Anti-gal-C antibody in autoimmune neuropathies subsequent to mycoplasma infection

Four of 82 patients with Guillain-Barré syndrome (GBS) and 1 of 12 with multifocal motor neuropathy (MMN), who previously had had Mycoplasma pneumoniae infections, had serum antibody to galactocerebroside (Gal-C). Two patients with GBS without mycoplasma infection also had anti-Gal-C antibody, whereas none of the normal or the disease controls had it. As Gal-C is a major glycolipid antigen in myelin, anti-Gal-C antibody may function in the pathogenesis of autoimmune demyelinative neuropathies. Mycoplasma pneumoniae appears to be an important preceding infectious agent in autoimmune neuropathies with anti-Gal-C antibody. © 1995 John Wiley & Sons, Inc.     

Chronic opioid treatment of neuroblastoma X dorsal root ganglion neuron hybrid F11 cells results in elevated GM1 ganglioside and cyclic adenosine monophosphate levels and onset of naloxone-evoked decreases in membrane K+ currents

Prolongation of the action potential duration of dorsal root ganglion (DRG) neurons by low (nM) concentrations of opioids occurs through activation of excitatory opioid receptors that are positively coupled via G_s regulatory protein to adenylate cyclase. Previous results suggested GM1 ganglioside to have an essential role in regulating this excitatory response, but not the inhibitory (APD-shortening) response to higher (μM) opioid concentrations. Furthermore, it was proposed that synthesis of GM1 is upregulated by prolonged activation of excitatory opioid receptor functions. To explore this possibility we have utilized cultures of hybrid F11 cells to carry out closely correlated electrophysiological and biochemical analyses of the effects of chronic opioid treatment on a homogeneous population of clonal cells which express many functions characteristic of DRG neurons. We show that chronic opioid exposure of F11 cells does, in fact, result in elevated levels of GM1 as well as cyclic adenosine monophosphate (AMP), concomitant with the onset of opioid excitatory supersensitivity as manifested by naloxone-evoked decreases in voltage-dependent membrane K⁺ currents. Such elevation of GM1 would be expected to enhance the efficacy of excitatory opioid receptor activation of the G_s/adenylate cyclase/cyclic AMP system, thereby providing a positive feedback mechanism that may account for the remarkable supersensitivity of chronic opioid-treated neurons to the excitatory effects of opioid agonists as well as antagonists. These in vitro findings may provide novel insights into the mechanisms underlying naloxone-precipitated withdrawal syndromes and opioid-induced hyperalgesia after chronic opiatf addiction in vivo. © 1995 Wiley-Liss, Inc.     

Neuromuscular synaptic function in mice lacking major subsets of gangliosides

Gangliosides are a family of sialylated glycosphingolipids enriched in the outer leaflet of neuronal membranes, in particular at synapses. Therefore, they have been hypothesized to play a functional role in synaptic transmission. We have measured in detail the electrophysiological parameters of synaptic transmission at the neuromuscular junction (NMJ) ex vivo of a GD3-synthase knockout mouse, expressing only the O- and a-series gangliosides, as well as of a GM2/GD2-synthase*GD3-synthase double-knockout (dKO) mouse, lacking all gangliosides except GM3. No major synaptic deficits were found in either null-mutant. However, some extra degree of rundown of acetylcholine release at high intensity use was present at the dKO NMJ and a temperature-specific increase in acetylcholine release at 35 degrees C was observed in GD3-synthase knockout NMJs, compared with wild-type. These results indicate that synaptic transmission at the NMJ is not crucially dependent on the particular presence of most ganglioside family members and remains largely intact in the sole presence of GM3 ganglioside. Rather, presynaptic gangliosides appear to play a modulating role in temperature- and use-dependent fine-tuning of transmitter output.     

Insights into the immunogenetic basis of two ganglioside-associated idiotypic networks

The heavy-chain variable regions (VH) from 14F7 MAb, an IgG1 antibody specific for GM3(NeuGc) ganglioside, and its anti-idiotype, the 4G9 MAb, were cloned and sequenced. Comparison with previously reported sequences showed that VH 14F7 belongs to the J558(VHI) gene family and that it is highly mutated. VH 4G9 belongs to the Q52(VHII) gene family. The HCDR3 14F7 sequence contains three basic residues that could be involved in the binding to 4G9 MAb, which bears acidic residues in its HCDR3. Studies performed in the syngeneic model showed that 14F7 MAb requires both coupling to KLH and the use of Freund's adjuvant to induce an effective anti-idiotypic IgG (Ab2) response. In contrast, P3 MAb, a germline gene-encoded Ab1 that also recognizes the GM3(NeuGc) ganglioside through a basic motif in its H-CDRs, has been reported to be immunogenic in syngeneic mice, even when injected in saline. In addition, when Leghorn chickens were immunized with 14F7 or P3 MAbs emulsified in Freund's adjuvant, only P3-immunized animals were able to develop antibodies that recognized NeuGc-containing gangliosides, antigens which are not present in the normal tissues of this animal species. This phenomenon could be due to the lack of idiotypic connectivity of 14F7MAb.     

Enhancement of liver cell proliferation by GM3 ganglioside

In experiments on rats subjected to partial hepatectomy and experimentally induced hepatitis it is shown that GM₃ ganglioside of equine erythrocytes can enhance liver cell proliferation. The effect was also observed in experiments on a primary hepatocyte culturein vitro; moreover, enhancement of cell proliferation did not depend on the type of sialic acid residues. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 4, pp 427–430, April, 1995     

GM1 and NGF synergism on choline acetyltransferase and choline uptake in aged brain

In the brain of aged rats high affinity choline uptake (HAChU) of the striatum, hippocampus, and frontal cortex is lower than in young rats, while choline acetyltransferase (ChAT) activity is lower in striatum and frontal cortex. Infusion into the lateral cerebral ventricle with nerve growth factor (NGF) enhances the low values of these cholinergic markers in a dose- and region-dependent manner. GM 1 ganglioside infused into the lateral ventricle, at a dose that is ineffective alone, together with NGF synergistically enhances the effect of NGF on ChAT and HAChU activities in the brain of aged animals. The pharmacology of this GM 1/NGF synergism suggests potentiation of response.     

神经节苷脂GM_1对胚基底前脑移植入Alzheimer病鼠的影响

用使君子酸毁损大鼠左侧基底大细胞核,制成Alzheimer病模型鼠。2周后进行移植,移植组分单纯胚基底前脑细胞悬液移植组(ST组)和含单唾液酸神经节苷脂(GM_1)的胚基底前脑悬液移植组(GM_1组)。移植后2月、6月行为测试发现,两移植组学习和记忆行为均有改善,GM_1T组行为指标在2月和6月时均与模型组有显著差异。而与正常组无显著差异;ST组仅在6月时与GM_1T组相似。GM_1T组动物在移植前后进行了体感诱发电位检测,结果发现移植前损毁侧正常出现的10 ms正波消失,而在移植后2月和6月时此波重新出现或潜伏期呈轻或中度延长。形态学观察发现,破坏后1周或6月时破坏侧基底大细胞核的AChE阳性细胞大部消失,同侧额、顶叶皮质AChE阳性纤维和终末明显减少。GM_1T组移植区较ST组移植区大。GM_1T组移植区AChE阳性细胞较ST组多而且突起长。两组均见有ChAT免疫阳性细胞。实验表明GM_1能保护植入受体脑内的胚脑细胞并促进它们在受体脑内发育生长并发挥功能效应。     

Differential accumulation of gangliosides by the brains of MPTP-lesioned mice

Although gangliosides have been reported to enhance recovery from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced lesions of the substantia nigra, evidence as to whether the administered gangliosides actually reach this or any other site of lesion in the central nervous system (CNS) at which they putatively enhance recovery is lacking. Therefore, studies were carried out to determine the amount of ³H-labeled ganglioside that was accumulated by the brains of MPTP-treated mice as well as by brains of control mice. No significant difference in the accumulation of ³/-bovine brain gangliosides or ³H-GD1a was seen between lesioned and control brains up to 240 min after injection of the labeled lipids. However, significantly more label was associated with the brains of MPTP-treated mice compared to controls 120 and 240 min after the injection of ³H-GM1. Analysis of the lipids extracted from the brain of a ³H-GM1-treated mouse revealed that the majority of label was still associated with ³-GM1, 240 min after its administration. Autoradiography of tissue sections from the brains of MPTP-treated mice injected with ³H-GM1 showed that label was present in the ventricular spaces of the brain. This observation suggests that the administered gangliosides are present in the cerebrospinal fluid, which indicates that they have the potential to reach the lesioned CNS site at which they putatively enhance recovery. © 1994 Wiley-Liss, Inc.     

GM1 ganglioside partially rescues cultured dopaminergic neurons from MPP-induced damage: dependence on initial damage and time of treatment

GM1 ganglioside is believed to be important in promoting the recovery of neurons from injury. The present study assesses the ability of GM1 to repair or prevent the damage of dopamine neurons caused by the neurotoxin 1-methyl-4-phenylpyridinium (MPP⁺). Treatment of mesencephalic cell cultures with 2.5 μM MPP⁺ resulted in the loss of 30% of tyrosine hydoxylase (TH) immunoreactive neurons. In contrast, cultures administered 100 μM GM1 ganglioside for 3 days after toxin treatment contained nearly control numbers of TH⁺ neurons (97%). This reparative effect of GM1 was reflected in parallel increases in TH enzyme activity, dopamine and dopac levels. Cultures sustaining greater insult from higher doses of MPP⁺ (5.0–10.0 μM) did not benefit from ganglioside treatment, suggesting that rescue by GM1 depended on the degree of initial damage to cells. Moreover, the timing of ganglioside treatment was critical; pretreatment with GM1 alone did not prevent or attenuate the damage caused by subsequent incubation in 2.5 μM MPP⁺.