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At least 19 recordsLinked to original sources
PubMed1989

Localization of C-PON immunoreactivity in the rat main olfactory bulb. Demonstration that the population of neurons containing endogenous C-PON display NADPH-diaphorase activity.

The presence of the neuropeptide C-terminal flanking peptide of neuropeptide-Y, C-PON, has been investigated in the main olfactory bulb of the rat using conventional fluorescence and peroxidase-antiperoxidase immunocytochemical techniques. The distribution of immunoreactive structures to C-PON was examined in both horizontal and coronal sections. Endogenous C-PON was localized within two types of short-axon cells including (1) superficial short-axon cells in the glomerular layer and (2) deep short-axon cells lying in the deepest portion of the granule cell layer and in the adjacent white matter. In addition, varicose immunoreactive processes were detected in all layers, although they were more numerous in the deepest portion of the granule cell layer. Immunoreactive cell bodies and processes were also observed in the nucleus olfactorius anterior and in the intrabulbar portion of the anterior commissure. Nevertheless, immunoreactive structures were not localized in the lateral olfactory tract. The indirect immunofluorescence technique to detect endogenous C-PON in combination with the enzyme histochemical demonstration of NADPH-diaphorase activity, in single sections, showed that the NADPH-diaphorase procedure is a reliable marker for these C-PON positive cells. Also, indirectly, that, in the rat main olfactory bulb, C-PON and neuropeptide-Y are contained in the same cell types. Many glomeruli were stained following the NADPH-diaphorase procedure, but they were not C-PON immunoreactives. Results of this study provide evidence suggesting that C-PON may influence polysynaptically the function of mitral cells and, therefore, the olfactory bulb output.

Animals↗
PubMed1985

Linkage relationships of paraoxonase (PON) with other markers: indication of PON-cystic fibrosis synteny.

The linkage relationships of the serum arylesterase paraoxonase (PON) was examined in our Danish material of normal families and in Danish and English cystic fibrosis families. Highest lod scores were found between PON and cystic fibrosis. The combined lod score for this relationship was z = 2.69 at theta = 0.07 in males and theta = 0.00 in females. When scored in accordance with a tentative three allele model for PON, the score was z = 3.70 at the same theta values. Linkage studies for PON against 64 other polymorphic marker systems did not give any lod score above +1.3 and PON still remains chromosomally unassigned. By the present screening about 2/3 of the genome could tentatively be excluded as the region of PON and cystic fibrosis.

Aryldialkylphosphatase↗
PubMed1975

[Nuclei of the medulla oblongata and pons in the red deer and roe. III. Nuclei of the pons and tegmentum pontis].

The material for the studies was obtained from fragments of the brain stem, including the pons Varoli, of 2- and 6-year old red deer and of 2- and 3-year old female roe. The fixed material was mounted in paraffin and cut transversely into 15 micron sections, of which every fifth was examined. Preparations of the alcohol-fixed brain of one red deer and one roe were stained with methylene blue according to Nissl's modified method. Sections of the formalin-fixed brain of the other red deer and roe were stained according to the method of Klüver-Barrera with 0.1% solution of Luxor Fast Blue. Part III describes the structure and localization of the nerve nuclei of the portion of the brain stem under consideration. The following nuclei in the pons Varoli of the red deer and roe were described: nucl. medianus pontis, nucl. paramedianus pontis, nucl. ventralis pontis, nucl. lateralis pontis, nucl. dorso-lateralis pontis, nucl. peduncularis pontis. The nuclei, and especially in the central portion of the pons Varoli, are well developed in the species under discussion. With regard to the tegmentum pontis of the red deer and roe, a description of the structure and topography of the following nuclei is given: nucl. dorsalis tegmenti pontis, nucl. latero-dorsalis tegmenti pontis, nucl. dorsalis raphe, nucl. loci coerulei, nucl. reticularis dorsalis tegmenti pontis, nucl. reticularis ventro-lateralis tegmenti pontis, and nucl. reticularis ventro-medialis tegmenti pontis. The structure and localization of the nuclei of the tegmentum pontis are similar in both species, but the two first nuclei are much better developed in the roe than in the deer. The nucleus loci coeruliei could not be found in the roe.

Animals↗
PubMed1984

Identification of catecholamine cell bodies in the pons and pons-mesencephalon junction of the cat brain, using tyrosine hydroxylase and dopamine-beta-hydroxylase immunohistochemistry.

Using a double labeling immunohistochemical method with antibodies to tyrosine hydroxylase and dopamine-beta-hydroxylase, we reexamined the topographical distribution of dopaminergic (DA) and noradrenergic (NA) cells in the pons-mesencephalon junction of the cat. Besides DA cells of SN and its extensions, DA cells were also observed more caudally in nucleus raphe linearis intermedius and dorsalis, decussation of brachium conjunctivum, fasciculus longitudinalis medialis and periaqueductal gray. In nucleus locus coeruleus, cells exhibited variable levels of DBH, but dopaminergic cells were not evidenced in this structure.

Animals↗
PubMed1988

Cholinergic neurons from the dorsolateral pons project to the medial pons: a WGA-HRP and choline acetyltransferase immunohistochemical study.

In this study we determined that cholinergic neurons from the lateral dorsal tegmental (LDT) and peribrachial pontine region (PPG) innervate the medial pontine reticular formation (medial PRF), a region involved in the generation of REM sleep. Wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) was injected into the medial PRF and the brainstem tissue was processed using a combined retrograde transport/immunocytochemical procedure. Results showed that 10-15% of choline acetyltransferase (ChAT) immunoreactive neurons in the LDT and PPG project to the medial PRF. It is hypothesized that these neurons play an important role in the generation of the REM sleep state.

Animals↗
PubMed1999

Human serum paraoxonase (PON 1) is inactivated by oxidized low density lipoprotein and preserved by antioxidants.

Human serum paraoxonase (PON1) can protect low density lipoprotein (LDL) from oxidation induced by either copper ion or by the free radical generator azo bis amidinopropane hydrochloride (AAPH). During LDL oxidation in both of these systems, a time-dependent inactivation of PON arylesterase activity was observed. Oxidized LDL (Ox-LDL) produced by lipoprotein incubation with either copper ion or with AAPH, indeed inactivated PON arylesterase activity by up to 47% or 58%, respectively. Three possible mechanisms for PON inactivation during LDL oxidation were considered and investigated: copper ion binding to PON, free radical attack on PON, and/or the effect of lipoprotein-associated peroxides on the enzyme. As both residual copper ion and AAPH are present in the Ox-LDL preparations and could independently inactivate the enzyme, the effect of minimally oxidized (Ox-LDL produced by LDL storage in the air) on PON activity was also examined. Oxidized LDL, as well as oxidized palmitoyl arachidonoyl phosphatidylcholine (PAPC), lysophosphatidylcholine (LPC, which is produced during LDL oxidation by phospholipase A2-like activity), and oxidized cholesteryl arachidonate (Ox-CA), were all potent inactivators of PON arylesterase activity (PON activity was inhibited by 35%-61%). PON treatment with Ox-LDL (but not with native LDL), or with oxidized lipids, inhibited its arylesterase activity and also reduced the ability of the enzyme to protect LDL against oxidation. PON Arylesterase activity however was not inhibited when PON was pretreated with the sulfhydryl blocking agent, p-hydroxymercurybenzoate (PHMB). Similarly, on using recombinant PON in which the enzyme's only free sulfhydryl group at the position of cysteine-284 was mutated, no inactivation of the enzyme arylesterase activity by Ox-LDL could be shown. These results suggest that Ox-LDL inactivation of PON involves the interaction of oxidized lipids in Ox-LDL with the PON's free sulfhydryl group. Antioxidants such as the flavonoids glabridin or quercetin, when present during LDL oxidation in the presence of PON, reduced the amount of lipoprotein-associated lipid peroxides and preserved PON activities, including its ability to hydrolyze Ox-LDL cholesteryl linoleate hydroperoxides. We conclude that PON's ability to protect LDL against oxidation is accompanied by inactivation of the enzyme. PON inactivation results from an interaction between the enzyme free sulfhydryl group and oxidized lipids such as oxidized phospholipids, oxidized cholesteryl ester or lysophosphatidylcholine, which are formed during LDL oxidation. The action of antioxidants and PON on LDL during its oxidation can be of special benefit against atherosclerosis since these agents reduce the accumulation of Ox-LDL by a dual effect: i.e. prevention of its formation, and removal of Ox-LDL associated oxidized lipids which are generated during LDL oxidation.

Amidines↗
PubMed1994

Role of the pons in the carotid sympathetic chemoreflex.

The mass discharges of the splanchnic sympathetic (SND) and phrenic nerves (PND) were recorded in urethananesthetized rats with resected vagal and aortic nerves. Carotid chemoreceptor (CC) stimulation with N2 inhalation (4-12 s) or cyanide (50-100 micrograms/kg iv) activated SND in bursts synchronized with the postinspiratory phase (mean SND increase: 105 +/- 8%), raised AP, and increased PND rate and amplitude (n = 40). Brain transection at superior collicular level produced no effect. The sympathetic (SChR) and respiratory chemoreflexes (RChR) were reduced after transections through the pons. Lesions of the dorsolateral pons (dl-pons) produced CO2-dependent apneusis and/or tachypnea at rest. After such lesions, CC stimulation produced expiratory apnea and a 30% increase in SChR due to tonic activation of SND. In contrast, bilateral lesions of the ventrolateral pons (vl-pons) reduced the SChR by 54-76%. Muscimol (Mus) injections (bilateral, 175 pmol/side) into vl-pons did not change resting SND, MAP, baroreflex, and RChR but reduced the SChR (54-82%). In conclusion, under anesthesia: 1) the pathway of the carotid chemoreflex is confined to the pons and medulla, 2) the dl-pons exerts indirect control over the SChR via its role in respiratory rhythmogenesis, and 3) neurons in the vl-pons contribute selectively to the SChR but not to PND activation during CC activation.

Animals↗
PubMed1981

The tectopontine projection the the rat with comments on visual pathways to the basilar pons.

The projection from the superior and inferior colliculi to the basilar pons in the rat was studied with the technique of orthograde transport of labeled amino acids and autoradiography. Injections restricted to the medial or lateral regions of the superior colliculus gave rise to grain labeling representing terminal fields over the ipsilateral peduncular, dorsolateral, and ventrolateral regions of the caudal basilar pons and over the dorsomedial area of the contralateral nucleus reticularis tegmenti pontis (NRTP). The pontine projection from the superior colliculus to the lateral basilar pons is topographically organized; the medial superior colliculus projects primarily to the peduncular region, whereas the lateral superior colliculus terminates chiefly in ventrolateral pontine areas. A projection from the superior colliculus to the contralateral dorsomedial pontine and medial peduncular pontine regions, a previously undescribed finding, has also been shown. Descending fibers from the inferior colliculus do not appear to terminate extensively within the basilar pons but rather course adjacent to pontine cells of the dorsolateral region in the caudal pons. Pretectal nuclei project ipsilaterally to medial and lateral nuclei in the rostral and middle basilar pons, respectively. A rostrocaudal topography exists in the tectopontine projection; the pretectum projects to rostromiddle basilar pons, the superior colliculus to more caudal pontine regions, and the inferior colliculus (although sparsely) to further caudal areas. The pontine projection pattern from the colliculi and pretectum differs from the pontine afferents from the visual cortices. The findings of this study, when compared to our results from previous investigations on the pontocerebellar projection system, suggest that the tectal inputs to certain lateral cerebellar lobules are relayed primarily through NRTP rather than the basilar pons. The collicular projection to midvermal lobules of the cerebellum appear to be mediated in part by both NRTP and lateral pontine nuclei.

Animals↗
PubMed1998

Role of the pons in hypoxic respiratory depression in the neonatal rat.

The main purpose of this study was to evaluate the role of the pons in hypoxic respiratory depression (HRD) of the neonatal rat. Experiments were conducted using the isolated brainstem-spinal cord preparation of the neonatal rat (1-3 days old). The brainstem was transected at various levels. We found that ablation of the diencephalon decreased respiratory frequency (fR), and conversely, that ablation of the midbrain or pons increased fR. In the preparation with the pons intact (without the midbrain), hypoxia (superfusate PO2 = 56 mmHg) caused strong depression of respiratory activity, which was characterized by a steady decrease in fR and in integrated inspiratory burst amplitude (integral of Phr). In the preparation with the intact ventral pons (without midbrain and dorsal pons) we observed similar, though weaker, HRD. When the entire pons was ablated, integral of Phr was little depressed by hypoxia and thus, HRD was further attenuated. We conclude that the pons contributes importantly to the induction of hypoxic respiratory depression in the neonatal rat. Both the ventral and dorsal portions of the pons are involved in the control of hypoxic respiratory depression. In addition, we show that the respiratory modulatory functions of the diencephalon (facilitating) and midbrain (inhibitory) are already expressed at the time of birth.

Animals↗
PubMed1996

Electrical activity of the acutely isolated pons in cats.

The cat's pons was isolated by two brainstem transections, at the junction of medulla and pons and at the junction of pons and midbrain. In the deafferented pons the EEG activity was virtually absent, whereas the spatial density of active units and the rate of their spontaneous spike activity were at a high level. In the pons of control preparations with brainstem transected only at the ponto-midbrain junction the EEG activity was present, while the single-unit activity was such as in the isolated pons. The electrical activity of the isolated pons was similar to that previously described in the cat's isolated midbrain. The discrepancy between EEG and single-unit activity suggests that in the deafferented pons or midbrain many neurones are asynchronously autoactive. Also, these results show that a flat EEG record is not necessarily a sign of absence of the neural activity and neural death.

Animals↗
PubMed1998

[Microvascular decompression of pons for idiopathic hemifacial spasm and exploration of its mechanism].

OBJECTIVE: To further explore the cause, mechanism and surgical treatment of idiopathic hemifacial spasm (IHFS). METHODS: Routine sagittal and coronal cryoslices of 8 (16 sides) pons were made. The sections were stained with Luxol fast blue and Nissl stains. The location of the facial nucleus and pathway of facial neurofibers in the pons were observed. Twenty-five patients with IHFS whose facial nerve root exit zone(REZ) was not compressed by vessels underwent microvascular decompression of pons. RESULTS: The distances from the facial nucleus to the ventral surface of pons, the median line, and the ventroexterior surface were 12.0-12.5 mm, 6.0 mm, and 7.5-9.0 mm respectively. The distance from the facial neurofibers in the pons to the surface of the pons was 1.0 to 2.0 mm, with an average of 1.65 mm. The vascular compression was at the surface of pons, within 4 mm anterosuperior to the REZ in 25 IHFS patients. The compressing vessels were the anterior inferior cerebellar arteries and their branches. The results of decompression in 25 patients with IHFS were as follows: spasm immediately disappeared in 8 patients, and within one week in 17 patients. No recurrence was found during a follow-up period from 6 months to 5 years. CONCLUSION: The main cause of IHFS was vascular compression, but the position of compression is not necessarily always at the REZ. The "short-circuiting" theory can only explain the cases with vascular compression at the REZ. But in cases who do not have vascular compression at the REZ, there might be dysfunction of the facial nucleus. In the present cases, vascular compression was at the surface of the brain stem anterosuperior to the REZ, pons microvascular decompression is an effective treatment.

Adult↗
PubMed2003

Expression of major HDL-associated antioxidant PON-1 is gender dependent and regulated during inflammation.

Paraoxonase 1, an HDL-associated enzyme that confers antioxidant activity on HDL, and its activity in serum have been correlated with protection against atherosclerosis, an oxidative disease. However, serum PON-1 activity is highly variable and its regulation is complex, involving both genetic and environmental factors. It is influenced by gender and inflammation, two important factors in atherosclerosis. Serum PON-1 activity has been shown to be lower in male mice and is decreased in male Syrian hamster during inflammation. Here we show that male mice had lower hepatic PON-1 mRNA that increased by 170% after castration. Our data also suggested that this effect was testes but not plasma testosterone dependent. Ovariectomy had no effect on PON-1 mRNA in female mice. LPS caused hepatic PON-1 mRNA to decrease further in male mice, and to increase moderately in female mice. Anti-inflammatory dexamethasone enhanced PON-1 mRNA level by 2-fold in male and female LPS-treated mice, and increased PON-1 expression by 8-fold in Hepa cell, a mouse hepatoma cell line. Therefore, antioxidant PON-1 is regulated at the mRNA level in a gender-specific manner by proinflammatory LPS and anti-inflammatory dexamethasone.

Animals↗
PubMed2004

Development of the human fetal pons: in utero ultrasonographic study.

OBJECTIVES: To examine the ultrasonographic feasibility of imaging the fetal pons and to construct a reference chart for its normal development during gestation. METHODS: A cross-sectional, prospective study on 293 healthy fetuses of low-risk pregnancies between 19 and 34 weeks was performed. The transfontanel approach, via the abdominal or vaginal routes, was used to evaluate the fetal metencephalon (pons and cerebellum). The anteroposterior diameter of the fetal pons was measured in a mid-sagittal plane. The longitudinal diameter of the cerebellar vermis was measured at the same plane and the vermis-pons ratio (VPR) was established. RESULTS: One hundred and forty-four fetuses were in vertex position. In 140 (97.2%) satisfactory visualization and measurements of the pons and cerebellar vermis were obtained. One hundred and forty-nine fetuses were breech presentations and measurements were successfully performed in 147 (98.6%). The pons anteroposterior and vermis longitudinal diameters showed a linear correlation with gestational age (GA) (r = 0.95 for both measurements; P < 0.001). The mean VPR was 1.5 (+/-0.1 SD) and did not change in the gestational interval that was considered. CONCLUSION: By using the transfontanel approach, evaluation of the fetal pons is feasible via the mid-sagittal plane. The nomograms developed and the ratio to fetal vermis provides reference data that may be helpful when evaluating anomalies of the brainstem.

Cross-Sectional Studies↗
PubMed1987

Development of the basilar pons in the North American opossum: dendrogenesis and maturation of afferent and efferent connections.

The present study provides data on temporal factors that may play a role in the development of precerebellar-cerebellar circuits in the North American opossum. In this study the basilar pons and cerebellum are analyzed from birth, 12-13 days after conception, to approximately postnatal day (PD) 80 at which time the brainstem and cerebellum have a mature histological appearance. In Nissl preparations, the basilar pons was first seen at PD 7 as a small cluster of tightly packed cells. Analysis of Golgi impregnations revealed that dendritic growth occurred between PD 25-80. During this period, dendrites gradually increased in length and in the complexity of their branching pattern. Horseradish peroxidase (HRP) was placed into the cerebellar and cerebral cortices in order to examine the development of efferent and afferent projections of the basilar pons, respectively. Evidence for the growth of pontine axons into the cerebellum was first detected on PD 17. Neurons located dorsally within the basilar pons appear to be the first neurons retrogradely labeled with horseradish peroxidase. By PD 27 retrogradely labeled neurons are found throughout the basilar pons. Afferent fibers from the cerebral cortex are not seen within the neuropil of the nucleus until after PD 25 and by PD 29, they have greatly expanded their terminal fields. Degeneration techniques reveal that afferent fibers from the cerebellum arrive by PD 19 and increase in number until PD 30 when their adult distribution is achieved. These data suggest that the time of afferent arrival from the cerebral cortex and deep cerebellar nuclei is closely correlated in time with the initiation of dendritic maturation and the outgrowth of pontocerebellar axons. Afferent axons from the cerebral cortex and deep cerebellar nuclei reach the basilar pons and afferents from the basilar pons grow into the cerebellum when the dendrites of the respective target neurons are very immature. Thus, the time of axon arrival in these circuits may be an important factor in determining their synaptic location on individual neurons. The data derived from the present study is compared to those obtained in previous studies on the inferior olive. The results of this comparison provide evidence for a similar sequence of events, but a differential timetable for the development of specific connections within precerebellar-cerebellar circuits.

Afferent Pathways↗
PubMed1987

Circling elicited from the anteromedial cortex and medial pons: refractory periods and summation.

Contraversive circling is evoked by stimulating the anteromedial cortex (AMC) of rats, and ipsiversive circling is evoked by stimulating the medial pons (PONS). During AMC circling, lateral and vertical head movements and vibrissae movements were exhibited. During PONS circling, although lateral head movements were exhibited, vertical head movements and vibrissae movements were not exhibited. Refractory periods were estimated by delivering trains of paired pulses and measuring the frequency thresholds for circling at various intrapair intervals. Refractory periods at AMC circling sites were much longer (range 1.4-3.3 ms) than at PONS circling sites (range 0.5-1.0 ms). To determine the degree of summation between the AMC and contralateral PONS, the two sites were stimulated concurrently. Summation of 95-100% was observed for AMC and PONS circling. No collision was observed at short intrapair intervals of paired pulses. Thus, the AMC and PONS are not connected axonally but are related, perhaps serially, for the production of circling.

Animals↗
PubMed1997

Prolongation in expiration evoked from ventrolateral pons of adult rats.

Activation of neurons in the ventrolateral (vl) pons was hypothesized to alter the breathing pattern because previous studies demonstrated apneusis after inhibiting neuronal activity with bilateral muscimol (10 mM) microinjections into the vl pons (17). The excitatory amino acid L-glutamate (10 mM) was microinjected (10-100 nl) into the vl pons in anesthetized, vagotomized, paralyzed, and ventilated adult rats (n = 8). In four of these animals, the target site was approached from the ventral surface of the pons to avoid penetrating the dorsolateral (dl) pons. The expiratory phase was prolonged transiently and concurrently with the microinjection. The location of the injection sites included the A5 area, was independent of the approach, and was distinct from the dl pons. These results complement our previous data and indicate that neurons located in the vl pons influence respiration specifically by prolonging expiration when activated and by delaying the inspiratory-to-expiratory phase transition when inhibited.

Animals↗
PubMed1994

Vascular contact with the fifth cranial nerve at the pons in patients with trigeminal neuralgia: detection with 3D FISP imaging.

OBJECTIVE: Vascular contact with the trigeminal nerve at the pons is known to cause trigeminal neuralgia; however, this finding also is present in some asymptomatic subjects. We evaluated the usefulness of high-resolution MR imaging and MR angiography of the posterior fossa to determine the presence or absence of vascular contact with the fifth cranial nerve at the pons in patients with trigeminal neuralgia and in control subjects. SUBJECTS AND METHODS: The trigeminal nerves in 40 symptomatic patients and 114 asymptomatic control subjects were examined for the presence or absence of vascular contact at the pons by using three dimension (3D) fast inflow with steady-state precession (FISP) imaging. Imaging parameters were 35/7/15 degrees (TR/TE/flip angle) with a slab thickness of 55 mm and 64 partitions. Contrast-enhanced imaging was done in 10 of 12 patients with normal findings on an unenhanced scan. Axial, coronal, sagittal, and maximum-intensity-projection images were reviewed by two observers who had no knowledge of the clinical details. The findings on MR images were prospectively compared with the surgical findings in 25 patients. RESULTS: On the unenhanced MR images, vascular contact with the trigeminal nerve at the pons was identified in 70% of 40 nerves in patients with trigeminal neuralgia and in a further 15% following injection of contrast medium. Contact between the nerve and two vessels at the pons was seen in 10% of cases, and deformity of the nerve was present in 30% of cases. In the control group, vascular contact with the nerve was identified in 8% of 114 nerves. Contact between the nerve and two vessels or deformity of the nerve was not identified in any control subject. The difference between the two groups was highly significant regarding the presence or absence of vascular contact with the nerve at the pons (p < 0.001, x2 test), distortion of the nerve (p < .001), and contact between the nerve and two vessels (p < .001). The imaging findings were in agreement with the surgical findings regarding the presence or absence of vascular contact with the nerve in all 25 patients who had surgery. Complete or partial pain relief was achieved following microvascular decompression in all patients who had surgery. CONCLUSION: Despite the fact that vascular contact with the trigeminal nerve at the pons is not specific for trigeminal neuralgia, high-definition unenhanced and enhanced 3D FISP imaging and MR angiography at the posterior fossa are useful in determining the presence or absence of vascular contact with or deformity of, the fifth cranial nerve in patients for whom surgery is planned for treatment of trigeminal neuralgia.

Arteries↗