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Biomedical subjects

I E Tóth

Publications and source records attributed to I E Tóth.

27 records · Page 2Linked to original sources
PubMed1990

Impaired corticosteroid production by isolated adrenocortical cells of hypercholesterolemic rabbits.

Changes in the structure and function of rabbit adrenocortical cells were studied eight weeks after cessation of a cholesterol-enriched diet. The plasma cholesterol level of the treated animals was still modestly elevated. All three zones of the adrenal cortex contained a slightly increased number of intracellular lipid droplets, and greater number of lipid-laden macrophages were located in the inner layers, as revealed by light and electron microscopy. The basal and ACTH-stimulated hormone production by the isolated adrenocortical cells were significantly inhibited compared with those of the controls. A possible causal relationship between the inhibited adrenocortical hormone production and the increased number of macrophages is discussed.

Adrenal Cortex↗
PubMed1988

Colloidal gold-labeled lipoprotein binding and internalization in adrenocortical cells in vitro.

Human (normal and adenomatous) and rat (normal) adrenocortical cells were incubated in vitro with colloidal gold labeled low-density (LDL-Au) and high-density (HDL-Au) lipoproteins, respectively, in order to visualize lipoprotein binding and internalization at an electron microscopic level. Both normal and adenomatous human adrenocortical cells accumulated LDL-Au by receptor-mediated endocytosis via coated pits, coated vesicles, noncoated vesicles, and lysosomes. HDL-Au was not internalized. In rat adrenocortical cells, both HDL-Au and to a lesser extent LDL-Au were internalized. It is concluded that LDL-Au and HDL-Au conjugates can be used to identify lipoprotein receptors and to follow lipoprotein internalization in adrenocortical cells.

Adrenal Cortex↗
PubMed1988

Caerulein in supramaximal doses fails to stimulate pancreatic growth, but it forces secretory granulopoiesis.

To determine how low or high dose of caerulein, a cholecystokinin analogue influence pancreatic growth, doses of caerulein were selected which were submaximal (1 microgram/kg i.p.) and supramaximal (10 micrograms/kg i.p.) for enzyme protein secretion. Rats were injected every 8 h for 7 days with saline, low, or high dose of caerulein. The low dose of caerulein significantly increased pancreatic weight and content of DNA, protein, and digestive enzymes. The high dose caerulein group did not differ from control in these parameters of pancreatic growth. The number of zymogen granules was increased in both caerulein-treated groups. However, zymogen granules in the high dose group were atypical, appearing lucent or having a dense core with a lucent halo. These results indicate that caerulein has a biphasic effect on both enzyme secretion and the trophic response of acinar cells, and that the inhibitory effect of high dose of caerulein on pancreatic growth is accompanied by alterations in acinar cell morphology.

Amylases↗
PubMed1987

Different types of nerve profile in the wall of the canine hepatic artery: an electron microscopic study.

The fine structure of the hepatic artery of dogs was studied at electron microscopic level. The majority of nerve fibres innervating the artery was found at the adventitial-medial border of the vessel, but some of them entered the middle part of the media. The average distance of nerve to muscle fibre was found to measure 450 nm. Three types of nerve profile could be observed, viz. adrenergic, cholinergic and cholinergic-peptidergic as suggested by the morphology of their vesicles. It is suggested that the cholinergic and cholinergic-peptidergic nerve endings probably modulate the release and the constrictor effect of the main neurotransmitter noradrenaline in the hepatic artery.

Adrenergic Fibers↗
PubMed1986

Morphological evidence of lysosomal uptake of high-density lipoproteins by rat adrenocortical cells in vitro.

The high-density lipoprotein (HDL) pathway in rat adrenocortical cells was studied at the electron microscopic level in vitro via colloidal gold labelling. Steroid hormone assays were performed to confirm that the cells remained intact, viable, responsive to ACTH under the applied conditions, and to reveal the steroidogenic effect of HDL. The gold-labelled HDL particles (HDL-Au) were observed on the surface of the parenchymal cells, often attached to the membranes of the microvilli, but rarely in coated pits and coated vesicles. HDL-Au was accumulated by non-coated vesicles, multivesicular bodies and lysosomes. The lysosomes were identified by means of a non-specific esterase reaction. It is concluded that HDL particles are internalized by both zona glomerulosa and zona fasciculata cells. HDL is required for the enhanced functional activity of these cells in long-term incubation, and the lysosomes are involved in the process.

Adrenal Cortex↗
PubMed1984

Correlation of lipid droplet content and steroidogenic capacity in zona glomerulosa and fasciculata cells from lipoprotein-deficient rats.

Lipoprotein deficiency was maintained for 48 h by applying 4-aminopyrazolo(3,4-d)pyrimidine in male albino rats and the effect on the structure and function of isolated adrenocortical cells was investigated. Neither the morphology nor the steroidogenic response of zona glomerulosa cells changed; however, in the zona fasciculata cells a marked reduction in the quantity of lipid droplets was associated with a decreased steroidogenic response to ACTH. The results indicate that despite lipoprotein deficiency, zona glomerulosa cells contain a reserve of intracellular cholesterol, thus retaining their responsiveness to stimulation. The fact that the lipoprotein deficiency does not affect lipid droplets located in the glomerulosa cells and in the fasciculata cells in a similar manner is probably due to the differences in their physical state and chemical composition.

Adenine↗
PubMed1984

Neuroeffector transmission of the hepatic and pancreatico-duodenal isolated arteries of the dog.

Direct evidence has been obtained that the neurogenic responses of the hepatic and pancreatico-duodenal arteries of the dog are mainly due to norepinephrine released from varicosities and that this effect is mediated via alpha 1-adrenoceptors. In addition, there is a prazosin-resistant response to nerve stimulation that is certainly not mediated via alpha 2-adrenoceptors. These vessels are 10-100 times less sensitive to applied norepinephrine than the great majority of peripheral arteries; however, the pA2 value for prazosin (7.5) is the same as in other systems. The varicose terminal plexus is located deep in the media, as shown by electron microscopic study. Findings indicate that these gastrointestinal arteries are mainly controlled by adrenergic innervation, that their density is as high as that of any other vessel, and that these arteries might be much less influenced by the circulating catecholamines than others. The neuroeffector transmission of hepatic and pancreatico-duodenal arteries is subject to presynaptic modulation. Muscarinic (oxotremorine) and P1 (adenosine) receptor agonists are effective inhibitors of transmission, whereas xylazine surprisingly has no effect.

Animals↗
PubMedDate not supplied

Neuropeptides in the adrenal gland: distribution, localization of receptors, and effects on steroid hormone synthesis.

In this review we defined and classified the neuropeptides (NPs) related to the adrenal gland, according to Palkovits (Frontiers Neuroendocrinol 10:1 1988). The concentration (RIA) and distribution (immunohistochemistry) of NPs, as well as the localization of the receptors (radioligand studies) were summarized. Direct effects of NPs on aldosterone and corticosterone synthesis obtained by in vivo, in situ perfusion, and in vitro experimental approaches were reviewed. Data (from different rat strains and genders) for 35 NPs are presented.

Aldosterone↗