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At least 595 records · Page 33Linked to original sources
PubMedDate not supplied

Synchronization of spontaneous activity of skeletal muscle, autonomic nerves, and brain structures in cats.

Acute and chronic experiments with recording of electrical activity of skeletal muscle, autonomic nerves, and some brain formations were performed on cats. Spectral correlation analysis showed that the spatial synchronization of electrical activity for the autonomic nerves and brain formations within the frequency range of 25--35 Hz, revealed by previous investigations, extends also to skeletal muscle. It is postulated that the presence of a widespread rhythm of 25--35 Hz is a factor facilitating the transmission of influences in the nervous system through frequency potentiation of synaptic action.

Animals↗
PubMed1979

[Drug-induced influence of the GABA-fluorescence in rat brain structures with some comments on the chemistry of the reaction (author's transl)].

1. GABA was demonstrated in rat brain in fluorescence histochemistry. The alteration by application of submaximal doses of drugs of the distribution and intensity of the transmitter fluorescence was studied in hippocampus and cerebellum. 2. Isonicotinic acid hydrazide and Penicillamine leads to a distinct grain formation and diminishing of the fluorescence product, normally appearing homogenous. These effects are considered to reflect an enzyme (GAD) inhibition. 3. By Cycloserine a distinct increase of the GABA fluorescence is effected, presumably by inhibiting GABA-transaminase-activity. 4. Chloropromazine causes diminishing, grain formation and dislocation as well of the fluorescent product, supposedly due to an affection of the membrane binding properties of GABA. 5. Hypotheses concerning the chemical events of the GABA-reaction are worded.

Animals↗
PubMedDate not supplied

[Effects of acute and chronic treatment with an adrenergic alpha receptor agonist, LE S3341, on the rate of catecholamine turnover in various peripheral organs and brain structures in the rat].

The turnover of catecholamines (CA) in some peripheral tissues and various areas of the rat brain was estimated by measuring the amine depletion after inhibition of their biosynthesis by alpha-methyl-p-tyrosine (alpha-MPT). Acute or chronic treatment with S3341 (3mg/kg i.p.) reduced NA turnover in submaxillary glands, brain stem and rest of the brain but had no effect on NA turnover in the hypothalamus. The dopamine (DA) levels were unaltered following chronic S3341 treatment but the alpha-MPT induced disappearance of DA was significantly retarded in the striatum and rest of the brain. The results of the present study demonstrate that no tolerance to the effect of S3341 on brain CA turnover develops during chronic drug administration. The central biochemical effects of S3341 appear different from those of other agonists of central alpha 2-adrenoceptors such as clonidine.

Adrenergic alpha-Agonists↗
PubMed1982

[Role of affective brain structures in regulation of the secretory function of the stomach].

The effects of self-stimulation (SS) of the brain reward sites on the gastric secretion were studied in 8 adult dogs with gastric fistula. The concentric (bipolar) electrodes were implanted in different sites of the brain reward system (hypothalamus, mamillary corpus, capsula interna, commissura grisea media, n. interstitialis striae terminalis, n. ventralis thalami, pes pedunculi cerebri) and then the instrumental reaction of the intracranial self-stimulation (ICSS) was induced. On recovery period normal acidity of the gastric juice was observed in 5 hungary dogs whereas in 3 hungry dogs the gastric acidity was significantly increased. In 3-5 min after the beginning of SS a lot of thick foamy slime and turbid juice was secreted. In dogs with initially normal pH of the gastric contents ICSS did not change it, whereas in dogs with increased pH ICSS made the gastric acidity normal pH of the gastric contents ICSS did not change it, whereas in dogs with increased pH ICSS made the gastric acidity normal. Bilateral supradiaphragmal vagotomy reduced the acidity in the animals of the last group, but only ICS made their pH quite normal. Therefore, positive emotional excitement associated with the stimulation of different areas of the brain reward system, makes gastric acidity normal and this reaction is not connected with the efferent systems of vagus nerves.

Animals↗
PubMed2004

Selective activation and deactivation of the human brain structures between speeded and precisely timed tapping responses to identical visual stimulus: an fMRI study.

We investigated the difference between brain activities in speeded and precisely timed responses to identical visual stimulus using fMRI. Stimulus used was a row of seven light-emitting diodes (LEDs) lightened up one after another with constant speed within a trial but with various speeds between trials. Subjects were asked to execute finger-thumb tapping with the right hand in response to the onset of the first LED light in the reaction time (RT) task and in anticipation of the onset of the last (i.e., seventh) LED light in the timing task. In control condition, they were asked to passively view the stimulus without motor response. Results showed that various movement-related areas including contralateral cingulate motor cortex were commonly activated for both tasks relative to the control condition, suggesting these structures are involved in general perception and response execution rather than specific function for speeded or precisely timed responses. In the RT task, the presupplementary motor area extending to the cingulate sulcus was activated more strongly than in the timing task probably to focus attention to the onset of the first LED light unpredictably presented after random foreperiods. The lateral occipital area extending to the temporo-parieto-occipital junction was activated more strongly in the timing task than in the RT task; the same area was deactivated in the RT task relative to the control condition. Auditory-related areas were also deactivated in the both tasks. This inter- and intramodal task-specific modification including deactivation underscores significance of the context for perception and action and can have an important role in dexterous or skilled performance.

Adult↗
PubMed1988

Insulin receptors in the brain: structural and physiological characterization.

The present study was conducted to characterize insulin receptors and to determine the effects of insulin in synaptosomes prepared from adult rat brains. Binding of 125I-insulin to synaptosome insulin receptors was highly specific and time dependent: equilibrium binding was obtained within 60 minutes, and a t1/2 of dissociation of 26 minutes. Cross-linking of 125I-insulin to its receptor followed by SDS-PAGE demonstrated that the apparent molecular weight of the alpha subunit of the receptor was 122,000 compared with 134,000 for the liver insulin receptor. In addition, insulin stimulated the dose-dependent phosphorylation of exogenous tyrosine containing substrate and a 95,000 MW plasma membrane associated protein, in a lectin-purified insulin receptor preparation. The membrane associated protein was determined to be the beta subunit of the insulin receptor. Incubation of synaptosomes with insulin caused a dose-dependent inhibition of specific sodium-sensitive [3H]norepinephrine uptake. Insulin inhibition of [3H]norepinephrine uptake was mediated by a decrease in active uptake sites without any effects in the Km, and was specific for insulin since related and unrelated peptides influenced the uptake in proportion to their structural similarity with insulin. These observations indicate that synaptosomes prepared from the adult rat brain possess specific insulin receptors and insulin has inhibitory effects on norepinephrine uptake in the preparation.

Animals↗
PubMed1977

[Effect of micropolarization of focal and extrafocal brain structures on experimental epilepsy].

The influence of micropolarization (MCP, 0.05-0.75 muA) was studied in chronic experiments on rabbits with epileptogenic foci provoked by penicillin (doses of 500 and 1000 U) injection into the motor cortex. A single MCP of extrafocal structure (the corpus calossum, nucleus caudatus) and the site of the focus inhibited the development of seizure reactions. Numerous MCP of the focus facilitated the seizure reactions. These effects may be explained not only by the specific role of the structures studied in the processes of the formation and propagation of the excitation, their initial functional state, but also by the dependence of the activity of these structures on the MCP regimen.

Animals↗
PubMed2006

Volumetric structural brain abnormalities in men with schizophrenia or antisocial personality disorder.

Brain abnormalities are found in association with antisocial personality disorder and schizophrenia, the two mental disorders most implicated in violent behaviour. Structural magnetic resonance imaging was used to investigate the whole brain, cerebellum, temporal lobe, lateral ventricles, caudate nucleus, putamen, thalamus, hippocampus, amygdala and the prefrontal, pre-motor, sensorimotor, occipito-parietal regions in 13 men with antisocial personality disorder, 13 men with schizophrenia and a history of violence, 15 men with schizophrenia without violent history and 15 healthy non-violent men. Compared to controls, the antisocial personality disorder group displayed reductions in whole brain volume and temporal lobe as well as increases in putamen volume. Both schizophrenia groups regardless of violence history exhibited increased lateral ventricle volume, while the schizophrenia group with violent history showed further abnormalities including reduced whole brain and hippocampal volumes and increased putamen size. The findings suggest that individuals with antisocial personality disorder as well as those with schizophrenia and a history of violence have common neural abnormalities, but also show neuro-anatomical differences. The processes by which they came to apparently common ground may, however, differ. The finding of temporal lobe reductions prevalent among those with antisocial personality disorder and hippocampal reduction in the violent men with schizophrenia contributes support for the importance of this region in mediating violent behaviour.

Adult↗
PubMed1985

Use of mRNA hybridization and radioimmunoassay to study mechanisms of drug-induced accumulation of enkephalins in rat brain structures.

The repeated administration of haloperidol or fenfluramine for several days led to an increase of enkephalin content in specific brain areas. In order to characterize the nature of the dynamic changes underlying this increase, we measured the content of proenkephalin mRNA (PE-mRNA), of high molecular weight (HMW) enkephalin precursors, and of low molecular weight enkephalin peptides (LMW) in various brain areas. To measure PE-mRNA, we hybridized the specific mRNA with a [32P]cDNA probe for human pheochromocytoma PE. HMW and LMW enkephalin content was measured by radioimmunoassay after separation of the immunoreactive peaks by Bio-Gel P-2 column chromatography and enzymatic digestion of the precursors. Haloperidol treatment increased enkephalins, the precursor, and PE-mRNA content in the striatum, suggesting that this drug might increase enkephalin steady state by increasing transcription, translation, or both processes. In contrast, fenfluramine increased hypothalamic and striatal enkephalin content by preferentially reducing neuropeptide utilization or decreasing its catabolism without changing its synthesis.

Animals↗