Acta physiologica Academiae Scientiarum Hungaricae最新文献

Recurrent depression of responses evoked in motoneurons by sciatic nerve volleys was studied at 1-3 degrees C body temperature in Rana esculenta. Gross recordings from the ventral root axons and intracellular recordings from the motoneurons were made. In accord previous data obtained from the same species using the same techniques at room temperature, recurrent volleys depressed the responses of motoneurons to sciatic nerve impulses also at low temperature. The latency and duration of the depression was increased by a factor of about two with cooling. The short latency components of the evoked responses suffered more than the late ones. Intracellularly was indicated depression by delay or blockage of postsynaptic discharge and diminution of epsp in motoneurons. The data are considered as evidence for the operation of simple polysynaptic pathways in the central nervous system of poikilothermic animals at temperatures near 0 degrees C. Properties of the interaction are in accord with those found at higher temperature and undergo the expected modifications with cooling.

Aqueous extracts of resting (C) and 30 h regenerating (P) rat livers were partially purified by a combination of ion exchange-, Sephadex- and paper chromatographic techniques. It was demonstrated that a limited number of the semipurified chromatographic fractions inhibited or stimulated both DNA synthesis and cell proliferation, the effect being partially determined by C or P liver origin of the fractions. It was also shown that biological activities were mediated by hepatic peptides of middle molecular size in the semipurified fractions. It is suggested that regulation of hepatocyte proliferation might be under a dual control operating through an interplay of stimulatory and inhibitory peptides, the final outcome determined by their interaction.

NaCl myosin was prepared from the annular smooth muscles of human bronchus. About 7 mg of gel filtered myosin was gained from 8 g minced tracheal muscle of the younger subject. The yield from the older (74-year old) subject was only 30% of that from the younger subject, even though the starting material was more (12 g minced tissue). Tracheal myosin contains P lipid in considerable amount; P lipids account for some 28% of the total phosphate content of the myosin, and even more (50-55%) in the case of the older subject. The preparation could be phosphorylated only in the presence of CAMP and PGF2 alpha, respectively. Cu2+ treatment liberated less phosphate when compared with myosin preparations from other smooth muscles; however, the majority of the phosphate bonds underwent hydrolysis upon the effect of KOH. The reactions specific for amino acids, and also other observations allow the conclusion that the majority of covalently bound phosphate is present in an ester-type bond. Lysine-vasopressin, and also diethylpyrocarbonate successfully protect the P content of myosin from the hydrolysis inherent to incubation.

The effect on sodium appetite of a single intracerebroventricular (IVT) injection of 1 microgram angiotensin II (AII) was studied in 264 young female CFY rats, comparing control and water depleted groups. The choice of demineralized water and 0.9, 2, 3 and 4% NaCl solution or 0.9% NaCl and 5% glucose solution was offered to the animals. During the 12-25 minute long dipsogenic action of AII, sodium intake was significantly increased as compared to the control group. Together with sodium intake water and glucose intake was found to increase proportionally, so the sodium appetite did not change significantly. At the same time, AII significantly increased the rate of sodium intake and the sodium appetite when a choice of water and NaCl was offered, and the basis of comparison was the water depleted group. When water was changed for 5% glucose, the animals receiving AII showed no significant sodium appetite, and drank so much glucose solution that their blood glucose increased to 202 +/- 26 mg/dl, and glucose appeared in their urine. The conclusion was drawn that AII does not cause an acute, specific alteration in sodium appetite.

The effects of intracerebroventricular administration of cholecystokinin (CCK) antiserum )specific for COOH-terminal four amino acids) of CCK were tested in three dilutions on the dopamine (DA), norepinephrine (NE) and serotonin (5-HT) contents of the hypothalamus, amygdala, septum, striatum and cerebral cortex in rats 24 h following application. CCK antiserum decreased the DA and NE contents in the hypothalamus, mesencephalon, amygdala and septum, while it increased the DA content and decreased the NE content of the striatum. It had a slight effect on the 5-HT contents of the amygdala, septum and striatum.

A new hypothesis is offered regarding the pathomechanism of generalized epilepsy with spike-wave paroxysms (GESw) based on the pertaining literature and personal investigations. The first section is devoted to a critical overview of the development of theories regarding GESw. The centrencephalic theory, the debate on subcortical versus cortical origin, the "corticoreticular" hypothesis of Gloor and, finally, the "dyshormic" concept of Niedermeyer are outlined. In the next section it is shown that there is a particular optimum zone between sleep and wakefulness and between REM and slow wave sleep which highly favours the occurrence of spike-wave paroxysms. According to our investigations into the dynamics within this critical zone, the spike-wave paroxysms always appear with characteristic fluctuations of the level of consciousness where the changes towards awakening are always followed by rebounds towards sleep. Hence, the dynamic properties of this unstable border zone become especially interesting in the genesis of spike-wave paroxysms. It has been shown that even without epilepsy, a dynamics can be observed in the micro-oscillations in the depth of sleep which could be interpreted according to the reciprocal induction regulation model. In our concept the process of falling asleep emerges from rebounds of the sleep promoting system in response to sensory inputs streaming in from the external environment. According to this model, arousal influences in sleep have a sleep promoting effect. We interpret in this way all synchronized EEG reactions elicited by sensory stimuli and we consider K-complex type synchronization reactions as a "building stone" of the process of falling asleep which contains the whole process in concentrated form. The manifold similarities between the K-complex and the spike-wave pattern are demonstrated. On this basis spike-wave paroxysms can be regarded as an epileptic "caricature" of the sleep induction momentum reflected in the K-complex phenomenon. Hence, the GESw is the epileptic disorder of the sleep promotion function. This hypothesis resolves and explains many contradictory features of our knowledge about this mechanism and gives a new biologically oriented framework for further research. In the light of the hypothesis it has been attempted to interpret some of the characteristic features of the GESw: the genetic determination, the age dependency, the link with the sleep-waking cycle as well as the functional-anatomical characteristics and the symptoms of the seizures.

Unilateral electrolytical and chemical (6-hydroxydopamine) lesions in the substantia nigra (SN) of rats were followed 7 days later by considerable bilateral decreases of neostriatal dopamine (DA) levels. Similarly, the DA content of the substantia nigra decreased not only ipsilaterally but contralaterally as well. Positive correlations were found between ipsi- and contralateral nigral DA levels, ipsi- and contralateral striatal DA and between the DA level of the SN and the striatum of the corresponding side both ipsi- and contralaterally to the lesion.

The glycogen content of Tetrahymena pyriformis was analysed by a cytophotometric method. Histamine and histamine antagonists were found to influence the glycogen content. It increases after acute histamine treatment, while it decreases after 4 days incubation with histamine. The H2 receptor antagonist methiamide was more effective than histamine, while the H1 receptor antagonist phenindamine had no effect on the glycogen content. The effect reflects the similarity or dissimilarity of the chemical structure of the antagonists and of histamine. Subdivision of the cytophotometric results indicated that all of the protozoa react to histamine or to its antagonists, but all agents increased the number of glycogen-rich Tetrahymena.

The dextran-induced anaphylactoid reaction in the rat is susceptible to changes in carbohydrate metabolism. Paw oedema evoked by dextran was studied in norma and streptozotocin diabetic rats whose blood sugar level was determined by the glucose oxidase method. Insulin and tolbutamide increased dextran oedema in normal animals, while butylbiguanide (BBG) did not. The marked inhibition observed in the diabetic state was reversed by insulin and BBG, but not by tolbutamide. The dextran response correlated with the blood sugar level. These results suggest that the weak response to dextran in diabetic rats is due to an impaired peripheral glucose utilization rather than insulin deficiency per se.

The effects of cholecystokinin octapeptide sulfate ester (CCK-8-SE) and unsulfated cholecystokinin (CCK-8-NS) were studied following intraventricular administration on active avoidance and conditioned feeding behaviour of rats. In the CCK-8-NS and CCK-8-SE treated animals the acquisition of active avoidance and conditioned feeding behaviour were considerably impaired compared to the control; furthermore, these peptides caused a facilitated extinction of active avoidance and conditioned feeding behaviour. The data suggest that cholecystokinin octapeptide is capable of modifying the fear and hunger motivated behaviours of rats.