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At least 19 recordsLinked to original sources
PubMed1988

Origins of descending projections to the medulla oblongata and rostral medulla spinalis in the urodele Salamandra salamandra (amphibia).

Descending projections to the medulla oblongata and rostral medulla spinalis have been examined in the urodele Salamandra salamandra with retrograde horseradish peroxidase tracing. Ipsilateral projections originate from the striatum and the nucleus ventrolateralis thalami and reach the medulla oblongata. The ipsilateral nucleus praeopticus magnocellularis reaches the medulla spinalis. The rostral part of the nucleus tuberculi posterioris projects to the ipsilateral medulla oblongata; its caudal part projects further caudally. Tectal efferents and the efferents of the nucleus praetectalis profundus project bilaterally, the nucleus praetectalis superficialis, nucleus mesencephalicus nervi trigemini, torus semicircularis, nucleus Darkschewitsch, and nucleus fasciculi longitudinalis medialis project ipsilaterally to the medulla oblongata. The nucleus mesencephalicus nervi trigemini, nucleus fasciculi longitudinalis medialis, and tectal efferents reach the rostral medulla spinalis. The nucleus ruber projects mainly via the contralateral dorsolateral funiculus to the medulla spinalis. A largely crossed medullary projection arises in the nucleus dorsalis tegmenti pars anterior, a bilateral projection arises in the nucleus dorsalis tegmenti pars posterior, and an ipsilateral projection arises in the nucleus ventralis tegmenti pars anterior. Cerebellar and statoacoustic efferents descend to the medulla spinalis. The nucleus reticularis isthmi, superior, medius and inferior as well as the nucleus raphes exhibit spinal trajectories. The nucleus vestibularis magnocellularis projects bilaterally, the nucleus vestibularis medialis projects ipsilaterally spinalward. The supposed nucleus descendens nervi trigemini descends mainly contralaterally. A small spinal projection arises in the nucleus tractus solitarii. The results indicate that salamander brains display elaborate descending connections which are similar to those in other vertebrates despite their scarcely differentiated neuronal cytoarchitecture.

Animals↗
PubMed1994

Vasoconstriction induced by inhalation of irritant vapour is associated with appearance of Fos protein in C1 catecholamine neurons in rabbit medulla oblongata.

The medulla oblongata was examined with Fos and tyrosine hydroxylase (TH) immunohistochemistry after 2 h of intermittent nasopharyngeal stimulation with formaldehyde vapour in the conscious rabbit. The stimulation caused apnoea, bradycardia and a rise in blood pressure known to be associated with vigorous vasoconstriction. Fos-positive neurons occurred in the spinal trigeminal nucleus, the nucleus tractus solitarius, the raphe nuclei and the ventrolateral medulla. In the rostral ventrolateral medulla, 68% of the Fos-positive neurons were TH-positive C1 cells. Our data indicate that nasopharyngeally-evoked peripheral vasoconstriction is associated with activation of C1 neurons.

Administration, Inhalation↗
PubMed1983

[Cholinergic neurons in the nuclear formations of the human fetal medulla oblongata].

The medulla oblongata of the human fetuses 22-27-week-old has been studied. Histochemical methods for cholinacetyltransferase (ChAT) and partly for acetylcholinesterase (AChE) have been used. Twenty-five nuclei have been described; four types of neurons with a low, middle, high and very high ChAT activity have been revealed in them. In the motor nuclei, neurons with a high, and in the sensitive nuclei--with a low ChAT activity predominate. In 13 nuclei a relative content of the cholinergic neurons has been calculated; it is low in the lateral reticular nucleus and in the Roller's nucleus (49-53%), high--in nuclei of the cranio-cerebral nerves (92-100%). In the motor neurons of the segmentary centers there is a certain correlation between the ChAT and AChE activity; in other neural centers (the inferior olive, the reticular substance nuclei) there is no such coincidence.

Choline O-Acetyltransferase↗
PubMed1983

[The role of the ventrolateral part of the medulla oblongata in the control of gonadotropin secretion. II. The effect of ovarian steroid implantation into the ventrolateral part of the medulla oblongata on LH secretion in the female rat].

To investigate whether neurons in the ventrolateral part of the medulla oblongata (VLMO) are sensitive to ovarian steroid, estradiol benzoate (EB) or progesterone (Prog.) was implanted through a stainless steel double cannula into the VLMO of ovariectomized, EB-primed rats and serum LH was measured. Two weeks after ovariectomy, rats were primed with 20 micrograms EB at 1200h and this day was arbitrarily defined as day 0. At 1200h on day 3, powdery steroid, EB or Prog., was unilaterally implanted into the VLMO. Implantation of EB into the VLMO was effective in increasing serum LH at 1600, 1800 and 2000h on days 3 and 4, but the serum LH concentration at 1600, 1800 and 2000h was much more increased on day 4 than on day 3. Implantation of Prog. into the VLMO failed to induce a significant increase in serum LH on days 3 and 4. To further investigate the effects of anterolateral hypothalamic (ALH) transection and complete spinal transection at T4-T7 levels on EB implantation into the VLMO was examined. It has been shown that both ALH transection and spinal transection at high thoracic levels (T4-T7) significantly blocked proestrous gonadotropin surges and ovulation. In rats with ALH transection, EB implantation into the VLMO was not effective in increasing serum LH at 1600, 1800 and 2000h on days 3 and 4, but in rats with complete spinal transection, EB implantation into the VLMO was effective in increasing serum LH at 1800 and 2000h on days 3 and 4. These results suggest that EB exerts its stimulatory feedback action on the VLMO and the anterolateral hypothalamic area is involved in the mechanism of this stimulatory feedback action of EB.

Animals↗
PubMed1983

[Role of the ventrolateral part of the medulla oblongata in the control of gonadotropin secretion. I. Electrophysiological studies on the neural features between the limbic-preoptic structures and the ventrolateral part of the medulla oblongata in the female rat].

Electrophysiological studies were undertaken in order to investigate the neural features between the preoptic suprachiasmatic nucleus (POSC) and the ventrolateral part of the medulla oblongata (VLMO) and between the bed nucleus of stria terminalis (BST) and VLMO by eliciting antidromic responses and performing microionophoresis of estradiol. Unit activity of neurons in the VLMO was recorded in ovariectomized estradiol benzoate-primed Wistar female rats under urethane anesthesia (1.2g/kg body weight). Antidromic activations were performed by applying negative square wave pulses (intensity 1.0--1.5mA, duration 0.1msec, frequency 0.6Hz) which were delivered through a bipolar concentric stainless steel electrode to the POSC or the BST. In total, 116 neurons in the POSC and 118 neurons in the BST with ascending projection were identified in the VLMO. Both in the POSC and the BST, two types of antidromic spike potentials were distinguished on the basis of their waveforms. One type ("fast spikes") was characterized by a sharp and smooth rising phase. The other ("slow spikes") had a notch in the rising phase. In the POSC, mean antidromic spike latency for the fast spikes was 9.8msec, while the value for the slow spikes was 30.4msec and in the BST, mean antidromic spike latency for the fast spikes was 10.2msec, while the value for the slow spikes was 31.5msec. In the POSC, ionophoretic injection of estradiol hemisuccinate was accomplished on 57 of the 116 antidromically identified cells, of which 32 showed slow responses and 25 responded with fast spikes. In cells with slow spikes, estradiol hemisuccinate facilitated (n = 14) or suppressed (n = 5) their generation of action potentials. None of the cells with fast responses changed their activity in response to estradiol hemisuccinate. In the BST, ionophoretic injection of estradiol hemisuccinate was accomplished on 51 of 118 antidromically identified cells, of which 30 showed slow responses and 21 responded with fast spikes. In cells with slow spikes, estradiol hemisuccinate facilitated (n = 9) or suppressed (n = 8) their generation of action potentials. None of the cells with fast responses changed their activity in response to estradiol hemisuccinate. In addition, POSC or BST unit responses to the VLMO stimulation (intensity 1.0--1.5mA, duration 0.1msec, frequency 0.6Hz) was examined. Unit firing activity in the POSC or BST, elicited by the VLMO stimulation, was much more enhanced in proestrous rats than in diestrous rats. After the injection of phenoxybenzamine, an alpha-adrenergic receptor blocker, the rate of facilitatory responses in the POSC or in the BST neurons was significantly decreased in proestrous rats.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Neuropeptide Y and galanin enhance the inhibitory effects of clonidine on norepinephrine release from medulla oblongata of rats.

The medulla oblongata is thought to play an important role in the central regulation of blood pressure. Neuropeptide Y (NPY) and galanin (Gal) coexist with norepinephrine (NE) and may have a functional interaction in this region. The aim of the present study was to investigate whether NPY and Gal could modulate the presynaptic neuronal mechanisms, especially the alpha-adrenoceptor function, inhibiting NE release in medulla oblongata. In slices of rat medulla oblongata, clonidine, an alpha-adrenoceptor agonist, inhibited the NE release elicited by electrical stimulation in a concentration-dependent manner. A combination of clonidine and low concentration of NPY (1 X 10(-9) mol/L) resulted in an increase in the inhibitory action of clonidine on stimulation-evoked NE release. The inhibitory action of clonidine was also potentiated by Gal (1 X 10(-8) mol/L). These results indicate the existence of the presynaptic NPY- and Gal-receptors on noradrenergic nerve terminals, which may enhance the presynaptic alpha-adrenoceptor function to inhibit NE release. This suggests a possible involvement of NPY and Gal in the regulation of sympathetic nerve activity in medulla oblongata.

Animals↗
PubMed2005

Neuronal expression of nuclear transcription factor MafG in the rat medulla oblongata after baroreceptor stimulation.

The medulla oblongata is the site of central baroreceptive neurons in mammals. These neurons express specific basic-leucine zipper transcription factors (bZIP) after baroreceptor stimulation. Previously we showed that activation of baroreceptors induced expression of nuclear transcription factors c-Fos and FosB in central baroreceptive neurons. Here we studied the effects of baroreceptor stimulation on induction of MafG, a member of small Maf protein family that functions as dimeric partners for various bZIP transcription factors by forming transcription-regulating complexes, in the rat medulla oblongata. To determine whether gene expression of MafG is induced by stimulation of arterial baroreceptors, we examined the expression of its mRNA by semi-quantitative reverse transcription-PCR method and its gene product by immunohistochemistry. We found that the number of MafG transcripts increased significantly in the medulla oblongata after baroreceptor stimulation. MafG-immunoreactive neurons were distributed in the nucleus tractus solitarii, the dorsal motor nucleus of the vagus nerve, the ambiguous nucleus and the ventrolateral medulla. The numbers of MafG-immunoreactive neurons in these nuclei were significantly greater in test rats than in saline-injected control rats. We also found approximately 20% of MafG-immunoreactive neurons coexpress FosB after baroreceptor stimulation. Our results suggest that MafG cooperates with FosB to play critical roles as an immediate early gene in the signal transduction of cardiovascular regulation mediated by baroreceptive signals in the medulla oblongata.

Animals↗
PubMed1985

Successful total extirpation of hemangioblastoma originating in the medulla oblongata.

Hemangioblastomas of the medulla oblongata were successfully excised in two separate cases. The uncertainties of this procedure involve the value of preoperative radiation therapy, the relationship between the tumor and the medulla oblongata, and the surgical techniques themselves. Cardiovascular and respiratory disorders often complicate this type of surgery, and postoperative dysphagia is a frequent sequela.

Adult↗
PubMed1996

Localization of neuropeptide Y Y1 receptor-like immunoreactivity in catecholaminergic neurons of the rat medulla oblongata.

Neuropeptide Y receptors in the medulla oblongata participate in central cardiovascular control. The neuropeptide Y1 receptor subtype gene and amino acid sequence have been identified by molecular cloning studies. In this study, a C-terminal peptide representing amino acids 355-382 of the neuropeptide Y1 receptor was synthesized and cross-linked to thyroglobulin to produce an antibody against a partial sequence of the neuropeptide Y1 receptor, used to localize neuropeptide Y1 receptor-like immunoreactivity in the catecholaminergic neurons of the medulla oblongata. The double colour immunofluorescence technique with a polyclonal antibody against the neuropeptide Y1 receptor and a monoclonal antibody against tyrosine hydroxylase revealed that in the rat medulla oblongata, a weak (the C3 cell group) to moderately intense (the A1, A2, C1 and C2 cell groups), diffuse cytoplasmic neuropeptide Y1 receptor-like immunoreactivity was distributed primarily in the noradrenergic and adrenergic cell bodies and occasionally seen in the noradrenergic and adrenergic cell processes. Almost all tyrosine hydroxylase-like immunoreactive cell bodies in the A1, A2, C1, C2 and C3 cell groups showed neuropeptide Y1 receptor-like immunoreactivity. The neuropeptide Y1 receptor-like immunoreactivity in the A2 cell group was somewhat stronger. The present findings show localization of specific neuropeptide Y1 receptor-like immunoreactivity in the vast majority of the noradrenergic and adrenergic cell bodies of the A1, A2, C1, C2 and C3 cell groups, which are putative cardiovascular regions. The results support the view that neuropeptide Y1 receptors in the medulla oblongata are involved in central cardiovascular control and may coexist with another important receptor, the alpha 2A-adrenoceptor, also involved in central, cardiovascular regulation, since the alpha 2A-adrenoceptor-like immunoreactivity has been shown to exist in almost all noradrenergic and adrenergic cell bodies in the brainstem. In conclusion, centrally administered neuropeptide Y may act in part via neuropeptide Y1 receptors located on the soma and dendrites of noradrenergic and adrenergic neurons, where it may interact with alpha 2-adrenoceptors at least in the noradrenergic A2 neurons. This noradrenaline system may be involved in at least part of the vasodepressor actions of neuropeptide Y, noradrenaline and adrenaline in the nucleus tractus solitarii in view of the present findings.

Animals↗
PubMed1996

Differential distribution of four types of tooth pulp neurons in the caudal medulla oblongata of the cat.

The medulla oblongata caudal to the obex was explored for neurons responsive to tooth pulp (TP) stimulation in cats. Four different classes of TP neurons were found. They were TP specific neurons, trigeminal wide dynamic range neurons with TP input, trigeminal subnucleus reticularis ventralis (SRV) neurons with TP input and convergent reticular formation with TP input. They were differentially distributed within the caudal medulla oblongata.

Animals↗
PubMed1991

Intracranial lipoma in the medulla oblongata.

Intracranial lipoma in the medulla oblongata has been rarely reported. Only two cases have been documented in the literature. This report concerns a patient who complained of nuchal soreness and an unstable gait for 6 months. An olivelike lipoma, arising from the posterior aspect of the medulla oblongata and embedded in the lower cranial nerves, was found at suboccipital craniectomy and posterior laminectomy of C1-2. Partial removal of the lipoma was performed for decompression; radical removal would have been hazardous. The clinical symptoms subsided postoperatively. The computed tomography scan and magnetic resonance image proved useful for properative diagnosis.

Aged↗
PubMedDate not supplied

A biphasic compartmentation of neuro-transmission associated metabolic patterns during electro-induced axoplasmic transport in sheep medulla oblongata.

In the sheep medulla oblongata, on the induction of polarity by the applied voltage gradient of direct current along the length, the enzymes such as acetylcholinesterase and glutamate dehydrogenase showed anodal transport while the enzyme arginase showed cathodal transport indicating the possession of negative and positive charge densities on the enzymes. These studies indicated that the glutamate bound metabolism, one towards ammonia formation and the other towards the energy production and neural transmission, have opposed electro-characteristics. The acetylcholinesterase system had anodal characteristics coupled to the glutamate dehydrogenase patterns. The existence of two charge based compartmentation is envisaged in the neural tissue.

Acetylcholinesterase↗
PubMed2000

[Microsurgery of cervical intramedullary ependymomas extending into the medulla oblongata].

Intramedullary spinal cord ependymomas are well-demarcated tumors, which can be totally resected without significant morbidity. However, it is challenging to remove intramedullary ependymomas extending into the medulla oblongata, because the medulla oblongata has such important roles as regulation of respiration, circulation, and digestion. We describe here three cases of intramedullary ependymomas extending into the medulla oblongata. The tumors were localized in the dorsal part of the caudal medulla oblongata and were surrounded by the nuclei and tracts related to the dorsal columns. The tumors were safely exposed by dividing the medulla oblongata along the posterior median sulcus and resected from the surrounding normal tissues. Although patients demonstrated transient dorsal column dysfunction postoperatively, the symptom finally recovered.

Adult↗
PubMed1979

Somatostatin-immunoreactive nerve cell bodies and fibers in the medulla oblongata et spinalis.

Complete serial sectioning of the medulla oblongata in monkey, cat, guinea pig, and japanese dancing mouse and incubation for somatostatin-immunoreaction was carried out. Numerous regions of the medulla oblongata such as the nucleus reticularis gigantocellularis, nucleus cuneatus et gracillis, nucleus raphe magnus, nucleus tractus solitarius, nucleus vestibularis, and parts of the oliva contain dense networks of somatostatin-immunoreactive nerve fibers. Cell bodies were seen in the nucleus reticularis medullae oblongatae. In the spinal cord the sections from each segment were analyzed, showing the highest concentrations of somatostatinergic fibers in the substantia gelantinosa of the columna dorsalis. Cell bodies were seen in the zona intermedia centralis, especially in the upper cervical segments. Many positive fibers were also seen in the entire zona intermedia and the columna ventralis. Especially prominent was the immunoreactivity in the zona intermediolateralis of the thoracic segments and the columna ventralis of the lower lumbar and sacral segments.

Animals↗
PubMed1993

Decreased norepinephrine content in the medulla oblongata in severely hypertensive rats.

1. To clarify possible abnormalities in catecholamines in the medulla oblongata in relation to severe hypertension, the authors measured changes in catecholamine levels in the medulla oblongata of malignant stroke-prone spontaneously hypertensive rats (M-SHRSP). Effects of the adrenal medullae and peripheral nerves were ruled out by adrenal demedullation and chemical sympathectomy. 2. The level of norepinephrine in the medulla oblongata was significantly lower in untreated M-SHRSP than in untreated WKY (control) rats at 10 weeks of age. Further, it was significantly lower in treated M-SHRSP than in the treated WKY group at both 6 and 10 weeks of age. The level of epinephrine in 6 week old treated M-SHRSP was significantly higher than that in age-matched treated WKY, but no other differences were observed in terms of epinephrine content. There were no age- or treatment-related differences in dopamine levels in the medullar oblongata. 3. Since norepinephrine has an inhibitory effect on blood pressure elevation in the nucleus tractus solitarii (NTS) in the medulla oblongata, the suppression of negative feedback due to a decrease in the activity of inhibitory neurons in the medulla oblongata appears to be involved in the development and progression of severe hypertension in M-SHRSP.

Adrenal Medulla↗