C-fos expression in the rat nucleus basalis upon excitotoxic lesion with quisqualic acid: a study in adult and aged animals

Acute effect of methylprednisolone on the brain in a rat model of allergic asthma

Asthma affects not only the airways but also the central nervous system (CNS). Corticosteroids are an effective therapeutic agents for asthma. In our study, we investigated the acute effect of ovalbumin (OVA) on the brain and the effectiveness of methylprednisolone (MP) in both the periphery and CNS in a rat model of allergic asthma. Rats sensitized to OVA and exposed to OVA aerosol challenge to induce allergic asthma were compared with control rats and rats sensitized to OVA and pretreated with MP before OVA exposure. In response to OVA stimulation, the amount of c-Fos and glial fibrillary acidic protein (GFAP) increased, while that of neuronal nitric oxide synthase (nNOS) decreased in the nucleus tractus solitarius (NTS). In addition, the c-Fos, GFAP, and nNOS levels in the hippocampus and the nNOS levels in the olfactory bulb increased. However, the expression of these proteins in the frontal and cerebellar cortices was not affected by OVA stimulation. In contrast, pretreatment with MP before OVA exposure decreased the protein expression of c-Fos in the CA1 area, GFAP in NTS, and nNOS in CA1 and olfactory bulb, and while it increased the nNOS content in the NTS. These findings suggest that the brain responds to OVA stimulation in a rat model of allergic asthma and that MP treatment cannot only ameliorate airway inflammation but also OVA-induced effects.

Behavioral and immunohistological effects of cholinergic damage in immunolesioned rats: Alteration of c-Fos and polysialylated neural cell adhesion molecule expression

The aim of this study was to determine the brain structures as well as the plasticity events associated with the behavioral effects of cholinergic damage. Rats were submitted to injection of 192 IgG-saporin in the medial septum/diagonal band of Broca complex and the nucleus basalis magnocellularis. The immunohistochemical expression of c-Fos protein and PSA-NCAM (polysialylated neural cell adhesion molecule) and the behavioral performances in the nonmatching-to-position task were assessed at various post-lesion times. Thus, 3 days after injection of the immunotoxin, increased c-Fos labeling was observed in the areas of infusion, indicating these cells were undergoing some plastic changes and/or apoptotic processes. A drastic increase was observed in the number of PSA-NCAM positive cells and in their dendritic arborization in the dentate gyrus. At 7 days post-lesion, no behavioral deficit was observed in immunolesioned rats despite the drastic loss of cholinergic neurons. These neurons showed decreased c-Fos protein expression in the piriform and entorhinal cortex and in the dentate gyrus. In the latter, PSA-NCAM induction was high, suggesting that remodeling occurred, which in turn might contribute to sustaining some mnemonic function in immunolesioned rats. At 1 month, cholinergic neurons totally disappeared and behavioral deficits were drastic. c-Fos expression showed no change. In contrast, the increased PSA-NCAM-labeling observed at short post-lesion times was maintained but the plastic changes due to this molecule could not compensate the behavioral deficit caused by the immunotoxin. Thus, as the post-lesion time increases, a gradual degeneration process should occur that may contribute to mnemonic impairments. This neuronal loss leads to molecular and cellular alterations, which in turn may aggravate cognitive deficits.

NGF treatment potentiates c-fos expression in the rat nucleus basalis upon excitotoxic lesion with quisqualic acid

The induction of the c-fos gene in the rat brain by NGF was studied in a model of acute cholinergic hypofunction, i.e., the lesion of the nucleus basalis magnocellularis (NBM) with quisqualic acid. Choline acetyltransferase and Fos immunoreactivity (IR) in the NBM were analyzed at different times after the excitotoxic lesion. NGF treatment induced a potentiation of Fos expression 4 and 24 h after lesion. The possibility is discussed that c-fos induction is one of the early mechanisms of the neuroprotective action of NGF.

c-fos expression in brains of patients with Down syndrome

c-fos is a protooncogene serving in multiple physiological processes in brain from signalling to proliferation and synaptic plasticity. We therefore decided to determine this transcription factor in control and Down Syndrome (DS) brain with the Rationale that c-fos may be linked to brain damage in DS. We determined mRNA steady state levels in frontal, parietal, occipital, temporal cortex and cerebellum of 9 patients with DS and 9 controls using RT-PCT. Significantly increased levels of mRNA c-fos normalized versus the housekeeping gene beta-actin mRNA were found in frontal, parietal and temporal cortex of DS brain. c-fox mRNA levels comparable to controls were found in occipital cortex and cerebellum. Deteriorated c-fos expression in the individual brain regions may be linked to increased apoptosis and neurodegeneration, overexcitation by excitatory amino acids of reactive oxygen species.