Monosialoganglioside internal ester stimulates the dopaminergic reinnervation of the striatum after unilateral hemitransection in rat

Dopaminergic sprouting in the rat striatum after partial lesion of the substantia nigra

The capacity of the dopaminergic nerve system to reinnervate the denervated adult striatum was analyzed in a model of partial 6-hydroxydopamine-induced unilateral lesion of rat substantia nigra pars compacta. Sprouting of dopaminergic fibers entering the ventrolateral part of the striatum from a narrow zone of the external capsule was detected on the lesioned side 4 and 7 months, but not 10 days, after lesioning. Ultrastructural examination of the zone of sprouting revealed hypertrophic dopaminergic fibers and growth-cone-like structures, confirming the existence of an ongoing process of spontaneous regrowth of dopaminergic fibers. The identification of the factors involved in the regrowth of dopaminergic fibers may help to orientate molecular research into new treatments for Parkinson's disease.

Comparison of GM1 ganglioside, AGF2, and D-amphetamine as treatments for spatial reversal and place learning deficits following lesions of the neostriatum

These experiments tested the effectiveness of parenterally administered gangliosides and amphetamine as treatments for spatial learning deficits caused by bilateral lesions of the neostriatum. In Expt. 1, rats were tested postsurgically for 30 days on a shock-avoidance, spatial reversal task. Treatments of gangliosides (GM1 at 30 mg/kg, and AGF2 at 20 mg/kg and 30 mg/kg) and D-amphetamine (2 mg/kg) significantly decreased lesion-induced learning deficits on this task, while treatments of 10 mg/kg AGF2 and the combination of GM1 (30 mg/kg) and D-amphetamine (2 mg/kg) were ineffective. In Expt. 2, rats were given bilateral neostriatal lesions and treated with GM1 (30 mg/kg), AGF2 (20 mg/kg) or D-amphetamine (2 mg/kg) and tested postsurgically for 5 days on a place learning task in the Morris water maze. Only the GM1-treated rats showed a reduction in lesion-induced place learning deficits on this task. Since in both experiments, cell counts near the area of the lesion revealed no differences among any of the brain-damaged groups, it was suggested that the treatments exert their behavioral effects by biochemically activating spared neurons, independent of any ultimate effects they may have on neuronal survival.

Post-injury treatment with GM1 ganglioside reduces nociceptive behaviors and spinal cord metabolic activity in rats with experimental peripheral mononeuropathy

In a rat model of painful peripheral mononeuropathy, this study examined the effects of post-injury treatment with a monosialoganglioside, GM1, on abnormal nociceptive behaviors and spinal cord neural activity resulting from loose ligation of the rat common sciatic nerve (chronic constrictive injury, CCI). Thermal hyperalgesia and spontaneous pain behaviors of CCI rats were assessed by measuring foot-withdrawal latencies to radiant heat and by rating spontaneous hind paw guarding positions, respectively. Neural activity within different regions of the spinal cord was inferred in both CCI and sham-operated rats by employing the [14C]-2-deoxyglucose (2-DG) autoradiographic technique to measure spinal cord glucose metabolism. Intraperitoneal (i.p.) GM1 treatment (10 mg/kg) initiated 1 h or 24 h after injury and once daily for the first 9 post-injury days reduced thermal hyperalgesia of the hind paw ipsilateral to nerve ligation and lowered spontaneous pain behavior rating scores in CCI rats. Sciatic nerve ligation reliably increased basal 2-DG metabolic activity of CCI rats in all four sampled regions (laminae I-IV, V-VI, VII, VIII-IX) of spinal cord lumbar segments (L2-L5) both ipsilateral and contralateral to nerve ligation 10 days after injury. Consistent with the drug's effects on spontaneous pain behaviors, 10 daily GM1 treatments (10 mg/kg, i.p.) initiated 1 h after nerve ligation reduced spinal cord 2-DG metabolic activity in laminae V-VI and VII ipsilateral to nerve ligation and in all four sampled regions contralateral to nerve ligation. This attenuation of the increased spinal cord glucose utilization that occurs in the absence of overt peripheral stimulation may reflect an influence of GM1 on increased neural activity contributing to spontaneous pain. Since gangliosides are thought to protect neurons from excitotoxic effects of excitatory amino acids, these results suggest that ganglioside treatment may result in attenuation of excitatory neurotoxicity that may occur following peripheral nerve injury. Thus, ganglioside treatment could provide a new approach to the clinical management of neuropathic pain syndromes following peripheral nerve injury.

Disposition of exogenous tritium-labelled GM1lactone in the rat

The disposition of labelled [3H]GM1lactone, the inner ester of ganglioside GM1, was studied in the rat. After i.v. administration [3H]GM1lactone was quickly converted to its corresponding open form most likely by plasma esterases, and then displayed a pharmacokinetic profile identical to [3H]GM1. Following intramuscular administration of [3H]GM1lactone [3H]GM1 levels in plasma and in tissues were higher than those obtained after the administration of an equivalent dose of [3H]GM1. This increased bioavailability means that GM1lactone can be considered as a potential prodrug of GM1.

Dopamine release and dopaminergic inhibition of acetylcholine release in rat striatal slices after nigro-striatal hemitransection and parenteral ganglioside administration

Hemitransection of the nigro-striatal bundle in adult rats reduced [3H]dopamine ([3H]DA) uptake into striatal slices from the lesioned side to about 20% of that in the contralateral side 5 days after surgery. Spontaneous recovery of [3H]DA uptake was observed at days 8 and 15 post-lesion (42 and 67% of the unoperated side, respectively). After a short treatment (3 days) with the GM1 ganglioside inner ester (AGF2, 30 mg/kg i.p., daily, starting on day 2 after surgery) [3H]DA uptake amounted to 52% of that in the unoperated side. The electrically evoked fractional overflow of [3H]DA was increased by 500% in slices prepared from the lesioned side 5 days after injury, largely due to the reduced re-uptake by the DA axon terminals. The increase on day 5 was only about 350% in AGF2-treated animals. The DA D2 receptor antagonist, (-)-sulpiride, potentiated the stimulus-evoked overflow of [14C]acetylcholine in slices from the unoperated side prelabelled with [14C]choline. The effect of (-)-sulpiride was much reduced (by about 80%) in the lesioned striata at days 5 and 8 after surgery. Partial recovery was seen at day 15. The lesion did not modify the (-)-sulpiride effect in animals treated with AGF2 from the 2nd to the 5th day post-lesion. Thus early ganglioside administration slows the loss of endogenous dopaminergic control of acetylcholine release caused by partial hemitransection of the nigro-striatal bundle.

Time course of nigrostriatal system changes after tract hemisection and effects of ganglioside treatment: a multiple retrograde fluorescent tracing study

The postlesion phenomena of nigrostriatal neurons following partial tract hemisection have been studied with retrograde axonal transport of dyes in rats treated with saline or GM1 ganglioside (30 mg/kg, i.p., daily for varying times). The time course of the plastic changes in both experimental animal groups was determined by a double retrograde fluorescent tracing technique, utilizing Fast blue (FB) as prelesion tracer, and Diamidino yellow (DY) as postlesion tracer. The data show that the number of nigral cells retrogradely labeled by the prelesion intrastriatal injection of FB declined progressively to 50% of their initial number over 3 weeks. The ganglioside treatment did not significantly influence this temporal pattern of labeled cell loss. By DY-labeling, an almost complete block of the retrograde axonal transport was observed up to 1 week postlesion and only after 3 weeks a partial recovery was evident, positively influenced by the GM1 treatment. Therefore, together with the findings on nigrostriatal cell loss, these data indicate that ganglioside treatment favors and/or accelerates the recovery of axonal transport of surviving nigral neurons but does not significantly affect their degenerative rate in the first 3 weeks after the lesion.

Ganglioside AGF2 prevents the cognitive impairments and cholinergic cell loss following intraventricular colchicine

Ganglioside AGF2 prevented the cognitive and locomotor alterations induced by intraventricular colchicine. Adult male rats were initially trained to perform a standard radial arm maze (RAM) task. Following training, they were injected intraperitoneally with 10 mg/kg AGF2 (COL/AGF2), cerebrospinal fluid (CSF/AGF2) or the saline vehicle (COL/SAL, CSF/SAL) for 3 days prior to and for 14 days following the bilateral injection of colchicine (7 micrograms/0.5 microliters) or artificial CSF into the lateral ventricles. Colchicine (COL/SAL) impaired performance of the standard RAM task as well as a working memory version of the task in which various delays were imposed between the fourth and fifth arm choices. Colchicine also produced a transient hyperactivity which subsided within 10 weeks following surgery. In contrast, AGF2 (COL/AGF2) prevented the impairments in RAM performance and the alterations in locomotor behavior. Colchicine also produced significant decreases in hippocampal ChAT activity and high affinity choline uptake that were prevented by prior treatment with AGF2. Finally, colchicine produced a 35% decrease in the number of acetylcholinesterase-positive (cholinergic) neurons in the medial septum and vertical limb of the diagonal band (MS/VLDB) which was also prevented by AGF2. Thus, the behavioral and neurochemical protection afforded by AGF2 was paralleled by a prevention of the loss of hippocampal cholinergic parameters and cholinergic neurons in the MS/VLDB.

Protective effects of a monosialoganglioside derivative following transitory forebrain ischemia in rats

We evaluated the effects of treatment with the inner ester derivative of the monosialoganglioside GM1 on cortical electroencephalographic activity and hippocampal CA1 morphology after transitory, near-complete cerebral ischemia in rats. Ischemia was induced by the four-vessel occlusion method, and we studied only the 58 rats that showed flattening of the cortical electroencephalogram for the entire 30 minutes of occlusion. The ganglioside (n = 30) or saline (n = 28) was administered intravenously immediately after release of the carotid clips and then intramuscularly for 21 days of observation. Cortical electroencephalographic activity was monitored throughout the experiment. After 21 days of recirculation we assessed hippocampal CA1 damage by light microscopy. The results indicate that treatment with the ganglioside reduces postischemic secondary damage to the cortical circuitry (as indicated by significantly higher cortical electroencephalographic activity late after reperfusion) and limits neuronal loss in the CA1 region. Our results lend support to the possible therapeutic use of ganglioside in human pathologic conditions associated with cerebrovascular insufficiencies.

Ganglioside AGF2 promotes task-specific recovery and attenuates the cholinergic hypofunction induced by AF64A

Ganglioside AGF2 attenuated both the cognitive impairments and the cholinergic hypofunction induced by ethylcholine aziridinium ion (AF64A). Adult male rats were initially trained to perform a standard radial arm maze (RAM) task. Following training, they were injected intraperitoneally with 10 mg/kg AGF2 (AF/AGF2, CSF/AGF2) or the saline vehicle (AF/SAL, CSF/SAL) for 3 days prior to and for 14 days following bilateral injection of AF64A (3 nmol/side) or artificial CSF into the lateral ventricles. AF64A (AF/SAL) impaired performance of the standard RAM task and a working memory version of the task in which various delays were imposed between the fourth and fifth arm choices. In contrast, animals that received AGF2 and AF64A (AF/AGF2) were initially impaired on the standard RAM task but rapidly recovered and were performing as well as the control groups (CSF/SAL, CSF/AGF2) by the end of training. The AF/AGF2 group, however, exhibited persistent deficits on the working memory version of the RAM task. These data demonstrate that AGF2 promotes behavioral recovery in a task-dependent manner in this model system. Neurochemical analysis revealed that AF64A produced a significant 37% decrease in hippocampal ChAT activity that was significantly attenuated, but not prevented, by prior treatment with AGF2. Thus the behavioral recovery afforded by AGF2 might be related to increased cholinergic activity in the hippocampus that is sufficient for the performance of tasks which either lack or have a minimal working memory component. An analysis of the temporal profile of AGF2-induced neurochemical recovery revealed that ChAT activity was enhanced at 20, but not 2 or 11, weeks following AF64A. Since AGF2 did not attenuate the cholinergic cell loss (35%) induced by AF64A in the medial septum these data indicate that AGF2 might have (1) enhanced sprouting of cholinergic terminals following the initial insult, (2) directly increased ChAT activity in surviving neurons, or (3) induced behavioral and neurochemical recovery through a combination of these or other mechanisms.

Derivatives of ganglioside GM1 as neuronotrophic agents: comparison of in vivo and in vitro effects

Exogenously administered gangliosides have been shown to behave as neuronotrophic/neuritogenic agents in a variety of cell culture systems and animal models, but it is not known whether they operate by the same mechanism in vivo and in vitro. To probe this question we have employed two derivatives of GM1 lacking the negative charge: the methyl ester (GM1-CH3) and the NaBH4 reduction product of the latter (GM1-OH) in which the carboxyl group is replaced by a primary alcohol. Both derivatives proved to be as neuritogenic as GM1 in 3 cell culture systems: neuro-2A cels, PC12 cells and explanted dorsal root ganglia. However, GM1-OH proved ineffective when applied to two animal models involving reduction of cholinergic markers in: (a) hippocampus following lesion of the lateral fimbria and (b) nucleus basalis magnocellularis following cortical lesion; GM1-CH3 showed marginal activity in (a) but more in (b), possibly owing to slow hydrolysis to GM1 which was highly active in both animal models. These results indicate the necessity of a negative change on the ganglioside molecule for in vivo but not in vitro activity and point to different mechanisms for the trophic effects of exogenous gangliosides.

The role(s) of gangliosides in neural differentiation and repair: a perspective

Gangliosides, sialylated glycosphingolipids, are found in greatest concentration in the brain. While they were first characterized as a unique class of lipids almost 50 years ago, little is known regarding their actual function. It is known that (a) ganglioside composition changes during development, (b) different types of neural cells have specific gangliosides associated with them, (c) the accumulation of gangliosides in certain inborn errors of metabolism results in the formation of aberrant meganeurites, and (d) gangliosides appear to enhance recovery from certain neural traumas. Recent work suggests that it is the oligosaccharide portion of the ganglioside that carries much of the biological specificity. Coupled with observations that ganglioside-binding proteins are present on the plasma membranes of cells, it suggests the hypothesis that gangliosides present on the surface of one cell may interact with specific ganglioside-binding proteins, "receptors," on target cells. As a result of the ganglioside-binding protein interaction, a signal could be transmitted to the cell. This might occur via modulation of the effect of the endogenous ganglioside on the activity of a kinase(s) or by an alteration in ionic flux. The signal would initiate the appropriate cellular response.

Synthesis, structure, and conformation of the dilactone derivative of GD1b ganglioside

Treatment of DG1b, beta-Gal-(1----3)-beta-GalNAc-(1---- 4)-[alpha-Neu5Ac-(2----8)-alpha-Neu5Ac-(2---- 3)]-beta-Gal-(1----4)-beta-Glc-(1----1)-Cer, with dicyclohexylcarbodi-imide in anhydrous methyl sulfoxide affords 95-98% of GD1b-dilactone. The carboxyl groups of the two sialic acid units are involved in ester linkages, as proved by ammoniolysis and reduction which gave derivatives containing the amide of sialic acid and N-acetylneuraminulose, respectively. 1H-N.m.r. spectroscopy showed that the lactone rings involved position 9 of the inner sialic acid and position 2 of the inner galactose and that the disialosyl chain is extended toward the -beta-Gal-(1 ----4)-beta-Glc- portion of the ganglioside moiety.

Accumulation of arachidonic acid cyclo- and lipoxygenase products in rat brain during ischemia and reperfusion: effects of treatment with GM1-lactone

The aim of our study was to investigate the changes of various biochemical parameters (concentrations of lactate, free arachidonate, cyclo- and lipoxygenase products) in rat brain after ischemia and reperfusion and the effects of pretreatment with the ganglioside derivative GM1-lactone on the same parameters. Ischemia was induced by reversible occlusion of common carotid arteries for 20 min, which included a final 5 min of respiration of 5% oxygen in nitrogen. Reperfusion was obtained by removing the occlusion. Pre-ischemic conditions were obtained on sham-operated animals. Animals were killed by microwave irradiation of their heads. Brain levels of lactate and of free arachidonate were markedly increased after ischemia and returned to normal values at 5 min of reperfusion. Levels of the cyclooxygenase metabolites prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 were increased after ischemia, whereas levels of the lipoxygenase metabolite leukotriene C4 (LTC4) did not change. After reperfusion, a very marked increase of the cyclooxygenase products occurred but not of LTC4. Treatment with GM1-lactone prevented the elevation of cyclo- and lipoxygenase metabolites especially during reperfusion, with limited effects on lactate and free arachidonate levels.

Selective working memory impairments following intradentate injection of colchicine: attenuation of the behavioral but not the neuropathological effects by gangliosides GM1 and AGF2

Bilateral injection of 3.5 micrograms of colchicine into the dentate gyrus produced specific learning and memory impairments together with a selective pattern of neuropathology. Animals injected with colchicine exhibited a significant impairment in their ability to perform the working memory, but not the reference memory, component of a multiple component T-maze task. These deficits were transient and over time all animals were able to reaquire the task to preoperative levels of performance. Histological analyses revealed that intradentate injection of colchicine produced 1) a significant decrease in the width of both the superior and inferior blades of the dentate gyrus reflecting the extensive loss of granule cells, 2) a related decrease in the size of the dentate molecular layer, and 3) a decrease in the number of cholinergic neurons in the medial septum. The second phase of the experiment demonstrated that gangliosides GM1 and AGF2 did not prevent the initial impairments in working memory performance induced by colchicine but rather accelerated the rate at which it recovered. The gangliosides did not decrease the extent of neuronal damage; there was no sparing of granule cells in the dentate gyrus or cholinergic neurons in the medial septum. These data further support a role for the hippocampus in working memory processes and they also indicate that gangliosides GM1 and AGF2 might be useful for treating the behavioral deficits induced by hippocampal damage.

Synthesis and structural characterization of the dilactone derivative of GD1a ganglioside

Treatment of GD1a [alpha-Neu5Ac-(2----3)-beta-GalNAc-(1----4)-[alpha- Neu5Ac-(2----3)]-beta-Gal-(1----4)-beta-Glc-(1----1)-Cer] with dicyclohexylcarbodi-imide in anhydrous methyl sulfoxide affords 94-98% of GD1a-dilactone. The involvement of the carboxyl groups of the two sialic acid residues in the lactone rings was proved by ammoniolysis and reduction experiments, which gave ganglioside derivatives containing the amide of sialic acid and N-acetylneuraminulose, respectively. 1H-N.m.r. spectroscopy showed that the lactone rings involved position 2 of each galactose residue in the ester linkages.

Ganglioside treatment: reduction of CNS injury and facilitation of functional recovery

Increased attention has focused on the use of brain gangliosides as a treatment for brain injury. This review traces the progression of in vitro and in vivo research which led to studies which have demonstrated that ganglioside treatment can facilitate recovery after CNS damage in animal models (for example, lesions, transections, hypoxia, ischemia). Hypotheses regarding the ability of gangliosides to stimulate neuronal plasticity, modulate trophic factors and reduce injury processes are presented.

Gangliosides (GM1 and AGF2) reduce mortality due to ischemia: protection of membrane function

As evidenced by their ability to reduce cerebral edema, exogenous ganglioside administration exerts acute effects on CNS injury processes. We report here that ganglioside (GM1 or AGF2) treatment results in a 52% decrease in mortality 48 hours after the induction of ischemia in gerbils by permanent unilateral ligation of the common carotid artery. By comparing the occluded vs. nonoccluded sides of the brain (cortex and hippocampus) we found a significant loss of membrane Na, K-ATPase activity due to ischemia in control animals, but no such differences were found between the hemispheres of ganglioside-treated gerbils. We hypothesize that gangliosides may be "protecting" membrane function as indicated by these ATPase analyses, reducing local CNS damage at the time of injury (i.e., reduced cell loss, fiber degeneration, membrane failure). By acutely limiting the extent of CNS tissue damage, conditions may be optimized for any subsequent CNS regrowth and functional recovery.

Acute effects of GM1 ganglioside: reduction in both behavioral asymmetry and loss of Na+, K+-ATPase after nigrostriatal transection

GM1 ganglioside injections (i.p.) reduce amphetamine-induced asymmetric rotation in rats 48 h after a partial unilateral transection of the nigrostriatal pathway. We found that this reduction was maximal when rats received their first GM1 injection within 2 h after surgery. Rats injected 4-12 h after surgery, or rats only pretreated with GM1, showed no significant effect on rotation. Striatal membrane Na+,K+-ATPase in rats injected with GM1 0-2 h after hemitransection showed only a 10% loss in activity (versus the untransected hemisphere) as compared to control losses of 38%. The maintenance of membrane Na+,K+-ATPase activity in GM1-treated rats may be one mechanism by which a balance between hemispheres in striatal dopaminergic transmission is preserved, resulting in reduced asymmetric rotation. The observation that there is a critical postsurgical period when GM1 administration results in optimal functional recovery supports our hypothesis that gangliosides are exerting an acute effect on damaged CNS tissue. This acute effect is further evidenced by the reduced loss of membrane Na+,K+-ATPase following injury.

GM1 monosialoganglioside inner ester induces early recovery of striatal dopamine uptake in rats with unilateral nigrostriatal lesion

The experiments concerned the effect of parenteral administration of GM1 monosialoganglioside inner ester on the uptake of [3H]dopamine ([3H]DA) in synaptosomes prepared from the corpus striatum of rats with a unilateral lesion of the nigrostriatal pathway. In the animals treated with the ganglioside, starting on the 2nd day after lesion, the apparent Vmax of [3H]DA uptake (desipramine-insensitive) showed a marked recovery (from 10% to 33% of the controlateral side) as early as after 3 days of treatment, with no changes in the apparent Km values.