Maedi-visna: the meningoencephalitis in naturally occurring cases.

Lesions were examined at different levels of the central nervous system (CNS) in 64 sheep with natural maedi-visna (MV) meningoencephalitis. All animals showed lesions in more than one of the CNS locations examined; the lesions in the cranial regions were periventricular, while those in the spinal cord affected the white matter funicles. Lesions were found particularly in the cerebellar peduncles (non-suppurative meningoencephalitis), followed by the corpus callosum, hippocampus and thoracic spinal cord. Vascular, infiltrative and malacic histopathological patterns were recognized. One pattern predominated in each section examined, although mixed forms occurred. Vascular lesions occurred with similar frequency at all CNS levels, but infiltrative and malacic lesions predominated at rostral and caudal levels, respectively. Cells consistent with macrophages and shown immunohistochemically to be associated with MV virus were seen in malacic and infiltrative lesions, at the periphery of damaged areas.

Brain response to cecal infection with Campylobacter jejuni: analysis with Fos immunohistochemistry.

Infections with bacterial pathogens can induce increased anxiety-like behaviors in rodents without otherwise noticeable behavioral or physiological symptoms of sickness, as shown with the food-borne pathogen Campylobacter jejuni. This observation implicates the ability of the brain to sense, and respond to, such an infection. We tested our hypothesis that intestinal infection with the gram-negative bacterium C. jejuni leads to activation of certain brain regions that process gastro-intestinal sensory information. The induction of c-Fos protein as a marker for neuronal activation was assessed in the brains of mice inoculated orally with live C. jejuni, as compared to saline-treated controls. Upon colonization of the intestines, C. jejuni activated visceral sensory nuclei in the brainstem (the nucleus of the solitary tract and the lateral parabrachial nucleus) both one and two days after the oral challenge. In addition, increased c-Fos expression occurred in the hypothalamic paraventricular nucleus on the second day. This neural response occurred in the absence of measurable systemic immune activation, as serum levels of tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 were undetectable and/or unchanged. These findings support the notion that information about infection with C. jejuni in the gut is indeed relayed to the visceral sensory structures in the brain. The brain responses observed could contribute to changes in behavior observed after infection.

Differential expression of inflammatory mediators in rat microglia cultured from different brain regions.

Microglial cells show a rather uniform distribution of cell numbers throughout the brain with only minor prevalences in some brain regions. Their in situ morphologies, however, may vary markedly from elongated forms observed in apposition with neuronal fibers to spherical cell bodies with sometimes extremely elaborated branching. This heterogeneity gave rise to the hypothesis that these cells are differentially conditioned by their microenvironment and, therefore, also display specific patterns of differential gene expression. In this study, microglia were isolated from 2-4 week-old mixed CNS cultures that had been prepared from neonatal rat diencephalon, tegmentum, hippocampus, cerebellum and cerebral cortex, and were investigated 24 h later. Messenger RNA levels of proteins involved in crucial immune functions of this cell type (TNF-alpha, CD4, Fcgamma receptor II, and IL-3 receptor beta-subunit) have been determined by semi-quantitative RT-PCR. The results clearly show, that three of these mRNAs (TNF-alpha, CD4, Fcgamma receptor II) are differentially expressed in microglia with hippocampal microglia displaying the highest levels of these mRNAs. The data strongly support the notion that the status of microglial gene expression depends on their localization in brain and on specific interactions with other neural cell types. Consequently, it is hypothesized that their responsiveness to signals arising in injury or disease may vary from one brain region to another.

Differential vasopressin and oxytocin innervation of the human parabrachial nucleus: no changes in Alzheimer's disease.

The distribution of vasopressin and oxytocin immunoreactive fibers was examined in the pontine parabrachial nucleus of the human brain using purified polyclonal antibodies. The results revealed a striking predominance of vasopressin in this brain region. No obvious density difference, either in vasopressin or in oxytocin innervation, was found between Alzheimer's disease patients and matched controls. The present study corroborates other reports that suggest that in Alzheimer's disease the vasopressin innervation in the caudal part of the human brain is not affected.

Antibody in the CSF of patients with multiple system atrophy reacts specifically with rat locus ceruleus.

Idiopathic chronic autonomic dysfunction may occur as pure autonomic failure (PAF) or in association with multiple system atrophy (MSA). CSF immunoreactivity to rat locus ceruleus occurred in a significantly greater number of samples from MSA patients compared to control subjects or patients with PAF. Other brain regions infrequently showed immunoreactivity. These findings suggest that degeneration in MSA may release antigen(s) that induce antibodies against locus ceruleus neurons. Further studies are required to determine whether immune abnormalities play a pathogenetic role in MSA. Lack of CSF immunoreactivity in PAF is consistent with primarily peripheral involvement.

An antibody in the CSF of Parkinson's disease patients disappears following adrenal medulla transplantation.

CSF from Parkinson's disease (PD) patients undergoing autologous transplantation of adrenal medulla tissue into their lateral ventricle was examined for the presence of IgG. CSF from 6 of 7 patients incubated with rat brain tissue reacted immunocytochemically to neuronal cell bodies in the substantia nigra and ventral tegmental region. This reactivity gradually disappeared in the months following transplantation. Five of 6 CSF samples from non-transplanted PD patients also produced this immunocytochemical reactivity whereas 26 non-PD samples were immunonegative. Possible implications to the transplant procedure are discussed.

The histological effects of intracerebral injection or infusion of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and MPP+ (1-methyl-4-phenylpyridinium) in rat and mouse.

Bilateral infusion of MPTP into the substantia nigra, ventral tegmental area or putamen of the rat brain provoked accumulation of leucocytes, but the periphery of nigral lesions showed no significant nerve cell loss. Tyrosine hydroxylase labelling of dopaminergic perikarya showed a normal staining pattern. In contrast, MPP+ was more destructive. After one day there was local degeneration of neuronal and glial elements. After one month there was tissue necrosis and central cavitation, but, like MPTP, there was no evidence of selective nigral cell loss. Striatal injection of MPP+ also failed to produce retrograde nigral damage. It is concluded that the toxicity of MPP+ applied directly to the dopamine system is a consequence of a severe non-selective necrotic lesion.

Somatostatin-like immunoreactivity in the midbrain of the cat.

Somatostatin (SS) immunoreactivity was localized in cat brain sections with an immunoperoxidase technique. Cell bodies in the midbrain containing SS immunoreactivity were found in the superficial and intermediate gray layers of the superior colliculus, the interpeduncular nucleus, the raphe, the inferior colliculus and nucleus of its brachium, the nucleus of the optic tract, and the lateral tegmental field. Additional positive neurons were seen in the parabigeminal nucleus and in the dorsal periaqueductal gray in kitten material. Immunoreactive fibers were observed in the periaqueductal gray and in the midbrain tegmentum, with particularly dense labeling just dorsal to the substantia nigra and in the parabrachial nuclei. This is the first report of the distribution of SS immunoreactivity in the midbrain of the cat. It is concluded that somatostatin has a distribution compatible with a role as a major neurotransmitter/neuromodulator within certain midbrain nuclei, especially the interpeduncular nucleus and the superior colliculus.