Guido Vantini

Choline acetyltransferase messenger RNA expression in developing and adult rat brain: regulation by nerve growth factor

The polymerase chain reaction (PCR) was used to develop a method for detection and relative quantification of the choline acetyltransferase (ChAT) mRNA in neonatal and adult rat CNS. Oligonucleotide primers derived from a porcine ChAT cDNA sequence were used in coupled reverse transcriptase (RT)-PCR to amplify a cDNA sequence of 206 bp which arises in a cycle- and RNA-dependent manner and which hybridizes with both an internal oligonucleotide and a ChAT cDNA probe. ChAT mRNA was detected in spinal cord, septal area, striatum, cortex and hippocampus but not in cerebellum and cardiac or skeletal muscle. In the septal area, relative quantitative evaluation of ChAT mRNA levels by RT-PCR indicates that this transcript is developmentally regulated and increased following intracerebral administration of nerve growth factor (NGF) to both neonatal and young adult rats. This suggests that the increases of ChAT activity observed in basal forebrain during development or after NGF administration are, at least in part, associated with an increase in corresponding levels of mRNA.

GM1 ganglioside potentiates the effect of nerve growth factor in preventing vinblastine-induced sympathectomy in newborn rats

The effects of vinblastine (VNB) and nerve growth factor (NGF) administrations were assessed on sympathetic nerve terminals by measuring the noradrenaline (NA) content in the heart, spleen and kidneys of developing animals. Six-day-old rats, treated with 0.15 mg/kg VNB on postnatal day 3 (P3) showed a dramatic decrease of NA content in all these organs. This reduction was prevented by daily administrations of NGF on P3, P4 and P5. The effectiveness of NGF in inhibiting the VNB-induced sympathectomy was related to the dose administered and to the time interval between the VNB administration and the first NGF injection given on P3. Dose-response curves to NGF (ranging from 0.01 to 0.5 mg/kg) were obtained in both heart and spleen of VNB-treated animals. Thus, this experimental paradigm provides a quantitative assessment of the NGF activity in vivo. The systemic administration of GM1 (30 mg/kg) on P3, P4 and P5, was able to potentiate the NGF activity in preventing the VNB-induced sympathectomy. This GM1 effect was more evident in the heart and may be, at least in part, attributed to increased NGF prevention of neuronal cell death due to VNB. These results suggest an in vivo interaction between exogenous GM1 and NGF and are consistent with the view that neuronal cell repair related to in vivo administration of this ganglioside may rely on its capability to modulate the activity of endogenously occurring neuronotrophic factors.

Nerve growth factor does not influence the expression of β amyloid precursor protein mRNA in rat brain: in vivo and in vitro studies

Abstract We investigated the effect of NGF on amyloid precursor protein (APP) mRNA levels in the rat septal/nucleus basalis system. Total APP mRNA and APP 695 mRNA were determined in basal forebrain primary cell cultures exposed acutely and chronically to NGF (150–300 ng/ml) and, in vivo, in the septal area and striatum of rat pups after multiple intracerebroventricular injections of NGF. The trophic factor was able to affect cholinergic neurons in both paradigms, as evidenced by the significant increase of choline acetyltransferase (ChAT) activity induced by NGF in cell cultures (+80%) and in the striatum (+240%) of rat pups. In spite of this effect, no significant change of APP mRNA expression was observed in neuronal cultures and brain tissues. These data indicate that the neurotrophic effect of NGF on forebrain cholinergic neurons is not always associated with an alteration of APP expression.

Intracerebroventricular administration of nerve growth factor affects muscarinic cholinergic receptors in the cerebral cortex of neonatal rats

The repeated intracerebroventricular administration of nerve growth factor (5 micrograms/2.5 microliters) to neonatal rats induced the activation of choline acetyltransferase in forebrain cholinergic neurons that was paralleled by a concomitant change in the density of muscarinic cholinergic receptors in the cerebral cortex. The administration of nerve growth factor altered muscarinic binding sites in a biphasic fashion during postnatal development. A significant stimulation of the developmental increase in the density of muscarinic binding sites occurred in nerve growth factor-treated animals at days 2 and 3 after birth. Conversely, nerve growth factor induced a significant decrease in the receptor number at postnatal days 8 and 14. Muscarinic receptor number returned to control values after treatment, suggesting that nerve growth factor-induced changes to muscarinic cholinergic receptors are reversible. Nerve growth factor administration did not affect muscarinic cholinergic receptor density in striatal membranes and did not alter the relative content of cortical messenger RNAs encoding m1 and m3 muscarinic cholinergic receptor subtypes at postnatal day 14, as determined by reverse transcriptase-polymerase chain reaction. The up- and down-regulation of muscarinic cholinergic receptors induced by nerve growth factor during postnatal development may be temporally related events associated with concomitant changes in the activity of choline acetyltransferase.

Ganglioside Involvement in Membrane-Mediated Transfer of Trophic Information

The systemic administration of GM1 monosialoganglioside has been shown to ameliorate outcome following injury to the adult mammalian central nervous system. In addition, cultured neurons, both primary and clonal, are known to respond to the ganglioside with pronounced morphological changes characteristic of cell differentiation. In cells with an absolute requirement for a neuronotrophic factor for survival and/or neurite outgrowth, the GM1 effects are associated with amplification of the effects of the trophic factor on its target neuronal cells.

Monosialoganglioside GM1 and Modulation of Neuronal Plasticity in CNS Repair Processes

Today we understand the brain as a dynamic, not static, organ. Central nervous system (CNS) neurons are endowed with the capacity to react to chemical signals presented from their microenvironment with morpho-functional modifications, a process termed plasticity. This phenomenon has provided the foundation for studies directed at elucidating the pathophysiological correlates of neuronal life and death, with the ultimate objective of developing strategies to improve neurological outcome following various types of CNS insults, in particular cerebrovascular insufficiency (stroke), head and spinal trauma, and neurodegenerative diseases.

Monosialogangliosides and Their Action in Modulating Neuroplastic Behaviors of Neuronal Cells

The phenomenon of neuronal plasticity reflects the ability of nerve cells to modify their behaviors under the influence of extrinsic agents. As with any living system, neural tissue represents a dynamic organization, whose elements are continuously changing due to interactions with one another and with their extraneural environment. Neurons are thus subject to influences from the extracellular fluid and matrix, and the other cells with which they are in direct contact. This array of extrinsic influences impinging on the neuron constitutes, in broad terms, what can be called the microenvironment of these cells. Because of their many origins and functions, agents affecting neuronal behaviors represent a crucial and diverse element in determining how nerve cells will respond to cues from the microenvironment. As we shall see later on, these cues can carry either positive or negative signals for the neuron. Our ability to alter the response(s) of neuronal cells to such extrinsic agents will constitute a powerful tool for modulating the neuroplastic behaviors of the former — an important consideration for effecting regeneration and repair processes in the brain. Such is the subject of the present chapter.

Effect of Nerve Growth Factor on Lesioned and Intact CNS

The presence of nerve growth factor (NGF) in the central nervous system (CNS) and its capability to affect “in vitro” and “in vivo” basal forebrain cholinergic neurons was reported in the early 1980s (Crutcher and Collins, 1982; Honegger and Lenoir, 1982; Gnahn et al., 1983). These observations have led to the hypothesis that NGF might exert a trophic action on selected neuronal cell populations of the CNS. Since these initial reports, many experiments have strengthened the notion that forebrain cholinergic neurons use NGF as a trophic factor (Hefti et al., 1989; Barde, 1989; Vantini et al., 1989). In addition, other CNS neuronal cell populations seem to respond to NGF including retinal ganglion cells (Carmignoto et al., 1989) and cerebellar Purkinje cells (Cohencory et al., 1991).