Avermectin exposure induces apoptosis in King pigeon brain neurons

The effect of avermectin was studied on King pigeon brain nerve cells by cytotoxicity [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide, MTT] and apoptosis [acridine orange/ethidium bromide (AO/EB) assay, transmission electron microscope (TEM) evaluation, measurement of mitochondrial membrane potential (Δψm), phosphatidylserine (PS) exposure, caspases activities, DNA fragmentation, reactive oxygen species (ROS) and caspase-3 mRNA expression] within the 2.5–10 μg L⁻¹ concentration-range. The results revealed that within the concentrations of 2.5–10 μg L⁻¹, avermectin showed obvious cytotoxicity and induced apoptosis in a dose-dependent manner to neurons of King pigeon in vitro. Cell viability were 99.93 ± 8.52%, 82.02 ± 4.99% and 78.23 ± 5.67% after 24 h of treatment with avermectin at the concentrations of 0, 2.5 and 5 μg L⁻¹, which decreased to 56.36 ± 2.17% of 10 μg L⁻¹. Treated cells showed typical apoptosis morphological changes including cytoplasmic vacuolation, chromatin condensation, unclear nuclear membrane and decreased/swollen mitochondria. Typical biochemical hallmarks of apoptosis including Δψm loss, PS exposure, activations of caspase-3, caspase-8 and caspase-9, DNA fragmentation were observed too. Moreover, the levels of ROS in the avermectin treatment groups increased significantly compared to control group. Furthermore, the caspase-3 mRNA levels increased significantly following AVM treatment. In conclusion, our experimental results show that avermectin has cytotoxicity to brain neurons of King pigeon in vitro and the mechanism of neurotoxicity induced by avermectin is closely related to apoptosis.     

低温结合GABA处理对樱桃番茄果实采后品质的影响

探讨低温贮藏结合GABA处理对樱桃番茄果实采后品质的影响,为寻找樱桃番茄采后保鲜新技术提供理论依据。本研究以‘粉娇’樱桃番茄为试材,设置清水浸渍+常温(25℃)贮藏、清水浸渍+低温(8℃)贮藏和GABA(500 mg/L)浸渍+低温(8℃)贮藏3个处理,在樱桃番茄16天的贮藏期内,调查果实腐烂率,测定果实呼吸强度、果实硬度、可溶性固形物、维生素C、柠檬酸和类胡萝卜素含量。结果表明,与常温(25℃)贮藏相比,低温及其结合GABA处理均显著降低了樱桃番茄果实贮藏期间的腐烂率,其中在贮藏16天时,防治效果分别达到了45.81%和63.11%,低温结合GABA处理优于单独低温贮藏。同时,低温结合GABA处理显著降低了果实的呼吸强度,延缓了果实硬度的降低,保持了较高的可溶性固形物、维生素C和柠檬酸含量,抑制了番茄红素、β-胡萝卜素和叶黄素的积累。因此,低温结合GABA处理可有效延缓樱桃番茄果实的腐烂和衰老,并能保持果实的采后品质,在樱桃番茄果实保鲜上具有良好的应用前景。     

γ-氨基丁酸对香蕉果实采后成熟的调控作用及其生理机制

香蕉是世界上最重要的水果之一,研究香蕉采后成熟与调控对香蕉品质形成及创新采后催熟技术具有重要意义。本实验室前期的研究结果发现Ma GAD1基因的表达与香蕉采后乙烯生物合成及果实成熟密切相关。本研究在此基础上,根据香蕉果实达到全黄并有黑色斑点期(YB)成熟度的天数为标准,筛选出Ma GAD1基因表达的诱导剂γ-氨基丁酸(GABA)能够促进香蕉果实采后成熟。生理学分析结果表明,外源GABA能够促使香蕉果实提前发生生理跃变。实时荧光定量PCR分析结果表明,外源GABA能够诱导Ma GAD1和Ma ACS1上调表达。因此,GABA通过诱导Ma GAD1和Ma ACS1上调表达及促进香蕉果实生理跃变,从而促进香蕉果实采后成熟。本研究不仅从理论上证明了GABA能够促进果实成熟,揭示了GABA促进果实成熟生理机制,并且从实际生产上为蕉催熟的应用提供了一种新方法。     

富含γ-氨基丁酸(GABA)的巨胚功能稻研究进展

富含γ-氨基丁酸(GABA)的巨胚稻米具有降血压、治疗癫痫病等功效,是水稻品质改良的研究热点之一。通过诱变和杂交转育技术,已经育成了“Haim inori”、“巨胚1号”、“6601”、“W 025”、“伽马-1”、“龙特浦geA”和“98-14geA”等10余个巨胚水稻品种(系),并摸索出了巨胚稻的栽培调控管理措施。经高效液相色谱(HPLC)及氨基酸组成分析,富集后巨胚稻米的GABA含量达到3500-4000mg/100g,其它许多营养成分也比普通稻米高。水稻巨胚受一隐性基因控制,控制稻米巨胚的3个等位基因gem、ge、ges已被定位在水稻第7染色体上,多个与胚大小有关的QTL也被检测。对巨胚稻米GABA的富集条件、加工工艺、市场开发前景也进行了综述。     

γ-氨基丁酸和植物提取物对肉鸡生产性能和血液指标的影响

试验旨在研究日粮中添加γ-氨基丁酸(GABA)和植物提取物对肉鸡生产性能和血液指标的影响。将504只1日龄爱拔益加(AA)商品肉鸡随机分成3组(1个对照组,2个试验组),每组设8个重复,每个重复21只鸡,对照组饲喂基础日粮,试验组分别饲喂含50mg/kg GABA和200mg/kg植物提取物的基础日粮,试验42d,结果显示,GABA和植物提取物的添加对于改善肉鸡的生产性能有一定的作用,且植物体提取物的效果比GABA的效果更好;GABA和植物提取物均提高了机体的内分泌机能和免疫机能。     

A native picrotoxin-resistant GABA-gated chloride channel receptor subtype in cockroach neurons

Among insect GABA receptors, the GABA-gated chloride channel subtype is insensitive to bicuculline and has been thought to be composed of two populations because of differences in chloride conductance increase, GABA and picrotoxin (PTX) sensitivity. To characterize this possible diversity in GABA-gated chloride channels, electropharmacological experiments were performed on giant interneuron synaptic GABA receptors and on somatic GABA receptors of dorsal unpaired median (DUM) neuron and fast coxal depressor (D_f) motoneuron of the cockroach Periplaneta americana (L). Electrophysiological assays performed at cercal-afferent giant interneuron synapses demonstrated that a biphasic increase in membrane conductance, in response to long-lasting (30 s) neuropilar microapplication of GABA, could be explained by the existence of two GABA-operated chloride channel receptor subtypes. The low stable membrane conductance increase, representing less than 30% of the maximum reached during the early transient phase, was not desensitized quickly. It was reproduced by neuropilar microapplication of cis-4-aminocrotonic acid (CACA) and, in contrast to the fast phase, was not antagonized by bath application of 10⁻⁵ M PTX. Long-lasting (3 min) pneumatic pressure application of GABA on the cell body of motoneuron D_f evoked a fast transient hyperpolarization followed by a slower phase of further hyperpolarization. PTX (10⁻⁵ M ) blocked the fast transient phase and revealed a slow stable hyperpolarization. PTX (10⁻⁴ M ) blocked the major part of the remaining GABA response. The slow hyperpolarization was reproduced by application of CACA. Similar effects of GABA and CACA were recorded on DUM neuron cell bodies. All of these observations are consistent with the possible existence of two GABA-gated chloride channel subtypes in the insect CNS. © 1999 Society of Chemical Industry     

Bicyclophosphorothionate antagonists exhibiting selectivity for housefly GABA receptors

2,6,7-Trioxa-1-phosphabicyclo[2.2.2]octane 1-sulfides (bicyclophosphorothionates) with various C_1–4 alkyl groups at the 3- and 4-positions were synthesized and tested for their ability to compete with [³H]4′-ethynyl-4-n-propylbicycloorthobenzoate (EBOB), a non-competitive antagonist of γ-aminobutyric acid (GABA) receptors, for specific binding to rat-brain and housefly-head membranes, and for their insecticidal activity against houseflies. Among the 3,4-substituted analogues, 20 compounds were selectively active for housefly GABA receptors versus rat GABA receptors. The 3-alkyl groups of C₃ length and the 4-alkyl groups of C₄ length were tolerated in housefly receptors, whereas such bulky substituents were deleterious in rat receptors. The 4-isobutyl-3-isopropyl analogue was the most potent in housefly receptors (IC₅₀ = 45.2 nM ), and tert-butylbicyclophosphorothionate (TBPS), with the 4-tert-butyl group and no 3-substituent, was the most potent in rat receptors (IC₅₀ = 62.2 nM ). Their receptor selectivities (rat IC₅₀/housefly IC₅₀) were 52 and 0.038, respectively. The insecticidal activity (LD₅₀) of 20 active analogues was well correlated with their potency (IC₅₀) in inhibiting [³H]EBOB binding to housefly-head membranes (r = 0.93). The results obtained in the present study indicate that the introduction of appropriate alkyl groups into the 3- and 4-positions of bicyclophosphorothionate leads to non-competitive antagonists with increased affinity and selectivity for housefly ionotropic GABA receptors versus rat GABA_A receptors. © 1999 Society of Chemical Industry     

不同割苗期对大麦苗产量、再生性及伽马氨基丁酸含量的影响

为获得麦苗生产的最佳割苗期,对大麦品种福大麦1号和11凡8设置五个割苗期、割苗两次,并对麦苗产量、伽马氨基丁酸(GABA)含量和生长速率进行统计分析。结果发现,各割苗期大麦苗干重和生长速率呈显著正相关,生长期越长麦苗干重越大,生长期与GABA含量不相关。响应面分析结果表明,福大麦1号第一次割苗在第5期,干重和GABA含量最大,分别为20.31g·m~(-2)和1.83mg·g~(-1),第二次割苗在第4期,干重和GABA含量最大,分别为18.44g·m~(-2)和1.43mg·g~(-1);11凡8第一次割苗在第5期,干重和GABA含量最大,分别为25.15g·m~(-2)和1.51mg·g~(-1),第二次割苗在第4期,干重和GABA含量最大,分别为20.78g·m~(-2)和1.25mg·g~(-1)。比较产量、再生性和GABA含量发现,福大麦1号比11凡8更适合生产麦苗。     

外源性γ-氨基丁酸抵抗仔猪氧化应激的效果及机制

【目的】 研究外源性γ-氨基丁酸（GABA）抵抗仔猪氧化应激的作用效果,及海马神经元GABA受体调节凋亡信号通路在其中可能的介导作用,为GABA作为动物应激调节剂的应用提供科学依据。【方法】 基于成功构建的仔猪活体和大鼠海马神经元氧化应激模型,考察外源性GABA对仔猪血清及海马组织中氧化/抗氧化相关指标、仔猪日增重、脑海马GABA受体以及大鼠海马神经元中GABA受体及凋亡信号通路相关基因表达水平的影响。【结果】 低、中、高浓度的GABA灌喂组（LD+OS; MD+OS;HD+OS）仔猪血清的MDA含量均极显著低于氧化应激（OS）组(P<0.01),而GSH水平均极显著高于OS组(P<0.01),同时HD+OS 组仔猪血清T-AOC水平极显著高于OS组和对照组(P<0.01);且高浓度(100 mg·kg^-1 BW)GABA降低仔猪血清MDA含量和增加GSH水平的幅度均高于低浓度(20 mg·kg^-1 BW)和中浓度(60 mg·kg^-1 BW)GABA。因此,后续研究仅考察100 mg·kg^-1 BW GABA的作用效果及其抗氧化应激的机制。OS组仔猪0-7、8-14和0-28日龄的日增重极显著低于对照组(P<0.01),而HD+OS组0-7、8-14和0-28日龄仔猪的日增重极显著高于OS组(P<0.01);OS组仔猪15-28日龄的日增重显著低于对照组(P<0.05),HD+OS组15-28日龄的日增重极显著高于OS组(P<0.01)。以上结果表明,100 mg·kg^-1 BW GABA的灌喂极显著地增加了仔猪的日增重。对照组、OS组和HD+OS组在前、中、后期的腹泻率均无显著差异(P>0.05)。氧化应激组海马组织的MDA含量极显著高于对照组和HD+OS组 (P<0.01),而T-AOC和GSH的水平均极显著低于另外两组(P<0.01),表明GABA能提高仔猪海马组织抗氧化能力。HD+OS组的海马组织GABA_A和GABA_B受体水平均极显著高于对照组和氧化应激组(P<0.01),表明GABA提高了海马组织GABA_A和GABA_B的水平。氧化应激组脑海马Bcl-2蛋白水平显著低于对照组(P<0.05),Bax和Caspase-3蛋白水平极显著高于对照组(P<0.01)。HD+OS组的Bcl-2蛋白水平极显著高于氧化应激组（P<0.01）,Bax蛋白水平极显著低于氧化应激组（P<0.01）,Caspase-3蛋白水平显著低于氧化应激组（P<0.05）。与此一致的是,氧化应激组、GABA+OS+Picrotoxin组和GABA+OS+CGP54626组大鼠海马神经元的Bax和Caspase-3蛋白水平均显著高于对照组和GABA+OS组（P<0.05）,表明GABA缓解了氧化应激状态下海马神经元的损伤,而GABA受体抑制剂的添加阻挡了GABA的抗应激损伤作用。【结论】 GABA降低了仔猪海马的氧化应激水平,而GABA抗应激的作用机制可能与其降低凋亡蛋白基因的表达相关,而GABA_A和GABA_B受体介导了该过程。