Glucose utilization and insulin binding in discrete brain areas of obese rats.

The present study was carried out to determine whether genetically obese Zucker rats present changes in brain glucose utilization and/or insulin binding when compared to their lean counterparts. Glucose utilization in the whole brain, determined by measurement of 2-deoxy(1-3H)glucose-6-phosphate, was significantly lower in obese than in lean Zucker rats. In order to precise the structure involved, we then used quantitative autoradiography methods after either (1-14C) 2-deoxyglucose injection or 125I-insulin incubation. In obese rats, local cerebral glucose utilization (LCGU) was significantly decreased in the external plexiform layer (-37%, p < 0.05), in the lateral hypothalamus (-23%, p < 0.05), and in the basolateral amygdaloid nucleus (-30%, p < 0.05). In contrast, no difference in specific insulin binding was found between the two genotypes in any of the areas studied. These results are consistent with some data showing a decrease of LCGU in hyperinsulinemic rats. All together, these data show perturbations of glucose utilization, particularly in structures linked to the regulation of body weight and food intake in obese Zucker rats.     

Immunocytochemical localization of the glucose transporter 2 (GLUT2) in the adult rat brain. II. Electron microscopic study

Following a former immunohistochemical study in the rat brain [Arluison, M., Quignon, M., Nguyen, P., Thorens, B., Leloup, C., Penicaud, L. Distribution and anatomical localization of the glucose transporter 2 (GLUT2) in the adult rat brain. I. Immunohistochemical study. J. Chem. Neuroanat., in press], we have analyzed the ultrastructural localization of GLUT2 in representative and/or critical areas of the forebrain and hindbrain. In agreement with previous results, we observe few oligodendrocyte and astrocyte cell bodies discretely labeled for GLUT2 in large myelinated fibre bundles and most brain areas examined, whereas the reactive glial processes are more numerous and often localized in the vicinity of nerve terminals and/or dendrites or dendritic spines forming synaptic contacts. Only some of them appear closely bound to unlabeled nerve cell bodies and dendrites. Furthermore, the nerve cell bodies prominently immunostained for GLUT2 are scarce in the brain nuclei examined, whereas the labeled dendrites and dendritic spines are relatively numerous and frequently engaged in synaptic junctions. In conformity with the observation of GLUT2-immunoreactive rings at the periphery of numerous nerve cell bodies in various brain areas (see previous paper), we report here that some neuronal perikarya of the dorsal endopiriform nucleus/perirhinal cortex exhibit some patches of immunostaining just below the plasma membrane. However, the presence of many GLUT2-immunoreactive nerve terminals and/or astrocyte processes, some of them being occasionally attached to nerve cell bodies and dendrites, could also explain the pericellular labeling observed. The results here reported support the idea that GLUT2 may be expressed by some cerebral neurones possibly involved in glucose sensing, as previously discussed. However, it is also possible that this transporter participate in the regulation of neurotransmitter release and, perhaps, in the release of glucose by glial cells.     

Outcomes of septorhinoplasty: a new approach comparing functional and aesthetic results

The aim of this study was to compare objective and subjective functional results of septorhinoplasty with subjective aesthetic results. A prospective study was performed including global and subgroup analyses (primary versus secondary septorhinoplasty). Three instruments were used to evaluate pre- and postoperative results: rhinomanometry for the objective functional analysis, the Nasal Symptom Obstruction Evaluation (NOSE) scale for the subjective functional analysis, and the Rhinoplasty Outcome Evaluation (ROE) scale for the subjective aesthetic analysis. A septorhinoplasty was performed in all cases. Thirty-five patients were included (22 female), of whom 74% underwent primary septorhinoplasty. The correlation between rhinomanometry, NOSE and ROE scores was analysed. Mean resistance of the two nasal cavities was 4.9 (standard deviation (SD) 8.35) sPa/ml before surgery and 0.8 (SD 0.7) sPa/ml after surgery. NOSE and ROE scores were, respectively, 72.5/100 (SD 21.7) and 7.5/24 (SD 11.3) before surgery and 22/100 (SD 20.6) and 18/24 (SD 17.3) after surgery. Patients complaining of postoperative nasal obstruction had a worse aesthetic evaluation. Correction of the functional disease appears to be as important as aesthetic correction. This study comparing functional and aesthetic results after septorhinoplasty could provide a basis for future studies.     

Glucose turnover rate in the lactating rat: effect of feeding a high fat diet

Feeding a high fat diet during lactation should reduce the competition for glucose utilization between the mammary gland and the other maternal tissues, because dietary fat is directly utilized for milk lipid synthesis. Glucose homeostasis was studied in nonlactating and lactating rats fed a high fat diet and compared with that in rats fed a high carbohydrate diet. In nonlactating rats fed a high fat diet, blood glucose concentration was slightly higher, whereas plasma insulin concentration was lower than in nonlactating rats fed a high carbohydrate diet. In the postabsorptive state, plasma free fatty acids and blood ketone bodies were not modified by the nature of the diet consumed. Glucose turnover rate and glucose metabolic clearance rate in the postabsorptive state in nonlactating rats fed a high carbohydrate diet were not different from those in rats fed a high fat diet [9.5 +/- 1.4 vs. 8.8 +/- 0.8 mg/(min X kg) and 8.9 +/- 1.2 vs. 7.9 +/- 0.7 mL/(min X kg)]. In lactating rats, blood glucose and ketone bodies, plasma insulin and free fatty acid concentrations were not affected in the postabsorptive state by the composition of the diet consumed. The glucose metabolic clearance rate in lactating rats fed the high carbohydrate diet was higher than that in nonlactating rats fed the same diet. However, the glucose metabolic clearance rate in lactating rats fed the high fat diet was not different from that in nonlactating rats fed the same diet.     

Distribution and anatomical localization of the glucose transporter 2 (GLUT2) in the adult rat brain--an immunohistochemical study

The aim of this work was to study the distribution and cellular localization of GLUT2 in the rat brain by light and electron microscopic immunohistochemistry, whereas our ultrastructural observations will be reported in a second paper. Confirming previous results, we show that GLUT2-immunoreactive profiles are present throughout the brain, especially in the limbic areas and related nuclei, whereas they appear most concentrated in the ventral and medial regions close to the midline. Using cresyl violet counterstaining and double immunohistochemical staining for glial or neuronal markers (GFAp, CAII and NeuN), we show that two limited populations of oligodendrocytes and astrocytes cell bodies and processes are immunoreactive for GLUT2, whereas a cross-reaction with GLUT1 cannot be ruled out. In addition, we report that the nerve cell bodies clearly immunostained for GLUT2 were scarce (although numerous in the dentate gyrus granular layer in particular), whereas the periphery of numerous nerve cells appeared labeled for this transporter. The latter were clustered in the dorsal endopiriform nucleus and neighboring temporal and perirhinal cortex, in the dorsal amygdaloid region, and in the paraventricular and reuniens thalamic nuclei, whereas they were only a few in the hypothalamus. Moreover, a group of GLUT2-immunoreactive nerve cell bodies was localized in the dorsal medulla oblongata while some large multipolar nerve cell bodies peripherally labeled for GLUT2 were scattered in the caudal ventral reticular formation. This anatomical localization of GLUT2 appears characteristic and different from that reported for the neuronal transporter GLUT3 and GLUT4. Indeed, the possibility that GLUT2 may be localized in the sub-plasmalemnal region of neurones and/or in afferent nerve fibres remains to be confirmed by ultrastructural observations. Because of the neuronal localization of GLUT2, and of its distribution relatively similar to glucokinase, it may be hypothesized that this transporter is, at least partially, involved in cerebral glucose sensing.     

Pattern of projections of group I afferents from elbow muscles to motoneurones supplying wrist muscles in man

Summary The pattern of projections of low threshold afferents from triceps and biceps brachii muscles onto motoneurones innervating muscles acting at the wrist was assessed by a reflex and a poststimulus time histogram (psth) technique. Activation of low-threshold afferents originating from elbow flexors or extensors resulted in an early, short-lasting inhibition of wrist flexor motoneurones (flexor carpi radialis, flexor carpi ulnaris). An inhibition was also found in the extensor carpi radialis (ECR) motoneurones after stimulation of low-threshold afferents from triceps. Evidence is presented that Ia fibres contribute to these effects. The inhibitory effects were found in all subjects, but they were constant in only 57% of the reflex experimental sessions and in 25% of the explored motor units. Stimulation of biceps low-threshold afferents was always ineffective on ECR motoneurones. No early facilitation was ever seen in motor nuclei innervating wrist muscles following stimulation of low threshold afferents from biceps and triceps. The pattern of transjoint projections of group I afferents from proximal to distal muscles and from distal to proximal ones (Cavallari and Katz 1989) is discussed in relation to that described in the cat forelimb.     

Sleep abnormalities and evoked potentials (VEP-BAER-SEP) in progressive supranuclear palsy

Few physiological studies have been performed in PSP. We studied: sleep abnormalities in 36 h polygraphic recordings; changes of PEV after pattern-reversal stimulation, of BAER and of short latency SEP after stimulation of the median nerve. The population was for the 1st group: 18 patients with full typical symptomatology, for the 2nd group: 7 patients with likely diagnose of PSP and for the 3rd group: 10 normal subjects as control sample. All patients of the 1st group had sleep abnormalities: decrease of total sleep time; decrease of the percentage of REM sleep; morphological abnormalities (specially horizontal ocular square wave jerks). Detail is given of the repartition of such abnormalities in the two groups of patients. There is no correlation between sleep abnormalities and the natural history of the disease. The PEV and BAER, abnormalities were present in 50% of the cases. The PES were always normal. The help that can be provided by electrophysiological studies in the diagnose of PSP is discussed (particularly in group 2).