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The presence of C-peptide, proinsulin, insulin-A-chain, and glicentin in human fetal pancreatic cells by using the PAP-technique was investigated and the results obtained compared with the occurrence of insulin or glucagon immunoreactive cells. In pancreatic sections obtained from 10 weeks old human fetuses we could identify cells reacting with antibodies directed against C-peptide, proinsulin, and insulin-A-chain. The majority of the cells were found in the duct epithelium and their number increased from the 10th to 14th week forming clusters near the ducts. The number and localization of the cells correspond exactly to the insulin positive cells. The presence of proinsulin and insulin-A-chains is a further proof of biological activity already in an early step of fetal development. The presence of glicentin-positive cells in the 10th week of gestational age as well as cells reacting with glucagon antibodies provide evidence for active glucagon biosynthesis. The number of these cells increased markedly in the 14th week of gestational age.

Zusammenfassung Die Untersuchungen wurden an mit Streptozotocin (SZ) behandelten, weiblichen Wistarratten (einmalige i.v. Injektion von 30 mg/kg Korpermasse) Bowie citratpuffer-behandelten Kontrolltieren durchgefuhrt. Nach Farbung der pankreatischen β -Zellen mit Aldehydfuchsin (AF), Viktoriablau nach Ivic bzw. FITC-markiertem Antiserum (indirekt) wurde das β -Zellvolumen nach einem point-sampling Verfahren ermittelt. Bei den Kontrolltieren ergeben alle 3 genannten β -zellspezifischen Farbemethoden das gleiche β -Zellvolumen. Mit Reduktion des Insulingehaltes im Pankreas and in den β -Zellen durch SZ-Applikation nimmt die Empfindlichkeit der histochemischen Farbemethoden im Vergleich zum immunhistochemischen Nachweis ab. Normoglykamische SZ-behandelte Tiere (Pankreasinsulingehalt ca. 30 % der Kontrollwerte) zeigen nach der AF-Farbung ein β -Zellvolumen von 0,22 %, nach der Ivic-Farbung von 0,14 %. Bei hyperglykamischen Tieren (ca. 6 % des Pankreasinsulingehaltes der Kontrolle) sind mit der AF-Farbung 0,08 % and nach Ivic 0,03 % β -Zellvolumen mesbar. Mit der Immunfluorescenzmethode Bind die β -Zellvolumine beider SZ-behandelten Gruppen identisch (0,34 %). Die nach SZ-Behandlung auftretende Abnahme des Pankreasinsulingehaltes ist auf die Reduktion des β -Zellvolumens, vor allem aber auf die starke Abnahme des Insulingehaltes pro β -Zelle zuruckzufuhren.

DNA synthesis and labelling index of isolated neonatal rat islets were investigated during a 4 to 5 culture period in TCM 199 (10 mmol/l glucose) under selected conditions, as change of serum concentration in the medium or addition of a proliferation stimulating fraction. Additionally it should be proved whether the DNA-synthesis of pancreatic islets, measured as [3H]-thymidine incorporation, is representative for the amount of cells during the S-phase (= "growth fraction"). There is a correlation between the incorporation of [3H]-thymidine into the TCA-precipitate and the labelling index of islets determined on HE-stained radioautographs. For this reason and because of being less time-consuming, the measurement of DNA synthesis is a suitable screening method for selection of factors increasing the growth fraction of pancreatic beta-cells. Only the addition of FGF-S3 (growth stimulating raw prepared isolated from bovine brain) during culture caused a significant increase of DNA synthesis and labelling index of the islets. The labelling index of radioautographs stained by immunofluorescence method for insulin did not differ significantly from that determined at HE-stained radioautographs. Insulin secretion and content of the islets were not influenced by the addition of FGF-S3.

Summary Using an indirect fluorescence technique and the unlabelled enzyme technique of Sternberger (PAP-techniques) we were able to demonstrate a widespread distribution of insulin, C-peptide and glucagon throughout the human brain.

Summary Using immunofluorescence technique a positive reaction to insulin antiserum could be revealed in different parts of the CNS of Wistar rats and sand rats. The functional concept that nervous tissue is insulin-insensitive was called in question by investigations showing an influence of insulin on blood plasma glucose levels after an application of the hormone to the CNS ( Szabo and Szabo 1972). Recently, the presence of specific insulin receptors in the brain was demonstrated by radiochemical ( Havkankova et al. 1978) and immunocytochemical ( Pansky and Hatfield 1978) means. No data, however, are yet available concerning the occurrence of the hormone itself in the CNS. We present evidence for the existence in the rat CNS of a substance giving an immunological reaction with insulin-antiserum.

Using the PAP technique, we investigated the presence of neuron-specific enolase in the human fetal pancreas of 10, 12, and 14 weeks of gestational age. Neuron-specific enolase is present in the islet cells in the 10th week. Positive cells are situated mainly in duct epithelium. The number of cells with a positive reaction increases from the 12th to the 14th week. In the 14th week, they are clustered either near the ducts or between the acini. The numbers and localizations of the cells correspond to those obtained in previous studies with 4 basic islet cell types in the same material. The present results are a further proof that islet cells are biologically active during early fetal development.

Summary The hypothalamic and extrahypothalamic distribution of somatostatin-like immunoreactivity (SLI) was investigated in fed adult sand rats ( Psammomys obesus ) of both sexes using the immunofluorescence technique. Blood glucose and insulin concentrations were determined in these animals prior to decapitation. In a blind study, the amount of immunofluorescence of certain CNS areas and the glucose: Insulin ratio were compared and found to be connected: High amounts of SLI were detected in the dorsal hippocampus, in some hypothalamic nuclei and the median eminence of rats displaying low glucose levels. Sand rats with high blood glucose values did not show SLI in the hippocampal formation and the immunofluorescence of the circumventricular (hypothalamic) regions and the Emmentia mediana was drastically reduced. A possible correlation of SLI with insulin concentrations in the blood could not be revealed. The data obtained are discussed as a possible expression of a CNS influence on glucoregulation in this species.

Summary 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 extrapancreating insulin production.

Summary Glukagon-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.

Summary The presence of glucagon-like immunoreactivity in nerve cells of different parts of the human brain was demonstrated by the indirect immunofluorescence technique. A bright fluorescent reaction was observed in the pyramidal cells of lamina V of the Neocortex. Less prominent concentrations of the glucagon-like material were detected in a few pyramidal cells of the Hippocampus and in some neurons of the Presubiculum and Subiculum. Within the Corpus amygdaloi-deum, only a few magnocellular neurons showed a positive reaction. The Hypothalamus was evidenced by a moderate, but widely distributed, reaction in magnocellular and medium-sized nerve cells in different nuclei (especially Nuc. ventromedialis and Nuc. arcuatus). A strong immunofluorescence was localized to some neurocytes in the Nuc. amibigus, and Nuc. n. hypoglossi. The Purkinje cells of the cerebellar cortex were free from immunoreactive material, but fluorescence occurred in some very small nerve cells of the Cerebellum (probably granular cells). A dependence of the strength of immunofluorescence of the time delay between autopsy and death is shown.