Afferent connections of the dorsal magnocellularis area of the cat red nucleus

Location within the brain of retrogradely labeled neurons putting out projections from the dorsal magnocellularis area of the red nucleus was investigated by means of microiontophoretic injection of horseradish peroxidase into the dorsal magnocellularis area of the cat red nucleus. Projections were found from a number of hypothalamic nuclei, the centrum medianum, parafascicular and subthalamic nuclei, zone incerta, Forel's field, nucleus medialis habenulae, pontine and bulbar reticular formation, and the following midbrain structures: the central gray matter, superior colliculus, Cajal's interstitial nucleus, reticular formation, and the contralateral red nucleus. Projections were also identified proceeding from more caudally located structures: the cerebellar fastigial nucleus, facial nucleus, medial vestibular and dorsal lateral vestibular nuclei, and ventral horns of the spinal cord cervical segments. Connections between the substantia nigra and the red nucleus were clarified. Projections to the red nucleus from the cerebral cortex, interstitial and dentate (lateral) cerebellar nuclei, the nucleus gracilis and cuneate nucleus were found, confirming data presented in the literature. Bilateral trajectories of retrogradely labeled fiber systems are described.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 19, No. 6, pp. 810–816, November–December, 1987.     

Distribution of norepinephrine-containing neurons projecting to the parietal association cortex and spinal cord in the cat locus coeruleus

Distribution of neurons forming projections to the parietal association cortex and spinal cord in the cat locus coeruleus (LC) was investigated by means of horseradish peroxidase retrograde transport and catecholamine histofluorescence techniques. Neurons projecting to the parietal cortex were found to be located mainly dorsally within the LC; largest numbers were observed on frontal plane P-1.0. Cells forming projections to the spinal cord were found in the ventral locus coeruleus; highest numbers of these were noted on frontal plane P-3.0. Labeled neurons were also identified in the midbrain reticular formation, pons, and medulla when applying horseradish peroxidase to the parietal cortex and spinal cord. Neurons projecting to the neocortex and spinal cord make up two different populations in the locus coeruleus, indistinguishable on grounds of neuronal morphological characteristics. It was concluded that the cat parietal association cerebral cortex, in common with the spinal cord, receives direct afferent inputs from the locus coeruleus and the reticular formation.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 1, pp. 112–121, January–February, 1989.     

Afferent connections of cat facial nucleus; a study using retrograde axonal transport of horseradish peroxidase

Neuronal populations in the brainstem and spinal cord — the sources of fiber pathways to the facial nucleus — were investigated in adult cats by microiontophoretically injecting horseradish peroxidase into restricted areas of the facial nucleus. Projections were identified from thenucleus nervi hypoglossi, nucleus praepositus hypoglossi, nucleus raphe pallidus, nucleus intercalatus, medial nucleus of the solitary tract, dorsal motor nucleus of the vagus, neurons of genu of the facial nerve, ipsilateral red nucleus, and reticular formation of the midbrain to the facial nucleus. Projections from a number of other brain structures to the facial nucleus also received confirmation. A topographic map was drawn up, showing how brainstem and spinal cord afferents are distributed in the facial nucleus.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 18, No. 1, pp. 35–45, January–February, 1986.     

Distribution of horseradish peroxidase-labeled neurons giving rise to descending fiber systems in the basal ganglia and hypothalamus in cats

The distribution of neurons giving rise to various descending fiber systems to brain-stem structures in the basal ganglia (including amygdaloid nuclei) and hypothalamus of the cat was studied by the retrograde axonal transport of horseradish peroxidase method. Neurons in the medial part of the central nucleus and of the magnocellular part of the basal nucleus of the amygdaloid group were shown to send axons to the dorsal hippocampus, substantia nigra, lateral part of the central gray matter, and the mesencephalalic reticular formation and also to the region of the locus coeruleus and the lateral medullary reticular formation at the level of the inferior olives. The predominant source of projections to the hypothalamus and brainstem structures is the central amygdaloid nucleus, which also sends projections to the nucleus of the tractus solitarius, the dorsal motor nucleus of the vagus nerve, and the superior cervical segments of the spinal cord. Uncrossed fiber systems descending from the basal ganglia terminate at the level of the pons, whereas uncrossed and crossed fiber systems descending from the dorsal and ventromedial hypothalamus can be traced into the spinal cord. The possible role of nuclei of the amygdaloid group, the hypothalamus, and their efferent projections in the regulation of somatic and vegetative functions and also of complex behavioral reactions is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 13, No. 1, pp. 14–23, January–February, 1981.     

Distribution and quantitative characterization of NADPH-diaphorase-reactive neurons in analgesic zones of the rat midbrain

The distribution of nitric oxide synthase (nicotinamide adenine dinucleotide phosphate diaphorase, NADPH-d)-containing neurons in the rat midbrain was studied. We found that NADPH-d-reactive neurons were predominantly concentrated in the dorsolateral part of the periaqueductal gray (PAG) and the dorsal raphe nucleus, which are implicated in the control of nociceptive transmission. Such neurons were also present in the supraoculomotor cap and laterodorsal tegmental nuclei. In the dorsolateral part ofPAG, the moderately stained small fusiform cells were revealed. In the dorsal raphe nucleus and laterodorsal tegmental nuclei, the densely stained multipolar or oval cells of larger size dominanted. The NADPH-d-reactive cells were not found in the ventrolateral part of central gray, which is considered the main source of antinociceptive descending influences. Quantitative analysis of histochemically revealed neurons showed that their number is somewhat higher in the caudal parts of dorsolateral central gray and considerably higher in the rostral regions of some dorsal raphe subnuclei. This peculiarity was expressed in significant accumulation of the NADPH-d-reactive neurons at the midbrain levels from Fr –7.6 to –8.0. The possible involvement of the NO-synthase-containing class of neurons in the functional organization of analgesic zones and formation ofPAG antinociceptive output signals is discussed.Neirofiziologiya/Neurophysiology, Vol. 28, No. 1, pp. 36–46, January–February, 1996.     

Immunohistochemical mapping of galanin-like neurons in the rat central nervous system

Using an antiserum generated in rabbits against synthetic galanin (GA) and the indirect immunofluorescence method, the distribution of GA-like immunoreactive cell bodies and nerve fibers was studied in the rat central nervous system (CNS) and a detailed stereotaxic atlas of GA-like neurons was prepared. GA-like immunoreactivity was widely distributed in the rat CNS. Appreciable numbers of GA-positive cell bodies were observed in the rostral cingulate and medial prefrontal cortex, the nucleus interstitialis striae terminalis, the caudate, medial preoptic, preoptic periventricular, and preoptic suprachiasmatic nuclei, the medial forebrain bundle, the supraoptic, the hypothalamic periventricular, the paraventricular, the arcuate, dorsomedial, perifornical, thalamic periventricular, anterior dorsal and lateral thalamic nuclei, medial and central amygdaloid nuclei, dorsal and ventral premamillary nuclei, at the base of the hypothalamus, in the central gray matter, the hippocampus, the dorsal and caudoventral raphe nuclei, the interpeduncular nucleus, the locus coeruleus, ventral parabrachial, solitarii and commissuralis nuclei, in the A1, C1 and A4 catechaolamine areas, the posterior area postrema and the trigeminal and dorsal root ganglia. Fibers were generally seen where cell bodies were observed. Very dense fiber bundles were noted in the septohypothalamic tract, the preoptic area, in the hypothalamus, the habenula and the thalamic periventricular nucleus, in the ventral hippocampus, parts of the reticular formation, in the locus coeruleus, the dorsal parabrachial area, the nucleus and tract of the spinal trigeminal area and the substantia gelatinosa, the superficial layers of the spinal cord and the posterior lobe of the pituitary. The localization of the GA-like immunoreactivity in the locus coeruleus suggests a partial coexistence with catecholaminergic neurons as well as a possible involvement of the GA-like peptide in a neuroregulatory role.     

Laminar distribution of sources of ascending spinocerebral fiber systems in the cat spinal cord

The location of labeled neurons that are sources of ascending crossed and uncrossed supraspinal fiber systems was studied in the laminae of gray matter of the spinal cord in 18 cats by the retrograde axonal transport of horseradish peroxidase method. Neurons in the lateral zones of the dorsal horn were shown to make direct, and cells in neighboring regions indirect (through relay nuclei of the dorsal columns) connections with the contralateral thalamus. In the lower segments of the spinal cord sources of crossed spinoreticular and spinothalamic fiber systems are located in the medial regions of the ventral horn and lateral zones of the lateral basilar region. Some large neurons in the motor nuclei were shown to send their axons into the lateral reticular nucleus of the medulla. On the basis of the results a scheme of the laminar organization of sources of ascending fiber systems in the cat spinal cord is constructed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 11, No. 5, pp. 451–459, September–October, 1979.     

Noggin is required for correct guidance of dorsal root ganglion axons

Members of the bone morphogenetic protein family of secreted protein signals have been implicated as axon guidance cues for specific neurons in Caenorhabditis elegans and in mammals. We have examined axonal pathfinding in mice lacking the secreted bone morphogenetic protein antagonist Noggin. We have found defects in projection of several groups of neurons, including the initial ascending projections from the dorsal root ganglia, motor axons innervating the distal forelimb, and cranial nerve VII. The case of the dorsal root ganglion defect is especially interesting: initial projections from the dorsal root ganglion enter the dorsal root entry zone, as normal, but then project directly into the gray matter of the spinal cord, rather than turning rostrally and caudally. Explant experiments suggest that the defect lies within the spinal cord and not the dorsal root ganglion itself. However, exogenous bone morphogenetic proteins are unable to attract or repel these axons, and the spinal cord shows only very subtle alterations in dorsal-ventral pattern in Noggin mutants. We suggest that the defect in projection into the spinal cord is likely the result of bone morphogenetic proteins disrupting the transduction of some unidentified repulsive signal from the spinal cord gray matter.     

Efferent projections of mesencephalic locomotor neurons in the cat

Efferent neuronal projections of the mesencephalic locomotor region were investigated in cats using a horseradish peroxidase retrograde axonal transport technique. It was found that neurons located within the locomotor area form ascending and descending projections to many structures of the spinal cord and the brain but that short-axon connections running to the reticular formation of the midbrain and the medulla predominate. Small numbers of long-axon fibers may merge into the locomotor strips of the medulla and the spinal cord. The locomotor regions of the two halves of the midbrain are interlinked.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 1, pp. 117–125, January–February, 1986.     

Ascending spinal systems in the nurse shark,Ginglymostoma cirratum

Summary The ascending spinal systems in the nurse shark were studied after spinal hemisections by use of the Nauta and Fink-Heimer techniques. The dorsal funicular fibers form a single bundle issuing fibers to the gray substance of the spinal cord, the dorsal funicular nucleus, and the vestibular complex. Some dorsal funicular fibers also appear to contribute to the spinocerebellar tract.The degenerated lateral funicular fibers are segregated into three fasciculi issuing fibers medially as they ascend through the brainstem. The largest target of these fibers is the reticular formation, but diffusely organized axons also reach 1) the gray matter of the spinal cord, 2) the dorsal motor nucleus of the vagus, 3) the nucleus A of the medulla oblongata, 4) the central gray substance of the brainstem, 5) the cerebellar cortex, 6) the cerebellar nucleus, 7) the nucleus intercollicularis, 8) the mesencephalic tectum, and 9) the dorsal thalamus. At the latter site the spinal input appears to partly overlap with the visual input.The results, compared with the strikingly similar findings in other classes of vertebrates, indicate that all vertebrate groups apparently have the same basic components of ascending spinal projections.     

Afferent projections to the mesencephalic locomotor region of the cat brain

Afferent projections to the functionally identified mesencephalic locomotor region were investigated in cats using the horseradish peroxidase retrograde axonal transport technique. Sources of afferent projections to this region were discovered in different structures of the fore-, mid-, and hindbrain. Numbers of horseradish peroxidase-labeled neurons were calculated in different brain structures after injecting this enzyme into the mesencephalic locomotor region. Apart from the endopeduncular nucleus, different hypothalamic structures, and the substantia nigra, labeled neurons were discovered in the central tegmental region, the central gray, raphe and vestibular nuclei, the solitary tract nucleus, and the brain stem reticular formation. Neurons accumulating horseradish peroxidase were also discovered in nuclei where ascending sensory tracts originate. This fact serves to bring out the structural inhomogeneity of the midbrain locomotor region; electrical stimulation of this area is an effect which may be attributed to excitation of neurons found within it and activation of accompanying fiber tracts.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev Translated from Neirofiziologiya, Vol. 18, No. 6, pp. 763–773, November–December, 1986.     

Experimental morphological study of primary afferent terminals at the base of the dorsal horn of the cat spinal cord

The distribution and ultrastructure of primary afferent terminals in the gray matter of the cervical and lumbar regions of the cat spinal cord were studied by the experimental degeneration method of Fink and Heimer. Most preterminals of primary afferents were shown to be concentrated in the region of the intermediate nucleus of Cajal (central part of Rexed's laminae VI–VII), in the substantial gelatinosa (laminae II–III), and in the nucleus proprius of the dorsal horn (central and medial parts of lamina IV). Fewer are found in the region of the motor nuclei. The number of degenerating axon terminals in the lateral parts of laminae IV and V differed: 31.5 and 0.4% respectively of all axon terminals. Many terminals of primary afferents in lamina IV contribute to the formation of glomerular structures in which they exist as terminals of S-type forming axo-axonal connections with other terminals. These results are in agreement with electrophysiological data to show that interneurons in different parts of the base of the dorsal horn differ significantly in the relative numbers of synaptic inputs formed by peripheral afferents and descending systems.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 5, No. 4, pp. 406–414, July–August, 1973.     

Evidence for projections from medullary nuclei onto serotonergic and dopaminergic neurons in the midbrain dorsal raphe nucleus of the rat

Summary The anterograde tracer Phaseolus vulgaris-leucoagglutinin was injected into the medial nucleus of the solitary tract and into the rostral dorsomedial medulla. A sequential two-color immunoperoxidase staining was accomplished in order to demonstrate the co-distribution of presumed terminal axons with chemically distinct neurons in the dorsal raphe nucleus of the midbrain central gray, i.e., B7 serotonergic and A10dc dopaminergic neurons. Black-stained efferent fibers from the medial nucleus of the solitary tract and the rostral dorsomedial medulla intermingled with brown-stained serotonergic (5-hydroxytryptamine-immunoreactive) or dopaminergic (tyrosine hydroxylase-immunoreactive) neurons. Light microscopy revealed that the black-stained efferent axons exhibited numerous en passant and terminal varicosities that were often found in close apposition to brown-stained serotonergic and dopaminergic somata, and to proximal and distal dendrites and dendritic processes. The close association of immunoreactive elements suggests the presence of axo-somatic and axodendritic synaptic contacts of medullary fibers with serotonergic and dopaminergic neurons in the dorsal raphe nucleus. These projections could be involved in the modulation of dorsal raphe neurons, depending on the autonomic status of an animal.     

Efferent connections of the caudate nucleus in cats

Structural and ultrastructural changes in the frontal areas of the cortex and in the region of the globus pallidus were investigated after local and extensive destruction of the caudate nucleus. It was shown by the Fink-Heimer method that after local injury to the caudate nucleus by means of electrodes implanted 2–16 months before electrolytic destruction, only a few degenerating fibers of medium and thin caliber were present. Extensive destruction of the caudate nucleus (without preimplantation of electrodes) was followed by massive degeneration of fibers of different caliber in the frontal area of the cortex. After local injury to the caudate nucleus numerous thin degenerating axons 0.5–0.6 µ in diameter and degenerating terminals were found in the region of the globus pallidus. Degenerative changes in the axo-dendritic and axo-somatic terminals followed the "dark" type of course. It is concluded that no considerable direct projections of neurons of the caudate nucleus are present in the cortex. Degenerating fibers of average caliber in frontal areas of the cortex after destruction of the caudate nucleus are evidently axons of thalamic neurons and not from cells of the damaged nucleus.A. A. Bogomol'ets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 7, No. 2, pp. 165–171, March–April, 1975.     

Preferential Potentiation of the Effects of Serotonin Uptake Inhibitors by 5-HT1A Receptor Antagonists in the Dorsal Raphe Pathway: Role of Somatodendritic Autoreceptors

Abstract: 5-HT_1A autoreceptor antagonists enhance the effects of antidepressants by preventing a negative feedback of serotonin (5-HT) at somatodendritic level. The maximal elevations of extracellular concentration of 5-HT (5-HT_ext) induced by the 5-HT uptake inhibitor paroxetine in forebrain were potentiated by the 5-HT_1A antagonist WAY-100635 (1 mg/kg s.c.) in a regionally dependent manner (striatum > frontal cortex > dorsal hippocampus). Paroxetine (3 mg/kg s.c.) decreased forebrain 5-HT_ext during local blockade of uptake. This reduction was greater in striatum and frontal cortex than in dorsal hippocampus and was counteracted by the local and systemic administration of WAY-100635. The perfusion of 50 µmol/L citalopram in the dorsal or median raphe nucleus reduced 5-HT_ext in frontal cortex or dorsal hippocampus to 40 and 65% of baseline, respectively. The reduction of cortical 5-HT_ext induced by perfusion of citalopram in midbrain raphe was fully reversed by WAY-100635 (1 mg/kg s.c.). Together, these data suggest that dorsal raphe neurons projecting to striatum and frontal cortex are more sensitive to self-inhibition mediated by 5-HT_1A autoreceptors than median raphe neurons projecting to the hippocampus. Therefore, potentiation by 5-HT_1A antagonists occurs preferentially in forebrain areas innervated by serotonergic neurons of the dorsal raphe nucleus.     

Decreased Release of D-Aspartate in the Guinea Pig Spinal Cord After Lesions of the Red Nucleus

This study attempts to determine if fibers that project from the guinea pig red nucleus to the spinal cord use L-glutamate and/or L-aspartate as transmitters. Unilateral injections of kainic acid were placed stereotaxically in the red nucleus to destroy the cells of origin of the rubrospinal tract. Six days after the injection, Nissl-stained sections through the lesion site showed that the majority of neurons in the red nucleus ipsilateral to the kainic acid injection were destroyed. In addition, the lesioned area included parts of the surrounding midbrain reticular formation. Silver-impregnated, transverse sections of the cervical spinal cord revealed the presence of degenerating fibers contralaterally in laminae IV-VII of the gray matter. Ipsilaterally, very sparse degeneration was evident in laminae VII and VIII of the gray matter. Two to six days after surgery, the electrically evoked, Ca2(+)-dependent release of both D-[3H]aspartate, a marker for glutamatergic/aspartatergic neurons, and gamma-amino[14C]-butyric acid ([14C]GABA) was measured in dissected quadrants of the spinal cervical enlargement. Lesions centered on the red nucleus depressed the release of D-[3H]aspartate by 25-45% in dorsal and ventral quadrants of the cervical enlargement contralaterally. The release of [14C]GABA was depressed by 27% in contralateral ventral quadrants. To assess the contribution of rubro- versus reticulospinal fibers to the deficits in amino acid release, unilateral injections of kainic acid were placed stereotaxically in the midbrain reticular formation lateral to the red nucleus. Nissl-stained sections through the midbrain revealed the presence of extensive neuronal loss in the midbrain and rostral pontine reticular formation, whereas neurons in the red nucleus remained undamaged. In the spinal cord, degenerating axons were present ipsilaterally in laminae VII and VIII of the gray matter. Some fiber degeneration was also evident contralaterally in laminae V and VI of the gray matter. This lesion did not affect the release of either D-[3H]aspartate or [14C]GABA in the spinal cord. The substantial decrements in D-[3H]aspartate release following red nucleus lesions suggests that the synaptic endings of rubrospinal fibers mediate the release of D-[3H]aspartate in the spinal cord. Therefore, these fibers may be glutamatergic and/or aspartatergic. Because other evidence suggests that rubrospinal neurons are probably not GABAergic, the depression of [14C]GABA release probably reflects changes in the activity of spinal interneurons following the loss of rubrospinal input.     

Spatial organization of direct connections of the sensomotor cortex with the rhombencephalon and spinal cord in the cat

The distribution and ultrastructure of terminals of corticofugal fibers in the rhombencephalon and spinal cord of the cat were studied by light and electron microscopy at various times (4–6 days) of experimental degeneration after extensive or local (about 3 mm in diameter) destruction of the sensomotor cortex. Definite topographical organization of corticofugal projections in the nuclei of the dorsal columns and in the spinal cord was detected by the Fink — Heimer method. After local destruction of the lateral zones of the sensomotor cortex, maximal foci of degeneration were found in the nucleus of Burdach and the lateral basilar region of the cervical segments; after local destruction of the medial zones of the sensomotor cortex maximal foci of degeneration of corticofugal fibers were observed in Goll's nucleus and the lateral basilar region of the lumbar segments. The results show that even an extremely localized area of the cat sensomotor cortex forms two separate systems of descending corticospinal fibers. The first projects into the dorsolateral and dorsomedial parts of the intermediate zone, chiefly contralaterally, whereas the second projects bilaterally into both dorsolateral and ventromedial parts of the intermediate zone. The possible physiological significance of this duality of projections is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 8, No. 2, pp. 126–133, March–April, 1976.     

Structural characteristics of connections between medial descending systems and spinal neurons

Structural and ultrastructural changes in the medial part of the ventral horn were studied in segments of the cat spinal cord following destruction of the ventral column at the level C₁–C₂. Analysis of results obtained by the Fink — Heimer method showed that degenerating preterminals occur mainly in Rexed's lamina VIII and also in ventromedial zones of lamina VII. Preterminals of descending pathways of the ventral column are also found in the intermediate nucleus of Cajal (central part of lamina VI) and in the ventromedial motor nucleus. Fewer of these preterminals are present in the thoracic and, in particular, in the lumbar segments. Staining by the Holländer — Vaaland method revealed degenerating myelinated axons of small diameter (3–5 µ), evidently collaterals of descending fibers entering the gray matter, in lamina VIII. Degenerative changes in myelinated axons may be manifested either as marked condensation and shrinking or as the appearance of numerous neurofilaments, polymembraneous structures, and cytolysomes. Degeneration also affects axon terminals (axo-dendritic, axo-somatic, and axo-axonal) with spherical or flattened synaptic vesicles. Counting the relative numbers of intact terminals of the various types and their comparison with the corresponding figures for normal animals shows that most connections of descending fibers with spinal neurons are axo-dendritic in character. No degenerating terminals were found on the soma of the "dark" neurons or their processes.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 4, No. 6, pp. 579–586, November–December, 1972.     

Changes in electrical activity of spinal cord neurons in adrenalectomized rats under the effects of corticosteroid hormones

The effects of glucocorticoid (dexamethasone) and mineralocorticoid (deoxycorticosterone) hormones on electrical excitability of nerve cells belonging to the dorsal and ventral horns of the spinal cord induced by stimulating the sciatic nerve, as well as background and evoked activity in single dorsal horn cells were investigated during experiments on adrenalectomized spinal rats using intracellular techniques for recording potential. Both hormones were found to produce mainly facilitatory effects in adrenalectomized animals, manifesting in increased background activity rates in single cells and higher amplitude of field potentials in nerve cells of the dorsal half of the spinal cord. It was shown that neuronal response followed different patterns in the ventral half of the spinal cord gray matter under the action of gluco- and mineralocorticoids: dexamethasone and deoxycorticosterone respectively increased and reduced the amplitude of field potentials in the motoneuronal region. Findings indicate the modulatory influence of adrenal cortical hormones on the electrical activity of spinal cord neurons.Institute of Experimental Biology, Academy of Sciences of the Armenian SSR, Erevan. I. A. Orbeli Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 21, No. 2, pp. 233–238, March–April, 1989.     

Autoradiographic distribution of I-galanin binding sites in the rat central nervous system

Galanin (GAL) binding sites in coronal sections of the rat brain were demonstrated using autoradiographic methods. Scatchard analysis of ¹²⁵I-GAL binding to slide-mounted tissue sections revealed saturable binding to a single class of receptors with a Kd of approximately 0.2 nM. ¹²⁵I-GAL binding sites were demonstrated throughout the rat central nervous system. Dense binding was observed in the following areas: prefrontal cortex, the anterior nuclei of the olfactory bulb, several nuclei of the amygdaloid complex, the dorsal septal area, dorsal bed nucleus of the stria terminalis, the ventral pallidum, the internal medullary laminae of the thalamus, medial pretectal nucleus, nucleus of the medial optic tract, borderline area of the caudal spinal trigeminal nucleus adjacent to the spinal trigeminal tract, the substantia gelatinosa and the superficial layers of the dorsal spinal cord. Moderate binding was observed in the piriform, periamygdaloid, entorhinal, insular cortex and the subiculum, the nucleus accumbens, medial forebrain bundle, anterior hypothalamic, ventromedial, dorsal premamillary, lateral and periventricular thalamic nuclei, the subzona incerta, Forel's field H₁ and H₂, periventricular gray matter, medial and superficial gray strata of the superior colliculus, dorsal parts of the central gray, peripeduncular area, the interpeduncular nucleus, substantia nigra zona compacta, ventral tegmental area, the dorsal and ventral parabrachial and parvocellular reticular nuclei. The preponderance of GAL-binding in somatosensory as well as in limbic areas suggests a possible involvement of GAL in a variety of brain functions.