Excitatory amino acid receptors in rat locus coeruleus

Summary The goal of this study was to investigate whether locus coeruleus neurons of the rat are sensitive to agonists of the different excitatory amino acid receptors. All experiments were performed on a midpontine rat slice preparation. Bath-applied l-glutamate, kainate, N-methyl-d-aspartate (NMDA) and quisqualate induced concentration-dependent activations of all neurons which were reflected in an increase of the neurons' mean discharge rate. The rank order of cell activation was kainate quisqualate > NMDA > l-glutamate. None of the agonists induced a bursting-type of discharge. The NMDA-receptor blocker dl-2-amino-5-phosphonovaleric acid (APV, 30 M) selectively antagonized the NMDA-induced increase in cell firing. Kynurenic acid (100 M) non-selectively attenuated the response to NMDA, kainate and quisqualate. Neither APV nor kynurenic acid per se had any effect on the spontaneous firing rate. If the Mg²⁺ concentration in the superfusion medium was lowered from 2 mM to nominally zero the response to NMDA was selectively increased. In conclusion, locus coeruleus neurons share with other neurons their sensitivity to agonists of all three types of excitatory amino acid receptors. However, in contrast to other neurons, they do not respond with a bursting type of discharge. Send offprint requests to H.-R. Olpe at the above address     

The sensitivity of cortical neurons to serotonin: Effect of chronic treatment with antidepressants,serotonin-uptake inhibitors and monoamine-oxidase-blocking drugs

Summary The sensitivity of rostral and cingulate cortical neurons to microiontophoretically administered serotonin (5-HT) was compared in groups of rats treated either acutely or chronically for different periods with various drugs. The drugs used were: desipramine (10 mg/kg), clomipramine (10 mg/kg), CGP 6085 (10 mg/kg), clorgyline (0.3 mg/kg), and deprenyl (1 mg/kg).Serotonin and, in some instances,-aminobutyric acid (GABA) were applied microiontophoretically over periods of 60 sec with various ejection currents to spontaneously active neurons in the rostral and cingulate cortex. Of all the compounds tested, only clorgyline produced a marked desensitization to 5-HT in both cortical areas. After prolonged treatment with all the other drugs, no change in the sensitivity to serotonin was observed. The desensitization to 5-HT induced by clorgyline developed after 4 to 10 days of treatment. The responsiveness of these cells to GABA was unchanged after chronic exposure to clorgyline.The present results are consistent with those biochemical studies showing that chronic treatment with 5-HT-uptake-blocking compounds has no effect on 5-HT-binding characteristics, as well as with the observation that prolonged treatment with the monoamine-oxidase A-type blocker clorgyline reduces the number of 5-HT-binding sites.     

Valproate enhances GABA-A mediated inhibition of locus coeruleus neurones in vitro

Summary It has previously been claimed that the anti-convulsant valproate acts by augmenting GABA-ergic transmission, however, the data supporting this claim is controversial. Here we demonstrate that valproate strongly and reversibly potentiates the depressant effects of the GABA-A receptor agonist muscimol on locus coeruleus neurones recorded extracellularly from a midpontine slice preparation of the rat. The depressant effect of muscimol (2 M) is augmented by bath applied valproate at concentrations of 50 M, 100 M and 1 mM. The effect of GABA is also potentiated by valproate. The potentiating effect is selective since the cell inhibition elicited by the GABA-B receptor agonist baclofen is not affected. Valproate on its own had no effect on the firing frequency. Send of print requests to H.-R. Olpe at the above address     

Fusarium Head Blight Control and Prevention of Mycotoxin Contamination in Wheat with Botanicals and Tannic Acid

Suspensions or solutions with 1% of Chinese galls (Galla chinensis, GC) or 1% of tannic acid (TA), inhibited germination of conidia or mycelium growth of Fusarium graminearum (FG) by 98%–100% or by 75%–80%, respectively, whereas dried bark from buckthorn (Frangula alnus, FA) showed no effect at this concentration. In climate chamber experiments where the wheat variety “Apogee” was artificially inoculated with FG and F. crookwellense (FCr) and treated with 5% suspensions of TA, GC and FA, the deoxynivalenol (DON) content in grains was reduced by 81%, 67% and 33%, respectively. In field experiments with two commercial wheat varieties and artificial or semi-natural inoculations, mean DON reductions of 66% (TA) and 58% (FA), respectively, were obtained. Antifungal toxicity can explain the high efficacies of TA and GC but not those of FA. The Fusarium head blight (FHB) and mycotoxin reducing effect of FA is probably due to elicitation of resistance in wheat plants. With semi-natural inoculation, a single FA application in the first half of the flowering period performed best. However, we assume that applications of FA at the end of ear emergence and a treatment, triggered by an infection period, with TA or GC during flowering, might perform better than synthetic fungicides.     

Effects of the peroxisomal proliferator-activated receptor-gamma agonist pioglitazone on renal and hormonal responses to salt in healthy men

Glitazones are used in the treatment of type 2 diabetes as efficient insulin sensitizers. They can, however, induce peripheral edema through an unknown mechanism in up to 18% of cases. In this double-blind, randomized, placebo-controlled, four-way, cross-over study, we examined the effects of a 6-wk administration of pioglitazone (45 mg daily) or placebo on the blood pressure, hormonal, and renal hemodynamic and tubular responses to a low (LS) and a high (HS) sodium diet in healthy volunteers. Pioglitazone had no effect on the systemic and renal hemodynamic responses to salt, except for an increase in daytime heart rate. Urinary sodium excretion and lithium clearance were lower with pioglitazone, particularly with the LS diet (P < 0.05), suggesting increased sodium reabsorption at the proximal tubule. Pioglitazone significantly increased plasma renin activity with the LS (P = 0.02) and HS (P = 0.03) diets. Similar trends were observed with aldosterone. Atrial natriuretic levels did not change with pioglitazone. Body weight increased with pioglitazone in most subjects. Pioglitazone stimulates plasma renin activity and favors sodium retention and weight gain in healthy volunteers. These effects could contribute to the development of edema in some subjects treated with glitazones.     

Adolescent idiopathic scoliosis – to operate or not? A debate article

Adolescent idiopathic scoliosis (AIS) represents a rare condition with a potentially detrimental impact on young patients. Despite vast clinical research and published treatment guidelines and algorithms, the optimal therapeutic choice for these patients remains highly controversial. While advocates of early surgery emphasize the benefits of surgical deformity correction with regard to physical and psychological outcome, the opponents base their arguments on the high risk of complications and a lack of documented subjective long-term outcome. In the present paper, the authors were invited to debate the opposite positions of "pro" versus "contra" surgical treatment of AIS, based on the currently available evidence and published guidelines.     

Neural control of appetite: cross-talk between homeostatic and non-homeostatic systems

The new lifestyle in the modern world is causing a rapid increase in the prevalence of obesity and associated health problems. Increased availability of palatable and energy dense foods, combined with a lack of physical activity overpower a homeostatic regulatory system that evolved to survive periods of famine rather than preventing obesity. Environmental and lifestyle factors influence energy balance mainly through their impact on cortico-limbic brain structures dealing with reward, cognitive, and social aspects of food intake and voluntary physical activity. To find new behavioral and pharmacological treatments of obesity, it will be important to identify the specific pathways that link these externally driven processes with the homeostatic regulatory system.     

The practical use of surface topography: following up patients with Scheuermann's disease

PURPOSE: The purpose of this study was to answer the question of whether a course of in-patient rehabilitation of 4-6 weeks results in a significant postural improvement in patients with a structural kyphosis. Since all clinical measuring parameters are liable to high margins of error and measuring the surface with the formetric system has shown high reliability in previous studies, this system has been used to evaluate the results of rehabilitation in patients with Scheuermann's disease. MATERIALS AND METHOD: A pre-/post-interventional study was undertaken including only patients (n = 136) with Scheuermann's kyphosis and a thoracic curve pattern. 62 female patients with an average age of 19 years and 74 male patients of average age 20 years were diagnosed with the Formetric system before an in-patient rehabilitation programme of 4-6 weeks. For this study, the maximal kyphotic angle was evaluated. RESULTS: The average kyphotic angle as measured by the surface topography system before inpatient rehabilitation was 60.7 degrees (SD 11.2) and after 54.9 degrees (SD 12.1) for the whole sample of 136 patients. The improvements where highly significant in the t-test. In the cases of the female patients, the maximal kyphotic angle decreased from 62 degrees to nearly 54 degrees; in the cases of the male patients it had decreased from 60 degrees to nearly 55 degrees by the end of the programme. DISCUSSION: After the in-patient treatment, the kyphotic angle decreased very significantly. The range of change was far greater than the margin of error and, thus, the following conclusion may be reached: In-patient rehabilitation with an intensive programme of treatment may result in a correction of structural kyphoses in which there are clear signs of Scheuermann's disease. Consequently in-patient rehabilitation is recommended for adolescents in cases of Scheuermann's kyphoses.     

Scavenger capacity of follicular fluid,decidua and culture medium with regard to assisted reproduction: an in vitro study using electron paramagnetic resonance spectroscopy

The natural scavenger capacity of follicular fluid of women pre-treated for in vitro fertilization (IVF) embryo transfer, Ham's F10 nutrient mixture used for oocyte culture and endometrium samples were studied in a hydroxyl free radical generating system, using electron paramagnetic resonance (EPR) spectroscopy. The EPR signals appearing after the addition of samples to the reaction mixture show a diversely decreasing production of phenyl-tertier-butylnitrone spin adducts. Presumably, the follicular fluid and endometrium samples contain active factors which function as radical scavengers. The findings suggest that appropriate augmentative antioxidative therapy might be advised for IVF patients.