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Biomedical subjects

M Palkovits

Publications and source records attributed to M Palkovits.

At least 289 records · Page 16Linked to original sources
PubMed1982

Cholecystokinin in the nucleus of the solitary tract of the rat: evidence for its vagal origin.

Nerve fibers and terminals immunoreactive for cholecystokinin (CCK) were demonstrated in the nucleus of the solitary tract (NTS) of the rat using light and electron microscopic immunocytochemistry. The following morphological and biochemical evidence suggests that CCK in the NTS seems to be of extrinsic, most probably vagal, origin: (1) axon fragments of the intracranial vagus were identified by immunostaining on their way to the solitary tract: (2) CCK-immunostaining could be localized in nerve terminals in the nucleus of the solitary tract, where only a very few immunopositive dendrites or cell bodies were present; and (3) transecting the major neuronal afferents (via solitary tract and/or more laterally) resulted in a complete disappearance of radioimmunoassayable CCK from the nucleus of the solitary tract.

Animals↗
PubMed1982

Somatostatin connections between the hypothalamus and the limbic system of the rat brain.

Somatostatin (SRIF) content of several brain structures was evaluated by radioimmunoassay in rats bearing various types of hypothalamic transections, as well as lesions of the amygdala. Analysis of the regional changes in SRIF concentrations after surgery suggest the following conclusions: (1) hypothalamic somatostatinergic neurons project to the limbic system, with the exception of the amygdaloid nuclei; (2) the olfactory tubercle, the lateral septal nucleus, the habenula and probably the hippocampus receive somatostatin projections from periventricular SRIF-containing cells; (3) somatostatin-containing fibers take a lateral course after leaving periventricular cells and join the medial forebrain bundle; (4) somatostatin innervation of the amygdala seems to be intrinsic.

Amygdala↗
PubMed1982

Meningeal relations of the rat hypothalamo-hypophyseal system. Extravascular fluid spaces in and around the median eminence.

Meningeal relations of the rat pituitary and basal hypothalamus including the pituitary stalk and median eminence, were studied by both light and electron microscopy, and by ink perfusion techniques. The dura mater encapsulates the pituitary gland. The arachnoid covers the basal surface of the hypothalamus except the caudal two-thirds of the median eminence and the pituitary stalk. No arachnoidea, i.e. no subarachnoideal space, was found in the sella. Pia mater covers the entire basal surface of the hypothalamus, including the median eminence and the pituitary stalk, but encapsulates only the posterior lobe of the pituitary. The superficial portal vessels (primary plexus and portal veins) are located in the subdural space, covered by the pia mater. The deep vessels in the median eminence are surrounded by the perivascular space, which is bordered by the vascular and neuropil basement membranes, and separated from the external fluid space around the median eminence only by the pia mater. This special topography suggests that molecules present in the portal vessels or in the cerebrospinal fluid, or in and around the pituitary gland, readily move from one liquid space to another.

Animals↗
PubMed1982

Regional distribution of substance P-like immunoreactivity in the lower brainstem of the rat.

A radioimmunoassay was used to quantify substance P-like immunoreactivity in the lower brainstem of the rat. The peptide was detectable in all brainstem nuclei investigated. A very high concentration was found in the substantia nigra, and high concentrations in the interpeduncular nucleus and central gray matter. Levels in the pons, the parabrachial nuclei; in the medulla, the nucleus tractus spinalis of the Vth nerve and the nucleus of the solitary tract were higher than the brain average.

Animals↗
PubMed1982

Intrinsic vasoactive intestinal polypeptide (VIP)-containing neurons in the baroreceptor nucleus of the solitary tract in rat.

Vasoactive intestinal polypeptide (VIP)-immunoreactive cell bodies, dendrites and nerve terminals in the nucleus of the solitary tract have been identified with electron microscopic immunocytochemistry in rats. The relatively high concentration of VIP in this nucleus, which corresponds to the primary baroreceptor center, was depleted only insignificantly by uni- or bilateral transection of the solitary tract, which eliminates peripheral neuronal (via glossopharyngeal and vagal nerves) input to the nucleus. Both immunocytochemical and biochemical data suggest that the majority of VIP in the nucleus of the solitary tract is present in intrinsic neurons.

Animals↗
PubMed1982

Distribution and quantitative measurements of somatostatin-like immunoreactivity in the lower brainstem of the rat.

A radioimmunoassay was used to identify and quantify somatostatin-like immunoreactivity in the lower brainstem of the rat. The peptide was detectable in all brainstem nuclei investigated. Highest levels were found in the nuclei parabrachiales, central gray, ocus coeruleus, and nucleus tractus solitarii. Extremely low levels were found in the substantia nigra and cerebellum.

Animals↗
PubMed1982

Distribution of cholecystokinin (CCK) in the rat lower brain stem nuclei.

The cholecystokinin (CCK) concentration in individual brain stem nuclei of rat was determined using the Palkovits punch method19 and the CCK RIA3, CCK has a unique distribution in the brain stem, unlike other neuropeptides and biogenic amines8,19. In general, the CCK levels in the brain stem are 5-20% of rat cerebral cortex. The colliculi, midbrain central gray, nucleus of the solitary tract, and the interpeduncular nucleus had the highest CCK content (2.7-1 ng CCK mg protein).

Animals↗
PubMed1982

Distribution of vasoactive intestinal polypeptide (VIP) in the rat brain stem nuclei.

The distribution of vasoactive intestinal polypeptide (VIP) in the individual nuclei of the rat brain stem was examined. Highest VIP concentrations in brain stem (greater than 1 ng/mg protein) are confined to dorsal regions, including periaqueductal gray and structures under the fourth ventricle. VIP concentrations are moderately high (0.8-1 ng/mg protein) in gracile nucleus, area postrema, nucleus of the solitary tract, motor nucleus of the XIIth, locus ceruleus and dorsal tegmental nucleus. Cerebellum and pontine nuclei contained only very low levels (less than 0.2 ng/mg protein) of VIP.

Animals↗
PubMed1982

Acute changes in cyclic AMP levels of certain brain areas following intraventricular injection of renin in rats.

Actions of the central angiotensin system on brain cAMP concentrations were studied after intraventricular injection of renin. Biosynthesis of endogenous brain angiotensin II was stimulated by 0.1 U renin and the blood pressure was elevated 40 min after the application. Stimulation of the brain angiotensin system affected cAMP metabolism in several brain areas, mostly expressed as decreased cAMP levels. Significant decreases in cAMP concentrations were found in the cerebral cortex, hippocampus, basal ganglia, various hypothalamic nuclei, substantia nigra, central grey matter and in the locus coeruleus. The unchanged cAMP levels in the nucleus of the solitary tract might indicate that intraventricular injection of renin induced an acute blood pressure elevation which is not associated with changes in the cAMP system in the primary baroreceptor area.

Angiotensin II↗
PubMed1982

Somatostatin in catecholamine-rich nuclei of the brainstem.

Somatostatin (SRIF) concentrations in catecholamine-rich nuclei of the rat brainstem were measured by radioimmunoassay. The study was performed both in control or sham operated animals and after transecting the major projections of hypothalamic SRIF-containing neurons. Concentrations of the peptide were found to be relatively high in the locus coeruleus, the parabrachial nucleus and the nucleus of the solitary tract; they were intermediate in the lateral reticular nucleus (A1 cell group) and low in the substantia nigra. Transection of hypothalamic periventricular efferents resulted in a 58% depletion of SRIF content in the locus coeruleus, while concentrations of the peptide in other areas were unaffected. Transection of the medial forebrain bundle at the level of the lateral hypothalamus decreased SRIF content by 55% in the substantia nigra, but not in the other nuclei tested. It is concluded that the hypothalamus contributes significantly to the somatostatinergic innervation of the locus coeruleus and the substantia nigra, whereas SRIF in the other nuclei is intrinsic or originates outside the hypothalamus.

Animals↗
PubMed1982

Simultaneous characterization of pre- and postsynaptic neuron contact sites in brain.

The combined application of electron microscopic study of nerve degeneration and immunocytochemical techniques enables both pre- and postsynaptic structures of central nervous system synapses to be characterized simultaneously. Information obtained from a model experiment is presented to indicate the usefulness of the method. After the surgical transection of the ventral noradrenergic bundle in rats, degenerating boutons of brainstem axons were demonstrated on luteinizing hormone-releasing hormone-positive and adrenocorticotropic hormone-positive neurons in the hypothalamic arcuate nucleus.

Animals↗
PubMed1982

The course of thyrotropin-releasing hormone fibers to the median eminence in rats.

The topographical distribution of fibers containing TRH that run to the median eminence has been investigated by RIA of TRH after hypothalamic surgical transections in rats. Anterolateral or lateral cuts bilaterally transecting fibers at the caudal edge of the optic chiasm (lateral retrochiasmatic area) diminish TRH levels in the median eminence by 95% and 73%, respectively. Paramedian cuts are ineffective. These results suggest that TRH fibers reach the medial basal hypothalamus from an anterolateral direction just as several other classes of peptide containing fibers do.

Animals↗
PubMed1982

Distribution of monoamines within the median eminence in rats.

The concentration of dopamine, norepinephrine, epinephrine and serotonin was determined in 6 rostrocaudal segments of the median eminence, 2 segments in the pituitary stalk, in the retrochiasmatic area and the pituitary lobes by radioenzymatic microassay in adult rats. The level of dopamine and norepinephrine was measured separately in the medial and lateral portions of the median eminence. All four amines measured were found unevenly distributed inside the median eminence: 1. the highest dopamine level was detected in the middle-caudal portions of the median eminence and in the rostral parts of the pituitary stalk; 2. high norepinephrine concentration was found in the retrochiasmatic area and this gradually diminished caudalwards; 3. relatively high epinephrine level was present in the rostral median eminence and retrochiasmatic area, but that in the caudal median eminence and pituitary stalk was low; 4. the level of serotonin increased caudalwards and showed a highest value in the caudal portion of the pituitary stalk. Relatively high dopamine and serotonin levels were also detectable in all three pituitary lobes where the concentration of norepinephrine was low and that of epinephrine was undetectable.

Animals↗
PubMed1982

Blood supply of the rat hypothalamus. VII. The lateral hypothalamus (medial forebrain bundle).

Using the double ink-filling technique the arteries and veins of the lateral hypothalamus are described in detail. This region occupied mainly by the fibres and interposed cells of the medial forebrain bundle is supplied by some own arteries and branches of the large basal vessels. Most of the arteries running to the rostral part of the lateral hypothalamus originate from the internal carotid, others belong to the anterior and middle cerebral arteries. Blood supply of the middle part comes from the middle hypothalamic and three tuberal arteries. All arteries of the caudal part originate from the posterior communicans. The abundant drainage of the lateral hypothalamus is collected by the basal and anterior interpeduncular veins from the rostral two-thirds and the caudal one-third, respectively.

Animals↗