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Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 361 records · Page 20Linked to original sources
PubMed1984

Influence of membrane fluidity changes upon the imprinting of polypeptide hormones in Tetrahymena.

Hormonal imprinting is a physiological phenomenon, in which after the first encounter the receptorial and functional responses of a cell change for future occasions. The present experiments demonstrate (using Tetrahymena as a model cell) that the imprinting is very sensitive to the changes in membrane physical state. Cultivation of Tetrahymena cells in 28 or 15 degrees C or in ergosterol-supplemented media caused only quantitative differences in the imprinting; however, the process of cooling (shift-down) or reheating (shift-up) resulted in a false reaction. The combined treatment by ergosterol and cooling completely abolished the imprinting. These results indicate that hormonal imprinting is a membrane-dependent process.

Animals↗
PubMed1984

Effect of benzo(a)pyrene treatment of neonatal and growing rats on steroid receptor binding capacity in adulthood.

A single treatment to rats of a low dose of benzo(a)pyrene within 24 hr after birth or at 3 weeks of age accounted for a considerable depression of the binding capacity of glucocorticoid receptors for dexamethasone at 4 months of age. The influence of pretreatment with benzo(a)pyrene was greater in the growing than in the neonatal age. Since the applied treatment did not alter receptor affinity, the decrease in binding capacity was in all probability due to a benzo(a)pyrene-induced decrease in the number of receptors.

Age Factors↗
PubMed1984

Phylogenetic changes in sensitivity to Anemonia sulcata toxin (ATX II), and impact of first interaction with the toxin (imprinting) on later response to it.

The Anemonia sulcata toxin ATX II is cardiotoxic and neurotoxic, and--at a high dose level--even lethal for the mouse, neurotoxic, but non-lethal for the frog, and has no adverse influence whatever on the Planaria and Tetrahymena; it even stimulates the growth of the Tetrahymena at a low dose level. It also induces imprinting in the Tetrahymena, as judged from the altered response of the latter to ATX II on re-exposure. No similar imprinting effect was demonstrable in mice.

Animals↗
PubMed1984

Impact of neonatal catecholamine treatment on adult response to vasopressin and norepinephrine.

The present experiments have shown that neonatal imprinting with certain catecholamines had a significant impact on adult vascular adrenergic response, and on adult response to vasopressin as well. This finding not only substantiates the existence of a hormonal imprinting mechanism, but also suggests a certain (receptor-level) interaction between the vasopressin and catecholamine receptors involved in vascular contraction.

Animals↗
PubMed1984

The present state in the phylogeny and ontogeny of hormone receptors.

Presence of signal receivers (for food, toxic, substances, "hostile" cells etc.) is essential at all levels of phylogenesis. The first encounter of a "hormone to be" with an aspecific membrane structure ("receptor to be") could result in the formation of a lasting receptor-hormone connection if it is adventageous for the cell or organism (which contains the cell), during phylogeny. At higher levels of phylogenesis receptors (ontogenetically) develop according to the differentiation program of the cell, however reinforcement (by the hormone) is necessary in a critical (neonatal) period of receptor development. This is the hormonal imprinting. In that time the receptor could be damaged by the presence of molecules analogous to the hormone. The hormonal imprinting belongs to the perinatal recognition mechanisms of organisms. The possible mechanisms of receptor development are also discussed.

Aging↗
PubMed1984

Impact of a single neonatal gonadotropin (FSH + LH) or thyrotropin (TSH) treatment on the sexual behaviour of the adult male rat.

A single gonadotropin (FSH + LH) treatment of neonatal male rats resulted in depression of sexual activity in adulthood. It appears that not only steroids, but also gonadotropins may alter adult sexual behaviour by a single neonatal exposure. The chemically related hormone thyrotropin (TSH) had a similar, but much less pronounced, effect on adult sexual activity.

Animals↗
PubMed1984

Receptor 'memory' in Tetrahymena: does it satisfy the general criteria of memory? An experimental study on induction and extinction by retroactive interference in a unicellular organism.

Diiodotyrosine induced receptor 'memory' at a concentration as low as 10(-18) M. Repeated exposure enhanced cellular responsiveness. Treatment with diiodotyrosine for 1 h, 4 times, induced receptor 'memory' more efficiently than a single uninterrupted treatment for 4 h. Immediately after induction, the receptor 'memory' is subject to retroactive interference by foreign hormonal stimuli, and can be extinguished completely by combined hormone treatment. Thus, the phenomenon of retroactive interference also takes effect at the unicellular level. The experimental observations indicate that receptor 'memory', induced in Tetrahymena by hormonal imprinting, has certain common features with the neuronal memory of higher organisms.

Diiodotyrosine↗
PubMed1984

Coated pits and coated vesicles in unicellulars (Tetrahymena, Crithidia) and in Hydra.

Coated pits and coated vesicles were observed in the ciliated unicellular Tetrahymena, in the flagellated unicellular Crithidia, and in Hydra. In the unicellulars the coated structures localized for the most part near to the origin of cilia or flagella, and many were present around the Golgi complex, whereas in Hydra they occurred in nonspecific random locations. Since the membrane receptors of the unicellulars serve originally as food receptors, the coated pits and vesicles are presumably involved in food selection, and represent as such the primitive form of the receptor-mediated ligand internalization mechanism operative in higher organisms.

Animals↗
PubMed1984

The effect of neonatal treatment of mice with opioid and dopaminergic agents on the late responsiveness of vasa deferentia to opioids in vitro.

Neonatal treatment of mice with opioid and dopamine antagonists (naloxone, haloperidol and sulpiride) failed to alter the in vitro responsiveness of vasa deferentia to opioid agonists in the adulthood. Single neonatal administration of some opioid or dopaminergic agonists, viz. Met-enkephalin and piribedil, tended to enhance the sensitivity of in vitro preparations to opioid agonists, tested in adult animals. Behavioural differences and late mortality were also observed.

Animals↗
PubMed1984

Hereditary transmission to the F1-generation of hormonal imprinting (receptor memory) induced in rats by neonatal exposure to insulin.

F1 rats bred from parents treated with insulin on a single occasion showed a considerable alteration in hepatocellular insulin binding when newborn compared to controls bred from parents not treated. In females, insulin binding increased and in males decreased relative to the controls. Neonatal insulin treatment of one parent only had a similar effect on the F1-generation regardless of the parent's sex, but the displacement of the initially bound surplus insulin took place more readily, owing presumably to a lesser stability of binding on uniparental transmission of hormonal imprinting.

Animals↗
PubMed1984

Hormonal imprinting in cell culture I. Impact of a single exposure to insulin on cellular insulin binding capacity in permanent cell lines.

Three permanent cell lines showed a durable change in cellular insulin binding capacity in response to a single exposure to insulin. Initial increase in binding of FITC-labeled insulin to both cytoplasmic and nuclear membrane was followed by a lasting decrease in the case of fibroblasts (NCTC) and return to approximately the control level in epithelial (Chang liver) and tumour (HeLa) cell cultures. While the amplifying effect of a single 4-h exposure was measurable as soon as after 24 h, that of a single 24-h exposure came into display only after 72 h in the epithelial and tumour cell cultures. The latter two lines showed return of the binding capacity to the control value and a drop of it to a minimum 20 days after exposure for 4 and 24 h, respectively. These observations support the implication that although the degree and manner of insulin binding differs between cell lines, the impact of a single exposure to insulin is durably "felt" by all.

Cell Line↗
PubMed1984

Study of the imprinting and overlap of insulin and concanavalin-A at the receptor level in a protozoan (Tetrahymena) model system.

In a protozoan (Tetrahymena) model system, insulin treatment produced a long-term imprinting which upon re-exposure to the hormone resulted in an enhanced binding of the hormone. Insulin pretreatment produced similar effect with regard to the binding of concanavalin-A. Concanavalin-A could only induce a short-term imprinting for itself and was not capable at all of inducing imprinting for insulin. Based on the results of this study it appears that the binding of the sugar component of the receptor, which can be achieved also by lectin, is not sufficient to induce imprinting but the whole (hormone) molecule is needed.

Animals↗
PubMed1984

Influence of prolonged life span on receptor 'memory' in a unicellular organism, Tetrahymena.

The first interaction of the Tetrahymena with a hormone-like molecule-diiodo-tyrosine (T2) in the present study - gives rise to hormonal imprinting, the effect of which is being preserved by receptor 'memory' over as many as 500 generations. The first interaction with the hormone modifies the growth potential of the cell also without reexposure. In the present study, we followed up the fate of receptor 'memory' in Tetrahymena cells maintained without exchange of medium, and thereby inhibited in division, over the period of a year. The cells continued to display increased responsiveness - receptor 'memory' - over the first 3 months which normally cover the change of 500 generations, and to a lesser degree over the next 3 months (after 6 months) as well, but they showed loss of 'memory' after 9 and 12 months, as judged from the similarity of their growth response to the control. At 9 months, the cells were able to recover their original growth potential within 4 days of return to normal medium, but the 'memory' of the behavioral (growth response) modification induced by T2 returned, in a not fully convincing form, only after 48 days. Receptor 'memory' returned in 21 days. It follows that receptor 'memory' can equally persist by cell-cell transmission or within the same nondividing cell of extremely prolonged life span. Evidence has also been presented that loss of receptor 'memory' with ageing is only virtual, because it can be reactivated if the aged cells are 'rejuvenated' under appropriate conditions.

Animals↗
PubMed1984

Hormonal imprinting in cell culture II. Evidence of hormonal imprinting and thyrotropin (TSH) -gonadotropin (FSH) overlap in a Chinese hamster ovary (CHO) cell line.

Reexposure of cultures of the Chinese hamster ovarian cell line CHO K1 to FITC-labeled hormone 48 h after the first 24-h exposure to FSH or TSH showed that hormonal imprinting, accounting for a greater binding capacity on reexposure, also took place in in vitro conditions. TSH amplified the receptors of FSH to a greater degree than FSH itself, although the reverse effect failed to happen. TSH was able to bind the ovarian cells at first exposure, and to amplify the receptors for itself and--remarkably--to a considerably greater degree for FSH, exactly as observed earlier in in vivo systems.

Animals↗