Polysynaptic connections between Barrington's nucleus and sacral preganglionic neurons.

The pontine micturition center, or Barrington's nucleus, is an essential component in the micturition reflex. The purpose of the present study is to examine the connections between Barrington's nucleus and sacral preganglionic neurons with an electrophysiological method using an intracellular recording technique. When the bladder pressure was near 0mmH2O, electrical stimulation of Barrington's nucleus either evoked no postsynaptic potential or evoked very small excitatory postsynaptic potentials (EPSPs) with ambiguous onset, in sacral preganglionic neurons. However, when the bladder showed micturition contraction, electrical stimulation of the nucleus evoked clear EPSPs in sacral preganglionic neurons. Latencies of EPSPs ranged from 21.9 to 47.5ms. The onset of the EPSPs was not fixed in any of the preganglionic neurons, indicating that they were evoked polysynaptically. The results thus demonstrated that the descending pathway from Barrington's nucleus to the sacral preganglionic neurons is polysynaptic. The results also showed that the descending pathway is strongly facilitated during the voiding phase, whereas this facilitatory effect is very weak when the bladder pressure is low. The study supports the idea that continuous firings of Barrington's nucleus are needed to activate the sacral preganglionic neurons that innervate the bladder muscle.

Skull base metastasis from follicular thyroid carcinoma -two case reports-.

A 58-year-old woman and a 71-year-old woman presented with extremely rare skull base metastases from follicular thyroid carcinoma (FTC). Surgical removal and external radiotherapy were performed followed by iodine-131 ((131)I) brachytherapy and thyroid hormone administration. The metastatic tumors in the skull base were well controlled. Treatment for skull base metastasis from FTC includes surgical debulking of the metastatic lesion, as well as complete resection of the thyroid gland, followed by internal irradiation with (131)I, external irradiation, and administration of thyroid hormone to prevent tumor growth by suppression of endogenous thyroid-stimulating hormone. Skull base metastases may be the initial clinical presentation of FTC, with silent primary sites. The possibility of skull base metastasis from FTC should be considered in patients with clinical symptoms of cranial nerve dysfunction and radiological findings of bone destruction.

Effects of acupuncture on autonomic nervous function and prefrontal cortex activity.

Acupuncture is helpful in treating various diseases, including autonomic nervous system (ANS) dysfunction caused by mental stress. On the other hand, the frontal lobe is suggested to play an important role in stress responses by modulating the ANS. The aim of the study was to evaluate the effects of acupuncture on ANS and frontal lobe activities. We investigated 18 normal adults. We measured the activity of prefrontal cortex (PFC) caused by real acupuncture (WHO-LI4) and sham acupuncture, employing optical topography. To evaluate ANS function, we analyzed heart rate variability (HRV). Analysis of HRV revealed a decrease of the LF/HF ratio, and an increase of the HF power by real acupuncture, indicating a shift to parasympathetic dominancy. Acupuncture also caused cerebral blood oxygenation changes in both directions, that is, an increase and/or a decrease of oxyhemoglobin (Oxy-Hb) in the bilateral PFC. However, the Oxy-Hb change was not correlated with HRV parameters in the majority of cases. One of the possible explanations of the poor correlations might be that the PFC activity induced by acupuncture is not closely linked with ANS function.

Is the periaqueductal gray an essential relay center for the micturition reflex pathway in the cat?

The periaqueductal gray (PAG), especially in a region between the levels the oculomotor nucleus and the trochlear nucleus, was suggested to be the essential relay center that conveys information of bladder fullness to the pontine micturition center (Barrington's nucleus). The present study examined this hypothesis by transecting the brainstem in anesthetized cats. In eight cases of the midbrain transection, all (n=3) or most (n=5) of the PAG between the levels the oculomotor nucleus and the trochlear nucleus was separated from the intact side of the brain. Furthermore, in the former three cases, the PAG at the level caudal to the trochlear nucleus was separated from the intact brain by more than half (n=2) or completely (n=1). In all these cases, there were no remarkable differences in the amplitude of the micturition contraction (80-98% of that before transection), irrespective of the levels of the transection. In the cases of the pontine transection, micturition contraction disappeared after transecting through the caudal part of Barrington's nucleus (n=1) or through regions caudal to this nucleus (n=5). In the one case that received a transection through the rostral part of Barrington's nucleus, the amplitude of the micturition contraction was 43% of that before transection. This study demonstrates that Barrington's nucleus is essential, but the PAG is not essential, for evoking micturition. Our results suggest that the information of bladder fullness in the cat is conveyed to Barrington's nucleus either directly from the lumbosacral neurons or indirectly via relay neurons located below the midbrain.

Co-transfection of EYFP-GH and ECFP-rab3B in an experimental pituitary GH3 cell: a role of rab3B in secretion of GH through porosome.

Recently, in order to elucidate the role of rab3B in porosome, we have observed the incorporation of rab3B in the secretion of GH through porosome under confocal laser scanning microscopy (CLSM). Transfected cells with GH-EYFP fusion protein and rab3B-ECFP fusion protein were observed under CLSM, which showed the colocalization of EYFP-GH and ECFP-rab3B in the budding configuration of secretory process. These structural and functional images of rab3B imply the incorporation of rab3B in the secretion of GH through porosome.

Transient uptake of thallium-201 into a cerebral infarction: a case report.

We describe a 51-year-old woman with a cerebral infarction that showed transient accumulation of thallium-201. On admission, this lesion was well-enhanced by gadolinium injection and gradually expanded, mimicking a malignant brain tumor. A cerebral angiogram, however, did not indicate the presence of a malignant brain tumor. Ethyl cysteinate dimer single photon computerized tomography showed perfusion defects throughout hospitalization. The final diagnosis of cerebral infarction was established by pathological examination. Six months after onset, the enhancement by gadolinium and the expansion of the lesion disappeared. A cerebral infarction showing transient uptake of thallium-201, and lesion expansion is indicative of a lesion in the liquefaction stage that might mimic a malignant tumor. Although thallium-201 scintigrams are useful for the differential diagnosis of radiation necrosis and recurrent brain tumor, the findings in this patient should alert clinicians to the differential diagnosis of intracerebral expansive lesions.

Disappearance of gadolinium enhancement in a chemoresistant astrocytoma of the tectum after high-dose interferon beta.

Interferon beta 6 million units per week was administered to a patient with an aggressive astrocytoma in the tectum that was resistant to cisplatin, etoposide, vinblastine, and the oral alkylating agent temozolomide. The tumor was immunopositive for O6-methylguanine-DNA methyltransferase (MGMT). Interferon beta caused the disappearance of the gadolinium-enhanced lesion in the tectum. Interferons have apoptotic and antiangiogenic effects on tumor cells, and the lesion's disappearance may have been induced by complexes of these effects. Administration of interferon beta might have a favorable effect on tectal gliomas that are immunopositive for MGMT and resistant to chemoradiotherapy including temozolomide.

Axonal pathways and projection levels of anterior semicircular canal nerve-activated vestibulospinal neurons in cats.

Using collision tests of orthodromically and antidromically generated spikes, we studied the axonal pathways, axonal projection levels, and soma location of anterior semicircular canal (AC) nerve-activated vestibulospinal neurons in decerebrate cats. AC nerve-activated vestibulospinal neurons (n=74) were mainly located in the ventral portion of the lateral vestibular nuclei and the rostral portion of the descending vestibular nucleus, which is consistent with previous studies. Of these neurons, 15% projected through the ipsilateral (i-) lateral vestibulospinal tract (LVST), 74% projected through the medial vestibulospinal tract (MVST), and 11% projected through the contralateral (c-) LVST. The vast majority (78%) of AC nerve-activated vestibulospinal neurons were activated antidromically only from the cervical segment of the spinal cord; 15% of neurons were activated from the T1 segment and only one neuron was activated from the L3 segment. AC nerve-activated vestibulospinal neurons may primarily target the neck muscles and thus contribute to the vestibulocollic reflex. Most of the c-LVST neurons were also activated antidromically from the oculomotor nucleus, suggesting that they are closely related to the control of combined eye-head movements.

Role of Barrington's nucleus in micturition.

Barrington's nucleus is a central component of the micturition circuit. This nucleus projects axons to the sacral parasympathetic nucleus, where preganglionic neurons innervating the urinary bladder are located. To clarify the functional role of this nucleus, the firing properties of Barrington's neurons that project axons to the spinal cord were examined. Based on these studies, a model begins to emerge that places Barrington's nucleus in the micturition pathway that is involved in increasing bladder pressure rapidly and strongly, while also maintaining high bladder pressure. In addition, Barrington's neurons are suggested to have another role, that is, increasing the probability of micturition contraction by activating a spinal excitatory pathway or disinhibiting a spinal inhibitory mechanism. In contrast to the excitatory role of Barrington's nucleus, this nucleus does not seem to trigger bladder relaxation.

Properties of Barrington's neurones in cats: units that fire inversely with micturition contraction.

Barrington's nucleus contains neurones that decrease their firing during micturition contraction, as well as neurones that increase their firing during this phase. These neurones are commonly termed inverse neurones and direct neurones, respectively. The aims of the present study were to determine whether inverse neurones send descending axons to the spinal cord and to clarify how these neurones regulate bladder contractility. Forty-five single neurones were recorded from the dorsolateral pontine tegmentum. Spinal-projecting neurones were identified by antidromic stimulation of the spinal cord. More than half of inverse neurones were located outside Barrington's nucleus. Only three were spinal-projecting neurones. The results were in marked contrast with direct neurones that we studied previously: the majority of them were located within Barrington's nucleus, and 56% were spinal-projecting neurones. The firing frequency of inverse neurones ranged between 6 and 37 Hz during the relaxation phase of the micturition contraction-relaxation rhythm. The firing of all neurones began to decrease within 8 s after the onset of micturition contraction. During micturition contraction, neurones displayed little firing, being virtually silent (n = 29) or displayed weak tonic firing (3-11 Hz; n = 16). All neurones began to increase their firing within 8 seconds after the onset of bladder relaxation. These results suggest that inverse neurones do not trigger bladder contraction or relaxation, despite the finding that a few of them send descending axons to the spinal cord. One possible role of the inverse neurone is to regulate firing activities of direct neurones in Barrington's nucleus.

Eye movements evoked by selective saccular nerve stimulation in cats.

OBJECTIVE: Because of technical obstacles in controlling current spread to adjacent peripheral nerve, eye movements evoked by activation of the otolith organs have not been investigated in detail compared to eye movements evoked by activation of the canal organs. We attempted to solve this problem by applying more sensitive methods using fine needle and strictly controlling stimulus current intensity compare with filed potential for selective stimulation. METHODS: Eye movements evoked by selective, unilateral saccular (SAC) nerve stimulation were investigated using both electrooculography (EOG) and video recording in decerebrated cats in the presence or absence of anesthesia. Electrical stimulation was applied to the SAC nerve through implanted acupuncture needles. RESULTS: In the absence of anesthesia and with stimulus intensities less than (3.1 +/- 2.7) x N(1)T, we found supraduction in both eyes or in either the ipsilateral or contralateral eye of different cats. We observed downward eye movements using a stronger stimulus intensity ((6.2 +/- 2.9)) x N(1)T). The threshold for downward eye movements was significantly greater than that for upward eye movements (P < 0.05). In anesthetized cats, only downward eye movements were observed when stimulus intensities less than 10 x N(1)T ((7.8 +/- 2.3) x N(1)T) were used. CONCLUSION: These results confirm the known sacculo-ocular anatomical connections, which are involved predominantly in vertical eye movements. Because the sacculo-ocular connections are relatively weak, the normal supraduction evoked by SAC activation can be easily modified by factors such as level of anesthesia and the method of stimulation.

Feed-forward and feedback regulation of bladder contractility by Barrington's nucleus in cats.

The purpose of the present study was to clarify how Barrington's nucleus regulates bladder contractility. Single neurones that discharge at higher rates during micturition contraction were recorded from Barrington's nucleus. Spinal-projecting neurones were identified by antidromic stimulation of the spinal cord. Seventy-six spinal-projecting neurones were classified into four types based on the firing patterns displayed during the relaxation phase of the micturition contraction-relaxation rhythm: (1) ramp-tonic neurones displayed a ramp increase in firing throughout the relaxation phase, (2) ramp-silent neurones were silent initially during the relaxation phase and displayed a ramp increase later, (3) flat-tonic neurones fired constantly, and (4) flat-silent neurones displayed little firing, being virtually silent throughout relaxation. During the relaxation phase, discharge volleys from Barrington's nucleus to sacral neurones were estimated to increase exponentially as micturition contraction approached. Twenty-two neurones increased firing even further within 3 s of micturition contraction, suggesting that they are involved in the final stages of initiation of micturition contraction. During micturition contraction, 18 neurones (of which 14 belonged to the ramp-silent class) displayed maximal firing rates before maximal bladder pressures were reached; firing gradually decreased during micturition contraction. Thirty-nine neurones (of which 25 belonged to the ramp-tonic class) displayed constant firing during micturition contraction. This suggests that ramp-silent neurones might be involved in increasing bladder pressure rapidly and strongly via feed-forward regulation, while ramp-tonic neurones might be involved in maintaining high bladder pressure via positive feedback from the bladder afferents. Sixty neurones continued to fire for 1-8 s after the onset of bladder relaxation, suggesting that Barrington's nucleus does not trigger bladder relaxation.

Properties of horizontal semicircular canal nerve-activated vestibulospinal neurons in cats.

Axonal pathways, projection levels, and locations of horizontal semicircular canal (HC) nerve-activated vestibulospinal neurons were studied. The HC nerve was selectively stimulated. Vestibulospinal neurons were activated antidromically with four stimulating electrodes, inserted bilaterally into the lateral vestibulospinal tracts (LVST) and medial vestibulospinal tracts (MVST) at the C1/C2 junction. Stimulating electrodes were also positioned in the C3, T1, and L3 segments and in the oculomotor nuclei. Most HC nerve-activated vestibulospinal neurons were located in the ventral portion of the medial, lateral, and the descending nuclei. Among the 157 HC nerve-activated vestibular neurons, 83 were antidromically activated by stimulation at the C1/C2 junction. Of these 83 neurons, axonal pathways of 56 HC nerve-activated vestibulospinal neurons were determined. Most (48/56) of these had axons that descended through the MVST, with the remainder (8 neurons) having axons that descended through the ipsilateral (i-) LVST. Laterality of the axons' trajectories through the MVST was investigated. The majority of vestibulospinal neurons (24/28) with axons descending through the contralateral MVST were also antidromically activated from the oculomotor nucleus, whereas almost all vestibulospinal neurons (19/20) with axons descending through the i-MVST were not. Most HC nerve-activated vestibulospinal neurons were activated antidromically only from the C1/C2 or C3 segments. Only one neuron that was antidromically activated from the T1 segment had an axon that descended through the i-LVST. None of the HC nerve-activated vestibulospinal neurons were antidromically activated from the L3 segment. It is likely that the majority of HC nerve-activated vestibulospinal neurons terminate in the cervical cord and have strong connections with neck motoneurons.

Eye movements evoked by the selective stimulation of the utricular nerve in cats.

OBJECTIVE: Eye movements evoked by otolith organ are not well-investigated compare with canal related eye movements due to the technical difficulties. We try to solve this problem by means of our methods. METHODS: Eye movements evoked by selective utricular (UT) nerve stimulation were investigated using both electrooculography (EOG) and video recording in decerebrated cats in the presence or absence of anesthesia. Electrical stimulation was applied to the UT nerve through implanted acupuncture needles. RESULTS: In the absence of anesthesia and with stimulus intensities less than 2.6+/-0.7 x N(1)T, we found ipsilaterally directed horizontal eye movements in both eyes in one cat, abduction in the ipsilateral eye in two cats, and adduction in the contralateral eye in another cat. Other types of eye movements (e.g., supraduction or diagonal eye movements) were observed in both eyes of cats in the absence of anesthesia at a stimulus intensity of 12.2+/-7.6 x N(1)T, an intensity in which current spread to the adjacent nerve could not be ruled out. In the presence of anesthesia, UT nerve stimulation alone failed to evoke horizontal eye movements, but with an intensity 13.8+/-6.4 x N(1)T, supraduction or diagonal eye movements were evoked. UT nerve stimulation at 2-3 x N(1)T facilitated horizontal eye movements induced by ipsilateral abducens (AB) nucleus stimulation or contralateral horizontal canal nerve stimulation. CONCLUSION: This is the first report to our knowledge in which UT nerve-evoked horizontal eye movements are documented. These results confirm the known monosynaptic and disynaptic anatomical connections from utricular primary afferents to the ipsilateral AB nucleus neurons.

Bladder contractility-related neurons in Barrington's nucleus: axonal projections to the spinal cord in the cat.

Barrington's nucleus projects directly to the sacral parasympathetic nucleus. The purpose of this study was to clarify whether neurons in Barrington's nucleus that increase their firing during bladder contractions project to the spinal cord and, if so, to which level(s) the axon reaches. Single units were recorded in Barrington's nucleus of cat with glass microelectrodes, and the termination level of descending axons was determined by antidromic stimulation of the spinal cord. Thirty-nine neurons projecting to the spinal cord were located in rostral parts of the dorsolateral pontine tegmentum, medial and ventral to the mesencephalic trigeminal tract. This finding is consistent with previous neuronal tracing studies. All neurons increased their firing rates during contraction associated with micturition. In 19 examined neurons, the most caudal level of the descending axon distributed between the L7 and the S3 level. Stimulation of the axon at this most caudal level resulted in antidromic spike latencies ranging between 19.5 msec and 45.0 msec. These antidromic latencies were much smaller than previously reported orthodromic conduction times between neurons in Barrington's nucleus and sacral preganglionic neurons innervating the bladder. The mean conduction velocity of the descending axon from the cell body to the border between Th13 and the L1 ranged between 7.2 m/sec and 27.7 m/sec. The decrease of the mean conduction velocity was observed at the lumbar as well as at the sacral segments, suggesting that axons issue collaterals to the lumbar level as well as to the sacral level.