynthesis is catalyzed by the phosphorylated, therefore activated, tyrosine hydroxylase (TH) that produces L-3,4-dihydroxy- phenylalanine from tyrosine. The aims of our present study were to investigate 1. the effect of local inhibition of the DA biosynthesis in the hypothalamic arcuate nucleus on PRL release, and to get 2. some information whether the phosphorylated TH is the target of enzyme inhibition or not. Methods - A TH inhibitor, α-methyl-p-tyrosine was injected either intracerebro-ventricularly or into the arcuate nucleus of freely moving rats and plasma PRL concentration was measured. Immunohistochemistry, using antibodies raised against to native as well as phosphorylated TH were used to compare their distributions in the arcuate nucleus-median eminence region. Results - Intracerebro-ventricular administration of α-methyl-p-tyrosine has no effect, unlike the intra-arcuatus injection of enzyme inhibitor resulted in a slight but significant elevation in plasma PRL. Parallel with this, the level of DA and DOPAC were reduced in the neurointermediate lobe while no change in norepinephrine concentration can be detected indicating a reduced biosynthesis of dopamine following TH inhibition. On the other hand, systematic application of the α-methyl-p-tyrosine that inhibits TH activity located in DA terminals of the median eminence and the neurointermediate lobe, resulted in the most significant elevation of PRL. Conclusion - Our results suggest that α-methyl-p-tyrosine administered close to the neuroendocrine DAergic neurons was able to inhibit only a small proportion of the TH. Moreover, it also indicate that the majority of the activated TH can be found in the axon terminals of DAergic neurons, therefore, the DA released into the pituitary portal circulation is synthesized at this site.]

Clinical Neuroscience

[USING BRAIN SLICE CULTURES OF MOUSE BRAIN TO ASSESS THE EFFECT OF GROWTH FACTORS ON DIFFERENTIATION OF BONE MARROW DERIVED STEM CELLS]

BRATINCSÁK András, LONYAI Anna, SHAHAR Tal, HANSEN Arne, TÓTH E. Zsuzsanna, MEZEY Éva

[Bone marrow derived stem cells (BMDSCs) have been reported to form neurons and supportive cells in the brain. We describe a technique that combines the simplicity of in vitro studies with many of the advantages of in vivo experiments. We cultured mouse brain slices, deposited GFPtagged BMDSCs evenly distributed on their surfaces, and then added test factors to the culture medium. Addition of both SDF-1 and EGF resulted in morphological changes of BMDSC and in the induction of islet-1, a marker of neuroepithelial progenitors. We conclude that organotypic tissue culture (OTC) may allow us to detect the effects of exogenous factors on the differentiation of BMDSCs (or any other type of stem cells) in an environment that may resemble the CNS after brain injury. Once such factors have been identified they could be evaluated for tissue regeneration in more complex, whole animal models.]

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Positive airway pressure normalizes glucose metabolism in obstructive sleep apnea independent of diabetes and obesity

KABELOĞLU Vasfiye, SENEL Benbir Gulçin, KARADENIZ Derya

The relationship among obstructive sleep apnea syndrome (OSAS), type 2 diabetes mellitus (DM2) and obesity is very complex and multi-directional. Obesity and increased visceral fat are important perpetuating factors for DM2 in patients with OSAS. On the other hand, OSAS itself leads to obesity by causing both leptin and insulin resistance as a consequence of activation of the sympathetic nervous system. Risk for developing DM2 further increases in patients with OSAS and obesity. Data regarding effects of positive airway pressure (PAP) therapy, gold standard treatment for OSAS, on glycemic control were inconsistent due to variability in duration of and adherence to PAP therapy. In our cohort study we investigated effects of PAP treatment on glucose metabolism in normal-weighted non-diabetic OSAS patients, in obese non-diabetic OSAS patients, and in OSAS patients with DM2. We prospectively analyzed 67 patients diagnosed with OSAS and documented to be effectively treated with PAP therapy for three months. Apnea-hypopnea index was highest in the diabetic group, being significantly higher than in the normal-weighted group (p=0.021). Mean HOMA values were significantly higher in obese (p=0.002) and diabetic group (p=0.001) than normal-weighted group; the differences were still significant after PAP therapy. HbA1c levels were significantly higher in diabetic group compared to those in normal-weighted (p=0.012) and obese (p=0.001) groups. After PAP treatment, decrease in HbA1c levels were significant in normal-weighted (p=0.008), obese (p=0.034), and diabetic (p=0.011) groups. There was no correlation with the change in HbA1c levels and age (p=0.212), BMI (p=0.322), AHI (p=0.098) or oxygen levels (p=0.122). Our study showed that treatment of OSAS by PAP therapy offers beneficial effect on glucose metabolism, not only in diabetic patients, but also in obese and normal-weighted OSAS patients. Although data regarding overall effects of PAP therapy on glycemic control present contradictory results in the literature, it should be emphasized that duration and adherence to PAP therapy were main determinants for beneficial outcome of treatment.

Lege Artis Medicinae

[The possibilities of pharmacological treatment of obesity]

PADOS Gyula, SIMONYI Gábor, BEDROS J. Róbert

[There have been attempts to treat obesity with medicines for nearly 100 years, since the discovery of ephedrine. For decades amphetamine derivates and agents stimulating or inhibiting the release of noradrenaline and dopamine have been applied. However, most of theses drugs had to be gradually withdrawn, due to their adverse effects on the cardiovascular and central nervous system or their sympaticotonic effect. Dexfenfluramine (Isolipan), which was introduced in the 90s, did not have such side effects, but it turned out to potentially cause valvular heart disease. Finally, sibutramin (Reductil) was introduced, which again had to be withdrawn in 2010 due to its hypertensive and cardiovascular side effects. After all, we were left without any appetite-suppressant drugs. Orlistat therapy, (Xenical 120 mg, alli 60 mg - OTC), which inhibits the absorption of fat, can eliminate only 30% of the consumed food’s fat content, at the price of gastrointestinal side effects. The latest result of research carried out wordwide is that in 2012 the FDA approved commercial distribution of the selective 5HT2/c serotonin agonist lorcaserin (Belviq), which enhances satiety, in the USA. Unfortunately, in 2013 the EMEA temporarily postponed the lauch of this drug, until certain adverse effects are excluded. For diabetic patients, the GLP-1 agonist exenatid and the GLP-analog liraglutid, which can also reduce body weight, are available in the form of injections.]

Clinical Oncology

[Obesity and cancer]

VALTINYI Dorottya

[The role of obesity in the development of cancer is well-known from ages. However, these days we witness the explosion-like increase of obesity, globally, but mainly in the economically advanced population, and, which is even more alarming, among youngsters. The prognosis of the obesity-related cancer is rather poor, therefore, the prevention, including the screening, have outstanding importance. Unfortunately, the participation of the obes persons, especially obes women, in these programs is very low. The diagnostics and therapies should consider the special features of obesity, which are related to the magnitude, distribution, composition of fatty tissue connected to the changes in pharmacokinetics. Moreover, the problems might be complicated with obesity-associated non-tumorous severe diseases (e.g. cardiovascular, diabetes type 2).This review covers different aspects of obesity-cancer relationships, with an emphasis on everyday oncology.]

Lege Artis Medicinae

[THE WORLDWIDE EPIDEMIC OF TYPE 2 DIABETES - CAUSES AND CONSEQUENCES]

JERMENDY György

[The prevalence of type 2 diabetes mellitus has recently dramatically increased worldwide. While many factors contribute to the startling data, including changes in the diagnostic criteria of glucose intolerance, increase of life expectancy, manifestation of diabetes at younger ages, and increased detection of unrecognized diabetes due to more efficient screening, the genuine, steep rise in the incidence of diabetes is explained by the increasing prevalence of obesity. Among the late complications of both diabetes and obesity, cardiovascular diseases are particularly important. Insulin resistance due to visceral obesity plays a central role in the pathomechanism of type 2 diabetes. In the prevention of both type 2 diabetes and obesity, non-pharmacological intervention such as life style changes should be considered first. Supplementary pharmacological treatment should target all cardiovascular risk factors.]

Hypertension and nephrology

[Deeper analysis of nebivolol effects]

KÉKES Ede

[Author presents the formation of nitric oxide as a largest vasodilator of human endothelium as well as the endothelial dysfunction a result of formation at adrenergic stimulus. He demonstrates in detail the benefits of selective β-1 blocker and β-3 adrenergic agonist nebivolol in the vascular system. This drug has also receptor independent effects. Complex effects of nebivolol causes vasodilation, inhibits oxidative stress and it is capable to neutralize the effects of free oxygen radicals and as a result the endothelial function will be better. Its clinical effects and the less wellknown beneficial properties are listed. The use of drug is discussed especially in hypertensives with smoking, COPD or PAD. The β-3 agonist effect provides positive reactions not only in the adipocytes and the myocardial tissue. but in the skeletal muscle as well: Increase in energy expenditure - as a compensatory mechanism - is increased in obesity and the glucose uptake + storage on skeletal muscle cells are increased in hyperglycemia. The insulin sensitivity will be better, leptin level is decreased, adiponectin level is increased by nebivolol. It is assumed this drug has antidiabetic and anti-obesity effects.]