Transmembrane Transport and Release of GABA in the Brain of Rats Subjected to Postnatal Hypoxia

We studied the effects of early postnatal hypoxia on the efficiency of active GABA transport through the plasma membrane of synaptic terminals (synaptosomes) isolated from the cerebral cortex, hippocampus, and thalamus of rats and on non-stimulated and Ca²⁺-stimulated GABA release. The state of hypoxia was induced by exposure of 10- to 12-day-old rats to a respiratory medium with low O₂ content (4% О₂ and 96% N₂) for 12 min (up to the initiation of clonico-tonic seizures). Animals were taken in the experiment 8 to 9 weeks after an episode of hypoxic stress. The intensity of transmembrane transport of GABA was estimated according to accumulation of [³Н]GABA in a coarse synaptosomal fraction. The process was characterized by calculation of the Michaelis constant K _m and also of the initial (within the 1st min) and maximum rates of accumulation of [³Н]GABA. The means of the initial rate of [³Н]GABA accumulation in preparations from the thalamus, cortex, and hippocampus were 205.5 ± 8.8, 266.2 ± 29.6, and 302.3 ± 31.2 pmol/min⋅mg protein, respectively. Hypoxic stress influenced the rates of accumulation of [³Н]GABA in synaptic terminals from the cortex and hippocampus but not in those from the thalamus. According to the characteristics of the response to hypoxic stress, all experimental animals could be classified into two groups. In some rats, accumulation of [³Н]GABA in both cortical and hippocampal synaptosomes decreased insignificantly (by about 15%), while in other animals this parameter increased significantly (by nearly 50%) for the cortex and decreased by 21.5%, on average, for the hippocampus. The affinity of the transporter with respect to [³Н]GABA in the cortex and hippocampus was nearly the same and showed no changes under the influence of hypoxia. The non-stimulated release of [³Н]GABA after the influence of hypoxia increased in all structures, while the depolarization-induced Ca²⁺-dependent release of [³Н]GABA was intensified only in synaptosomes from the cerebral cortex. The mechanisms of development of modifications of GABA-ergic processes under the influence of hypoxic stress in the course of the perinatal period are discussed. Neirofiziologiya/Neurophysiology, Vol. 40, No. 4, pp. 293–302, July–August, 2008.     

Vagus nerve stimulation inhibits seizure activity and protects blood–brain barrier integrity in kindled rats with cortical dysplasia

AimsThis study investigates the effects of vagus nerve stimulation (VNS) on seizure severity and blood–brain barrier (BBB) integrity in kindled rats with cortical dysplasia (CD).Main methodsPregnant rats were exposed to 145 cGy of gamma-irradiation on day 17 of pregnancy. In offsprings, kindling was induced by giving subconvulsive doses of pentylenetetrazole. Left VNS was performed for 48 h at output currents of 0.5 or 1 mA. Horseradish peroxidase (HRP) was used to study the BBB permeability. Immunohistochemistry for occludin and P-glycoprotein (P-gp) was also performed.Key findingsKindled rats with CD exhibited seizures with mean Racine's scores of 3.57 ± 1.2 during video EEG recording. Kindled animals with CD receiving VNS at 0.5 and 1.0 mA did not exhibit either clinical or electrophysiological signs of seizure. Immunostaining for occludin, a tight junction protein, in hippocampus remained relatively intact in all groups. VNS-treated and -untreated kindled animals with CD revealed intense immunostaining for P-gp in hippocampal formation (P < 0.01). Electron microscopic observations revealed frequent transport vesicles containing electron-dense HRP reaction products in the cytoplasm of brain capillary endothelial cells in both cerebral cortex and hippocampus of kindled animals with CD. Those which were exposed to 1 mA VNS were observed to have brain capillary endothelial cells largely devoid of HRP reaction products in both cerebral cortex and hippocampus.SignificanceThe results of this study suggest that VNS therapy at 1 mA inhibits seizure activity and protects BBB integrity by limiting the enhancement of transcellular pathway in kindled animals with CD.     

Treatment with Actovegin improves spatial learning and memory in rats following transient forebrain ischaemia

This study aimed to investigate whether Actovegin, which is a deproteinized ultrafiltrate derived from calf blood, demonstrates neuroprotective effects in a rat model of transient global cerebral ischaemia. Forty Sprague Dawley rats were subjected to four‐vessel occlusion to induce transient global cerebral ischaemia followed by either saline or Actovegin treatment. Sham operations were performed on 15 rats. Actovegin (200 mg/kg) or saline was administered 6 hrs after carotid artery occlusion and then daily until Day 40. Learning and memory were evaluated using the Morris water maze test over two different 5‐day periods, and grip strength testing was also performed to control for potential motor impairments. Rat brains were harvested for histological analysis on Day 68. In comparison to controls, Actovegin‐treated rats exhibited a decreased latency to reach the hidden platform on the second learning trial of water maze testing (46.82 ± 6.18 versus 27.64 ± 4.53 sec., P < 0.05; 38.3 ± 8.23 versus 13.37 ± 2.73 sec., P < 0.01 for the first and second 5‐day testing periods, respectively). In addition, Actovegin‐treated rats spent more time in the platform quadrant than saline‐treated rats during memory trials (P < 0.05). No differences in grip strength were detected. Histological analyses demonstrated increased cell survival in the CA1 region of the hippocampus following Actovegin treatment (left hemisphere, 166 ± 50 versus 332 ± 27 cells, P < 0.05; right hemisphere, 170 ± 45 versus 307 ± 28 cells, P < 0.05, in saline‐ versus Actovegin‐treated rats, respectively). In rats, Actovegin treatment improves spatial learning and memory following cerebral ischaemia, which may be related to hippocampal CA1 neuroprotection.     

Monophosphoryl Lipid A and Pam3Cys Prevent the Increase in Seizure Susceptibility and Epileptogenesis in Rats Undergoing Traumatic Brain Injury

Five percent of all epilepsy cases are attributed to traumatic brain injury (TBI), which are known as post-traumatic epilepsy (PTE). Finding preventive strategies for PTE is valuable. Remarkable feature of TBI is activation of microglia and subsequent neuroinflammation, which provokes epileptogenesis. The toll-like receptor agonists monophosphoryl lipid A (MPL) and tri-palmitoyl-S-glyceryl-cysteine (Pam3Cys) are safe, well-tolerated and effective adjuvants existing in prophylactic human vaccines. We examined the impact of early injection of MPL and Pam3Cys to rats, on the rate of kindled seizures acquisition following TBI. Rats received a single dose (1 µg/rat) of MPL or Pam3Cys through intracerebroventricular injection. 5 days later, trauma was exerted to temporo-parietal cortex of rats by controlled cortical impact device. After 24 h, traumatic rats underwent amygdala kindling. Brain level of the inflammatory cytokine tumor necrosis factor-alpha (TNF-α) was also measured in traumatic rats by immunoblotting. Compared to non-traumatic (sham-operated) rats, traumatic rats showed three times lower seizure threshold (133?±?5 µA vs. 416.3?±?16 µA, p?<?0.001); about three times less number of stimuli to become kindled (5?±?1 vs. 14?±?2, p?<?0.01); longer duration of kindled seizure parameters including entire seizure behavior, generalized seizures, and afterdischarges (p?<?0.001); and a two times increase in the TNF-α level. MPL and Pam3Cys did not change kindling rate and the seizure parameters in sham-operated rats. The MPL- and Pam3Cys-pretreated traumatic rats displayed seizure threshold, speed of kindling, and duration of kindled seizure parameters, similar to the non-traumatic rats. Pretreatment by MPL and Pam3Cys prevented the increase in TNF-α level by trauma. Given that MPL and Pam3Cys currently have clinical use as well-tolerated vaccines with reliable safety, they have the potential to be used in prevention of PTE.     

Behavioral Deficit and Decreased GABA Receptor Functional Regulation in the Hippocampus of Epileptic Rats: Effect of <Emphasis Type="Italic">Bacopa monnieri</Emphasis>

In the present study, alterations of the General GABA and GABA_A receptors in the hippocampus of pilocarpine-induced temporal lobe epileptic rats and the therapeutic application of Bacopa monnieri and its active component Bacoside-A were investigated. Bacopa monnieri (Linn.) is a herbaceous plant belonging to the family Scrophulariaceae. Hippocampus is the major region of the brain belonging to the limbic system and plays an important role in epileptogenesis, memory and learning. Scatchard analysis of [³H]GABA and [³H]bicuculline in the hippocampus of the epileptic rat showed significant decrease in B_max (P < 0.001) compared to control. Real Time PCR amplification of GABA_A receptor sub-units such as GABA_Aά1, GABA_Aά5, GABA_Aδ, and GAD were down regulated (P < 0.001) in the hippocampus of the epileptic rats compared to control. GABA_Aγ subunit was up regulated. Epileptic rats have deficit in the radial arm and Y maze performance. Bacopa monnieri and Bacoside-A treatment reverses all these changes near to control. Our results suggest that decreased GABA receptors in the hippocampus have an important role in epilepsy associated behavioral deficit, Bacopa monnieri and Bacoside-A have clinical significance in the management of epilepsy.     

Inactivation of clathrin heavy chain inhibits synaptic recycling but allows bulk membrane uptake

Synaptic vesicle reformation depends on clathrin, an abundant protein that polymerizes around newly forming vesicles. However, how clathrin is involved in synaptic recycling in vivo remains unresolved. We test clathrin function during synaptic endocytosis using clathrin heavy chain (chc) mutants combined with chc photoinactivation to circumvent early embryonic lethality associated with chc mutations in multicellular organisms. Acute inactivation of chc at stimulated synapses leads to substantial membrane internalization visualized by live dye uptake and electron microscopy. However, chc-inactivated membrane cannot recycle and participate in vesicle release, resulting in a dramatic defect in neurotransmission maintenance during intense synaptic activity. Furthermore, inactivation of chc in the context of other endocytic mutations results in membrane uptake. Our data not only indicate that chc is critical for synaptic vesicle recycling but they also show that in the absence of the protein, bulk retrieval mediates massive synaptic membrane internalization.     

Caffeine consumption attenuates neurochemical modifications in the hippocampus of streptozotocin-induced diabetic rats

Type 1 diabetes can affect hippocampal function triggering cognitive impairment through unknown mechanisms. Caffeine consumption prevents hippocampal degeneration and memory dysfunction upon different insults and is also known to affect peripheral glucose metabolism. Thus we now characterized glucose transport and the neurochemical profile in the hippocampus of streptozotocin‐induced diabetic rats using in vivo¹H NMR spectroscopy and tested the effect of caffeine consumption thereupon. We found that hippocampal glucose content and transport were unaltered in diabetic rats, irrespective of caffeine consumption. However diabetic rats displayed alterations in their hippocampal neurochemical profile, which were normalized upon restoration of normoglycaemia, with the exception of myo‐inositol that remained increased (36 ± 5%, p < 0.01 compared to controls) likely reflecting osmolarity deregulation. Compared to controls, caffeine‐consuming diabetic rats displayed increased hippocampal levels of myo‐inositol (15 ± 5%, p < 0.05) and taurine (23 ± 4%, p < 0.01), supporting the ability of caffeine to control osmoregulation. Compared to controls, the hippocampus of diabetic rats displayed a reduced density of synaptic proteins syntaxin, synaptophysin and synaptosome‐associated protein of 25 kDa (in average 18 ± 1%, p < 0.05) as well increased glial fibrillary acidic protein (20 ± 5%, p < 0.05), suggesting synaptic degeneration and astrogliosis, which were prevented by caffeine consumption. In conclusion, neurochemical alterations in the hippocampus of diabetic rats are not related to defects of glucose transport but likely reflect osmoregulatory adaptations caused by hyperglycemia. Furthermore, caffeine consumption affected this neurochemical adaptation to high glucose levels, which may contribute to its potential neuroprotective effects, namely preventing synaptic degeneration and astrogliosis.     

Effects of Fluoride on Synaptic Membrane Fluidity and PSD-95 Expression Level in Rat Hippocampus

The objective of this study is to investigate the neurotoxicity of drinking water fluorosis on rat hippocampus. Just weaning male Sprague–Dawley rats were randomly divided into four groups and given 15, 30, and 60 mg/L NaF solution and distilled water, respectively, for 9 months. The fluidity of brain synaptic membrane and expression level of postsynaptic density 95 (PSD-95) were tested. Results showed that the fluidity of brain synaptic membrane decreased gradually with increasing of fluoride concentration, and it was significantly decreased (P < 0.05) in moderate-fluoride group compared with control group, and expression level of PSD-95 was significantly decreased (P < 0.01) in moderate-fluoride group when compared with that of control group. These results indicate that decrease of synaptic membrane fluidity and PSD-95 expression level may be the molecular basis of central nervous system damage caused by fluoride intoxication; PSD-95 in CA3 region of hippocampus is probably a target molecule for fluoride.     

AP180 Couples Protein Retrieval to Clathrin‐Mediated Endocytosis of Synaptic Vesicles

How clathrin‐mediated endocytosis (CME) retrieves vesicle proteins into newly formed synaptic vesicles (SVs) remains a major puzzle. Besides its roles in stimulating clathrin‐coated vesicle formation and regulating SV size, the clathrin assembly protein AP180 has been identified as a key player in retrieving SV proteins. The mechanisms by which AP180 recruits SV proteins are not fully understood. Here, we show that following acute inactivation of AP180 in Drosophila, SV recycling is severely impaired at the larval neuromuscular synapse based on analyses of FM 1‐43 uptake and synaptic ultrastructure. More dramatically, AP180 activity is important to maintain the integrity of SV protein complexes at the plasma membrane during endocytosis. These observations suggest that AP180 normally clusters SV proteins together during recycling. Consistent with this notion, SV protein composition and distribution are altered in AP180 mutant flies. Finally, AP180 co‐immunoprecipitates with SV proteins, including the vesicular glutamate transporter and neuronal synaptobrevin. These results reveal a new mode by which AP180 couples protein retrieval to CME of SVs. AP180 is also genetically linked to Alzheimer's disease. Hence, the findings of this study may provide new mechanistic insight into the role of AP180 dysfunction in Alzheimer's disease.      

The Neuroprotective Effect of Curcumin and Nigella sativa Oil Against Oxidative Stress in the Pilocarpine Model of Epilepsy: A Comparison with Valproate

Oxidative stress has been implicated to play a role in epileptogenesis and pilocarpine-induced seizures. The present study aims to evaluate the antioxidant effects of curcumin, Nigella sativa oil (NSO) and valproate on the levels of malondialdehyde, nitric oxide, reduced glutathione and the activities of catalase, Na⁺, K⁺-ATPase and acetylcholinesterase in the hippocampus of pilocarpine-treated rats. The animal model of epilepsy was induced by pilocarpine and left for 22 days to establish the chronic phase of epilepsy. These animals were then treated with curcumin, NSO or valproate for 21 days. The data revealed evidence of oxidative stress in the hippocampus of pilocarpinized rats as indicated by the increased nitric oxide levels and the decreased glutathione levels and catalase activity. Moreover, a decrease in Na⁺, K⁺-ATPase activity and an increase in acetylcholinesterase activity occurred in the hippocampus after pilocarpine. Treatment with curcumin, NSO or valproate ameliorated most of the changes induced by pilocarpine and restored Na⁺, K⁺-ATPase activity in the hippocampus to control levels. This study reflects the promising anticonvulsant and potent antioxidant effects of curcumin and NSO in reducing oxidative stress, excitability and the induction of seizures in epileptic animals and improving some of the adverse effects of antiepileptic drugs.     

Overexpression of sema3a in myocardial infarction border zone decreases vulnerability of ventricular tachycardia post‐myocardial infarction in rats

The expression of the chemorepellent Sema3a is inversely related to sympathetic innervation. We investigated whether overexpression of Sema3a in the myocardial infarction (MI) border zone could attenuate sympathetic hyper‐innervation and decrease the vulnerability to malignant ventricular tachyarrhythmia (VT) in rats. Survived MI rats were randomized to phosphate buffered saline (PBS, n = 12); mock lentivirus (MLV, n = 13) and lentivirus‐mediated overexpression of Sema3a (SLV, n = 13) groups. Sham‐operated rats served as control group (CON, n = 20). Cardiac function and electrophysiological study (PES) were performed at 1 week later. Blood and tissue samples were collected for histological analysis, epinephrine (EPI), growth‐associated factor 43 (GAP43) and tyrosine hydroxylase (TH) measurements. QTc intervals were significantly shorter in SLV group than in PBS and MLV groups (168.6 ± 7.8 vs. 178.1 ± 9.5 and 180.9 ± 8.2 ms, all P < 0.01). Inducibility of VT by PES was significantly lower in the SLV group [30.8% (4/13)] than in PBS [66.7% (8/12)] and MLV [61.5% (8/13)] groups (P < 0.05). mRNA and protein expressions of Sema3a were significantly higher and the protein expression of GAP43 and TH was significantly lower at 7 days after transduction in SLV group compared with PBS, MLV and CON groups. Myocardial EPI in the border zone was also significantly lower in SLV group than in PBS and MLV group (8.73 ± 1.30 vs. 11.94 ± 1.71 and 12.24 ± 1.54 μg/g protein, P < 0.001). Overexpression of Sema3a in MI border zone could reduce the inducibility of ventricular arrhythmias by reducing sympathetic hyper‐reinnervation after infarction.     

Evidence for the involvement of d-aspartic acid in learning and memory of rat

d-Aspartic acid (d-Asp) is an endogenous amino acid present in neuroendocrine systems. Here, we report evidence that d-Asp in the rat is involved in learning and memory processes. Oral administration of sodium d-aspartate (40 mM) for 12–16 days improved the rats’ cognitive capability to find a hidden platform in the Morris water maze system. Two sessions per day for three consecutive days were performed in two groups of 12 rats. One group was treated with Na-d-aspartate and the other with control. A significant increase in the cognitive effect was observed in the treated group compared to controls (two-way ANOVA with repeated measurements: F _{(2, 105)} = 57.29; P value < 0.001). Five further sessions of repeated training, involving a change in platform location, also displayed a significant treatment effect [F _{(2, 84)} = 27.62; P value < 0.001]. In the hippocampus of treated rats, d-Asp increased by about 2.7-fold compared to controls (82.5 ± 10.0 vs. the 30.6 ± 5.4 ng/g tissue; P < 0.0001). Moreover, 20 randomly selected rats possessing relatively high endogenous concentrations of d-Asp in the hippocampus were much faster in reaching the hidden platform, an event suggesting that their enhanced cognitive capability was functionally related to the high levels of d-Asp. The correlation coefficient calculated in the 20 rats was R = −0.916 with a df of 18; P < 0.001. In conclusion, this study provides corroborating evidence that d-aspartic acid plays an important role in the modulation of learning and memory.     

Does fin damage allow discrimination among wild,escaped and farmed Sparus aurata (L.) and Dicentrarchus labrax (L.)?

The present study compares fin damages in gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) according to their wild, escaped or farmed origins. In addition, the potential applicability of fin condition indices (Fin Erosion Index ‘FEI’ and Fin Splitting Index ‘FSI’) as identification tools is discussed. Farmed seabream fins evidenced more erosion and splitting (FEI ± SD: 2.1 ± 0.3; FSI ± SD: 1.9 ± 0.6) than wild seabream fins (FEI: 0.8 ± 0.6; FSI: 1.2 ± 0.9), a result of farming conditions in open‐sea cages. Escaped seabream fin erosion was between that of farmed and wild seabream (FEI: 1.6 ± 0.4), which could indicate that fins in farmed fish recover over time from farming abrasions once they are in the wild. However, the fins of escaped seabream seem to be weaker than those of the wild fish, and therefore might be more susceptible to suffer other types of erosion such as splitting or nipping (FSI: 2.3 ± 0.7). No significant differences were found in seabass FEI according to their origins, although wild seabass presented significantly more split caudal fins (FSI: 3.3 ± 2.8) than the farmed seabass (FSI: 1.2 ± 1.1) and escapees (FSI: 2.5 ± 1.6). Therefore, FEI for seabream could be used as tools not only to distinguish between wild and farmed fish, but also to identify recent escapees, improving further assessments on the contribution of seabream escapees in fishery landings. However, the healing potential of damaged fins must be considered for the proper identification of escapees. Use of fin condition indices from both species could be helpful for aquaculture management, to assess fish welfare in fish farms stocks, and improve the knowledge of handling, stock densities and open‐sea cage environment conditions.     

Transplantation of Neural Stem Cells Overexpressing Cardiotrophin-1 Inhibits Sprouting of Hippocampal Mossy Fiber in a Rat Model of Status Epilepticus

In this study, we studied the effects of hippocampal transplantation of neural stem cells (NSCs) overexpressing cardiotrophin 1 (CT1) on hippocampal mossy fiber sprouting (MFS) in a rat model of status epilepticus (SE). SE rats (lithium–pilocarpine model) were randomized into four study groups (18 rats per group): CT1-NSCs group, NSCs group, SE control group, and normal control group. Six rats were randomly chosen from each group at 1, 4, and 8 weeks after transplantation. MFS in hippocampal dentate gyrus was scored (Timm staining) at these time points. The MFS scores were as follows: CT1-NSCs 0.77 ± 0.04, 2.48 ± 0.89, and 2.39 ± 0.82 (1, 4, and 8 weeks after transplantation, respectively); NSCs 1.12 ± 0.62, 3.17 ± 0.64, and 3.88 ± 0.51; SE control 1.32 ± 0.35, 3.28 ± 0.75, and 4.32 ± 1.55; and normal control 0.37 ± 0.06, 0.34 ± 0.07, and 0.43 ± 0.04. Compared to SE control group and NSCs group, the scores of MFS in CT1-NSCs group were significantly lower (P < 0.05). In conclusion, transplantation with NSCs overexpressing CT1 inhibits hippocampal MFS and facilitates reduction of recurrent seizures.     

Structure of vegetation patches in northwestern Patagonia, Argentina

Vegetation of arid and semiarid environments has in general a patchy distribution. Our objective was to (a) determine several qualitative and quantitative analytical characteristics of vegetation patches in an arid zone of Patagonia, Argentina, and (b) investigate relationships between them. Annual precipitation in this area was 200 mm during 1999–2005. Eight transects involving ten patches each were studied within a 15 × 15 km area. Mean (±1 SE) values (n = 80) in the vegetation patches were 315 ± 25 and 207 ± 16 cm for the greatest and lowest patch diameter, respectively; 23 ± 2 cm for mound height; 113 ± 12 cm for maximum vegetation height; and 170 ± 18 cm and 58 ± 2% for distance to the next vegetation patch and vegetation patch cover within a transect, respectively. Correlations between greatest and lowest diameters, mound height, maximum plant height and distance to the closest vegetation patch were all significant (P < 0.01; n = 80). In all vegetation patches, the greatest and lowest frequencies were found for the grass Stipa spp. (71.2%) and the shrub Grindelia chiloensis (Cornel.) Cabrera (12.5%). Stipa spp. and the shrub Atriplex lampa (Moq.) D. Dietr. showed the highest simultaneous frequency (50%). A reasonable association among species (>45%) was found for Stipa spp., Atriplex lampa and the shrubs Larrea divaricata Cav., Lycium chilense Miers ex Bertero and Junellia ligustrina (Lag.) Moldenke. Larrea divaricata and Atriplex lampa contributed more than 84% of the total patch standing crop (5,777 ± 435 g). Average patch size and specific diversity were 5.93 ± 0.33 m² and 1.31 ± 0.11, respectively. Aboveground standing crop of the two dominant shrubs decreased as plant species diversity increased (P < 0.05). Conservation of vegetation patches is crucial to prevent increased soil erosion and desertification in the study ecological system.     

Endocytic Structures and Synaptic Vesicle Recycling at a Central Synapse in Awake Rats

The synaptic vesicle (SV) cycle has been studied extensively in cultured cells and slice preparations, but not much is known about the roles and relative contributions of endocytic pathways and mechanisms of SV recycling in vivo, under physiological patterns of activity. We employed horseradish peroxidase (HRP) as an in vivo marker of endocytosis at the calyx of Held synapse in the awake rat. Ex vivo serial section scanning electron microscopy and 3D reconstructions revealed two categories of labelled structures: HRP‐filled SVs and large cisternal endosomes. Inhibition of adaptor protein complexes 1 and 3 (AP‐1, AP‐3) by in vivo application of Brefeldin A (BFA) disrupted endosomal SV budding while SV recycling via clathrin‐mediated endocytosis (CME) remained unaffected. In conclusion, our study establishes cisternal endosomes as an intermediate of the SV cycle and reveals CME and endosomal budding as the predominant mechanisms of SV recycling in a tonically active central synapse in vivo.     

Human stoned B interacts with AP-2 and synaptotagmin and facilitates clathrin-coated vesicle uncoating

Synaptic vesicle biogenesis involves the recycling of synaptic vesicle components by clathrin-mediated endocytosis from the presynaptic membrane. stoned B, a protein encoded by the stoned locus in Drosophila melanogaster has been shown to regulate vesicle recycling by interacting with synaptotagmin. We report here the identification and characterization of a human homolog of stoned B (hStnB). Human stoned B is a brain-specific protein which co-enriches with other endocytic proteins such as AP-2 in a crude synaptic vesicle fraction and at nerve terminals. A domain with homology to the medium chain of adaptor complexes binds directly to both AP-2 and synaptotagmin and competes with AP-2 for the same binding site within synaptotagmin. Finally we show that the µ2 homology domain of hStnB stimulates the uncoating of both clathrin and AP-2 adaptors from clathrin-coated vesicles. We hypothesize that hStnB regulates synaptic vesicle recycling by facilitating vesicle uncoating.     

戊四氮点燃癫痫大鼠海马P75NTR及NF-κB的表达变化

目的探讨戊四氮点燃癫痫大鼠海马神经营养因子受体P75NTR及核转录因子NF-κB表达的变化,以探讨癫痫的发病机制。方法戊四氮腹腔注射诱导大鼠癫痫持续状态（SE）,观察大鼠行为学改变,分别选取1,6,24,72h四个时间点运用反转录多聚酶链反应（RT-PCR）方法检测SE大鼠和对照组海马P75NTR mRNA及NF-κB mRNA的表达。结果SE后6h,P75NTR和NF-κB表达开始增高,24h达高峰（P〈0.01）,72h略有下降,但仍高于对照组水平（P〈0.05）。各组间两两比较差异有统计学意义（P〈0.05）。结论癫痫SE时,P75NTR高表达同时伴NF-κB活性增强,二者变化具有相关性,可能为SE致痫的共同途径。     

Effect of host plants on the infectivity of nucleopolyhedrovirus to Spodoptera exigua larvae

Previous studies have shown that the infectivity of baculovirus to herbivores is affected by phytochemicals ingested during the acquisition of viral inoculum on the foliage of host plants. Here, we measured the effects of 14 host plant species on the infectivity of Spodoptera exigua nucleopolyhedrovirus (SeNPV) to its larvae. The order of the LD₅₀ values of SeNPV among the host plants was Ipomoea aquatica > Brassica oleracea > Raphanus sativus > Amaranthus tricolor > Spinacia oleracea > Vigna unguiculata > Solanum melongena > Capsicum annuum > Apium graveolens > Allium fistulosum > Lactuca sativa > Brassica chinensis > Zea mays > Glycine max, with 940.1 ± 2.26, 424.0 ± 0.60, 295.2 ± 1.13, 147.3 ± 0.63, 138.6 ± 0.22, 119.9 ± 0.07, 119.8 ± 0.02, 109.2 ± 0.18, 104.8 ± 0.62, 102.1 ± 0.66, 97.9 ± 0.22, 89.9 ± 0.32, 79.0 ± 0.13 and 64.0 ± 0.38 OBs per larva, respectively, and the values of mean time to death of virus‐infected larvae were 6.21 ± 0.11, 7.12 ± 0.10, 7.33 ± 0.21, 6.97 ± 0.02, 7.06 ± 0.01, 7.29 ± 0.03, 7.32 ± 0.05, 7.07 ± 0.08, 7.24 ± 0.11, 7.09 ± 0.13, 7.50 ± 0.06, 7.23 ± 0.01, 7.30 ± 0.02 and 7.19 ± 0.07 days, respectively. The mean time to death of larvae decreased with increasing viral dose, and corrected mortality decreased as the larval mean time to death increased. These findings have significance for understanding the effects of host plants on the infectivity of baculovirus to noctuids.