Hans-Gert Bernstein

Cytochemical investigations on the localization of 5'-nucleotidase in the rat hippocampus with special reference to synaptic regions.

SummaryThe fine structural localization of the 5′-nucleotidase was investigated in the CA3 region of the rat hippocampus. The attention was focussed on the occurrence of the enzyme in the synaptic region. The 5′-nucleotidase activity was demonstrated at the surface membranes of axons and dendrites. Prominent portions of enzyme activity were detectable in the nuclei and the nuclear envelope, whereas the cytoplasmic organelles were nearly devoid of reaction product. In synapses five types of 5′-nucleotidase localization were revealed. A participation of the enzyme in the process of neurotransmission is discussed.

Insulin immunohistochemistry of rodent CNS: Apparent species differences but good correlation with radioimmunological data

SummaryUsing an indirect immunofluorescence technique the distribution of insulin was mapped in brains of Wistar strain rats and mice. Insulin immunoreactivity was found to be widely distributed throughout mouse CNS, whereas in rat brain a restriction of immunoreactive material to cerebral blood vessels and ependymal cells and/or tanycytes of the brain ventricles was observed. In radioimmunological studies the amount of insulin (IRI) was estimated for different brain areas (cerebral cortex, brain stem, cerebellum, hippocampus, thalamus and hypothalamus). In the case of Wistar rats very low levels of IRI were found. On the contrary, the same regions in mouse brain contained considerably greater amounts of IRI. The comparison between histochemical and biochemical data revealed a good correlation. It is concluded that part of the insulin measured by radioimmunoassay is associated with neuronal structures.

Insulin-like immunoreactivity in the human brain

SummaryThe localization and regional distribution of insulin-like immunoreactivity (IRI) was studied in human brain autopsy material using the indirect immunofluorescence technique. A positive reaction for IRI could be observed in many neurons of the hypothalamus, the hippocampus, corpus amygdaloideum, medulla oblongata (especially within the nuclei of cranial nerves IX, X and XII), and the cerebral cortex, whereas the cerebellar cortex was lacking in immunohistochemically detectable insulin-like material. No nerve fibres containing polypeptides could be revealed. Additionally, the inuslin content of various brain regions was estimated by radioimmunosassay. Insulin concentrations in human nervous tissue were found to be elevated in comparison to blood plasma levels.

Regional distribution of glucagon-like immunoreactive material in the brain of rats and sand rats. An immunohistochemical investigation

Glucagon-like immunoreactivity was demonstrated in different parts of rat and sand rat central nervous system by the indirect immunofluorescence method. In hyperglycemic animals the level of immunoreactive material was reduced to a great extent.

Cerebral insulin-like immunoreactivity in rats and mice. Drastic decline during postnatal ontogenesis.

We studied the behavior of the insulin-like immunoreactivity in brains of rats and mice during the first 20 d post natum by immunohistochemistry and radioimmunoassay. It was found that a dramatic decline in the concentration of the peptide, accompanied by a strong reduction of immunoreactive cells, takes place during this period. A possible role of cerebral insulin as a promoter of nerve cell growth and development is briefly discussed.

An immunofluorescent reaction appears to insulin-antiserum in different CNS regions of two rat species

Using immunofluorescence technique a positive reaction to insulin antiserum could be revealed in different parts of the CNS of Wistar rats and sand rats.

C-peptide immunoreactive neurons in human brain

C-peptide/C-peptide-like immunoreactivity was shown to be present in the cytoplasm of the soma and the proximal part of apical dendrites of some pyramidal cells in the Neocortex (Gyrus precentralis) and Hippocampus of man. C-peptide (connecting peptide) is a metabolic product in insulin biosynthesis and its localization in neurons is a proof for extrapancreatic insulin production.

Occurrence of somatostatin-like immunoreactivity (SLI) in the dorsal hippocampus of the sand rat (Psammomys obesus).

Somatostatin-like immunoreactivity (SLI) was demonstrated in neurons of the dorsal hippocampus of the sand rat by means of the immunofluorescence technique.

Towards a specific histochemical localization of adenylate cyclase in the rat hippocampus I. Methodical aspects

The adequate histochemical demonstration of adenylate cyclase still involves serious methodical problems (low basal activity, fixation procedures, heavy metal ions as capture agents etc.). We have tried to revise fixation approach and composition of incubation medium in order to specify the mode of demonstration of the enzyme. The influence of strontium and barium (instead of lead) as well as dithiothreitole and sodium fluoride on the survive of adenylate cyclase activity was studied using a radiochemical model system.

Introducing a monoclonal antibody to insulin: the islets of Langerhans as a model for immunocytochemistry.

Summary The usefulness of a newly prepared monoclonal antibody to insulin was demonstrated by the immunofluorescent localization of the hormone to the B cells of the human islets of Langerhans .