Food intake and peripheral factors after recovery from insulin-induced hypoglycemia

Rats increased food intake after plasma glucose returned to normal in the wake of an insulin-induced hypoglycemic episode. Whereas increased eating 6-8 h after insulin occurred only when plasma glucose levels fell below 70 mg/dl, intakes were not related to the degree of prior hypoglycemia. Administration of glucose in the first 3 h after insulin prevented increased eating, whereas glucose given 4-6 h after insulin was less effective. Intravenous infusions of fructose given in the first 3 h after insulin injection prevented increased food intake in normal but not hepatic-vagotomized rats. Determination of various metabolic variables in parallel experiments showed that insulin treatment resulted in changes in peripheral metabolism, which persisted at the time feeding tests were conducted, and that administration of glucose or fructose tended to reverse these changes. The results suggest that increased food intake after recovery from hypoglycemia is associated with peripheral metabolic consequences of ongoing or previous counterregulatory responses which occur during hypoglycemia and that alterations in hepatic metabolism are sufficient to inhibit this insulin-induced eating.     

Tonotopic bands produced by tones commenced long after 2-deoxyglucose injection

Presentation of two different tones at two different time periods each under two different types (¹⁴C or ³H) of 2-deoxyglucose (2-DG) produced two bands of labelling in the inferior colliculus (IC) of a guinea pig. Filtering tests revealed that both bands were produced by only one of the labels (¹⁴C). Four guinea pigs were given one injection of 2-DG and then stimulated with two tones, each presented at different time periods. Two bands of labelling were produced in IC, with one band being produced by tones given 55–90 min after injection. The implications of this long lasting effect of 2-DG are discussed for the general 2-DG model and for sequential double labelling experiments.     

Modulation of the feeding response to peripheral insulin, 2-deoxyglucose or 3-O-methyl glucose injection

The effects of circadian rhythm, delayed access to food, bilateral subdiaphragmatic vagotomy and bilateral adrenal medullectomy were examined. Like normal insulin injected subcutaneously, 2-deoxy-D-glucose injected intraperitoneally induces feeding in sated rats by night as well as by day. The unmetabolized glucose analogue 3-O-methyl-D-glucopyranose detectably increases feeding by day. On delayed return of food after 2-deoxyglucose injection into mildly deprived rats, feeding is at first inhibited and then facilitated. Vagotomy but not medullectomy interferes with 2-deoxyglucose-induced feeding, whereas medullectomy but not vagotomy interferes with insulin-induced feeding, when dosages near the optima for intact rats are used. However, when low doses are given, neither surgically induced deficit is evident.     

Freeze-mount microautoradiographic study in the mouse hippocampus after intravenous injection of tritiated 2-deoxyglucose and glucose

Differences in the uptake of tracers from radioactive 2-deoxyglucose ([1,2-3H] and [2,6-3H]), and glucose ([1-3H], [3-3H]) into hippocampal regions were investigated by freeze-mount microautoradiography after 45 min for 2-deoxyglucose, and after 15 and 45 min for glucose. Silver grains were assessed quantitatively by an image analyser. (1) The radioactivity (silver grains/mm2) in the stratum lacunosum-moleculare of Ammon's horn from 2-deoxyglucose autoradiograms was significantly higher than that in other hippocampal regions (P less than 0.01), while lowest in the hilus fascia dentata (P less than 0.01). (2) Autoradiograms of [1-3H]glucose and 15 min of [3-3H]glucose showed the radioactivity in the dentate molecular layer to be significantly higher than that in other regions, excepting the stratum lacunosummoleculare (P less than 0.05). (3) The 2-deoxyglucose and 45-min glucose autoradiograms showed intensely labeled perikarya of pyramidal cells in the CA3a sector. (4) Radioactivity in the dentate granular layer from the 45-min autoradiogram of [3-3H]glucose was significantly higher than that in the molecular layer (P less than 0.05). The results imply that the metabolic fate of glucose, i.e. whether it is mainly used for energy production or amino acid synthesis, depends on each structure of the hippocampus.     

Central control of peripheral circulating somatostatin in dogs: effect of 2-deoxyglucose

Circulating plasma somatostatin concentrations are known to fluctuate in response to nutrients and hormones. However, little is known about neural or central nervous system (CNS) control of somatostatin secretion. To test whether peripheral circulating somatostatin is influenced by a central stimulus, 2-deoxyglucose (37.5 mg/kg) was infused into a lateral cerebral ventricle of six conscious dogs over a period of 15 min. Plasma somatostatin levels rose from a base line of 105 +/- 6 pg/ml (mean +/- SE) to a peak of 154 +/- 10 pg/ml (P less than 0.005) at 30 min after the onset of the infusion. Somatostatin levels were still significantly elevated (P less than 0.025) at 60 min (119 +/- 6 pg/ml) and thereafter gradually returned toward base line. Plasma glucose and glucagon levels increased in response to intraventricular 2-deoxyglucose. Glucose concentrations rose from 105 +/- 5 mg/dl to peak at 203 +/- 16 mg/dl (P less than 0.005) at 80 min and remained elevated to 120 min. The concentration of plasma glucagon increased from 41 +/- 6 to 92 +/- 18 pg/ml at 60 min (P less than 0.05) and then declined. In marked contrast to intraventricular 2-deoxyglucose, similar concentrations of 2-deoxyglucose administered intravenously (n = 4) resulted in a slight fall in plasma somatostatin. Intraventricular saline did not result in a change in plasma somatostatin. It is concluded that peripheral circulating somatostatin may be susceptible to central nervous system control.     

Feeding and arteriovenous differences of blood glucose in rats after injection with 2-deoxy-D-glucose and after food deprivation

Normal and adrenally demedullated rats injected with approximately 200 mg per kg of 2-deoxy-D-glucose (2-DG) ate just over 1 g more food than controls in 3-hr eating tests. This eating response was unaffected by delaying access to food by 30 min. Injections of 6-deoxy-D-glucose also increased eating, but less than 2-DG. Rats deprived of food for 24 hr ate about twice as much food as those injected with 2-DG. Drinking was increased following 2-DG in some but not all the experiments. Ether anaesthesia at the time of the injection depressed subsequent drinking but not eating. Arteriovenous differences of blood glucose (measured between carotid artery and jugular vein, and between carotid artery and femoral vein) were decreased after 24 hr deprivation of food, but slightly increased after injections of 2-DG. 2-DG stimulates eating without decreasing the rate of uptake of glucose from the blood.     

Oligodendrocyte degeneration and recovery after focal cerebral ischemia

The vulnerability of oligodendrocytes to ischemic injury may contribute to functional loss in diseases of central white matter. Immunocytochemical methods to identify oligodendrocyte injury in experimental models rely on epitope availability, and fail to discriminate structural changes in oligodendrocyte morphology. We previously described the use of a lentiviral vector (LV) carrying enhanced green fluorescent protein (eGFP) under the myelin basic protein (MBP) promoter for selective visualization of oligodendrocyte cell bodies and processes. In this study, we used LV-MBP-eGFP to label oligodendrocytes in rat cerebral white matter prior to transient focal cerebral ischemia, and examined oligodendrocyte injury 24 h, 48 h and 1 week post-reperfusion by quantifying cell survival and assaying the integrity of myelin processes. There was progressive loss of GFP+ oligodendrocytes in ischemic white matter at 24 and 48 h. Surviving GFP+ cells had non-pyknotic nuclear morphology and were terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-negative, but there was marked fragmentation of myelin processes as early as 24 h after stroke. One week after stroke, we observed a restoration of GFP+ oligodendrocytes in ischemic white matter, reflected both by cell counts and by structural integrity of myelin processes. Proliferating cells were not the main source of GFP+ oligodendrocytes, as revealed by bromodeoxyuridine (BrdU) incorporation. These observations identify novel transient structural changes in oligodendrocyte cell bodies and myelinating processes, which may have consequences for white matter function after stroke.     

银杏达莫注射液联合骨髓间充质干细胞移植改善脑梗死后的神经功能

背景：通过细胞移植重建损伤脑组织成为治疗脑梗死的新途径,骨髓间充质干细胞成为近年来细胞移植治疗领域的研究热点。 目的：探讨银杏达莫注射液联合骨髓间充质干细胞移植对脑梗死大鼠神经功能的改善作用及相关机制。 方法：利用线栓法制作大鼠大脑中动脉闭塞模型,建模成功后60只SD大鼠随机分为对照组、细胞移植组及联合组。对照组尾静脉注射PBS、细胞移植组尾静脉注射2.5×109 L-1的骨髓间充质干细胞悬液、联合组尾静脉注射2.5×109 L-1的骨髓间充质干细胞悬液和银杏达莫2 mL/kg,1次/d,连续注射5 d。于移植后的1,3 d及1,2 周进行mNSS行为学评分,以观察大鼠神经功能缺损状况。移植后2周RT-PCR检测脑组织中脑源性神经生长因子、生长相关蛋白43基因表达变化,TUNEL法检测细胞凋亡情况,免疫组化法检测BrdU阳性细胞数。 结果与结论：移植后的1,3 d各组大鼠神经功能缺损评分差异无显著性意义(P > 0.05),在移植后1,2周,联合组神经功能缺损评分低于细胞移植组及对照组(P < 0.05);移植后2周,联合组脑源性神经生长因子、生长相关蛋白43 mRNA表达明显高于细胞移植组及对照组(P < 0.05),联合组凋亡细胞数目明显少于细胞移植组及对照组(P < 0.05),联合组BrdU阳性细胞数量明显多于细胞移植组及对照组(P < 0.05)。结果表明骨髓间充质干细胞联合银杏达莫干预能促进脑梗死组织脑源性神经生长因子、生长相关蛋白43 mRNA的表达,抑制细胞凋亡,改善大鼠神经功能。  中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程      

Functional recovery after peripheral nerve injury and implantation of a collagen guide

Although surgery techniques improved over the years, the clinical results of peripheral nerve repair remain unsatisfactory. In the present study, we compare the results of a collagen nerve guide conduit to the standard clinical procedure of nerve autografting to promote repair of transected peripheral nerves. We assessed behavioral and functional sensori-motor recovery in a rat model of peroneal nerve transection. A 1cm segment of the peroneal nerve innervating the Tibialis anterior muscle was removed and immediately replaced by a new biodegradable nerve guide fabricated from highly purified type I+III collagens derived from porcine skin. Four groups of animals were included: control animals (C, n=12), transected animals grafted with either an autologous nerve graft (Gold Standard; GS, n=12) or a collagen tube filled with an acellular skeletal muscle matrix (Tube-Muscle; TM, n=12) or an empty collagen tube (Collagen-Tube; CT, n=12). We observed that 1) the locomotor recovery pattern, analyzed with kinetic parameters and peroneal functional index, was superior in the GS and CT groups; 2) a muscle contraction was obtained in all groups after stimulation of the proximal nerve but the mechanical muscle properties (twitch and tetanus threshold) parameters indicated a fast to slow fiber transition in all operated groups; 3) the muscular atrophy was greater in animals from TM group; 4) the metabosensitive afferent responses to electrically induced fatigue and to two chemical agents (KCl and lactic acid) was altered in GS, CT and TM groups; 5) the empty collagen tube supported motor axonal regeneration. Altogether, these data indicate that motor axonal regeneration and locomotor recovery can be obtained with the insertion of the collagen tube RevolNerv. Future studies may include engineered conduits that mimic as closely as possible the internal organization of uninjured nerve.     

Shift of motor activation areas during recovery from hemiparesis after cerebral infarction: a longitudinal study with near-infrared spectroscopy

Motor functional recovery after stroke may be attributable to cerebral reorganization. We used near-infrared spectroscopy, which measures non-invasively the changes in oxy- and deoxy-hemoglobin concentrations in response to neural activation, for monitoring cerebral activation in stroke patients, and investigated the longitudinal changes in functional laterality of activations in the primary sensorimotor cortex during unilateral audio-paced (1 Hz) hand movement. We examined five ischemic stroke patients (4 females and 1 male, 52-67 years old) with mild to moderate hemiparesis at acute stages and chronic stages at least 1 month later. Normal subjects (3 females and 2 males, 47-63 years old) were also included. Unilateral hand movement activated predominantly the contralateral primary sensorimotor cortex in the normal subjects and the stroke patients when they moved unaffected hand. Affected hand movements activated bilateral sensorimotor cortices early after stroke (< 25 days of stroke onset), whereas the activation pattern returned toward normal at later periods (> 35 days). The contralaterality index (0.34 +/- 0.12 in normal control) was reduced at early periods (0.00 +/- 0.03, p < 0.01) after stroke, and returned to normal (0.35 +/- 0.24) as motor function recovered. These findings suggest that a transient increase in motor activation in the ipsilateral intact hemisphere within 1 month may play an important role in the recovery from motor dysfunction after stroke.     

Cardiovascular recovery from stress and hypertension risk factors: A meta-analytic review

Recent research has suggested that cardiovascular recovery from stress can play a potential role in hypertension pathogenesis. Sixty nine studies were included in meta analytic review to evaluate the effect of various hypertension risk factors (e.g., race, lack of exercise) on cardiovascular recovery from stress. Small mean effect sized were observed for studies examining hypertension status and race as risk factors associated with delayed diastolic blood pressure recovery. Lack of fitness was also associated with delayed heart rate recovery. These results revealed that, for the specified risk factors and cardiovascular variables, high risk individuals exhibited delayed cardiovascular recovery as compared with low risk individuals. Further, the relationships between hypertension status, race and cardiovascular recovery were typically associated with the use of “ctive” laboratory stressors. The relationship between lack of fitness and cardiovascular recovery was also associated with the use of “active” and exercise laboratory stressors.     

Oxidized galectin-1 advances the functional recovery after peripheral nerve injury

Oxidized galectin-1 has been shown to promote axonal regeneration from transected-nerve sites in an in vitro dorsal root ganglion (DRG) explant model as well as in in vivo peripheral nerve axotomy models. The present study provides evidence that oxidized galectin-1 advances the restoration of nerve function after peripheral nerve injury. The sciatic nerve of adult rats was transected and the distal nerve was frozen after being sutured into a proximal site with four epineurial stitches. An osmotic pump delivered oxidized galectin-1 peripherally to the surgical site. Functional recovery was assessed by measurement of the degree of toe spread of the hind paw for 3 months after the sciatic nerve lesion. The recovery curves of toe spread in the test group showed a statistically significant improvement of functional recovery after day 21 by the application of oxidized recombinant human galectin-1 (rhGAL-1/Ox) compared to the control group. This functional recovery was supported by histological analysis performed by light microscopic examination. The regenerating myelinated fibers at the site 21 mm distal to the nerve-transected site were quantitatively examined at 100 days after the operation. The frequency distribution of myelinated fiber diameters showed that exogenous rhGAL-1/Ox increased the number and diameter of regenerating myelinated fibers; the number of medium-sized (6–11 μm in diameter) fibers increased significantly (P < 0.05). These results indicate that oxidized galectin-1 promotes the restoration of nerve function after peripheral nerve injury. Thus, rhGAL-1/Ox may be a factor for functional restoration of injured peripheral nerves.     

Increased phagocytic activity of peripheral blood monocytes after intravenous injection of phospholipase A2 to monkeys

One of the expressions of the activity of phagocytic cells such as monocytes or macrophages is a burst of increased oxidative activity on stimulation. The free oxygen radicals liberated, mainly O2- and H2O2, lead to chemoluminescence, which is thus a measure of activation. Chemoluminescence also depends on arachidonic acid metabolism, and this depends on phospholipase A2 (PLA2). We modified monocyte activity in monkeys by injecting them i.v. with this enzyme and observed that 30 min after injection, the phagocytic activity of peripheral blood monocytes and the chemoluminescence they emitted was greater than that of controls. We suggest that PLA2 may act as an in vivo immunomodulator in mammals.     

Hemodilution with liposome-encapsulated low-oxygen-affinity hemoglobin facilitates rapid recovery from ischemic acidosis after cerebral ischemia in rats

Liposome-encapsulated hemoglobin (LipoHb) with low oxygen affinity (P₅₀ = 40–50mmHg) has been developed. The purpose of this study was to evaluate the effects of the LipoHb on incomplete cerebral ischemia. Wistar rats were randomly assigned to one of the following three groups: (A) exchange transfusion with LipoHb solution (Hb = 6g/dl) (LipoHb, n = 7), (B) exchange transfusion with rat red blood cell (RBC) solution (Hb = 6g/dl) (RBC, n = 7), (C) no exchange transfusion (control, n = 7). Forebrain ischemia was induced for 9min by bilateral carotid artery occlusion combined with a decrease in the mean arterial pressure (MAP) to 40mmHg. ³¹P-magnetic resonance spectroscopy was performed during ischemia and 60min of reperfusion. After exchange transfusion, the MAP increased in the LipoHb group and decreased in the RBC group (LipoHb versus RBC; P = 0.0028). During ischemia, intracellular pH (pHi) rapidly decreased in all groups; after reperfusion, the pHi recovery to preischemic levels was more rapid in the LipoHb group than in the RBC group (P < 0.05). Phosphocreatine and -adenosine triphosphate decreased during ischemia and returned to the preischemic level in all groups following reperfusion. Inorganic phosphate (Pi) increased during ischemia and decreased to the normal value after reperfusion. The LipoHb group had a smaller production of Pi than the other two groups and demonstrated a rapid normalization, although the differences were not significant. Hemodilution with liposome-encapsulated low-oxygen-affinity hemoglobin facilitates rapid pHi recovery from incomplete forebrain ischemia in the rat.     

Two columnar systems in the auditory neostriatum of the chick: Evidence from 2-deoxyglucose

Summary In chicks, monaurally deafened at 3 weeks of age, 2-deoxyglucose labeling of the input layer L₂ in the auditory neostriatum (field L) was analyzed after acoustic stimulation. Two types of stimuli were used: narrow band frequency modulations and white noise. Both stimuli provide evidence that there are bands or columns with different inputs from the contra- and ipsilateral ear, a rostral, intermediate, and caudal band, all oriented orthogonal to the isofrequency contours. The intermediate band, in addition, shows multiple alternating columns of ipsivs. contralateral dominant input, parallel to the isofrequency contours. Consequently, the tonotopic gradient is interrupted several times by these columns. The organization of field L bears interesting parallels to the mammalian auditory cortex and is the first evidence of columnar organization in a submammalian forebrain. The multiple interruptions of the tonotopic gradient between low and high frequencies in the intermediate band by alternating aural dominance has possible implications for understanding directional hearing, as well as for understanding formant analysis of species-specific sounds.Supported by the Deutsche Forschungsgemeinschaft, SFB 45     

Three-dimensional MRI of cerebral projections in rat brain in vivo after intracortical injection of MnCl2

In this study we investigated the potential of in vivo MRI detection of axonal Mn2+ transport for tracing neuronal projections originating in the sensorimotor cortex in healthy and lesioned rat brains. Special attention was given to the potential of visualizing neuronal sprouting of central nervous system across the midline. After injecting unchelated MnCl2 into the forelimb area of sensorimotor cortex of 18 healthy and 10 lesioned rats corticofugal projections could be traced through the internal capsule to the cerebral peduncle and the pyramidal decussation. Although the neuronal tract was visible as early as 6 h after MnCl2 injection, best contrast was achieved after 24-48 h. Beside the cortico-spinal tract, the cortico-thalamic fibres were also visualized by anterograde Mn2+ transport. Cortico-striatal fibres were partially masked by the very high signal near the MnCl2 injection site but could be discerned as well. Slight, diffuse signal enhancement of cortical tissue contralateral to the MnCl2 injection site in healthy rat brains suggests interhemispheric connections or passive diffusion of Mn2+. However, enhanced fibre tract contrast connecting both hemispheres was visible 16 weeks after onset of focal photothrombotic cortical injury. In conclusion our study has shown that we were able to visualize reproducibly the main descending corticofugal projections and interhemispheric connections by non-invasive MRI after localized injection of MnCl2. The appearance of interhemispheric Mn2+-enhanced fibres after photothrombotic focal injury indicates that the method may bear potential to follow non-invasively gross plastic changes of connectivity in the brain after injury.