Search PubMed⌕ Search

Biomedical subjects

M Palkovits

Publications and source records attributed to M Palkovits.

At least 343 records · Page 19Linked to original sources
PubMed1978

Blood supply of the rat amygdala.

The cerebral vessels of the rat were filled with inks of different colours. The topography of the vessels of the amygdala were reconstructed from serial sections. The circulation of the individual amygdaloid nuclei was studied in detail. The arteries of the amygdala arise from the deep and cortical branches of the internal carotid and middle cerebral arteries. Eight major arteries were found to supply blood to the amygdala. All amygdaloid nuclei receive branches from both arterial trunks. The vast majority of the veins are collected by the middle cerebral and basal veins. Only a small fraction drains into the hippocampal vein. Of particular importance are the veins ending in the basal vein and those cortical ones that run in the rhinal sulcus. All amygdaloid nuclei have a multidirectional drainage.

Amygdala↗
PubMed1978

The arterial and venous blood supply of the preoptic region in the rat.

A study has been made of the arterial and venous circulation of the preoptic region in the rat, using the double Indian ink technique. A detailed description is offered on supply of the nucleus preopticus medialis, lateralis, suprachiasmatis and periventricularis, as well as of the nucleus interstitialis striae criminalis and of the preoptic portion of the medical forebrain bundle. The arteries of the region emerge from the anterior communicans artery and from the anterior cerebral artery. The blood of the region is collected by the anterior cerebral artery. Veins collected by the v. cerebri magna, are also running dorsalwards from the nucleus interstitialis striae terminalis. The blood supply of the organon vasculosum laminae terminalis is described with special regard to its vascular connection with the preoptic nuclei.

Animals↗
PubMed1978

Ascending brain stem pathways to the diencephalon and limbic regions: a light and electron microscopic study in the rat.

Total and partial meso-diencephalic transections and lesions of the central gray matter were performed to trace with the Fink--Heimer silver impregnation method the ascending brain stem pathways to the forebrain. Most of these pathways are located near the midline at the level of their entry into the diencephalon. Fibers directed to the hypothalamus either leave the central gray matter and proceed rostralwards in the periventricular tissue layers, or, after traversing the ventral tegmental area, join the medial forebrain bundle. It can be established on the basis of electron microscopical studies that the ascending brain stem pathways project to all hypothalamic nuclei and to the median eminence.

Animals↗
PubMed1977

The area postrema and control of arterial blood pressure; absence of hypertension after excision of the area postrema in rats.

Acute surgical excision of the area postrema (AP) in the rat failed to affect arterial blood pressure or heart rate. The was no effect on cardiovascular reflex responses during diving or on the heart rate responses to acute decreases or increases of blood pressure caused by bradykinin or angiotensin, respectively. Electrolytic lesions of the AP in acute experiments caused variable damage to the nucleus tractus solitarii (NTS). In these rats large variations in blood pressure occurred. Excision of the AP in a chronic experiment failed to change blood pressure, heart rate, water intake or plasma renin activity. In contrast, bilateral electrolytic lesions of the NTS at the level of the AP caused a severe acute hypertension and completely blocked cardiovascular reflex responses. Hypertension also existed in rats with NTS lesions studied for a longer period of time. There experiments failed to confirm the hypothesis that the AP exerts a tonic inhibitory control of basal blood pressure. Hypertension previously reported after ablation of the AP may be explained by damage to the NTS.

Acute Disease↗
PubMed1977

Serotonergic innervation of the forebrain: effect of lesions on serotonin and tryptophan hydroxylase levels.

Concentrations of serotonin and tryptophan hydroxylase activity in individual hypothalamic and limbic nuclei, as well as cortical regions, were measured by radioenzymatic microassays after dorsal raphe nucleus lesions and various surgical transections of the brain stem. Fourteen days after lesioning of the dorsal raphe nucleus there were 43-65% decreases in 5-HT concentrations of certain hypothalamic and limbic nuclei. More pronounced decreases were found in the parietal cortex and in the locus coeruleus and substantia nigra. Degenerations of nerve terminals in various regions of the hypothalamus and the limbic system were detected by electron microscopic studies 1-8 days after dorsal raphe nucleus lesions. There was no change in the 5-HT concentration of the spinal cord following dorsal raphe nucleus lesions. Surgical transections at the level of mesencephalic-pontine junction caused no significant changes in 5-HT concentrations or tryptophan hydroxylase levels in the hypothalamus, limbic system, cerebral cortex or spinal cord. Serotonergic fibers ascending from the mesencephalic raphe nuclei constitute a well circumscribed bundle dorsal to the interpeduncular nucleus. The axons enter the hypothalamus between the mammillary body and crus cerebri just ventral to the medial forebrain bundle. The ascending pathway contains all the ascending 5-HT fibers innervating the hypothalamus and the rostral limbic and cortical areas.

Animals↗
PubMed1977

Total and partial hypothalamic deafferentations for topographical identification of catecholaminergic innervations of certain preoptic and hypothalamic nuclei.

After total deafferentation of the medial hypothalamus in the rat, noradrenaline concentration in the nucleus arcuatus and the eminentia mediana diminished to one-third. The same decrease of noradrenaline concentration resulted also from partial (anterolateral) deafferentation. Rostral and caudal cuts from the medial hypothalamus did not induce any change in the noradrenaline concentration of the two above-mentioned areas. This indicates that noradrenaline containing axons enter the medial basal hypothalamus laterally from the medial forebrain bundle. Total or partial deafferentation of themedial hypothalamus did not affect noradrenaline or dopamine concentrations in the nucleus preopticus medialis, the nucleus interstitialis striae terminalis, the nucleus hypothalamicus anterior and nucleus supraopticus. The catecholaminergic fibres supplying these regions do not pass the medial hypothalamus, but probably ascend laterally from it, in the medial forebrain bundle. The noradrenaline innervation of the nucleus dorsomedialis takes its origin in the ventral noradrenaline bundle and the fibres from the medial forebrain bundle ascend into the nucleus from the lateral side. After total or lateral deafferentation of the medial hypothalamus, that ransects the fibres running to the nucleus laterally, noradrenaline concentration decreases, apart from the nucleus located within or outside the deafferented island. In this case anterior or posterior deafferentation of the hypothalamus is ineffective. Total deafferentation did not change dopamine concentration in the nuclei of the medial basal hypothalamus, thereby furnishing evidence for its intrahypothalamic origin from the A12 cell group. However, after total deafferentation, some slight decrease of dopamine concentration could be observed in the median eminence. This suggests that the dopamine concentration in the median eminence does not originate exclusively from thenucleus arcuatus but to some extent originates from extrahypothalamic sites. After posterior deafferentation, which destroys the fibres of the incertohypothalamic dopamine system, dopamine concentration in the nucleus dorsomedialis decreases. After total deafferentation of the medial hypothalamus, which isolates the nucleus from the ventral nuclei (and so also from the A12 cell group) of the medial hypothalamus, the dopamine concentration in the nucleus dorsomedialis did not change.

Animals↗
PubMed1977

Distribution of a behaviorally highly potent ACTH4-9 analog in rat brain after intraventricular administration.

Distribution within the brain of a 3-fold modified ACTH4-9 analog with a remarkably potentiated behavioral activity, 4-MET (O2), 8-d-Lys, 9-Phe-ACTH4-9, was investigated. The radioactive labeled [7-3H-Phe]ACTH4-9 analog was administered intraventricularly in urethane anesthetized rats in a dose of approximately 170 ng. Total radioactivity in CSF, measured in samples drawn from the cisterna magna, decreased over the period of 0.5-4 h after injection from 51 to 2% of the injected dose. Intraventricular injection of the ACTH4-9 analog resulted in high intact peptide levels in the brain. At 2 h after injection the distribution of radioactivity over 2500 micronm and 300 micronm frontal cut brain slices was rather homogenous. Data from distribution studies over topographically defined gross brain structures indicated that the septal area, which is involved in eliciting behavioral activities of ACTH-like neuropeptides, accumulated most of the injected radioactivity per gram wet weight. The distribution profiles within the brain of the [3H]ACTH4-9 analog and [3H]Phe showed considerable differences. Uptake studies in various brain nuclei after intraventricular administration of the [3H]ACTH4-9 analog demonstrated that the greatest part of the investigated nuclei exhibited relative low or medium uptake of radioactivity. This was also true for hippocampal and thalamic nuclei, which have been suggested as effected sites of action for ACTH peptides. Very high accumulation of radioactivity occurred only in the septal nuclei, particularly the dorsal and fimbrial septal nuclei. The results indicate selective uptake of the ACTH4-9 analog in the septal area, suggesting a possible significance of this area as a site of action of ACTH neuro-peptides.

Adrenocorticotropic Hormone↗
PubMed1977

Catecholamines in individual hypothalamic nuclei of acutely and repeatedly stressed rats.

Norepinephrine (NE) and dopamine (DA) concentrations in 17 individual hypothalamic nuclei and 3 other brain regions were measured in rats, acutely or repeatedly stressed by immobilization, using a microdissection technique and a radioisotopic-enzymatic assay. Following the first 20 min immobilization (IMO) a significant NE decrease in the ventromedial (NVM) and supraoptic (NSO) nuclei and a DA decrease in the arcuate nucleus (NA) as well as NE and DA increase in the dorsomedial nucleus (NDM) were seen. Repeated IMO (40 times) produced a NE increase in the NVM, NDM, NSO paraventricular nucleus (NPV) and median eminence (ME), and a DA increase in the NDM and NPV. Changes of NE and DA concentration found in some individual hypothalamic nuclei under the influence of stress indicate that catecholamines (CAs), particularly in the medial basal hypothalamus, could be involved in the regulation of some neuroendocrine processes which are being activated during stress, especially ACTH release.

Animals↗
PubMed1977

Measurements on the kidneys and vasa recta of various mammals in relation to urine concentrating capacity.

Maximum urine-concentrating capacity (UCC) differs widely among mammals of different species, being very high in some desert species (e.g. kangaroo rats) and very low in freshwater acquatic species (e.g. beaver). In this study, kidneys of 21 species of mammals from widely different habitats were studied in histological sections to determine whether differences in UCC can be attributed to differences in kidney structure. Parameters studied included the ratio of medullary to cortical thickness, the proportional subdivision of the medulla into inner and outer zones, and the dimensions of the vasa recta expressed in terms of the total area and the number of lumens within the vascular bundles. Determinations were made at a level where the size of individual vasa recta bundles has reached a constant maximum size, i.e. in the distal half of the outer zone. A positive correlation was found between the UCC and the ratio of medullary length to cortical thickness. No clear correlation existed between the proportion of the medullary length comprised of outer or inner zones and the UCC, although a trend to higher UCC in animals with relatively longer inner zones was apparent. Thus, it appears that the relative length of the entire medullary region is a major factor determining UCC, but the length of individual medullary zones is of lesser importance. A correlation was also found between the density of vasa recta per cubic millimeter of medullary tissue (the number of lumens regardless of identify in bundles, based on the number counted at the level sampled) and the UCC of the species. Data reported here support the view that UCC can be correlated with two parameters of kidney structure - the length of medulla relative to that of cortex and the density of vasa recta within the outer zone. It is proposed that the anatomical characteristics of the vascular supply to the medulla - that is, the vasa recta - are equally as important for the concentration of urine as is the primary mechanism determined by the characteristics of the loop of Henle and collecting ducts.

Anatomy, Comparative↗