Immunocytochemical localization of acyl-CoA oxidase in the rat central nervous system

Peroxisomal β-oxidation, consisting of four steps catalysed by an acyl-CoA oxidase, a multifunctional protein and a thiolase, is responsible for the shortening of a variety of lipid compounds. The first reaction of this pathway is catalysed by a FAD-containing acyl-CoA oxidase, three isotypes of which have been so far recognised. Among these, straight-chain acyl-CoA oxidase (ACOX) acts on long and very long chain fatty acids, prostaglandins and some xenobiotics. We investigated ACOX localisation by means of a sensitive, tyramide based, immunocytochemical technique, thus obtaining a complete distribution atlas of the enzyme in adult rat CNS. Granular immunoreaction product was found in the cytoplasm of neuronal and glial cells, both in the perikarya and in the cell processes. ACOX immunoreactive neurons were present to variable extent, in either forebrain or hindbrain areas. Specifically, the strongest signal was detected in the pallidum, septum, red nucleus, reticular formation, nuclei of the cranial nerves, and motoneurons of the spinal cord. We then compared the ACOX immunoreactivity pattern with our previous distribution maps of other peroxisomal enzymes in the adult rat brain. While ACOX appeared to colocalise with catalase in the majority of cerebral regions, some differences with respect to d-amino acid oxidase were noted. These observations support the hypothesis of heterogeneous peroxisomal populations in the nervous tissue. The wide distribution of the enzyme in the brain is consistent with the severe and generalised neurological alterations characterising the peroxisomal disorder caused by ACOX deficiency (pseudo-neonatal adrenoleukodystrophy).     

Immunocytochemical evidence for the presence of oxytocin in rat testis

Summary The presence of oxytocin, vasopressin and neurophysin in the testis of adult Wistar and Brattleboro rats has been examined immunocytochemically. After fixation in modified Bouin's solution, or Bouin's sublimate fixative, immunostaining was accomplished with the peroxidase-antiperoxidase method. The presence of immunoreactive oxytocin was demonstrated in 80% of the interstitial cell population of both rat strains while no staining was observed for vasopressin or neurophysin.     

Immunocytochemical localization of the precursor protein for beta-amyloid in the rat central nervous system

Two rabbit polyclonal antibodies generated against different portions of the amyloid precursor protein were used to localize this protein in normal rat brain. Light and electron microscopic immunohistochemical localizations demonstrate that the protein is widely distributed throughout the neuraxis, with the highest concentrations of immunoreactive neurons occurring in the olfactory bulb, cerebral cortex, septum-diagonal band, globus pallidus, cerebellum, and hippocampus. Immunoreactive astrocytes are also present in the cerebral cortex in relation to both neurons and capillaries. However, immunoreactivity was not observed within the endothelium of the cerebral vasculature. These data demonstrate that the beta-amyloid precursor is widely distributed in the CNS and provide further insight into the cellular elements that may be involved in the neuropathological changes associated with Alzheimer's disease.     

Immunocytochemical evidence for the specific localization of aldose reductase in rat Sertoli cells

Evidence that the enzyme aldose reductase (AR) is specifically located in Sertoli cells is presented by means of an established immunocytochemical technique and with a variety of approaches. By staining tissue sections, the enzyme was shown to be present in Sertoli cells at birth and the intensity of the immunocytochemical stain increased by 5 days of age to that found in the testes of older rats. By means of enzyme dispersion of mature testes; the culture of enriched Sertoli cell preparations from the testes of immature rats; and the collection of newly released testicular spermatozoa in rete testis fluid, it was shown that immunoreactive AR was not present in any testicular cell type except the Sertoli cell. The significance of the specific localization in Sertoli cells of a principal enzyme concerned in the sorbitol or polyol pathway for the conversion of aldose sugars to their corresponding ketoses is discussed.     

Immunocytochemical evidence for the presence of an albumin-like substance in the rat pineal gland

Summary Two rabbits and two guinea pigs were immunized with arginine vasotocin (AVT) conjugated to bovine albumin with glutaraldehyde. Only one preparation of antiserum (anti-G 7) was of value. Anti-G 7 immunochemically defined the same rat pineal cells previously reported as presumptive AVT cells. However, absorption of anti-G 7 with bovine albumin inhibited the staining of the pineal cells demonstrating that they contained an albumin-like substance. Positive immunochemical staining of the rat pars nervosa suggested that anti-G 7 contained antibodies able to react with arginine vasopressin (AVP). Loss of a positive reaction in the posterior lobe on absorption of anti-G 7 with AVT or AVP confirmed this. However, the addition of AVT to anti-G 7 failed to inhibit the immunochemical staining of the pineal cells. This study reports the presence of an albumin-like substance in pineal cells previously described as presumptive AVT cells, and discusses possible explanations for the inability of anti-G 7 to recognize immunocytochemically the native AVT molecule. Confirmation of AVT in the pineal gland by immunocytochemistry must await the availability of more specific antisera.     

Immunocytochemical identification of nuclear structures containing snRNPs in isolated rat liver cells

Small nuclear ribonucleoproteins (snRNPs) containing U1, U2, U4, U5, and U6 small nuclear RNAs were detected by ultrastructural immunocytochemistry in the nuclei of isolated rat hepatocytes using Fab fragments of anti-Sm and anti-RNP autoantibodies. Their localization was carried out in normal cells and in cells treated with two drugs, the adenosine analog DRB and CdCl2, which alter the number and distribution of nuclear RNP components. It was found that more precise determination of the distribution of these small RNAs could be obtained by using two complementary procedures in parallel rather than either one alone. They consisted of an indirect immunoperoxidase labeling carried out before embedment and an indirect immunogold labeling applied to thin sections of cells embedded in Lowicryl K4M. The results indicate that snRNPs are associated with all extranucleolar perichromatin fibrils and granules and interchromatin fibrils, which confirms that they occur in structures involved in the synthesis and processing of hnRNA. The snRNPs are not associated with nucleolar perichromatin granules induced by DRB, which confirms that there may be two kinds of perichromatin granules. The snRNPs are also associated with the still enigmatic interchromatin granules which apparently do not contain hnRNA but at least in DRB-treated cells, also contain ribosomal RNA.     

Cellular receptors of gonadotropic hormones. Immunocytochemical evidence in rat testicle]

We have performed topical applications of HCG and LH on fixed paraffin-embedded sections of adult rat testes. Thereafter, immuno-cytochemical demonstration of the peptides was carried on and demonstrated that HCG and LH specifically bound to the cell membrane of Leydig cells. This technique is highly reproductible provided that adequate fixation (with formalin containing fixatives) as been performed.     

Immunocytochemical localization of glycogen phosphorylase in primary sensory ganglia of the peripheral nervous system of the rat

Neuronal localization was investigated of glycogen phosphorylase (GP) in ganglia of the peripheral nervous system of the rat. Immunofluorescence and immunoenzymatic procedures were applied with a monoclonal anti-bovine brain GP antibody on paraformaldehyde-fixed, paraffin-embedded tissues. Immunoreactivity was only present in the somatic neurons of the mesencephalic trigeminal nucleus in the brain stem and in dorsal root ganglia (DRG), but not in the autonomic neurons of the superior cervical ganglia or in the sensory nuclei of the spinal cord. GP immunoreactivity was present as early as day 1 after birth. In the adult rat, staining was present in neurons of different sizes, and to varying intensities. No relationship was apparent between the staining intensities and morphologically distinguishable types of neurons. In DRG, the type of reactivity was the same from cervical to sacral ganglia. The selected occurrence of GP in specific neurons of the peripheral nervous system in contrast to the ubiquitous occurrence in all astrocytes of the central nervous system may indicate a different role of neuronal glycogen compared to astrocytic glycogen.     

Immunocytochemical localization of glycogen phosphorylase isozymes in rat nervous tissues by using isozyme-specific antibodies

Isozyme-specific antibodies were raised against peptides from the low-homology regions of the sequences of rat glycogen phosphorylase BB and MM isozymes by immunization of rabbits and guinea pigs. Immunocytochemical double-labelling experiments on frozen sections of rat nervous tissues were performed to investigate the isozyme localization pattern. Astrocytes throughout the brain and spinal cord expressed both isozymes in perfect co-localization. Ependymal cells only expressed the BB isozyme. Most neurones were not immunoreactive. The rare neurones that contained glycogen phosphorylase only expressed the BB isozyme. Nearly all of these neurones formed part of the afferent somatosensory system. These findings stress the general importance of glycogen in neural energy metabolism and indicate a special role for the glycogen phosphorylase BB isozyme in neurones in the somatosensory system.     

Human bite losses of the lower lip

In two years, in our hospital in Nigeria, we saw 16 patients with lower lip losses caused by human bites. These are presented, together with the methods used for early management and subsequent repair.     

Neuronal plasticity in the adult invertebrate nervous system

This essay provides a brief overview of neuronal plasticity in adult invertebrate nervous systems. Our discussion focuses on the factors which influence sprouting by adult neurons, i.e., (1) the nature of the neuron itself, (2) axon integrity, (3) the presence of targets, (4) diffusible factors, and (5) ageing. Evidence that the neurites of some adult neurons exhibit a dynamic equilibrium of expansion and retraction is presented, a topic which prompted us to speculate on the significance of such plasticity in altered behavioral states. We conclude with some suggestions as to specific questions that need to be addressed by future studies in this challenging area.