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D J Reis

Publications and source records attributed to D J Reis.

At least 343 records · Page 19Linked to original sources
PubMed1982

Electron microscopic immunocytochemical localization of substance P in the area postrema of rat.

Electron microscopic immunocytochemistry was employed to examine the ultrastructure of processes containing substance P-like immunoreactivity (SP-LI) in the area postrema of rat. SP-LI was present within axons and axon terminals which formed synapses with dendrites of intrinsic neurons in the rat area postrema. Specialized contacts between labeled processes and perivascular or ependymal glia cells were not observed. These data suggested that substance P may act as a neurotransmitter involved primarily with neuronal (axodendritic) interactions within the area postrema.

Animals↗
PubMed1982

Electron microscopic immunocytochemical localization of tyrosine hydroxylase in the area postrema of rat.

The ultrastructural morphology and specialized neuronal, vascular, and ventricular associations of tyrosine hydroxylase-labeled neurons are examined within the area postrema of rat brain. Specific antiserum to the purified enzyme is localized throughout the rostrocaudal and dorsoventral extent of the area postrema by means of the peroxidase-antiperoxidase technique. In all regions, peroxidase immunoreactivity for tyrosine hydroxylase is distributed throughout the cytoplasm of selectively labeled neuronal perikarya and processes. The perikarya contain a large nucleus, infolded nuclear membrane, numerous cytoplasmic organelles, and form axosomatic synapses with unlabeled terminals. The majority of the labeled processes are dendrites, which contain ribosomes, microtubules, mitochondria, and scattered vesicles. These dendrites are postsynaptic to unlabeled axon terminals and show membrane specializations with other labeled dendrites and perikarya. In contrast to dendrites, peroxidase-labeled profiles clearly distinguished as axons or axon terminals are sparse and never show membrane specializations with other neuronal or nonneuronal structures within the area postrema. Numerous large processes which could be either axons or dendrites are associated with blood vessels and the ventricular surface of the area postrema. With respect to blood vessels, processes are located either in direct apposition to the external glial membrane, or less frequently, within the perivascular space. The ventricular processes are either associated with blood vessels in the subpial space or distributed among the cilia and villi at the anterior margins of the area postrema. The neuronal and nonneuronal associations of the tyrosine hydroxylase-labeled processes are consistent with a receptor or chemosensor function for catecholamines in this circumventricular organ.

Animals↗
PubMed1982

Reevaluation of projections from the mesencephalic trigeminal nucleus to the medulla and spinal cord: new projections. a combined retrograde and anterograde horseradish peroxidase study.

Microinjection of horseradish peroxidase (HRP) into the medullary parvocellular reticular formation (NPvc) resulted in retrograde labeling of neurons throughout the mesencephalic trigeminal nucleus (Mes V). Labeled cells were large and ovoid and were distributed primarily in the expanded pontine part of the nucleus. However, none of the small neurons in Mes V were labeled. Injections of HRP made into adjacent brainstem structures including the nucleus gigantocellularis, ventrolateral reticular formation, vestibular complex, and the spinal trigeminal nucleus failed to label neurons in Mes V. Injections made into the medullary raphe and into regions reported to receive inputs from Mes V--spinal cord, nucleus tractus solitarius, hypoglossal nucleus, and facial nucleus--were also not followed by transport to Mes V. Anterograde axonal transport of HRP from the region of reticular formation innervated by Mes V also labeled axons projecting to Mes V and to visceral and somatic sensorimotor nuclei in the lower brainstem. Recent reports of afferents from the amygdala to Mes V suggest that reflexes involving the mesencephalic trigeminal nucleus might be modulated by signals from limbic and autonomic as well as somatic centers in the brain.

Animals↗
PubMed1982

The inheritance and genetic correlation of tyrosine hydroxylase activities in the substantia nigra and corpus striatum in the C x B recombinant inbred mouse strains.

In mouse, strain differences in the activity of tyrosine hydroxylase (TH) in ventral midbrain dopamine systems of substantia nigra-A10 (SN) region of mouse brain and in a terminal field, the striatum (CS), can be entirely attributed to variations in the number of dopaminergic neurons2. To obtain further information about the complexity of the genetic systems influencing phenotypes for regional TH activity, we examined TH activity in the SN and CS of 7 recombinant inbred (RI) mouse strains, their progenitor strains (BALB/cBy and C57BL/6By), their reciprocal F1 hybrids and a CB6F2 segregating generation. Genetic analysis indicated that TH activity in both brain regions seems unlikely to be controlled by single gene effects. However, the mode of inheritance is presumably not very complex. Estimates of the degree of genetic determination for TH activity in SN and CS were relatively high with significant and positive correlations with respect to either the RI lines (r = 0.82) or the CB6F2 generation (r = 0.53). These positive correlations suggest that some of the genes of two gene sets influencing TH activities in the SN and CS are the same. However, additional non-shared genes may also be present. Assuming that our two measures reflect the number of dopaminergic neurons in SN-A10 area and density of their processes in corpus striatum, our results lead us to the hypothesis that the number of dopaminergic neurons and the axonal arborization of these neurons in the nigrostriatal system are in part under a common genetic control but that other genes may contribute to branching of SN neurons.

Animals↗
PubMed1982

Role of the nucleus parabrachialis in cardiovascular regulation in cat.

Electrical stimulation of the nucleus parabrachialis (NPB) and surrounding areas of the dorsolateral pons in anesthetized immobilized cats elicits a rise of arterial pressure (AP) and tachycardia: the parabrachial pressor response (PBPR). The most excitable sites were concentrated within the intermediate one-third of the NPB in its medial and lateral subdivisions. The magnitude of pressor responses and their stimulus sensitivity were substantially greater in NPB than in adjacent areas of the dorsal pons including nucleus locus coeruleus and brachium conjunctivum, suggesting that cardiovascular responses heretofore attributed to locus coeruleus may have been due to excitation of the NPB. The PBPR persisted after chronic cerebellectomy, acute transection of the brain stem at the lower midbrain, or acute bilateral lesions of the nucleus tractus solitarii (NTS), the latter abolishing baroreceptor reflexes. Thus the PBPR cannot be attributed to antidromic or orthodromic stimulation or from NTS. Change in blood flow and regional vascular resistances during the PBPR were measured by electromagnetic flow meters placed on the thoracic aorta, superior mesenteric, renal and femoral arteries. When elicited with stimuli 5 times threshold, the PBPR was associated with an 80% increase in AP, 14+ increase in heart rate, 25% increase in cardiac output, and a 42% increase in total peripheral resistance. There was a differentiated vasoconstriction in the order of superior mesenteric greater than renal greater than femoral arteries. The baroreflex elicited by electrical stimulation of the carotid sinus nerve was reduced during stimulation of the NPB. The tachycardia was abolished by bilateral vagotomy, combined with beta-adrenergic blockade. Such treatment attenuated but did not abolish the hypertension which was only eliminated by subsequent alpha-adrenergic blockade. Thus the hypertension caused by stimulation of NPB is a result both of an increase of total peripheral resistance and of cardiac output. The cardiovascular pattern of the PBPR differ from other responses elicited from the dorsal pons, including the defense response, and the response to cerebral ischemia. We conclude that a powerful cardiovascular response pattern is organized within intrinsic neurons of the NPB. This nucleus may play an important role in organization of cardiovascular control by brain.

Animals↗
PubMed1982

Effect of hydrocortisone on catecholamines and the enzymes synthesizing them in the developing sympathetic ganglion.

Newborn rats were daily injected with 0.2 mg hydrocortisone acetate for seven days. They were killed 1, 7 or 21 days after the last injection, together with untreated controls. Hydrocortisone caused a great increase in the number of the small, intensely fluorescent (SIF) cells and the appearance of similar small cells with intense immunohistochemical reactions for tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH) and phenylethanolamine (noradrenaline) N-methyltransferase (PNMT) in the superior cervical ganglion. At the same time, the adrenaline content and the PNMT activity of the ganglion greatly increased, while no significant changes were observed in the dopamine or noradrenaline content or TH or DBH activity. All these changes essentially disappeared after a recovery period of seven or 21 days. It is concluded that hydrocortisone caused a temporary increase in the number of SIF cells by causing a synthesis of TH, DBH and PNMT in previously existing small, non-fluorescent cells, which start to synthesize and store adrenaline, thus becoming intensely fluorescent SIF cells. These SIF cells are different from the normal SIF cells of the same ganglion, most of which appear at a later stage of postnatal development when response to hydrocortisone is lost, which contain TH but neither DBH nor PNMT, and which permanently remain in the ganglion.

Animals↗
PubMed1982

Arterial pressure and heart rate changes during natural sleep in rat.

Mean arterial pressure and heart rate data during quiet wakefulness and phases of sleep in conscious rat are sampled by a computer at a rate of 100/sec. Average values and variability expressed as standard deviation are computed for each recording session. Mean arterial pressure and heart rate and their variability decrease from quiet wakefulness to synchronized sleep. During desynchronized sleep, mean arterial pressure increases to the level of quiet wakefulness, and is more variable than during synchronized sleep. Heart rate is lower and more uniform during sleep than during quiet wakefulness, and there is no difference between synchronized and desynchronized sleep except that a greater variability occurs during desynchronized sleep. The study shows that characteristic and specific cardiovascular changes accompany the phases of sleep and that a hierarchy of arterial pressure is present during the resting behavior in rat.

Animals↗
PubMed1982

Time of appearance during development of differences in nigrostriatal tyrosine hydroxylase activity in two inbred mouse strains.

The greater activity of tyrosine hydroxylase (TH) in substantia nigra and corpus striata of adult BALB/cJ than CBA/J mice, is attributable to differences in the number of dopamine neurons in the ventral midbrain tegmentum. To determine if strain differences in TH activity develop postnatally we have measured the development of TH in the midbrain (SN) and in the corpus striatum (CS). In the midbrain neonatal TH activity was 20% of adult levels. Thereafter, TH activity increased rapidly achieving adult levels by 11 days. A 25% "overshoot' above adult values at 15 days was followed by a gradual decrease to adult activity at 4 weeks. In the CS neonatal activity was about 10% of adult levels and increased slowly to reach adult values at 4 weeks. Striatal choline acetyltransferase (CAT) activity in the neonate was only 3.7% of adult values and at 21 days had only reached 70% of adult activity. Neonatal glutamic acid decarboxylase (GAD) activity was relatively high in both brain regions and increased gradually to adult activity by 4 weeks. Strain differences in TH activity were not present at birth but first appeared at 9 days in SN and 11 days in CS. Once established, the differences were maintained. These results suggest that strain differences in TH are most probably a consequence of differences in postnatal neuron survival, although the possibility that some neurons lose their phenotypic expression of TH cannot be excluded.

Animals↗
PubMed1982

Different forms of adrenal phenylethanolamine N-methyltransferase: species-specific posttranslational modification.

Phenylethanolamine N-methyltransferase was purified from rat and cow adrenal glands. The enzymes from the two species have the same molecular weight of 31,000, but differ in electrophoretic mobility. During polyacrylamide gel electrophoresis, the rat form migrates faster than the bovine form. Antibodies to bovine enzyme precipitated equally well the rat and cow form of the enzyme, but antibodies against rat enzyme precipitated poorly the bovine form. In contrast, both antibodies recognized a similar protein in the in vitro translation products of poly(A+)mRNA isolated from cow adrenal glands. The results suggest that the primary protein structure of rat and bovine enzyme is similar and that differences in electrophoretic mobility are due to posttranslational modification of the enzyme molecule.

Adrenal Glands↗
PubMed1982

Global cerebral vasodilation by stimulation of rat fastigial cerebellar nucleus.

The effects of electrical stimulation of the pressor area of the fastigial nucleus (FN) of cerebellum on regional cerebral blood flow (CBF) were examined in anesthetized, paralyzed rats. CBF was measured in tissue homogenates by the Kety principle using 14C-iodoantipyrine as an indicator during FN stimulation, during stimulation of the vermal cortex, or after placement of electrodes in FN (unstimulated controls). Blood gases and systemic arterial pressures were comparable in the three groups. FN stimulation elicited a widespread and significant (P less than 0.005) increase in CBF in 12 of 13 areas. Flow was maximally increased in cerebral cortex (up to 220% of control) but also rose in selected regions of telencephalon, diencephalon, mesencephalon, lower brain stem, and in white matter of the corpus callosum (172%). Flow was not increased in cerebellum. The increase in CBF persisted after transection of the spinal cord at C1 or cervical sympathectomy. In five rats, hypercarbia (PCO2 to 63 mmHg) increased CBF in all 13 regions but in a pattern differing from FN stimulation. Excitation of neurons originating in, projecting to, or passing through FN can elicit a potent and virtually global increase of CBF. The effect appears mediated by intrinsic pathways of the central nervous system.

Animals↗
PubMed1981

Projections from the spinal trigeminal nucleus to the entire length of the spinal cord in the rat.

Using retrograde transport of horseradish peroxidase, projections were found from the spinal trigeminal nucleus to all levels of the spinal cord in rat. In addition to the previously described projections from nucleus caudalis, axons originate from two areas - one overlapping the nucleus caudalis and interpolaris and one in the ventral division of nucleus oralis - and descend as far as the lumbosacral cord. Projections from the nucleus caudalis and interpolaris are primarily ipsilateral to all levels of the spinal cord. Cells in the nucleus oralis innervating the cervical cord are distributed bilaterally. Projections from the nucleus oralis to the thoracic and lumbosacral segments are entirely crossed, lighter and less extensive than those to cervical levels. Trigeminospinal cells originate from several loci that strongly overlap the distributions of both trigeminotectal and trigeminocerebellar neurons. These findings thus reveal a new and more complexly organized system of trigeminospinal projections than previously recognized.

Animals↗
PubMed1981

Ultrastructural immunocytochemical localization of tyrosine hydroxylase in the neostriatum.

The morphology and synaptic associations of dopaminergic axons in the n. caudate-putamen (neostriatum) of the adult rat brain are examined. Identification of dopaminergic axons is based upon the electron microscopic immunocytochemical localization of the catecholamine synthesizing enzyme, tyrosine hydroxylase. Immunoreactivity for the enzyme is detected in unmyelinated axons and axon terminals in serial sections collected throughout the neostriatum. The labeled terminals range from 0.1 to 1.5 micron in diameter and have peroxidase reaction product located around closely packed, round vesicles with a diameter of 40-60 nm. The tyrosine hydroxylase containing axon terminals constitute approximately 21% of the total number of terminals in the n. caudatus-putamen and include 3 types which differ in size and synaptic specializations. The most prevalent (82% of total), type I, is small (0.15-0.39 micron in diameter) and forms symmetric junctions with dendrites and dendritic spines. The other two terminal types (II and III) have a medium to large diameter (0.4-1.5 micron) and show either no membrane specializations or asymmetric junctions with dendrites. The axon terminals without observable membrane densities are occasionally oriented so as to suggest an association with dopaminergic and non-dopaminergic axon terminals. These findings indicate that while the dopaminergic terminals may form axoaxonic connections, the primary synaptic contacts are with dendrites of intrinsic neurons in all regions of n. caudatus-putamen.

Animals↗
PubMed1981

Afferent projections to cardiovascular portions of the nucleus of the tractus solitarius in the rat.

Horseradish peroxidase was injected unilaterally into the intermediate portion of the nucleus of the tractus solitarius. The most extensive retrograde labeling was present contralaterally in the rostral fastigial nucleus, bilaterally in the Koelliker-Fuse nucleus, and bilaterally with ipsilateral predominance in the posterolateral hypothalamus and paraventricular hypothalamic nucleus. These projections may represent the anatomical substrates by which these brain areas modulate baroreceptor reflex function.

Afferent Pathways↗