SEARCH · Search PubMed

Results for “Pons”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

PubMed2001

Hypertensive brain stem encephalopathy: clinically silent massive edema of the pons.

Hypertensive encephalopathy is a medical emergency whose clinical manifestations are associated with bilateral parieto-occipital lesions. We describe a case of hypertensive brainstem encephalopathy in which high blood pressure was accompanied only by nuchal headaches of violent onset. T2-weighted magnetic resonance images showed hyperintensity and edema of the pons without any parietooccipital lesions, but with hyperintense lesions at the level of the basal nuclei, insula and temporal lobes. The lesions rapidly regressed once the hypertension had been controlled.

Adult↗

PubMed1977

Amino acid incorporation in medulla, pons, midbrain and cortex following spinal cord hemisection in the cebus monkey (Cebus apella).

The effects of spinal cord hemisection on protein labeling in the medulla, pons, midbrain, and cortex in the Cebus monkey were studied by measuring the uptake of [3H]lysine into the trichloroacetic acid (TCA) precipitable and non-precipitable fractions of brain. Animals were sacrificed 3, 6 or 13 days after hemisection. Two normal animals and a 3-day sham operate were utilized as controls. Differences included individual animals, operated vs. unoperated animals, brain areas, and variation of brain areas over all postoperative days. The overall trend in brain radioactivity over postoperative days indicates stress and non-stress related components of brain response to spinal injury. Left-right side differences (L greater than R) were noted in the uptake of [3H]lysine into specific areas of brain over postoperative time, including leg areas of motor cortex, occipital cortex, and superior colliculus. A biphasic action of leg sensory cortical areas over time was noted, where L greater than R for the first 6 postoperative days and R greater than L at day 13. The factors possibly mediating radiolabeled amino acid uptake into protein are discussed in relation to demonstrated anatomical and neurochemical regenerative processes.

Animals↗

PubMed1982

A new double labeling technique using tyrosine hydroxylase and dopamine-beta-hydroxylase immunohistochemistry: evidence for dopaminergic cells lying in the pons of the beef brain.

Despite numerous data on the organization of the central catecholaminergic (CA) system, the nature of many CA terminal fields, fiber pathways and cell bodies, remains unknown. The discrepancies between the results obtained by CA histofluorescence and dopamine-beta-hydroxylase (DBH) immunofluorescence method suggest that certain areas described as noradrenergic (NA) may be in fact dopaminergic (DA). A method to solve this problem is to compare the localization of the two CA synthetizing enzymes: tyrosine hydroxylase (TH) and DBH. The first enzyme is a marker of all CA neurons, whereas the second one is a specific marker of noradrenergic and adrenergic neurons. We decided to develop a technique which allows visualization of both antigens on a same section. We chose to combine immunofluorescence and immunoperoxidase techniques which yield very different staining. The optimal conditions for this double labeling technique were developed in bovine brain, the homologous system for our antibodies. The results obtained by this procedure provide evidence that DA cells together with NA cells extend throughout the rostral part of the pons, and outline a successful technique for a more extensive investigation of the DA system. The same method should be applicable to other investigations involving other antigens.

Animals↗

PubMed1990

Corticofugal influence on taste responses in the parabrachial pons of the rat.

Although the anatomy of centrifugal input to gustatory neural structures has been described, little is known of the physiological mechanisms that convey this influence or of their functional significance. As a first step in the investigation of these issues, the effect of a reversible lesion in the gustatory neocortex (GN) on the neural code for taste in the parabrachial nucleus of the pons (PbN) was studied in rats. Electrophysiological responses to taste stimuli bathed over the tongue were recorded from single units in the PbN before, after and following recovery from an infusion of procaine-HCl into the GN. Test stimuli consisted of sapid solutions of NaCl (0.1 M), HCl (0.01 M), sucrose (0.5 M), Na-saccharin (0.004 M) and quinine-HCl (0.01 M). Infusions of procaine into the GN were correlated with both specific and nonspecific effects on the responsivity to gustatory stimuli in the PbN. Specific effects included: (1) changes in the magnitude of response to some tastants, but not others, in a given PbN unit, (2) changes in the across unit patterns produced by sweet stimuli and (3) the appearance of OFF responses in a subset of PbN units. Nonspecific effects were evidenced by changes in the spontaneous rates of activity and by enhancement or suppression of responses across all the tastants tested in a subset of PbN units. Comparison of these results with reports on the effects of decerebration suggests that some of these effects may be accounted for by interruption of the descending input from the GN to the PbN. In addition, the stimulus-specific effects that were noted following procaine infusion into the GN provide support for the suggestion that the GN specifically modifies the electrophysiological patterns that are evoked by salient taste stimuli.

Animals↗

PubMed1978

Properties of apneusis produced by reversible cold block of the rostral pons.

Reversible cold block of the rostral pons was used to compare properties of normal and apneustic respiration in anesthetized, vagotomized, artificially ventilated cats. During apneusis we observed high frequency oscillations (HFO) in phrenic nerve activity which were reduced in frequency compared with those during a normal inspiration. Apneusis produced by mid-pontine transection or punctate pneumotaxic center (PC) lesion produced similar HFO changes. The minimal intensity of superior laryngeal nerve electrical stimulation needed to terminate a breath was higher early in an apneusis than at the same time during a normal breath. Later in apneusis the intensity required became constant and was approximately the same as that needed to end a normal inspiration at its natural termination. With intact vagi lung inflation produced a greater prolongation of expiration during apneustic respiration than during normal respiration. Apneustic type activity was observed in both phrenic and vagal inspiratory motoneurons. We suggest that: (1) HFO are generated without the PC, but the PC elevates the oscillation frequency; and (2) apneusis may result in part from a delayed activation of the normal inspiratory off-switch mechanism.

Action Potentials↗

PubMed1981

Activity responses to morphine and amphetamine in rats with elevated NE levels in the pons.

The catecholaminergic basis of the stimulant actions of amphetamine and morphine was investigated in adult rats treated neonatally with 6-hydroxydopamine (6-OHDA) to produce depletion of cortical catecholamines and marked elevation of norepinephrine in the pons. On days 3, 5, 7 and 9 after birth, rat pups were injected bilaterally in the lateral ventricles with 100, 200, or 400 micrograms of 6-OHDA, dissolved in artificial cerebrospinal fluid (CSF). A control group was injected with the CSF vehicle. The capacity of amphetamine (2 mg/kg) and morphine (1.25, 2.5, and 3.5 mg/kg) to produce behavioral stimulant effects was then subsequently tested in adults. The stimulant effect of amphetamine was attenuated in animals pretreated with 100 and 200 micrograms 6-OHDA and was blocked in those treated with 400 micrograms 6-OHDA. The stimulant effects obtained with morphine were blocked by all 6-OHDA doses (100 and 200 micrograms). For morphine, no tests were made in the 400 micrograms 6-OHDA group on the basis of results obtained in animals pretreated with the lower doses of 6-OHDA. These results are discussed in terms of differing roles played by the catecholamine systems in the production of behavioral stimulation.

Amphetamine↗

PubMed1986

Cerebral venous angioma of the pons: report of a case with pontine hemorrhage.

Cerebral venous angioma in the pons associated with pontine hemorrhage in a 39-year-old normotensive woman was identified with computed tomography and angiography. Venous angioma in the brain stem is usually silent and rarely found by chance at autopsy. Only a few cases have been clinically reported. Our report indicates that in unusual cases of intracerebral hemorrhage, vascular malformations should be suspected and scrutinized with radiologic examination including angiography.

Adult↗

PubMed1992

Direct projections from the globus pallidus to the midbrain and pons in the cat.

Employing the anterograde and retrograde axonal tracing techniques with Phaseolus vulgaris leucoagglutinin and cholera toxin B subunit, we demonstrated direct projections from the globus pallidus (GP) to the midbrain and pons in the cat. Cells of origin of these projections were localized in the caudal 2/3 of the GP, and their major target sites included the peripeduncular region, nucleus of the brachium of the inferior colliculus, para-lateral lemniscal zone, nucleus sagulum, external and pericentral nuclei of the inferior colliculus, and cuneiform nucleus. A combination of retrograde axonal tracing and immunohistochemistry for choline acetyltransferase revealed that GP neurons giving rise to such descending projections were primarily non-cholinergic.

Animals↗

PubMed1996

The effects of ozone exposure on the sleep-wake cycle and serotonin contents in the pons of the rat.

Polysomnographic studies were done at hourly intervals during 0.00, 0.35, 0.75 and 1.50 ppm of ozone (O3) exposure. We found a significant decrease in paradoxical sleep after 2 h and an increase in slow wave sleep after 12 h at all concentrations of O3. High resolution liquid chromatography demonstrated an increase in 5-HT concentration in the rat pons, in a roughly stepwise fashion as the O3 concentration increased. We propose that reaction products derived from O3 exposure, such as prostaglandins, could be affecting those physiological and biochemical mechanisms critical for the generation and maintenance of the sleep-wake cycle.

Animals↗

PubMed1989

Taste responses in the parabrachial pons of male, female and pregnant rats.

Sex-related and pregnancy-related variations in taste preferences have long been known to exist in humans as well as animals. However, the neurophysiological underpinnings of these variations have not yet been described. In an effort to discover whether differences in hormonal state are reflected in the neural processing within the gustatory system, electrophysiological responses to representatives of the 4 basic taste qualities were recorded in the parabrachial nucleus of the pons (PbN) of male, diestrous female and pregnant rats. Results revealed that PbN units in female and pregnant rats showed larger responses to sweet stimuli than units in male rats. Also, a greater proportion of units in female and pregnant rats were classified as sweet-best compared with units in males. This result may correlate with the greater preference for sweet stimuli in female rats compared with males that has been reported in the behavioral literature. Analysis of response profiles with multidimensional scaling techniques showed that units that responded best to a given stimulus were placed near that stimulus for units from males, but not for units from female and pregnant rats. Hierarchical cluster analysis of response profiles suggested 3 clusters of units within each group of PbN units. Response profiles within clusters showed different types of units in male, female and pregnant rats. Collectively, these data suggest that ovarian hormones may act to alter the central processing of gustatory information. Evidence for both activational and organizational effects of ovarian hormones on the gustatory system is discussed.

Action Potentials↗

PubMed1990

Taste responses in the parabrachial pons of ovariectomized rats.

Since the early 1970s it has been known that female rats prefer higher concentrations of sweet stimuli compared with males. Recent data have revealed that electrophysiological responses to sweet tastes recorded in the parabrachial nucleus of the pons (PbN), the second relay in the neural pathway for taste, are larger in diestrus female rats compared with those in males. Because it has been shown that ovariectomized rats have lowered preferences for saccharin compared with intact females, it is possible to predict that responses to sweet stimuli in the PbN of ovariectomized rats might be smaller than those in intact females. To investigate this hypothesis, electrophysiological responses to representatives of the 4 basic taste qualities, i.e., salty, sour, sweet and bitter, were recorded in the PbN of ovariectomized rats. Gustatory stimuli included NaCl (0.1 M), HCl (0.01 M), sucrose (0.5 M), quinineHCl (0.01 M) and Na-saccharin (0.004 M). Comparison of taste responses of 49 PbN units in ovariectomized rats with those in the PbN of intact female and male rats showed that responses to sweet stimuli were of comparable magnitude to those in female rats but elevated compared with those in male rats. However, responses of PbN units to quinine appeared to be larger in ovariectomized rats compared with those in the PbN of both intact female and male rats. These results suggest that decreased saccharin preference in ovariectomized rats may reflect a greater sensitivity to the bitter components of the taste of saccharin. Moreover, these data provide evidence that taste responses in the PbN are influenced by both the activational and organizational actions of ovarian hormones.

Animals↗

PubMed1992

Corticofugal input to taste-responsive units in the parabrachial pons.

Taste responses in units in the parabrachial nucleus of the pons (PbN) that receive direct projections from the gustatory neocortex (GN) were examined in the rat. Electrical stimulation was applied to the GN with bipolar stimulating electrodes. Time-locked responses to GN stimulation were observed in 19 of 62 (31%) taste-responsive units identified in the PbN. Of these, 17 units produced excitatory responses following GN stimulation and 2 units showed evidence of inhibition. No evidence of antidromic activation of PbN units was apparent. These results are consistent with descriptions of the anatomical projections from the GN to the PbN and demonstrate that some portion of taste-responsive neural elements within the PbN receive direct cortical input. PbN units that followed GN stimulation could not be distinguished from those that did not follow either by their spontaneous rates or their response profiles. These results suggest that axons from the GN do not select targets within the PbN based on the particular response properties.

Animals↗

PubMed2004

Separate populations of neurons in the rostral ventromedial medulla project to the spinal cord and to the dorsolateral pons in the rat.

Activation of neurons in the rostral ventromedial medulla (RVM) directly modulates spinal nociceptive transmission by projections to the spinal cord dorsal horn and indirectly by projections to neurons in the dorsolateral pons (DLP) that project to the spinal cord dorsal horn. However, it is not known whether the same neurons in the RVM produce both direct and indirect modulation of nociception. Deposits of the retrograde tracers Fluoro-Gold (FG) in the spinal cord dorsal horn and DiI in the DLP were used to determine whether the same RVM neurons project to both of these regions. Only 0.9+/-0.1% of RVM neurons retrogradely labeled with Fluoro-Gold from the spinal cord were also labeled with DiI placed in the DLP. In addition, spinally projecting RVM neurons were significantly larger than RVM neurons that project to the DLP. Finally, spinally projecting neurons were found predominantly on the midline and within the RVM; neurons that project to the DLP had a wider distribution and were present both within and outside of the RVM. Thus, separate and morphologically distinct populations of RVM neurons appear to modulate nociception by direct and indirect descending pathways.

Animals↗

PubMed2005

Patterns of fos expression in the rostral medulla and caudal pons evoked by noxious craniovascular stimulation and periaqueductal gray stimulation in the cat.

Functional imaging studies and clinical evidence suggest that structures in the brainstem contribute to migraine pathophysiology with a strong association between the brainstem areas, such as periaqueductal gray (PAG), and the headache phase of migraine. Stimulation of the superior sagittal sinus (SSS) in humans evokes head pain. Second-order neurons in the trigeminal nucleus that are activated by SSS stimulation can be inhibited by PAG stimulation. The present study was undertaken to identify pontine and medullary structures that respond to noxious stimulation of the superior sagittal sinus or to ventrolateral PAG stimulation. The distribution of neurons expressing the protein product (fos) of the c-fos immediate early gene were examined in the rostral medulla and caudal pons of the cat after (i) sham, (ii) stimulation of the superior sagittal sinus, (iii) stimulation of the superior sagittal sinus with PAG stimulation, or (iv) stimulation of the PAG alone. The structures examined for fos were the trigeminal nucleus, infratrigeminal nucleus, reticular nuclei, nucleus raphe magnus, pontine blink premotor area, and superior salivatory nucleus. Compared with all other interventions, fos expression was significantly greater in the trigeminal nucleus and superior salivatory nucleus after SSS stimulation. After PAG with SSS stimulation, on the side ipsilateral to the site of PAG stimulation, fos was significantly greater in the nucleus raphe magnus. These structures are likely to be involved in the neurobiology of migraine.

Afferent Pathways↗

PubMed2005

Nuclear parcellation of certain immunohistochemically identifiable neuronal systems in the midbrain and pons of the Highveld molerat (Cryptomys hottentotus).

The present paper details our findings following immunohistochemical examination of the midbrain and pons of the Highveld molerat (Cryptomys hottentotus) using antibodies for vesicular acetylcholine transporter (cholinergic neurons), tyrosine hydroxylase (dopaminergic and noradrenergic neurons), and serotonin (serotonergic neurons). The aim was to see if, in this microphthalmic rodent that lacks a distinct circadian rhythm, the nuclei involved in aspects of visual processing and the sleep-wake cycle exhibited specific loss or morphological alteration. For all of the neural systems investigated we found nuclei that can be considered direct homologues of those found in the laboratory rat. There was no specific loss of any nuclear group of any of the systems investigated, but there was significant reduction (as judged qualitatively) in the number of neurons in the visual associated nuclei. The fact that we could identify all nuclear groupings from three systems in this species is suggestive of an evolutionary constraint acting at the level of the organization of the neural system.

Acetylcholine↗

PubMed2006

Effect of 2,4-dinitrophenol under non-oxygenated condition in pons-medulla-spinal cord preparations in newborn rats: comparison with medulla-spinal cord preparations.

We tested whether depression of respiratory frequency (fR) under non-oxygenated artificial cerebrospinal fluid (aCSF) in pons-medulla-spinal cord (PMS) and medulla-spinal cord (MS) preparations is significantly influenced by the mitochondrial uncoupler 2,4-dinitrophenol (2,4-DNP) in newborn rats. Preparations were obtained from 0- to 4-day-old rats, and fR was monitored at the C4 ventral root in environmental temperature (24 degrees C). 2,4-DNP was dissolved in aCSF (1, 10 or 30 microM; pH 7.4), and we measured fR in PMS (n=19) and MS (n=16), both of which were superfused with aCSF equilibrated with oxygenated (95% O2-5% CO2) or non-oxygenated (10% O2-5% CO2, balanced with pure N2) gas. Our results showed that: (1) fR was significantly lower in PMS than MS, (2) fR was significantly decreased under non-oxygenated aCSF in both PMS and MS and (3) fR under non-oxygenated aCSF was significantly increased by 2,4-DNP applications at 10 and 30 microM in PMS but not in MS. Our results suggest that depression in fR under non-oxygenated aCSF in PMS and MS may not be due simply to O2 limitation, and 2,4-DNP has a stimulant effect on the medullary respiratory rhythm generator (RRG) through pontine RRG regulatory mechanisms under non-oxygenated aCSF.

2,4-Dinitrophenol↗

PubMed2004

Overall distribution of GLYT2 mRNA-containing versus GAD67 mRNA-containing neurons and colocalization of both mRNAs in midbrain, pons, and cerebellum in rats.

We aimed to clarify the overall distribution of glycinergic neurons in the midbrain, pons, and cerebellum in rats, using in situ hybridization for mRNA encoding glycine transporter 2 (GLYT2), which reliably detects glycinergic cell bodies. We combined this method with in situ hybridization for mRNA encoding glutamic acid decarboxylase isoform 67 (GAD67), and have presented for the first time global and detailed views of the distribution of glycinergic neurons in relation to GABAergic neurons. In addition to this single-detection study, we performed double-detection of GLYT2 mRNA and GAD67 mRNA to determine the distribution of neurons co-expressing these mRNAs. We have shown that many areas of the brainstem and cerebellum, not only areas where previous immunohistochemical studies have specified, involve double-labeled neurons with GLYT2 and GAD67 mRNAs. In particular, when lightly labeled GLYT2 mRNA-positive neurons were distributed within the area of GAD67 mRNA-positive neurons, almost all such GLYT2 mRNA-positive neurons were GAD67 mRNA-positive. Areas or neuron groups expressing exclusively GLYT2 mRNA or GAD67 mRNA were rather limited, such as the superior colliculus, nucleus of the trapezoid body, and Purkinje cells. The present study suggests that the corelease of glycine and GABA from single neurons is more widespread than has been reported.

Amino Acid Transport Systems, Neutral↗

PubMed2004

Purkinje cell functions in the in vitro cerebellum isolated from neonatal rats in a block with the pons and medulla.

The cerebellum dissected from neonatal rats in a block including the pons and medulla and maintained in a modified Krebs solution provides a unique preparation of brain tissue with preserved major fiber connections. Electrophysiological and optical recordings revealed that, at postnatal days 4-8 (P4-P8), Purkinje cells in the lateral portion of the cerebellum responded to the stimulation of climbing fiber afferents at the inferior olive and of parallel fibers at the posterior vermis, and that the combination of these inputs induced long-term depression. These observations and pharmacological testings indicate that certain functional features of Purkinje cells mature around P5 in the lateral portion of the cerebellum.

Animals↗