Lesion profiles and gliosis in the brainstem of 135 Swiss cows with bovine spongiform encephalopathy (BSE).

Lesion profiles are considered to be an important tool for the comparison of the various animal and human spongiform encephalopathies and to obtain information upon prion strain variations. Histological and immunohistochemical reactions (PrPsc, GFAP) in 13 brain areas at 4 levels in the brainstem from 135 BSE-positive and 45 BSE-negative cases were retrospectively evaluated. In this retrospective study a lesion profile based on histological features was worked out on the basis of BSE cases originating from Switzerland over a period of ten years. They were confirmed post mortem by histology and immunohistology. Our findings were reviewed in comparison with lesion profiles published in England. No striking differences comparing type and quality of lesions in the relevant areas between the Swiss and the English cases were evident. Moreover, the lesion profiles and the character of the lesions did not differ between animals born before or after the offal feeding ban, which supports the hypothesis that the Swiss epidemic is sustained by the same single, stable strain of the BSE agent, which is probably the same as in the English epidemic. There was a good correlation between PrPsc accumulation and spongiform changes, in particular in those areas which were morphologically most affected. Astrocytosis in BSE was quantified. A significant rise in GFAP-positive cells could be shown comparing the brain stem nuclei of BSE affected with BSE-unaffected cattle, despite considerable variation between the cases and between the nuclei. The observed astrocytosis did correlate with vacuolation of the neuropil and of perikarya as well as with PrPsc accumulation.

Distribution of alpha-neoendorphin immunoreactivity in the diencephalon and the brainstem of the dog.

Alpha-neoendorphin (alpha-NE) is an opiate decapeptide derived from the prodynorphin protein. Its anatomical distribution in the brain of mammals other than the rat, particularly in carnivores, is less well known than for other opiate peptides. In the present work, we have charted the distribution of alpha-NE immunoreactive fibers and perikarya in the diencephalon and the brainstem of the dog. The highest densities of labeled fibers were found in the substantia nigra and in patches within the nucleus of the solitary tract. Moderate densities appeared in the arcuate nucleus (Ar), median eminence, entopeduncular nucleus, ventral tegmental area, retrorubral area, periaqueductal central gray, interpeduncular nucleus and lateral parabrachial nucleus. Groups of numerous labeled perikarya were localized in the magnocellular hypothalamic nuclei, Ar and in the central superior and incertus nuclei in the metencephalon. Moreover, less densely packed fibers and cells appeared widely distributed throughout many nuclei in the region studied. These results are discussed with regard to the pattern described in other species. In addition, the present results were compared with the distribution of met-enkephalin immunoreactivity in the diencephalon and the brainstem of the dog that we have recently described. Although the distributions of these two peptides overlap in many areas, the existence of numerous differences suggest that they form separate opiate systems in the dog.

Immunohistochemical localization of atrial natriuretic factor and autoradiographic distribution of atrial natriuretic factor-binding sites in the brain of the cave salamander Hydromantes genei (Amphibia, Plethodontidae).

The distribution of atrial natriuretic factor (ANF)-like immunoreactivity in the central nervous system of the cave salamander Hydromantes genei (Amphibia, Plethodontidae) was investigated by using antisera raised against rat and human ANF(1-28). Concurrently, the location of ANF-binding sites was determined by autoradiography, using radioiodinated human ANF(1-28) as a tracer. In several regions of the brain, including the olfactory bulb, the preoptic area, the ventral thalamus, the tectum of the mesencephalon, and the choroid plexuses inside the ventricles, a good correlation was observed between the distribution of ANF-immunoreactive elements and the location of ANF-binding sites. Mismatching was found in the habenular nucleus, the commissura habenularis, the fasciculum retroflexus, and the interpeduncular nucleus, which contained high levels of binding sites but were devoid of ANF-immunoreactive structures. In contrast, a few other regions, such as the pineal gland and the subcommissural organ, showed a high concentration of ANF-like immunoreactivity but did not contain ANF-binding sites. This study provides the first localization of ANF-like immunoreactivity and ANF-binding sites in the brain of an urodele amphibian. The results show that the ANF peptidergic system in the cave salamander has an organization more simple than the organizations described for the brain of frog or other vertebrates. This feature is probably related to the expression of highly pedomorphic characters in plethodontids. The anatomical distribution of ANF-immunoreactive elements and ANF-binding sites suggests that ANF-related peptides may act as hypophysiotropic hormones as well as neurotransmitters and/or neuromodulators in the salamander brain.

The metencephalic floor plate of chick embryos expresses two secretory glycoproteins homologous with the two glycoproteins secreted by the subcommissural organ.

The nature and the function of the compounds secreted by the floor plate (FP) of the metencephalon are little known. The FP cells of the hindbrain react with antibodies (AFRU) against the glycoproteins secreted by the subcommissural organ (SCO). One of the these proteins, RF-Gly I, is a 540-kDa core glycosylated protein. The aims of the present investigation were to identify by immunoblot the AFRU-immunoreactive compound secreted by the FP of chick embryos, to establish temporal and regional patterns of this secretory activity, and to obtain information about the fate of these compounds. It was established that the SCO and FP of chick embryos secrete two AFRU-immunoreactive compounds of 540 and 230 kDa. The two compounds secreted by the FP have been designated as FP-Gly I and FP-Gly II. The expression of these proteins was circumscribed to the metencephalic FP, and occurred from HH 29 to HH 36. Within the FP cells, FP-Gly I and FP-Gly II were confined to the supranuclear and apical regions, which under the electron microscope displayed numerous cisternae of the rough endoplasmic reticulum and granules. Aggregates of AFRU-immunoreactive material appeared on the free surface of the FP. The possibility that FP-Gly I and FP-Gly II are released into the ventricle to reach distant targets is discussed.

Distribution of parvalbumin immunoreactivity in the brain of the tench (Tinca tinca L., 1758).

The distribution of parvalbumin (PV) immunoreactivity in the tench brain was examined by using the avidin-biotin-peroxidase immunocytochemical method. This protein was detected in neuronal populations throughout all main divisions of the tench brain. In the telencephalic hemispheres, PV-immunopositive neurons were distributed in both the dorsal and ventral areas, being more abundant in the area ventralis telencephali, nucleus ventralis. In the diencephalon, the scarce distribution of PV-containing cells followed a rostrocaudal gradient, and the most evident staining was observed in the nucleus periventricularis tuberculi posterioris and in a few nuclei of the area praetectalis. In the mesencephalon, abundant PV-immunoreactive elements were found in the tectum opticum, torus semicircularis, and tegmentum. In the tectum opticum, PV-immunoreactivity presented a laminar distribution. Three PV-containing neuronal populations were described in the torus semicircularis, whereas in the tegmentum, the PV staining was mainly located in the nucleus tegmentalis rostralis and in the nucleus nervi oculomotorii. In the metencephalon, Purkinje cells were PV-immunopositive in the valvula cerebelli, lobus caudalis cerebelli, and in the corpus cerebelli. In the myelencephalon, PV immunoreactivity was abundant in the nucleus lateralis valvulae, in the nucleus nervi trochlearis, nucleus nervi trigemini, nucleus nervi abducentis, nucleus nervi glossopharyngei, and in the formatio reticularis. Mauthner cells were also PV immunostained. By contrast to other vertebrate groups, only a restricted population of PV-containing neurons was GABA-immunoreactive in the tench, demonstrating that this calcium-binding protein cannot be considered a marker for GABAergic elements in the teleost brain. This study demonstrates a low phylogenetic conservation of the distribution of PV comparing teleosts and tetrapods.