Gino Toffano

GM1 ganglioside stimulates the regeneration of dopaminergic neurons in the central nervous system

The effect of GM1 ganglioside on the recovery of nigro-strital dopaminergic neurons was studied in rats after unilateral hemitransection. We find that repeated administration of GM1 significantly increased the HVA content, the tyrosine hydroxylase activity and the tyrosine hydroxylase-related immunofluorescence in the striatum ipsilateral to the lesion. Futhermore, GM1 reduced the sensitivity of lesioned rats to apomorphine. The data comparable with the view that a functional dopaminergic reinnervation of the striatum is facilitated by GM1 treatments after hemitransection.

Changes in monamines and their metabolite levels in some brain regions of aged rats

The concentrations of dopamine (DA) norepinephrine (NE), serotonin (5HT) and their metabolites, HVA, DOPAC, MHPG-SO4 and 5HIAA were measured in several brain areas of rats aged 4, 18 and 29 months. Dopamine and its metabolites showed a decline, statistically correlated with age, in all the dopaminergic areas considered, indicating that this system is profoundly affected in the senescent rat. The changes in the noradrenergic system were more complex. This neurotransmitter was reduced in spinal cord and in limbic area, but was not modified in hippocampus, cerebellum, striatum and s. nigra. In cortex, MHPG-SO4, the main NE metabolite, showed a significantly age-related increase. Tyrosine hydroxylase (TH) activity was low in striatum, and brainstem but not in hypothalamus of aged rats. Neither 5HT nor its metabolites was affected by age. The results indicate that central catecholaminergic systems are markedly affected in senescent rats.

Chronic GM1 ganglioside treatment reduces dopamine cell body degeneration in the substantia nigra after unilateral hemitransection in rat

The effect of GM1 ganglioside on the recovery of dopaminergic nigro-striatal neurons was studied in rats after unilateral hemitransection. GM1 treatment partially prevented the decrease of tyrosine hydroxylase (TH) activity caused by hemitransection in the substantia nigra ipsilateral to the lesion. Concomitantly a significant increase of TH-immunoreactivity in the substantia nigra was also detected. In particular, chronic treatment with GM1 prevented the disappearance of TH-positive cell bodies in the substantia nigra and induced the appearance of longer TH-positive dendrites with respect to the saline treatment. These data indicate that GM1 treatment maintains the number of dopaminergic cell bodies in the substantia nigra after hemitransection by protecting against retrograde neuronal degeneration.

Biochemical changes of rat brain membranes with aging

Modification of membrane composition and enzymatic activities both in total brain homogenate and purified synaptic plasma membrane of 3 and 24 month old rats has been investigated. Protein, cholesterol and phospholipid content and (Na+, K+)ATPase and 2′, 3′ cyclic nucleotide phosphohydrolase activities were determined. The major changes occurred in the whole homogenate where a general increase in total protein and cholesterol content with age and a significant increase of the cholesterol/phospholipids molar ratio has been detected. In S.P.M. aging process induced a decrease of protein, cholesterol and phospholipids content associated with an increased membrane viscosity and a decrease of ΔE. These data are consistent with a change in the structural organization and in the distribution pattern of different cell population in the aging brain. A possible artifactual effect of freezing on the reported parameter is also discussed.

2 – Culture and Use of Primary and Clonal Neural Cells

Publisher Summary This chapter discusses procedures for preparing and culturing a variety of neural cell types. It discusses advantages and limitations as well as on some selected applications of these methods to neurobiological problems. Neural cell cultures have proved to be a basic and indispensable tool for identifying and purifying substances that influence the differentiation and maturation of the nervous system, for defining their cellular and molecular consequences, and for investigating the mechanisms eliciting these consequences. In vitro neural systems also serve to study interdependences between cell types, for example, neuronal and glial cells, associations believed to occur in vivo . The study shows that the plasticity of nerve cells is more evident in the cultures of neural tissue or cells in in vitro . Neuronal cultures provide the neuroscientist with a powerful tool for identifying and analyzing extrinsic agents affecting neuronal survival and development, and for investigating the underlying cellular and molecular events. The several types of neural cultures, such as clonal cell lines, explants, and monolayers can provide different and complementary views of neural behaviors. Monolayer neuronal cultures permit the widest opportunities for the quantitative analysis of both positive and negative microenvironmentally applied influences as well as parameters at the single-cell level.

Chronic phosphatidylserine treatment improves spatial memory and passive avoidance in aged rats

Learning/memory deficits in senescent animals are widely used as a tool to evaluate the therapeutic potential of agents for treatment of age-associated cognitive dysfunction. As assessed in the Morris water maze test, aged (21–24 months) rats showed a variable loss of spatial memory. Aged non-impaired rats performed as well as young subjects, while aged impaired rats exhibited a severe and persistent place-navigation, deficit. Passive avoidance retention was similarly affected in the two aged subpopulations. Chronic oral administration of phosphatidylserine (50 mg/kg/day for up to 12 weeks), a pharmacologically active phospholipid, was found to improve both the spatial memory and the passive avoidance retention of aged impaired rats. Results are discussed with reference to the phosphatidylserine-induced improvement of age-associated deterioration of brain functions in rats.

Dendritic spine loss in hippocampus of aged rats. Effect of brain phosphatidylserine administration.

Dendritic spine density of pyramidal cells in region CA1 of the hippocampus has been evaluated in young (3 months), old (27 months) and old phosphatidylserine (BC-PS)-treated rats. BC-PS (50 mg/kg, suspended in tap water) was administered daily, starting at the age of 3 months until 27 months. Spine density was analyzed on Golgi-stained pyramidal neurons by a computerized analysis system. In 27-month-old rats, spine density showed with respect to 3-month-old animals, a significant decrease in both basal and apical dendrites (p less than 0.01; one-way ANOVA), with a mean loss of 12.11% in the basal dendrites and of 10.64% in the apical ones. In 27-month-old rats treated with BC-PS, values of spine density were not statistically different when compared to those of 3-month-old animals. The mechanisms underlying the beneficial effect of BC-PS treatment on neuronal connectivity might be explained on the basis of its pharmacological actions on neuronal membranes [9], neurotransmission [43] and/or interaction with NGF [7].

Age-dependent spontaneous EEG bursts in rats: effects of brain phosphatidylserine

During aging, male Sprague-Dawley rats display increasing frequency of bursts of seizure-like EEG patterns. They also have a decreased retention of passive avoidance response and a loss of spontaneous alternation in a Y maze. A study was made on the effects of chronic administration of phosphatidylserine in aged rats. It was found that BC-PS reduced by 65% the number of seizures, and by 70% their duration. It also facilitated retention of passive avoidance and of spontaneous alteration behavior. These results suggest that phosphatidylserine can affect electrophysiological and behavioral parameters in aged rats probably by counteracting age-related biochemical changes.

Reversal of scopolamine-induced amnesia by phosphatidylserine in rats

Scopolamine (2 mg/kg IP) and propranolol (55 mg/kg IP), given before a single learning trial, reduce retention of a passive avoidance response in rats. Phosphatidylserine, 30–60 mg/kg IP, antagonizes the amnesic effect of scopolamine but not that of propranolol. The retention of the passive avoidance response is not affected by phosphatidylserine given alone. The results indicate that this phospholipid selectively counteracts the action of scopolamine on passive avoidance acquisition, probably via a cholinergic mechanism.

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

The effects of the administration of GM1 monosialoganglioside internal ester, AGF2, on the dopaminergic reinnervation of the striatum in rats with unilateral hemitransection has been studied. AGF2 increases the apparent Vmax and the density of tyrosine‐hydroxylase‐positive nerve terminals in the striatum of the lesioned side, without modification of the tyrosine‐hydroxylase activity in the unlesioned side. AGF2, at lower doses, is more active than its parent natural molecule GM1. AGF2 has a larger half‐life and a higher distribution volume than GM1, and undergoes a slow hydrolysis in the serum releasing the original natural compound GM1. Mannitol and dexamethazone, often used to prevent swelling of the brain after injury, or isoaxonine, proposed to stimulate neurite growth are unable to reproduce the effects of AGF2 on the recovery of striatal tyrosine‐hydroxylase activity after hemitransection. The data are compatible with the view that AGF2, through its conversion into GM1, facilitates the collateral sprouting of the nigro‐striatal dopaminergic neurons.