Lateral Cuneate Nucleus Research Articles

Dorsal Column Nuclei Projection to the Cerebellar Caudal Vermis in the Rabbit Revealed by the Fluorescent Double-Labeling Method

The organization of the projection from the dorsal column nuclei (DCN) to the lobules of the cerebellar caudal vermis was studied in the rabbit. Following unilateral injections of the retrograde fluorescent tracers fast blue (FB) and diamidino yellow (DY) into the pyramis (Pr) and uvula (Uv), respectively, a great number of single FB- (40%) and DY-labeled (60%) neurons were observed in the ipsilateral (79%) and contralateral (21%) DCN subdivisions. These neurons, as parents for the DCN-Pr and DCN-Uv projections, were numerous in the lateral cuneate nucleus (CuL; 84 and 74%, respectively) and in the complex of the gracile (Gr) and medial cuneate nuclei (CuM; Gr+CuM; 14 and 25%, respectively). A small percentage of the Pr projecting neurons was found in the CuM and Gr nuclei (2% in total). As regards the Uv, a rare and only ipsilateral projection arose from the CuM (1%), and no connection originated from the Gr. The distribution pattern of labeled neurons within individual subnuclei indicates that there are both separate regions and, to a great extent, common regions of the DCN-Pr and DCN-Uv projections. In these common regions, a small population of double FB+DY-labeled neurons (1.2%) was identified. Such neurons, present exclusively in the ipsilateral CuL and Gr+CuM, were the source of projection by way of axonal collaterals to the Pr and Uv simultaneously. It is suggested that the described connections may play a role in coordination of the axial and proximal forelimb muscles.

Activity of the Helix in Ear Acupuncture: Corresponding to the Segmental Innervation of the Human Body?: Part II: Elaboration of a Segmental Cartography of the Helix

Background Intrigued by the two postulations of René Bourdiol, the one on the influence of the helix border on the segmental innervation of the body and the other on the differentiation into an anterior sensory side and a posterior motor side, we looked for further clinical evidence. Aim The aim is to present the elaboration of a chart of the helix border with its segmental indications. Method In a series of two articles we present a clinical body of evidence for the elaboration of the segmental chart of the helix border. This evidence was found by detection of painful points in the ear of patients with different diagnoses. Results We find very intense activity on the helix border over its entire length, going from the bulbar tail to point Zero on the root. The segmental representation follows a proportional and logical distribution in the succession of the segments. Although this study is qualitative in nature, needling is so influential therapeutically that a statistical study would be highly recommended. Conclusion On the basis of clinical evidence, we confirm the postulation of René Bourdiol on segmental influence of the helix but propose to extend this action to the entire border of the helix. We find also confirmation for the second postulation of René Bourdiol, on the sensory nature of the anterior border and the motor nature of the posterior border. During our investigation however we found also a vascular influence of the cornice (internal hidden border of the helix). On cross section of the helix therefore, we situate three transversal points, cutaneous, motor and vascular, representing the sensory, motor and vascular innervation of the same segmental level. The bulbar thickening of the tail contributes perhaps to a cervical enlargement for the plexus brachialis, but the bulbar tail is much more convincingly identifiable with the medulla oblongata containing the therapeutically interesting spinal trigeminal nucleus and the accessory cuneate nucleus. The localization of the tubercle of Darwin is only present in 10 % of the population. Even when present, the localization of this segmental landmark is too variable and does in my view not represent a lumbosacral enlargement for the innervation of the lower limb as suggested by Bourdiol.

Differential localization of γ‐aminobutyric acid type a and glycine receptor subunits and gephyrin in the human pons, medulla oblongata and uppermost cervical segment of the spinal cord: An immunohistochemical study

Gephyrin is a multifunctional protein responsible for the clustering of glycine receptors (GlyR) and gamma-aminobutyric acid type A receptors (GABA(A)R). GlyR and GABA(A)R are heteropentameric chloride ion channels that facilitate fast-response, inhibitory neurotransmission in the mammalian brain and spinal cord. We investigated the immunohistochemical distribution of gephyrin and the major GABA(A)R and GlyR subunits in the human light microscopically in the rostral and caudal one-thirds of the pons, in the middle and caudal one-thirds of the medulla oblongata, and in the first cervical segment of the spinal cord. The results demonstrate a widespread pattern of immunoreactivity for GlyR and GABA(A)R subunits throughout these regions, including the spinal trigeminal nucleus, abducens nucleus, facial nucleus, pontine reticular formation, dorsal motor nucleus of the vagus nerve, hypoglossal nucleus, lateral cuneate nucleus, and nucleus of the solitary tract. The GABA(A)R alpha(1) and GlyR alpha(1) and beta subunits show high levels of immunoreactivity in these nuclei. The GABA(A)R subunits alpha(2), alpha(3), beta(2,3), and gamma(2) present weaker levels of immunoreactivity. Exceptions are intense levels of GABA(A)R alpha(2) subunit immunoreactivity in the inferior olivary complex and high levels of GABA(A)R alpha(3) subunit immunoreactivity in the locus coeruleus and raphe nuclei. Gephyrin immunoreactivity is highest in the first segment of the cervical spinal cord and hypoglossal nucleus. Our results suggest that a variety of different inhibitory receptor subtypes is responsible for inhibitory functions in the human brainstem and cervical spinal cord and that gephyrin functions as a clustering molecule for major subtypes of these inhibitory neurotransmitter receptors.

An immunocytochemical mapping of methionine-enkephalin-arg 6-gly 7-leu 8 in the human brainstem

Using an indirect immunoperoxidase technique, we studied the distribution of immunoreactive fibers and cell bodies containing methionine-enkephalin-Arg 6-Gly 7-Leu 8 in the adult human brainstem. Immunoreactive cell bodies were found in the reticular formation of the medulla oblongata (in which we observed the highest density of immunoreactive cell bodies) and the pons, the solitary nucleus, the hypoglossal nucleus, the medial and spinal vestibular nuclei, the lateral cuneate nucleus, the nucleus prepositus, the central gray of the pons and mesencephalon, the central and pericentral nuclei of the inferior colliculus, the superior colliculus, ventral to the superior olive and in the midline region of the pons and mesencephalon. The highest density of immunoreactive fibers containing methionine-enkephalin-Arg 6-Gly 7-Leu 8 was found in the spinal trigeminal nucleus, the central gray and the reticular formation of the medulla oblongata, pons and mesencephalon, the solitary nucleus, the spinal vestibular nucleus, the dorsal accessory olivary nucleus, the raphe obscurus, the substantia nigra and in the interpeduncular nucleus. The widespread distribution of immunoreactive structures containing methionine-enkephalin-Arg 6-Gly 7-Leu 8 in the human brainstem indicates that this neuropeptide might be involved in several physiological mechanisms, acting as a neurotransmitter and/or neuromodulator.

A multifocal symmetrical necrotising encephalomyelopathy in Angus calves.

To define a neurological disorder in Angus calves. Clinical and pathological examinations were performed on affected Angus calves from a herd experiencing 1% annual mortality from neurological disease. Angus calves developed ataxia, nystagmus, strabismus, muscular tremors, opisthotonus, bruxism, hyperaesthesia, tetanic spasms and episodic convulsions at 2 to 6 weeks of age. Death occurred 4 to 7 days after the onset of clinical signs. GROSS PATHOLOGY: Bilaterally symmetrical, yellow-grey foci were present in the medulla oblongata. Symmetrical degenerative lesions affected the dorsal vagal motor, lateral cuneate and olivary nuclei in the medulla oblongata and sometimes the spinal cord, substantia nigra and cerebellar peduncles. Malacia was characterised by spongiosis of the neuropile, vascular hyperplasia, infiltration of gitter cells, spheroid formation and delayed degeneration of neurones. Angus calves may develop a multifocal symmetrical necrotising encephalomyelopathy.

Development of the human lateral cuneate nucleus: a morphometric evaluation

The morphometric development of the human lateral cuneate nucleus was examined in nine fetuses and neonates at 18–40 weeks of gestation, a 2-month-old infant and a 63-year-old adult. The authors observed serial sections of the brain containing lateral cuneate nucleus and measured the volume of nuclear column and the number, cell body area and perimeter of neurons using a microscope with a drawing tube and an image-analyzing computer system. A morphometric evaluation revealed that a turning point in the development of the human lateral cuneate nucleus occurring at 30 WG, as this marks the beginning of a gradual increase in the average area and average perimeter; And it is the point at which the neuropil index suddenly increases sharply, to fall back down to lower levels afterwards. The establishment of a neuronal connection between the lateral cuneate nucleus and the cerebellum, which is necessary for proper performance of movements in the upper part of the body.

Biochemical and autoradiographic studies of the central noradrenergic system in dystonia musculorum mutant mice

The autosomal recessive mutation dystonia musculorum ( dt J / dt J ) causes degenerative alterations of peripheral and central sensory pathways leading to ataxia. To determine the consequences of this pathology on the central noradrenergic (NA) system, NA contents were measured by high-performance liquid chromatography (HPLC) in 22 brain regions and spinal cord, while NA transporters, or uptake sites, were evaluated by quantitative ligand binding autoradiography, using [ 3H]nisoxetine, in wild-type and dt J / dt J mutant mice. The only significant differences in NA contents between the two genotypes were increased levels in hypothalamus and mesencephalic dopaminergic regions A9/A10 of dt J / dt J mutants. The dt J / dt J spinal cord showed a similar result, but its NA content remained unchanged when taking into account its reduced volume. Binding to NA transporters revealed increased densities in sensory nuclei of cranial nerves, granular layer of the cerebellar cortex, as well as in cerebellar-related and basal ganglia structures, such as the lateral cuneate nucleus, pontine nuclei, substantia nigra, pontine reticular formation, median raphe nucleus and superior colliculus. Forebrain regions were relatively unaffected in the dt J / dt J mutants, although NA transporter densities were higher in piriform cortex, hippocampal subdivisions and ventro-anterior thalamic nucleus. In contrast, densities of NA transporters were decreased in hypothalamic subregions and in two ventrobasal thalamic nuclei. The results are discussed in relation to expression of the dystonin gene in normal brain, cellular defects resulting from the loss of gene transcription in the dt J / dt J mutation, functional circuits of the central nervous system and some of the phenotypical characteristics of dystonia musculorum mutants.

Immunohistochemical localization of heat shock protein 70 in the human medulla oblongata in forensic autopsies

Heat shock protein 70 (hsp70) can be induced under various stresses in experimental animals. We investigated hsp70 immunoreactivity in the human medulla oblongata in forensic autopsies. Hsp70 immunoreactivity was observed in the cytoplasm of some neurons in the hypoglossal nucleus (XII), the dorsal motor nucleus of the vagal nerve (X), the lateral cuneate nucleus (Cun), and the inferior olive (Oli). Neurons with positive hsp70 immunoreactivity were statistically significantly fewer in the Oli than in the XII, X, and Cun. There was no statistically significant correlation between the AMI (the antemortem interval between the onset of injury and death) or PMI (the postmortem interval between death and autopsy), and the percentage of positive cytoplasmic hsp70 immunoreactivity in any of the nuclei studied. Age had a statistically significant negative correlation with the percentage of positive hsp70 immunoreactivity in the Oli. The percentages of positive hsp70 immunoreactivity in the XII and Cun were statistically significantly lower in burn cases than in other cases. Therefore, the induction of hsp70 immunoreactivity in the medulla oblongata may not reflect the duration of stress in the AMI, but may reflect the regional (nuclei) and conditional (burns) differences in autopsy specimens.

Immunohistochemistry of neuron-specific enolase in neurons of the medulla oblongata from human autopsies

Neuron-specific enolase (NSE) is a glycolytic enzyme specifically expressed in neurons. NSE has been used as a marker for neuronal damage in brain injury. We studied the immunohistochemical localization of this enzyme in the medulla oblongata obtained from human forensic autopsy specimens. Neurons in the dorsal motor nucleus of vagal nerve expressed statistically significantly less NSE immunoreactivity in the cytoplasm than in the hypoglossal nucleus (XII), solitary nucleus, spinal trigeminal nucleus, and lateral cuneate nucleus. Cases of carbon monoxide intoxication by burning showed a higher incidence of NSE immunoreactivity in the cell nucleus of the XII than other cases, while there was no statistically significant correlation between NSE immunoreactivity in the cell nucleus and the Nissl amount. This indicates that the accumulation of NSE immunoreactivity in the cell nucleus might be a vital reaction rather than a postmortem artifact.

Joseph Disease with Severe Atrophy of the Brain Stem Tegmentum: Report of an Autopsied Case

An autopsied case of Joseph disease with severe atrophy of the brain stem tegmentum is reported. A Japanese male noticed unsteady gait at age 30 and showed cerebellar ataxia, pyramidal signs, progressive external ophthalmoplegia, peripheral amyotrophy, sensory disturbance, and bradykinesia. He also developed mild dementia and nocturnal delirium at the terminal stage of his illness. His mother, older and younger brothers and daughter also presented progressive ataxia. The mode of inheritance is considered to be autosomal deminant. He died of cardiac failure at age 57. The autopsy revealed significant atrophy of the brain stem and spinal cord. Microscopic examination showed severe degeneration of the dentato‐rubral and subthalamo‐pallidal systems, pontine nuclei, spinal anterior horn, Clarke's column, accessory cuneate nucleus and spinocerebellar tract, moderate degeneration of the brain stem motor nuclei including the oculomotor nuclei and substantia nigra, and mild degeneration of the spinal posterior and intermediolateral column, and cerebellar cortex. An additional finding, which has received little attention in this disease, was severe atrophy of the brain stem tegmentum associated with degeneration of the reticular formation, raphe nuclei and locus ceruleus. The significance of brain stem tegmental atrophy in Joseph disease is discussed.

Distribution and brainstem origin of cholecystokinin‐like immunoreactivity in the opossum cerebellum

In order to determine the distribution of the peptide cholecystokinin (CCK) within the cerebellum and medullary precerebellar nuclei of the adult opossum, sections of these brain regions were processed for peroxidase-antiperoxidase immunohistochemistry. Within the inferior and superior cerebellar peduncles, fine-beaded fibers are evident and a beaded plexus of fibers is present in all the cerebellar nuclei. In the overlying cerebellar cortex, CCK-positive mossy fiber rosettes are present in all lobules, where their morphology varies from simple enlargements to more complex rosettes. However, their distribution varies particularly in vermal lobules II, III, VII, and IX where they are organized in parasagittal bands. Climbing fibers that are positive for CCK are present in very restricted areas of vermal lobules IV, VII, and VIII. After colchicine pretreatment, CCK-positive cell bodies are seen in restricted regions of the posterior interposed and fastigial nuclei as well as within several precerebellar nuclei known to give rise to mossy fibers. Such nuclei include the lateral cuneate nucleus, the nucleus prepositis hypoglossi, the nucleus reticularis lateralis, the nucleus raphe obscurus, the paramedian reticular nucleus, the nucleus reticularis gigantocellularis, and the medial vestibular nucleus. To localize the brainstem origin(s) of the CCK fibers in the cerebellum, a double-label paradigm employing a retrograde tracer and CCK immunohistochemistry was used. These experiments indicate that CCK mossy fibers originate primarily within the lateral cuneate nucleus, the perihypoglossal complex, and the lateral reticular nucleus. Some also originate within the medial vestibular nucleus and the nucleus reticularis gigantocellularis. In addition, double-labeled cell bodies are present within the caudal medial accessory inferior olive, the likely source of the CCK-positive climbing fibers. These data indicate that specific populations of climbing fibers and mossy fibers may utilize CCK to alter the firing rate of their target neurons.

Further evidence for a central nervous system component in equine laryngeal hemiplegia

Evidence for a central nervous system component of the distal axonopathy associated with equine laryngeal hemiplegia was found in this survey of 33 horses (control, 15; subclinical, 8; clinical, 10). Significantly higher numbers of axonal spheroids were present in sections of the lateral cuneate nuclei in layngeal hemiplegic horses than in those unaffected by the disease.

The distribution of MAG in association with the axonal lesions of canine progressive axonopathy

The distribution of myelin-associated glycoprotein (MAG) was examined by immunocytochemistry in the spinal cord, accessory cuneate nucleus and lumbar ventral nerve roots of dogs affected by progressive axonopathy. These areas were chosen because of the frequency of spheroids and the associated changes in the myelin sheath, including vacuolation, demyelination, remyelination and accumulation of a granular, amorphous material within the sheath. Normal animals demonstrated the expected distribution of MAG; periaxonal and associated with uncompacted membrane such as Schmidt-Lanterman incisures. The majority of early axonal spheroids were surrounded by a MAG-positive zone but in the larger swellings and longer duration cases this was sometimes absent in places even though the axon was associated with Schwann cell processes. Axons in vacuolated fibres were commonly surrounded by a single adaxonal process of Schwann cell and normal periaxonal space. This was immunoreactive for MAG but in situations where the process was incomplete or the space distorted, staining was absent. The granular material failed to stain for MAG. Distorted Schmidt-Lanterman incisures, a feature of the advanced disease, were strongly positive. In the CNS, spheroids without myelin sheaths or unassociated with oligodendroglial processes were negative for periaxonal MAG. The study confirms the localization of MAG at the periaxonal space. It also raises the question of how the distribution of periaxonal MAG is affected by axonal swelling with a consequent increase in axonal surface area.

β-Endorphin in the brainstem, pituitary, and spinal fluid of infants at autopsy: Relation to sudden infant death syndrome

Immunohistochemical localization of β-endorphin was studied in the pituitaries and medullas of forty human infants at autopsy. β-Endorphin immunoreactivity was found in anterior pituitary cells in all cases. In the medulla, β-endorphin immunoreactivity was found in the neurons of the medial and lateral cuneate nuclei in ten out of the forty cases. In eight of these ten cases, the infants died of causes other than sudden infant death syndrome (SIDS). Only two of 25 SIDS cases had demonstrable β-endorphin in the brainstem nuclei. β-endorphin levels in the spinal fluids of all the cases showed no correlation to cause of death, age or gender.

Projections from the red nucleus and surrounding areas to the brainstem and spinal cord in the cat. An HRP and autoradiographical tracing study

HRP injections at the C 2, T 1 and S 1 spinal levels and in the medullary lateral tegmental field revealed that the contralaterally projecting rubro-bulbospinal neurons are located not only in the caudal but also to a certain extent in the rostral red nucleus (RN). These RN projections are somatotopically organized. Neurons projecting to the sacral cord are located in the ventrolateral RN, those projecting to the upper part of the spinal cord lie in the dorsomedial RN and those projecting to the medullary lateral tegmentum were found in the dorsal portions of the RN. These last neurons are smaller than many of the other RN neurons. The HRP results also revealed that the RN does not project to the caudal raphe nuclei. The autoradiographical results confirmed the HRP findings. They further indicated that the contralateral RN projections to the caudal brainstem precerebellar nuclei (nucleus corporis pontobulbaris, lateral reticular nucleus, lateral cuneate nucleus) and the dorsal column nuclei are also somatotopically organized. This was also true for the RN projections to the dorsomedial and intermediate facial subnuclei and the caudal pontine and medullary lateral tegmental field. These areas receive afferents from mainly the dorsal portions of the RN. Regarding the RN projections to the spinal cord, the autoradiographical tracing results revealed somatotopically organized contralateral RN projections to laminae V, VI and VII. Moreover, a small but distinct RN projection to a dorsolaterally located group of motoneurons at the C 8-T 1 level was demonstrated. Ipsilaterally a minor projection to the cervical and upper thoracic lateral intermediate zone was observed. Finally, strong ipsilateral projections from the rostral mesencephalon to the inferior olive were seen. These projections were derived from various rostral mesencephalic areas, including the nucleus of Darkschewitsch, the nucleus accessorius medialis of Bechterew, the interstitial nucleus of Cajal and the area of the rostral interstitial nucleus of the medial longitudinal fasciculus. In the cat it was difficult to define which of the mesencephalic areas projecting to the inferior olive represented the parvocellular RN. A new subdivision of the RN is proposed based on its projections and not on the size of its cells. In this concept the first group is formed by the RN neurons projecting contralaterally to the caudal brainstem and spinal cord. The second group consists of RN neurons projecting to the inferior olive. However, it is difficult, especially in the cat, to determine the exact location of this second group of RN neurons, since they take part in a much wider mesencephalo-olivary projection system.

The central projections of the great auricular nerve primary afferent fibers — an HRP transganglionic tracing method

A study of the central distribution of the primary afferent fibers of the great auricular nerve (GAN) was made in 18 rabbits by means of transganglionic transport of horseradish peroxidase (HRP), HRP applied in the cut central end of the GAN was detected ipsilaterally in the dorsal root ganglion cells (segments C 2-C 3) and the superior cervical ganglion cells. The transganglionically labeled fibers were seen in the dorsal column of the upper 4 cervical segments and in the cranial nerve nuclei of the medulla oblongata. The afferent projections were rather strong in the regions of laminae I–V of C 2, the caudal subnucleus of the spinal tract of the trigeminal nerve (NVSpc), the solitary nucleus (SN), the medial and lateral cuneate nuclei etc. The results showed that the primary afferent impulses of the GAN and the peripheral nerves which supply the head, face, trunk and viscera might converge on the upper cervical cord, the NVSpc and the SN, and play a certain role of modulation on the transmission of somaticovisceral sensations, especially pain.

Connections of the corpus cerebelli in the green sunfish and the common goldfish

Examination of the connections of the corpus cerebelli in one perciform (Lepomis cyanellus) and one cypriniform teleost (Carassius auratus) reveal that ipsilateral afferent connections in both species arise from an anterior group of nuclei in the diencephalon and mesencephalon, and a posterior group of nuclei in the rhombencephalon. Some nuclei of the anterior group and all those of the posterior group have in addition a weaker, and the medial octavolateralis nucleus a stronger, contralateral component. The inferior olivary nucleus in both species projects solely contralaterally. Nucleus paracommissuralis, the ventral accessory optic nucleus and nucleus isthmi are minute in Carassius compared to Lepomis. The latter species has in addition a bilateral corpopetal projection (ipsilaterally stronger) from the lateral cuneate nucleus. Efferent fibers in both species reach the contralateral nucleus ruber, oculomotor nucleus, nucleus of the medial longitudinal fasciculus, torus semicircularis, ventromedial and ventrolateral thalamic nuclei, optic tectum and superior and inferior reticular formation. An additional weaker ipsilateral terminal field could be observed in all nuclei except in the ventrolateral and ventromedial thalamic nuclei, the dorsal periventricular pretectal nucleus and the optic tectum. Lepomis in addition has a bilateral terminal field in the ventral accessory optic nucleus (contralaterally stronger). In both species, stronger ipsilateral and weaker contralateral terminal fields were present in the torus Iongitudinalis and the valvula cerebelli. The two patterns of corpopetal connections in Lepomis and Carassius were used as models for perciforms and cypriniforms in the analysis of the existing information in the literature on teleosts. While most discrepancies in the literature on percomorphs and ostariophysines could be interpreted consistently, the available information on mormyrids revealed a very different pattern of corpopetal organization: presence of additional connections (from a division of the nucleus preglomerulosus) and absence of otherwise well-established corpopetal connections in teleosts. In a second step, a phyletic analysis of teleostean corpopetal organization revealed that while teleosts share with all other vertebrates a group of corpopetal connections from the rhombencephalon, they evolved many new, more anteriorly located afferent inputs to the corpus cerebelli. Furthermore, electroreceptive mormyrids in addition evolved newly at least one corpopetal connection and lost many others.

Chapter 32 Postural compensation in the guinea pig following unilateral labyrinthectomy

Recent behavioural and neural studies of vestibular compensation in guinea pigs are reviewed. Vestibular compensation is not a unitary process in that ocular motor and postural symptoms recover at different rates. Selective section of the horizontal canal nerve alone, rather than total unilateral labyrinthectomy, produces the usual spontaneous nystagmus in light (without roll head tilt or maintained yaw head tilt) which compensates faster than after total unilateral labyrinthectomy. Commissural connections between the guinea-pig vestibular nuclei are not necessary for the compensation of the postural symptoms. Neuronal recordings in compensating animals show a return of resting activity to horizontal canal neurons in the medial vestibular nucleus on the lesioned side which parallels the behavioural recovery. There are permanent neuronal gain changes. It is hypothesized that resting activity returns by virtue of changes in the membrane excitability of neurons in the medial vestibular nucleus, just as it has been demonstrated to occur in deafferented neurons in the lateral cuneate nucleus. Vestibular compensation is probably an unusual and inadequate example of ‘plasticity’ in the central nervous system.

Cerebro-Hepato-Renal (Zellweger) Syndrome

Selective neuronal lipidosis and neuroaxonal dystrophy of the dorsal nucleus of Clarke and lateral cuneate nucleus were the neuropathological findings in 3 males with Zellweger syndrome examined at the Medical Unit S Carolina, Charleston, SC, the John F.

Distribution and possible origin of β-endorphin and ACTH in discrete brainstem nuclei of rats

Immunoreactive ACTH and β-endorphin in the lower brainstem nuclei of intact and brainstem-hemisected rats were quantified by radioimmunoassay. The distribution of these peptides was almost identical throughout the lower brainstem. The concentrations of ACTH and β-endorphin were essentially equal when expressed on a molar basis. Both peptides were distributed unevenly in the lower brainstem. High concentrations were found in the periaqueductal central gray matter and the dorsal raphe nucleus, and moderate levels were present in the locus coeruleus, the parabrachial nuclei, the nucleus raphe magnus and in the nucleus of the solitary tract. β-Endorphin was measurable in all 43 brainstem nuclei investigated; ACTH was non-detectable in the red and lateral cuneate nuclei. Except in certain areas in the medulla oblongata (nucleus of the solitary tract, lateral reticular nucleus, reticular formation) ACTH and β-endorphin declined in brainstem nuclei 10 days after midbrain hemisections. Retrograde accumulation of ACTH and β-endorphin was found in the arcuate nucleus 3 days after midbrain hemisection, which was mainly ipsilateral to the lesion. Data from brainstem-hemisected rats also indicated that ACTH and β-endorphin in the nucleus of the solitary tract are primarily of local origin, whereas the lateral reticular nucleus (A1 and A5 catecholaminergic cell groups) and medullary reticular formation may receive ACTH and β-endorphin innervation from both hypothalamic and medullary neurons.