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PubMed1990

Bilateral trochlear nerve palsies from a brainstem hematoma.

We present a case of bilateral superior oblique palsies after a spontaneous brainstem hematoma. A computerized tomographic scan of the brain revealed a high-density mass lesion consistent with bleeding in the area caudal to the inferior colliculi, where the trochlear nerves decussate and exit the dorsal brainstem. Subsequent studies showed resolution of the density and persistent failure to enhance. Bilateral trochlear nerve palsies due to the nontraumatic brainstem bleeding are extremely rare.

Brain Stem↗
PubMed1990

The GABAA receptor complex in hepatic encephalopathy. Autoradiographic evidence for the presence of elevated levels of a benzodiazepine receptor ligand.

Autoradiographic analysis was used to examine radioligand binding to benzodiazepine (BZ) and GABAA receptors in the brains of rabbits with hepatic encephalopathy (HE). Thin sections of whole brain from normal rabbits and rabbits with HE were mounted on slides and subdivided into two groups. One group was washed before incubation with radioligand, while the second group was not prewashed. [3H]Flunitrazepam binding to BZ receptors was decreased by 22% to 42% (p less than 0.05) in the cerebral cortex, superior and inferior colliculi, and cerebellum of unwashed sections from rabbits with HE compared to all other groups. The binding of [3H]Ro 15-1788 to unwashed sections from rabbits with HE was reduced by a similar degree (18% to 37%, p less than 0.05) in the cerebral cortex, hippocampus, superior colliculus, and cerebellar cortex. Incubation of sections with the GABA-mimetic muscimol and NaCl produced an additional decrease in [3H]flunitrazepam binding to the cortex and hippocampus (25% to 31%, p less than 0.05) in unwashed HE rabbit brain, but increased radioligand binding (27% to 71%, p less than 0.05) to several regions in control rabbits. No changes in radioligand binding to either GABAA or peripheral benzodiazepine receptors was observed between HE and control rabbit sections. These findings are consistent with previous electrophysiologic and neurochemical observations indicating no significant changes in either the function or density of GABAA or BZ receptors in this model of HE. Further, they indicate that a reversible BZ receptor ligand with agonist properties is present in the brain in HE. This substance may contribute to the enhancement of GABAergic tone observed in this syndrome.

Animals↗
PubMed1990

Developmental characteristics in the daily rhythm of serotonin concentration within rabbit brainstem regions.

To examine the development of daily rhythms in serotonin levels, we measured serotonin concentration within five distinct brainstem regions in 3-day-old, 21-day-old and adult rabbits at 09.30, 15.30, 21.30 and 03.30. Serotonin was measured by radioenzymatic assay in the superior and inferior colliculi, rostral pons, caudal pons and medulla, and serotonin concentration was expressed relative to wet tissue weight. In addition to defining the presence of a daily rhythm in serotonin concentration in whole brainstem, we were interested in identifying brainstem region-specific differences in this rhythm. Our data suggest that daily rhythms for serotonin are established by 3 days of life. Analysis of gross brainstem rhythm data suggests a nocturnal peak in serotonin concentration in 3-day-old and adult animals in contrast to a diurnal peak for 21-day-old animals. These gross rhythms reflect the net sum of distinct region-specific patterns in serotonin concentration. Analysis by region reflects a region-specific ontogeny in the development of daily rhythms in serotonin concentration. Serotonin is involved in the initiation of sleep. The observed developmental patterns may relate to the maturation and integration of sleep/wake states.

Aging↗
PubMed1987

Autoradiographic differentiation of mu, delta, and kappa opioid receptors in the rat forebrain and midbrain.

While there is an abundance of pharmacological and biochemical evidence to suggest the existence of multiple opioid receptors, their precise localization within the brain is unclear. To help clarify this issue, the present study examined the distributions of the mu, delta, and kappa opioid receptor subtypes in the rat forebrain and midbrain using in vitro autoradiography. Mu and delta receptors were labeled with the selective ligands 3H-DAGO (Tyr- D-Ala-Gly-MePhe-Gly-ol), and 3H-DPDPE (D-Pen2, D-Pen5-enkephalin), respectively, while the kappa receptors were labeled with 3H-(-)bremazocine in the presence of unlabeled DAGO and DPDPE. Based on previous findings in our laboratory, the labeling conditions were such that each ligand selectively occupied approximately 75% of each of the opioid sites. The results demonstrated that all 3 opioid receptor subtypes were differentially distributed in the rat brain. Mu binding was dense in anterior cingulate cortex, neocortex, amygdala, hippocampus, ventral dentate gyrus, presubiculum, nucleus accumbens, caudate putamen, thalamus, habenula, interpeduncular nucleus, pars compacta of the substantia nigra, superior and inferior colliculi, and raphe nuclei. In contrast, delta binding was restricted to only a few brain areas, including anterior cingulate cortex, neocortex, amygdala, olfactory tubercle, nucleus accumbens, and caudate putamen. Kappa binding, while not as widespread as observed with mu binding, was densely distributed in the amygdala, olfactory tubercle, nucleus accumbens, caudate putamen, medial preoptic area, hypothalamus, median eminence, periventricular thalamus, and interpeduncular nucleus. While all 3 opioid receptor subtypes could sometimes be localized within the same brain area, their precise distribution within the region often varied widely. For example, in the caudate putamen, mu binding had a patchy distribution, while delta and kappa sites were diffusely distributed, with delta sites being particularly dense ventrolaterally and kappa sites being concentrated ventromedially. These results support the existence of at least 3 distinct opioid receptors with possibly separate functional roles.

Animals↗
PubMed1988

[Anoxic encephalopathy after cardiocirculatory insufficiency. Neuropathological study apropos of 16 cases].

Sixteen cases of anoxic encephalopathy in adult patients admitted to the intensive Care Department of Raymond Poincaré Hospital (Garches) have been selected on the following criteria: resuscitation by external cardiac massage for cardio-respiratory failure, without any previous history of anoxia and with detailed data on the subsequent evolution of neurological signs and symptoms. Main clinical features were compared to the results of the neuropathological examination. The pattern and the distribution of changes are detailed. The cerebral cortex was always involved by diffuse ischemic cell changes or by laminar necrosis. The Sommer's sector of Ammon's horn was affected in 15 cases, the basal ganglia in 14, the cerebellum in 11, the brain stem in 6. The very rarely mentionned necrotic brain stem changes, which involved inferior colliculi, periaqueductal gray matter and substantia nigra were sometimes associated with lesions of the floor of the IVth Ventricle and of the mamillary bodies. They were different from Wernicke's encephalopathy with could be dismissed on clinical and pathological grounds. No clinical signs or symptoms specific for this distribution of changes could be found by the retrospective study of the clinical files.

Adolescent↗
PubMed1986

[In utero demonstration of the functional activity of the auditory system of the fetus of guinea pigs by 14C 2-deoxyglucose autoradiography].

Pregnant guinea pigs injected with 2-DG between 10 to 2 days before birth, were exposed to loud free field pure tones (nine frequencies tested from 0.8 to 20 kHz). Specific bands of labeling were observed in the Inferior Colliculi of most of the fetuses whatever the frequency tested. The location of these isofrequency laminae shifted with stimulus frequency, their orientation were similar to those observed in the mothers. No such bands were found either in the control females or their fetuses. These results demonstrate that the auditory system of the fetus responds to frequencies up to 20 kHz, exhibits frequency selectivity and tonotopic organization in utero.

Animals↗
PubMedDate not supplied

The use of reverse-phase chromatographic procedures coupled with radioimmunoassay in studying regional distribution of beta h-endorphin in the human brain.

Fast reverse-phase chromatographic procedures (Sep-Pak C18 cartridges and high pressure liquid chromatography) combined with radioimmunoassay is presented. It provides accurate assessment of brain tissue concentrations of beta h-endorphin (beta h-E). The method was used to study the distribution of the endogenous opioid in nine distinct human brain regions. The beta h-E was found mainly localized in the hypothalamus anterior, hypothalamus posterior followed by a lower concentration in the Corpora mamillaria and the Substantia grisea centralis. Concentrations below 1.0 fmol/mg fresh brain tissue were determined in the Pons dorsalis, Substantia nigra, Colliculi inferiores, Glandula pinealis and in Nucleus ruber.

Brain Chemistry↗
PubMed1986

Postmortem studies on posthypoxic and post-methyl bromide intoxication: case reports.

In two cases of action myoclonus following hypoxic or shock encephalopathy, neuropathological examination disclosed mild or moderate scattered changes involving thalamus, griseum centrale mesencephali, and nucleus centralis superior. Other areas were affected only in one of these cases (striatum, nucleus subthalamicus or hippocampus, nuclei pontis, and cerebellar cortex). In another case (an alcoholic patient), the changes, which involved only corpus mamillare and thalamus, were those of Wernicke-Korsakoff encephalopathy. In one case of oscillatory myoclonus following septic shock, there were marked cerebellar changes involving deep nuclei and mild abnormalities in the thalamus and inferior olive. The last case of action myoclonus following acute methyl bromide intoxication was characterized by marked changes in the inferior colliculi and moderate or mild abnormalities of thalamus, griseum centrale mesencephali, nucleus centralis superior, nucleus reticularis tegmenti pontis, nuclei pontis, and dentatus. The findings are compared with the data of seven previously reported neuropathological examinations in action myoclonus following hypoxic encephalopathy.

Adult↗
PubMed1985

Experimental clinicopathological study of the Habu (Trimerusurus flavoviridis) venom. I. A light microscopic study of terminal degeneration in some brainstem nuclei of the cat following intracisternal injection of the venom.

Central neurotoxic effect of habu venom was studied in cats after intracisternal injections. Thirteen nuclei from the medulla oblongata, eleven from the pons and ten from the midbrain were observed. In the medulla oblongata, the nuclei most affected were the gracile and cuneate nuclei and the nucleus of the spinal tract of the trigeminal nerve; in the midbrain, degeneration was mainly observed in the superior and inferior colliculi. The present findings are discussed and correlated with the behavioral and physiological changes which have been reported previously.

Animals↗
PubMed1979

Origins of the scalp recorded frequency-following response in the cat.

The frequency-following response (FFR) is a short-latency scalp-recorded evoked potential elicited by the presentation of low-frequency acoustic stimuli. It is thought to be the result of the synchronous electrical activity in brain stemauditory nuclei to each wave in the acoustic signal. The present investigation constitutes an attempt to determine the generators of the FFR in the cat by analysis of the response and by section of brain stem auditory nuclei and tracts. Among the results were the following: (1) the cochlear nuclei contribute approximately 50% of the amplitude of the scalp-recordedFFR in the cat. (2) The cochlea also makes a significant contribution, accounting for an average of nearly 25% of the response amplitude. (3) The superior olivary nuclei (and/or the nuclei of the lateral lemnisci) account for about 20% of the response amplitude. (4) The contributions from the inferior colliculi (contrary to earlier studies) were found to be relatively insignificant. (5) As a consequence of the existence of multiple generators, the FFR ample area of hair cell excitation for each stimulus frequency involved in the mediation of the FFR, suggestion that scalp-recorded FFRs could be used to ascertain low-frequency hearingsensitivity in uncooperative human subjects.

Animals↗
PubMedDate not supplied

Auditory brainstem volume-conducted responses: origins in the laboratory mouse.

Volume-conducted, short-latency auditory-evoked potentials were examined in the laboratory mouse with lesions and local recording used to localize their sources. PI corresponds in time with N1 recorded from the round window, while isolation of the eighth cranial nerve from the brainstem results in the loss of all post-PI components. PII latency agrees with that of evoked potentials recorded from the cochlear nucleus. PIII latency corresponds with that of evoked potentials from the vicinity of the contralateral superior olivary nucleus, and lesions of this and closely related contralateral structures abolish PIII from the vertex recordings. PIV is reduced in amplitude by unilateral brainstem lesions between the superior olive and the inferior colliculus. Evoked potentials and lesions localized PV to the vicinity of the lateral regions of the contralateral inferior colliculus. PVI disappeared when areas anterior to the inferior colliculi were lesioned. Although minor species differences may exist, it was concluded that the sources for PI to V in the mouse closely resemble those in the cat, and they agree well with the limited data from the human. This technique may now be applied to studies of the numerous auditory mutants of the laboratory mouse.

Animals↗
PubMed1979

Efferent projections of the area postrema demonstrated by autoradiography.

The efferents connections of the area postrema (AP) have been studied autoradiographically following iontophoretic injections of 3H-glycine or 3H-leucine into the area postrema. Precise control of the diffusion of the labelled amino acids injected iontophorectically into the AP was made using the technique of sectioning with a cryostat. AP projects to a great number of structures. Projections to nucleus tractus solitarius (NFS), dorsal vagal nucleus, nucleus intercalatus, nucleus praepositus hypoglossi, nucleus hypoglossal, the mesencephalic nucleus of V nerve, locus coeruleus and superior and inferior colliculi are shown bilaterally. The density of the efferents was greatest to the NFS and the LC. Corelations are suggested with functional mechanisms of cardiovascular regulation.

Animals↗
PubMed1977

The pharmacology of N-carbamoyl-2-(2,6-dichlorophenyl)acetamidine hydrochloride (LON-954) a new tremorogenic agent.

The tremorogenic properties of a series of benzylimidoylurea derivatives are described. The most potent member, N-carbamoyl-2-(2,6-dichlorophenyl) acetamidine hydrochloride (LON-954), produces a reproducible, dose-dependent rest tremor in the mouse with oral doses of 5-100 mg/kg which is also seen in other species (rat, cat, dog, rabbit). The tremor is of constant frequency, rapid onset and short duration. It is not accompanied by akinesia, muscle ridigity, antinociceptive activity, parasympathomimetic effects or marked hypothermia and in these respects differs from tremor produced by oxotremorine. Pretreatment with a microsomal enzyme inhibitor had no effect on the tremor. An LD50 of 165 mg/kg p.o. was calculated in the mouse. After repeated administration both acute and chronic tolerance developed to the tremorogenic effects of LON-954. Evidence for a central site of action is presented, since the tremor could be reproduced following injection of small quantities (50-100 microgram) into the cerebral ventricles of the mouse. Furthermore, the use of spinal, decorticate and and decerebrate rats indicated that although tremor is not of cortical origin, it arises in an area rostral to the inferior colliculi. The mechanism underlying the tremor appears to involve dopaminergic pathways, since the action of LON-954 was antagonised by L-dopa and apomorphine and potentiated by pimozide. Atropine and carbachol were without effect. It is suggested that LON-954 could be used as an alternative to oxotremorine for the detection of anti-Parkinson drugs, particularly those exerting their effects through dopaminergic mechanisms.

Analgesics↗
PubMed1984

The distribution of immunoreactive alpha-neo-endorphin in the central nervous system of the rat.

Using a specific radioimmunoassay, we have found that immunoreactive (ir) alpha-neo-endorphin has a widespread and unique distribution in the rat brain and spinal cord. The highest concentration in brain is in the substantia nigra (1692.1 fmol/mg of protein). Very high concentrations of ir-alpha- neo-endorphin (greater than 500 fmol/mg of protein) are also found in the lateral preoptic nucleus, dentate gyrus, parabrachial nuclei, nucleus accumbens, globus pallidus, median eminence, and anterior hypothalamic nucleus. Relatively high concentrations of ir-alpha-neo-endorphin (250 to 500 fmol/mg of protein) are present in the bed nucleus of the stria terminalis, paraventricular nucleus, nucleus of the solitary tract, dorsomedial nucleus, central amygdaloid nucleus, periaqueductal gray matter, suprachiasmatic nucleus, periventricular nucleus, hippocampus, prepositus hypoglossal nucleus, arcuate nucleus, ventromedial nucleus, medial preoptic nucleus, zona incerta, dorsal premamillary nucleus, medial forebrain bundle (hypothalamic and preoptic), nucleus of the diagonal band, locus ceruleus, lateral septal nucleus, and nucleus ambiguus . Moderate levels (100 to 250 fmol/mg of protein) are found in the posterior hypothalamic nucleus, ventral premamillary nucleus, dorsal raphe nucleus, motor hypoglossal nucleus, caudate-putamen, periventricular thalamic nucleus, subcommissural organ, sensory trigeminal nucleus, perifornical nucleus, area postrema, supraoptic nucleus, cuneate nucleus, medial amygdaloid nucleus, and organum vasculosum laminae terminalis. Low concentrations of ir-alpha-neo-endorphin (less than 100 fmol/mg of protein) are found in many cortical structures, claustrum, thalamic nuclei, habenular nuclei, lateral geniculate body, red nucleus, superior and inferior colliculi, paramedian reticular nucleus, pontine nuclei, superior olive, vestibular nuclei, motor facial nucleus, gigantocellular reticular nucleus, and subfornical organ.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

[Morphological studies of the regulatory mechanisms of intracerebral blood circulation].

The intracerebral branches of the posterior and medial cerebral arteries in the area of the grey and white substances of the parietal, occipital and temporal cerebral lobes, of the nuclei in the superior and inferior colliculi in the tectum mesencephali. as well as in the pons have been studied in 36 male corpses at the age of 5--49 years by means of Cajal, Koelle, Furness and Costa methods. Presence of sensitive neural terminals, cholinergic plexuses has been stated in the intracerebral artery walls with the diameter up to 100 mcm and more, as well as adrenergic neural network on the arteries with the diameter up to 100 mcm and more, as well as adrenergic neural network on the arteries with the diameter up to 40 mcm and more. Besides, near the cerebral substance vessels monoaminocytes situating both in the area of the sphincter torus and in the arterial walls have been revealed. A suggestion is made that the proper neural and other apparatuses of the intracerebral circulatory bed play a certain role in regulation of the local cerebral circulation.

Acetylcholinesterase↗
PubMed1982

Prenatal development of mouse central nervous structures: time of neuron origin and gradients of neuronal production. A radioautographic study.

In order to obtain an overall view of neurogenesis in the main central nervous structures of the mouse, we have undertaken a systematic study of the time of neuron origin and of the gradients of neuronal production. The animals were the offspring of pregnant females given a pulse label of 3H-thymidine on selected days after conception. These days were chosen to cover the principal brain development stages: E10.5, E11.5, E12.5, E13.5, E14.5, E15.5, E16.5, E17.5 and E18.5. The offspring were sacrificed during the fourth postnatal week and labeling indices were calculated in the different brain structures. The study of labeling indices as a function of the day of injection and of the brain level studied provided us with information on the major periods of neuronal proliferation in these structures and allowed us to analyse the formation gradients inside a given nervous structure. As a whole, for a majority of nervous structures (olfactory, cortical, septal, hippocampal, preoptic, thalamic, epithalamic, hypothalamic and cerebellar structures), our results are in good agreement with the already published observations. However, we outlined two major phenomena apparently unobserved until now in the mouse: the first is a rostrocaudal gradient of neuronal production in the inferior colliculi, and the second is the long period of neuronal proliferation in the caudate nucleus lasting from E11.5 to E18.5, along a complex inside-out and mediolateral gradient.

Animals↗
PubMed1981

[Cholinergic neurons of the human midbrain].

By the histochemical method of Burt for choline acetyltransferase (ChAT) activity, the nuclei of the human midbrain were studied at the age of 7-8 lunar months. Owing to the histochemical procedure applied, a certain quantity of the residue was obtained and 4 types of neurons were revealed: with low, moderate, high and very high ChAT activity. In all the nuclei studied, the part of every neuronal type was determined. A direct dependence between the level of the ChAT activity and the size of the neuron was stated. The nuclei possessing motor activity contained mainly the neuronal cells with the highest ChAT activity. The amount of the cholinergic cells in the nuclei of the midbrain varied from 98 +/- 3% (in the mesencephalic nucleus of the trigeminal nerve) up to 45 +/- 12% (in the parabrachial mesencephalic nucleus). While studying the neural centers by means of the luminescent method, that reveals biogenic amines, it was stated that the nuclei have neurons with various mediator specificity. Cholinergic function of the mesencephalic parabrachial, supratrochlear, periansiform, subcuneiform, paranigral nuclei and the nucleus between the inferior colliculi was demonstrated.

Choline O-Acetyltransferase↗
PubMed1995

Developmental and regional expression pattern of a novel NMDA receptor-like subunit (NMDAR-L) in the rodent brain.

A novel NMDA receptor-like (NMDAR-L) cDNA was isolated that contained an open reading frame coding for a predicted polypeptide of 1115 amino acids that shares approximately 27% identity with NMDA receptor subunits. In situ hybridization experiments indicated that NMDAR-L mRNA was expressed in the developing rodent CNS. On postnatal day 1 (P1), NMDAR-L mRNA expression was pronounced in the entorhinal cortex, the subiculum and the thalamus, in layer V of the developing neocortex, in the superior and inferior colliculi, and various regions of the hindbrain, excluding the cerebellum. On P5, NMDAR-L mRNA was expressed in layer V of the neocortex, in the entorhinal cortex, in the subiculum, and in the thalamus. On P14, NMDAR-L mRNA was expressed in layers II-VI of the neocortex, in the entorhinal and piriform cortex, in the subiculum and CA1 field, and in the nucleus of the lateral olfactory tract. In the adult brain, NMDAR-L mRNA was detected predominately in the nucleus of the lateral olfactory tract. Injection of NMDAR-L cRNA into Xenopus oocytes did not lead to the expression of homomeric glutamate-activated channels. However, coinjection of the triple combination of NMDAR-L with NMDAR1 and NMDAR2B cRNAs led to a striking decrease in the current magnitude compared to currents obtained after coexpression of the double combination of NMDAR1 with NMDAR2B. While the function of NMDAR-L remains to be established, its developmental and regional expression pattern suggests that NMDAR-L may influence axonal outgrowth and synaptogenesis during brain development.

Aging↗