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Biomedical subjects

F Sundler

Publications and source records attributed to F Sundler.

At least 505 records · Page 28Linked to original sources
PubMed1978

Peptidergic (VIP) nerves in the pancreas.

Vasoactive intestinal peptide (VIP) was found to occur in nerves in the pancreas of all species examined, as demonstrated by immunohistochemistry. Immunoreactive nerve terminals were seen to run in the stroma, around acini, and in the wall of blood vessels. Clusters of immunoreactive nerve cell bodies were encountered in the parenchyma; in addition other ganglia were densely innervated by VIP nerves. A particularly dense network of VIP nerves accurred in the wall of the main pancreatic duct. The present observations provide the morphological basis for accepting the action of VIP on pancreatic secretion as physiological.

Animals↗
PubMed1978

Sympathetic innervation and noradrenaline content of normal human thyroid tissue from fetal, young, and elderly subjects.

In man, as well as in the mouse, there is morphologic and functional evidence for a direct, stimulatory influence of the sympathetic nervous system on the secretion of thyroid hormone by noradrenaline (NA), released from interfollicular adrenergic nerve terminals. In mice and rats, an age-related reduction of the sympathetic innervation of the thyoid has recently been observed. In the present study, possible age-related variations of the sympathetic innervation and the concentration of NA in human thyroid tissue were examined. Interfollicular adrenergic nerve terminals were studied by fluorescence histochemistry, and the tissue concentration of NA was measured by fluorometry. In apparently normal thyroid tissue, obtained from fetuses, young (20-45), and elderly (greater than 60) euthyroid people with thyroid cancer or hyperparathyroidism, the number of interfollicular adrenergic nerve terminals appeared to be reduced with increasing age, and the thyroid tissue concentration of NA was significantly lower in elderly than in young people. These findings may have functional importance.

Adult↗
PubMed1978

Evidence for H2-receptor-mediated feed-back regulation of histamine release from endocrine cells in the rat stomach.

1. Pentagastrin reduces the concentration of gastric mucosal histamine in the rat. This effect is counteracted by large doses of histamine H2-receptor agonists which are particularly effective if infused I.V. 2. After blockade of histamine H2-receptors but not of H1-receptors, the pentagastrin-induced reduction of mucosal histamine is greatly augmented and H2-receptor agonists no longer inhibit the response to pentagastrin. 3. It is suggested that in the rat stomach, H2-receptors occur on the histamine storing endocrine cells as well as on parietal cells and that mobilized mucosal histamine inhibits further release of histamine by way of H2-receptor-mediated auto feed-back.

Animals↗
PubMed1978

Peptidergic (VIP) innervation of the esophagus.

Nerves displaying vasoactive intestinal polypeptide (VIP) immunoreactivity were demonstrated in the esophagus of rats, cats, and pigs. Furthermore, electron microscopy revealed the presence of nerve terminals displaying the features of peptidergic nerves. VIP nerves were abundant within the smooth muscle layer of the lower esophagus of cat and pig. Immunoreactive nerve fibers and nerve cell bodies were found in the plexuses of the esophageal wall. In pig fetuses VIP immunoreactive nerve cell bodies were observed already at crown-rump length of 4 cm. VIP nerves were also observed in human fetal esophagus. For recording of the motor effects of VIP, segments were taken from cat esophagus close to the esophagogastric junction. VIP induced a dose-dependent relaxation upon contraction by carbamylcholine.

Animals↗
PubMed1977

Formaldehyde-ozone-induced fluorescence in pituitary ACTH cells: effect of adrenalectomy.

ACTH and MSH cells of the pituitary are rich in peptides with NH2-terminaltryptophan, as revealed by fluorescence histochemistry. Adrenalectomy stimulates the ACTH cells but not the MSH cells. As a result, ACTH as well as tryptophyl-peptides disappear from the ACTH cells but not from the MSH cells. It is concluded that the tryptophyl-peptides are stored together with the respective hormone in the ACTH and MSH cells and that tryptophyl-peptides in the ACTH cells are released together with the hormone.

Adrenal Glands↗
PubMed1977

Ultrastructure of the gut neurotensin cell.

In mammals, neurotensin cells occur scattered in the epithelium of the jejunum-ileum. In chicken, neurotensin cells are abundant in the region of the gizzard-duodenal junction (antrum) where they occur intermingled with numerous somatostatin and gastrin cells. The neurotensin cells in chicken, dog and man were identified at the electron microscopic level by immunocytochemistry, using the consecutive semithin/ultrathin section technique. They contain numerous electron dense cytoplasmic granules, pre-dominantly in the basal portion of the cell. It was shown that these granules are the storage site for neurotensin. The neurotensin granules are round, highly electron dense and of about the same size in the different species examined (mean diameter 260--290 nm). In dog and man the granules have a tightly applied surrounding membrane while in the chicken a relatively electron lucent zone separates the electron dense core from the granule membrane. The ultrastructure of the neurotensin granules in chicken is somewhat reminiscent of that of the gastrin granules. The mean diameter of the gastrin granules in chicken antrum is 230 nm; for the somatostatin granules the mean diameter is 305 nm.

Animals↗
PubMed1977

Distribution, ontogeny and ultrastructure of the mammalian secretin cell.

Immunocytochemically, secretin cells have been demonstrated to occur in the duodenum and jejunum of several mammals. Calculations on the relative frequency of such cells indicate that the bulk of secretin occurs in the jejunum, a fact supporting the view that secretin may be released by physiological stimulants other than hydrochloric acid. Electron microscopical identification of cat and pig secretin cells confirmed their identity with the ultrastructurally defined S cells, and staining experiments revealed that secretin cells were argyrophilic both with the method of Grimelius and with that of Hellerström and Hellman. Secretin cells are detected already in the 17-day old fetal rat duodenum and show a developmental pattern similar to that displayed by the gastrin cells. It is suggested that secretin may play a role in the early regulation of growth of the fetal gastrointestinal tract.

Animals↗
PubMed1977

Substance P and 5-HT in granules isolated from an intestinal argentaffin carcinoid.

Intestinal argentaffin carcinoids, thought to originate from enterochromaffin cells, occasionally contain large amounts of substance P-like immunoreactivity in addition to 5-HT. The cytoplasmic granules of one such tumour were isolated. The granules, which in the electron microscope were shown to be argentaffin, contained both substance P-like immunoreactivity and 5-HT. The results support the view that substance P is localized in a population of enterochromaffin cells where it is stored in the cytoplasmic granules together with 5-HT.

Adult↗
PubMed1977

Ontogeny of rat pancreatic polypeptide (PP) cells.

Cells storing pancreatic polypeptide (PP) appear in rat pancreas at the time of parturition, much later than insulin and glucagon cells. At this stage, the pancreatic polypeptide (PP) cells occur scattered in the exocrine parenchyma and in the islets. Subsequently, 5-7 days postnatally, an abrupt increase in the number of PP cells occurs. At this stage, they are fairly numerous in the islets and comparatively rare in the exocrine parenchyma. Not until 8-10 days after birth is the number of PP cells similar to that in the adult pancreas. A few PP cells were seen in the antral mucosa during the first 10 days after birth. They were not seen elsewhere in the gut.

Age Factors↗
PubMed1977

Effect of alloxan on rat pancreatic polypeptide (PP) cells.

Injection of alloxan caused an almost total disappearance of insulin cells in the rat pancreas. Planimetric analysis revealed a 50 per cent reduction of the mean islet volume. The number of immunoreactive pancreatic polypeptide (PP) cells per sectioned islet was significantly increased, and the PP cell volume per islet doubled. Assuming an unchanged number of islets, the results indicate an increase in total PP cell mass following alloxan administration.

Animals↗
PubMed1977

Immunohistochemical localization of neurotensin in endocrine cells of the gut.

Endocrine cells displaying neurotensin immunoreactivity are found scattered in the jejuno-ileum of all mammals studied, including man. They are rather scarce in rat, guinea pig, rabbit and pig and fairly numerous in cat, dog and man. In most mammals the neurotensin cells predominate on the villi. Only in the dog are they more numerous in the crypts. In the chicken, neurotensin cells occur all along the intestinal tract. They are particularly numerous in the zone that joins the gizzard with the duodenum. The ontogeny of the neurotensin cells in the gut was studied in rats and chickens. In the rat, the cells are first observed in the jejuno-ileum immediately before birth. The adult frequency is reached 4-5 days later. In the chicken, neurotensin cells first appear in the colon in the 18 day old embryo and in the small intestine two days later (i.e. one or two days before hatching). A few days after hatching, the gut has achieved the adult number of neurotensin cells per unit area.

Age Factors↗
PubMed1977

Colchicine inhibits stimulated release of gastric histamine but not activation of histidine decarboxylase.

In the rat, gastric mucosal histamine is mobilized and histidine decarboxylase activated by treatment with insulin or pentagastrin. Colchicine pretreatment prevented the histamine release without preventing the enzyme activation. The results suggest a) that histamine release and histidine decarboxylase activation are independent events, and b) that microtubules are involved in the release of histamine.

Animals↗
PubMed1977

Suppression of rat stomach histidine decarboxylase activity by histamine: H2-receptor-mediated feed-back.

1. Gastrin activates rat stomach histidine decarboxylase. Exogenous histamine suppressed the basal enzyme activity in unoperated, in nephrectomized, in vagally denervated and in antrectomized rats, and counteracted the pentagastrin-induced enzyme activation in unoperated rats.2. Kinetic analysis of enzyme-catalysed histidine decarboxylation in extracts from untreated vagotomized and from histamine-treated vagotomized rats showed that the histamine-induced suppression of histidine decarboxylase activity probably reflects a reduced enzyme concentration. Moreover, the enzyme half-life in vagotomized rats after treatment with histamine was shorter than the half-life observed after inhibition of enzyme synthesis. These observations suggest that administration of histamine not only inhibits enzyme synthesis but also causes an accelerated rate of elimination of histidine decarboxylase.3. Intravenous infusion of histamine caused marked displacement of the pentagastrin dose-response curve, in a manner suggesting a reduced sensitivity to pentagastrin.4. After H(2)-receptor blockade, but not after H(1)-receptor blockade, histamine was less effective in suppressing the enzyme activity. Furthermore, H(2)-receptor blockade augmented the pentagastrin-induced enzyme activation.5. The results suggest that histamine (via H(2)-receptors) reduces the sensitivity of the histamine-storing cells to gastrin and that H(2)-receptor blockade induces the opposite effects.6. We propose that the histamine-storing cells in the rat stomach are endowed with H(2)-receptors and that exogenous histamine is capable of acting directly on the histamine cells. This may reflect a physiological control mechanism whereby mobilized endogenous histamine modifies its own synthesis and release.

Animals↗