Assay of 2-Hydroxyputrescine in Various Regions of Rat Brain by Gas Chromatography-Mass Spectrometry

2-Hydroxyputrescine in seven regions of single rat brains was measured with a sensitive, specific assay by gas chromatography-mass spectrometry. The regions were the cerebral cortex, cerebellum, medulla oblongata, hypothalamus, striatum, hippocampus, and midbrain. The level of 2-hydroxyputrescine was very high in the cerebral cortex and cerebellum, high in the medulla oblongata, hypothalamus, and hippocampus, and low in the striatum and midbrain. The level of 2-hydroxyputrescine in the cerebellum was significantly higher than in the striatum and midbrain.     

Crustacean cardioactive peptide-immunoreactive neurons innervating brain neuropils,retrocerebral complex and stomatogastric nervous system of the locust,Locusta migratoria

The distribution and morphology of crustacean cardioactive peptide-immunoreactive neurons in the brain of the locust Locusta migratoria has been determined. Of more than 500 immunoreactive neurons in total, about 380 are interneurons in the optic lobes. These neurons invade several layers of the medulla and distal parts of the lobula. In addition, a small group of neurons projects into the accessory medulla, the lamina, and to several areas in the median protocerebrum. In the midbrain, 12 groups or individual neurons have been reconstructed. Four groups innervate areas of the superior lateral and ventral lateral protocerebrum and the lateral horn. Two cell groups have bilateral arborizations anterior and posterior to the central body or in the superior median protocerebrum. Ramifications in subunits of the central body and in the lateral and the median accessory lobes arise from four additional cell groups. Two local interneurons innervate the antennal lobe. A tritocerebral cell projects contralaterally into the frontal ganglion and appears to give rise to fibers in the recurrent nerve, and in the hypocerebral and ingluvial ganglia. Varicose fibers in the nervi corporis cardiaci III and the corpora cardiaca, and terminals on pharyngeal dilator muscles arise from two subesophageal neurons. Some of the locust neurons closely resemble immunopositive neurons in a beetle and a moth. Our results suggest that the peptide may be (1) a modulatory substance produced by many brain interneurons, and (2) a neurohormone released from subesophageal neurosecretory cells.     

Distribution of immunoreactive mesotocin and vasotocin in the brain and pituitary of chickens

The distribution of vasotocin and mesotocin in the pituitary and central nervous system in male chickens was determined using radioimmunoassays. Neither peptide was detected in the pineal. Mesotocin, but not vasotocin, was detected in the cerebellum. Both peptides were found in the septal area, archistriatum, paleostriatum, optic lobe, anterior, medial and posterior hypothalamus, midbrain, pons, medulla oblongata, and the anterior and posterior pituitary. Equal amounts of the 2 peptides were present in the septal area, archistriatum and anterior hypothalamus whereas vasotocin was more abundant (2- to 10-fold) in the paleostriatum, optic lobe, midbrain, and pituitary. The amount of mesotocin was about twice that of vasotocin in the medulla oblongata and the medial and posterior hypothalamus. The wide distribution of vasotocin and mesotocin in extrahypothalamic sites in the central nervous system suggests that the peptides may, as in mammals, have a role in a variety of autonomic and endocrine regulatory processes in chickens.     

Developmental Changes in the NGF Content in the Brain of Young,Growing, Low-Birth-Weight Rats

The NGF content in each region of the brain of four-week-old rats was ranked in the decreasing order of cerebral cortex, hippocampus, cerebellum, midbrain/diencephalon, and pons/medulla ob-longata, and the NGF concentration, in the decreasing order of hippocampus, cerebral cortex, cerebellum, midbrain/diencephalon, and pons/medulla oblongata in both AFD and SFD groups. The NGF content and concentration in the cerebral cortex were about the same value at each age between those in the AFD and SFD groups. Those in the hippocampus were a little higher in the SFD group than in the AFD group at the ages of three and four weeks, unlike those in the other regions, where the values for the cerebellum, midbrain/diencephalon and pons/medulla oblongata tended to be somewhat higher in the AFD group than in the SFD group. The NGF concentrations in the hippocampus and cerebral cortex increased with growth: the concentration in the hippocampus at four weeks of age was about 4-fold of that at one week in the AFD group and about 5.7-fold of that at one week in the SFD group; and likewise the concentration in the cerebral cortex at four weeks of age was about 5.3-fold in the AFD group and about 7-fold in the SFD group. The NGF concentrations in the cerebellum decreased, and those in midbrain/diencephalon and pons/medulla oblongata hardly changed with growth in either AFD or SFD group. From these results NGF may have stronger implications for the neuronal growth in the hippocampus compared with those in the lower brain regions of the SFD rats.     

Comparative anatomy of pigment-dispersing hormone-immunoreactive neurons in the brain of orthopteroid insects

Summary In a comparative study, the anatomy of neurons immunoreactive with an antiserum against the crustacean -pigment-dispersing hormone was investigated in the brain of several orthopteroid insects including locusts, crickets, a cockroach, and a phasmid. In all species studied, three groups of neurons with somata in the optic lobes show pigment-dispersing hormone-like immunoreactivity. Additionally, in most species, the tritocerebrum exhibits weak immunoreactive staining originating from ascending fibers, tritocerebral cells, or neurons in the inferior protocerebrum. Two of the three cell groups in the optic lobe have somata at the dorsal and ventral posterior edge of the lamina. These neurons have dense ramifications in the lamina with processes extending into the first optic chiasma and into distal layers of the medulla. Pigment-dispersing hormone-immunoreactive neurons of the third group have somata near the anterior proximal margin of the medulla. These neurons were reconstructed in Schistocerca gregaria, Locusta migratoria, Teleogryllus commodus, Periplaneta americana, and Extatosoma tiaratum. The neurons have wide and divergent arborizations in the medulla, in the lamina, and in several regions of the midbrain, including the superior and inferior lateral protocerebrum and areas between the pedunculi and -lobes of the mushroom bodies. Species-specific differences were found in this third cell group with regard to the number of immunoreactive cells, midbrain arborizations, and contralateral projections, which are especially prominent in the cockroach and virtually absent in crickets. The unusual branching patterns and the special neurochemical phenotype suggest a particular physiological role of these neurons. Their possible function as circadian pacemakers is discussed.     

Tangential medulla neurons in the mothManduca sexta. Structure and responses to optomotor stimuli

InManduca sexta, large tangential cells connect the medulla via the lobula valley (LoV) tract to the midbrain and the contralateral medulla. Tract neurons have been stained and recorded to determine their responses to optomotor stimulation. Neurons in the LoV-tract comprise a physiologically and anatomically heterogeneous population:

1. Motion insensitive medulla tangential (Mt) neurons arise from cell bodies in the ventral rind. Heterolateral cells arborize massively in both medullae and one or both halves of the midbrain. Mt-neurons respond to changes in light intensity. Physiological and anatomical evidence argues for their monocularity and transmission from the medulla on the side of the soma to the central brain and the contralateral medulla.
2. Motion sensitive neurons with cell bodies behind the protocerebral bridge connect the midbrain to the ipsior contralateral medulla. Direction-selective responses are characterized by excitation to motion in the preferred and inhibition in the opposite direction with maxima either in a horizontal or vertical direction. Peak values appear at contrast frequencies of appr. 3/s. The results suggest that these neurons are binocular and relay information from the midbrain to the medulla. They have been labelled as centrifugal medulla tangential (cMt) neurons.

The possible roles for tract neurons in visually guided behaviour are discussed.     

Time coding in the midbrain of mormyrid electric fish. I. Physiology and anatomy of cells in the nucleus exterolateralis pars anterior

In mormyrid electric fish, species-specific electric organ discharge waveforms are thought to be analyzed by the Knollenorgan electroreceptor subsystem. The midbrain anterior and posterior exterolateral nuclei (ELa and ELp) are thought to be the sites of this analysis. This paper is an electrophysiological study of the properties of the neurons in ELa. We recorded intracellularly from three classes of cells within ELa: the afferent axons from the nucleus of the electrosensory lateral line lobe (NELL), the large interstitial cells of ELa and an unidentified cell type. The large cells and the NELL axons were identified by intracellular injection of biocytin and are physiologically similar. Cells in ELa responded to square pulse stimuli with one or more time-locked action potentials with 2.8–3.0 ms latency. Both large cells and NELL axons arborized extensively in ELa and contacted numerous small cells. Based on the pattern of arborizations, we constructed a counter- current flow model of temporal coding by the small cells of ELa. We postulate that individual small cells are not selectively tuned for specific stimulus durations, but rather, the firing patterns of groups of small cells must be analyzed by neurons further up in the sensory hierarchy to determine the stimulus duration. Accepted: 25 June 1997     

Electrophysiological investigation of medullary neurons connected with lateral line organs of the catfish (Ictalurus nebulosus)

Unit responses in the acoustic-lateral region of the medulla to electrical and mechanical stimulation of the lateral line organs were investigated in acute experiments on curarized catfish. Of the total number of neurons 70% possessed spontaneous activity. An electrical stimulus evoked a tonic response both in spontaneously active and in "silent" cells. Three main types of firing pattern of the neurons were distinguished: fast-adapting, slow-adapting, and grouped. As regards the relation of the neurons to polarity of the stimulus they were subdivided into two groups. The thresholds of unit responses to electrical stimulation varied considerably: from 2.5·10^–9 to 5·10^–12 A/mm². The effect of intensity of the electrical stimulation on unit responses in the medulla is analyzed. The precise dependence of on- and off-responses of each neuron on stimulus intensity of any polarity was determined. The neurons were shown to be sensitive to both electrical and mechanical stimuli. It is postulated that this phenomenon is due to convergence of impulses from electrical and mechanical receptors of the lateral line on the neurons. The properties of the central neurons are compared with those of the peripheral electroreceptor system in catfish.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 5, No. 2, pp. 156–163, March–April, 1973.     

Coping with flow: behavior, neurophysiology and modeling of the fish lateral line system

With the mechanosensory lateral line fish perceive water motions relative to their body surface and local pressure gradients. The lateral line plays an important role in many fish behaviors including the detection and localization of dipole sources and the tracking of prey fish. The sensory units of the lateral line are the neuromasts which are distributed across the surface of the animal. Water motions are received and transduced into neuronal signals by the neuromasts. These signals are conveyed by afferent nerve fibers to the fish brain and processed by lateral line neurons in parts of the brainstem, cerebellum, midbrain, and forebrain. In the cerebellum, midbrain, and forebrain, lateral line information is integrated with sensory information from other modalities. The present review introduces the peripheral morphology of the lateral line, and describes our understanding of lateral line physiology and behavior. It focuses on recent studies that have investigated: how fish behave in unsteady flow; what kind of sensory information is provided by flow; and how fish use and process this information. Finally, it reports new theoretical and biomimetic approaches to understand lateral line function.     

Pigment-dispersing hormone (PDH)-immunoreactive neurons form a direct coupling pathway between the bilaterally symmetric circadian pacemakers of the cockroach Leucophaea maderae

Circadian locomotor activity rhythms of the cockroach Leucophaea maderae are driven by two bilaterally paired and mutually coupled pacemakers that reside in the optic lobes of the brain. Transplantation studies have shown that this circadian pacemaker is located in the accessory medulla (AMe), a small neuropil of the medulla of the optic lobe. The AMe is densely innervated by about 12 anterior pigment-dispersing-hormone-immunoreactive (PDH-ir) medulla (PDHMe) neurons. PDH-ir neurons are circadian pacemaker candidates in the fruitfly and cockroach. A subpopulation of these neurons also appears to connect both optic lobes and may constitute at least one of the circadian coupling pathways. To determine whether PDHMe neurons directly connect both accessory medullae, we injected rhodamine-labeled dextran as neuronal tracer into one AMe and performed PDH immunocytochemistry. Double-labeled fibers in the anterior, shell, and internodular neuropil of the AMe contralaterally to the injection site showed that PDH-ir fibers directly connect both accessory medullae. This connection is formed by three anterior PDHMe neurons of each optic lobe, which, thus, fulfill morphological criteria for a direct circadian coupling pathway. Our double-label studies also showed that all except one of the midbrain projection areas of anterior PDHMe neurons were innervated ipsilaterally and contralaterally. Thus, anterior PDHMe neurons seem to play multiple roles in generating circadian rhythms. They also deliver timing information output and perform mutual pacemaker coupling in L. maderae. This work was supported by the Deutsche Forschungsgemeinschaft (DFG) grants STE 531/7-1, 2, 3, and Human Science Frontier     

Homocarnosinase activity in the rat brain areas kidneys under different states of hyperbarooxygenation

The homocarnosinase activity in different brain areas and kidneys of the normal rats and under different conditions of hyperbarooxygenation are determined. The highest activity of this enzyme is observed in cerebellum. The high homocarnosinase activity is typical of kidneys as well. The action of oxygen in a dose of 0.425 MPa for 60 min (in the absence of convulsions) increases the homocarnosinase activity in the cerebral hemispheres by 18.6%, in the midbrain by 18.6%, in midbrain and diencephalon--by 56.5%, and in the medulla oblongata--by 40.6%. The homocarnosinase activity in the cerebellum decreases by 16.7%, in kidneys--by 18.5%. At the convulsive stage of oxygen intoxication caused by the effect of 0.7 MPa dose of oxygen the homocarnosinase activity in cerebral hemispheres rises by 158.5%, in the midbrain and diencephalon--by 141.5%, in the medulla oblongata by--161.1%. Under the same conditions homocarnosinase activity in the cerebellum is unchanged as compared with the control.     

STEARYL COENZYME A DESATURASE ACTIVITIES IN RAT BRAIN MICROSOMES

—A quantitative assay for the rat brain microsomal stearyl CoA desaturase is described. The method was used to determine the developmental pattern and regional distribution of the desaturase in rat brain. Even though the specific activity of the enzyme decreased to one-third from 8 to 60 days of age, the total activity per brain remained the same. The regional distribution of the activity in adult brain was of the order midbrain > medulla oblongata > cerebral hemispheres > cerebellum, with midbrain activity being about twice as that of the cerebellum.     

Endocrine cells share expression of N-CAM with neurones

The expression of the neural cell adhesion molecule, N-CAM, was examined in the anterior lobe of rat hypophysis by immunocytochemistry at light and electron microscope levels. In addition, N-CAM antigenic determinants present in adrenal medulla, anterior hypophysis and PC12 cells were compared by immunoblotting with those found in cerebellum. All secretory cells in the anterior hypophysis were found to be N-CAM positive on their surfaces, but not all of the three polypeptide determinants typical of cerebellum were present in the endocrine tissues or cell line tested. In addition, a new N-CAM determinant of 49 kDa not present in cerebellum was found in adrenal medulla and hypophysis, although it was absent from PC12 cells. The possible implications of these data are discussed.     

End buds: non-ampullary electroreceptors in adult lampreys

Summary Shared anatomical and physiological characters indicate that the low-frequency sensitive electrosensory system of lampreys is homologous with those of non-teleost fishes and amphibians. However, the ampullary electroreceptor organs which characterize all of these gnathostomes are not found in lampreys. Experimental anatomical and physiological studies reported here demonstrate that the epidermal end buds are the electroreceptors of adult lampreys.End buds, consisting of both sensory and supporting cells, are goblet-shaped with the top (25–60 m diameter) at the epidermal surface and the stem directed toward the dermis (Fig. 1A). Short lines or clusters of 2–8 end buds (Fig. 1B) are distributed over both trunk and head. Injections of horseradish peroxidase (HRP) into vitally-stained end buds labeled anterior lateral line afferents terminating in the ipsilateral dorsal nucleus (Fig. 2A) — the primary electrosensory nucleus of the lamprey medulla. Conversely, after HRP injection into the dorsal nucleus HRP-filled fibers and terminals were present on ipsilateral end buds (Fig. 2B).End buds are usually not visible without staining. However, in adult sea lampreys the presence of end buds was histologically confirmed in skin patches containing the receptive fields of electroreceptor fibers recorded in the anterior lateral line nerve. Additionally, in the rare instance of two silver lampreys in which end buds were visible without staining, electrosensory activity indistinguishable from that of the primary electroreceptor afferents was recorded from the end bud surface (Figs. 3, 4).End buds were initially characterized as chemoreceptors (Johnston 1902) but were later correctly advanced as lateralis receptors based on the presence of presynaptic dense bodies in the receptor cells (Whitear and Lane 1981). Unlike all other low-frequency electroreceptors, end buds lack canals. The receptor cells contact the epidermal surface and possess apical microvilli rather than the kinocilium of most gnathostomes with homologous electrosensory systems of the primitive (non-teleost) type.Larval lampreys and newly transformed adults lack end buds although at least the latter are electroreceptive. End buds, therefore, may be the form taken by electroreceptors only in the final portion of a lamprey's life.     

Cerebral blood flow in the fetal guinea-pig

To measure brain blood flow in the fetal guinea-pig, radioactive microspheres were injected in the lateral saphenous vein whilst a reference sample of blood was withdrawn from the right axillary artery. Measurements were made near term of pregnancy, on the 60th-66th day, during anaesthesia with pentobarbitone and diazepam. Fetal blood pressure was 4.25 +/- 0.12 kPa and fetal heart rate was 250 +/- 7 beats per min. The arterial oxygen content varied between 1.9-5.1 mmol 1(-1). Blood flow to the whole brain (mean 1.13 +/- 0.14 ml min-1 g-1) was significantly correlated to the reciprocal of arterial oxygen content (r = 0.84). Four regions of the brain were examined: the cerebral hemispheres, the cerebellum, the thalamus and midbrain, and the pons and medulla. In each region blood flow was inversely related to arterial oxygen content (r = 0.80-0.83) but the rate of perfusion of the brain stem was greater than that of the cerebral hemispheres or cerebellum.     

The contribution of mast cells to the histamine content of the central nervous system: A regional analysis

W/W^V mice are severely deficient in mast cells. The absence of mast cells in skin and salivary glands was found to be paralleled by a drastic decrease of the histamine levels in these tissues when compared to non-anemic +/+ control mice. Brains of W/W^V mice are also devoid of mast cells. A comparison of the histamine concentrations in several brain regions of W/W^V mice and controls revealed a moderate decrease in cerebral cortex, thalamus, hypothalamus and midbrain but no change in pons, medulla and cerebellum. These findings provide strong evidence that mast cells contribute to the histamine content in forebrain regions but not in hindbrain regions. It is speculated that there may exist histaminergic neurons intrinsic to the medulla and pons.     

Innervation of the superficial pineal of the rat using retrograde tracing methods

Fast blue (FB), rhodamine microspheres (RH), horseradish peroxidase (HRP), and wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) were used as retrograde tracers to study the innervation of the rat superficial pineal gland (SP). One of the tracers was injected into the gland of each animal. All four retrograde tracers injected into the gland always labeled neurons in the superior cervical ganglia (SCG). No retrograde labeling was ever seen in the suprachiasmatic nuclei, paraventricular hypothalamic nuclei, lateral hypothalamus, habenular nuclei, amygdalar nuclei, or superior salivatory nuclei. Retrograde labeling was seen in the anterior hypothalamic nuclei, anterior thalamic nuclei, lateral geniculate bodies, and midbrain tectal structures when a tracer spread from the injection site to the overlying cortex, tectum, or commissures. Control studies included injection of tracer into the subarachnoid space around the SP or into structures adjacent to the SP. Only the injection of FB or WGA-HRP into the subarachnoid space labeled neurons in the SCG. This labeling was probably due to the spread of tracer to the choroid plexus. These results agree with recent work confirming the existence of a direct projection of the SCG into the interstitium around pinealocytes. The evidence does not substantiate an innervation originating in the habenular nuclei; the superior salivatory nuclei; or any other diencephalic, midbrain, pontine, or medullary structure.     

Regional Distribution of Kininase in Rat Brain

Kininase activity, which inactivates kinins, was measured in seven regions of the rat brain (i.e., the cerebral cortex, cerebellum, striatum, midbrain, hippocampus, hypothalamus, medulla oblongata), and in the spinal cord with a bioassay method using bradykinin as the substrate. Specific kininase activities in the cerebellum and striatum were higher than those in the other five regions or the spinal cord. Angiotensin-converting enzyme activity, which was measured fluorometrically using Hip-His-Leu as substrate, showed high activity in the striatum and cerebellum. These findings suggest that the presence of high concentrations of peptidases plays a role in the degradation of kinins and/or other peptides in these areas.     

延髓头端腹外侧区神经元电活动与心血管活动相干性的研究

本文分析了大鼠延头端腹外侧区（ＲＶＬＭ）神经元单位活动与心血管活动的相干性,观察了ＲＶＬＭ区神经元电 对电刺激中脑防御反应区的诱发反应,以及对压力感受性反射的反应,并用ＦＦＴ对ＲＶＬＭ区神经元自发单位放电和血压波进行频域的相干性分析,以判断是具有心节律。还分析了ＲＶＬＭ区单位放电变异性与心率变异性的相干性。结果显示：ＲＶＬＭ区大多数神经元对电刺激中脑防御反应区呈兴奋反应（６７％）,７０％神经元放电     

Thalamic center for the lateral line system in the catfish Ictalurus nebulosus: Evoked potential evidence

By means of evoked potential methods, a lateral line center in the thalamus of the bullhead catfish is here identified. The locus of this lateral line center corresponds to the mechanoreceptive thalamic zone and/or torothalamic tract identified by anatomical means. The thalamic lateral line area responds to acoustic stimuli as well as lateral line nerve shock but fails to respond to electroreceptor inputs that do cause responses in their special part of the midbrain torus semicircularis. The latency of the first peak of response to lateral line nerve shock, which is also the main response peak, is 30 ms for the thalamic zone compared to 15 ms for the earliest peak response in the mechanoreceptive part of the torus semicircularis. The thalamic response fatigues much more quickly than the toral response and has different dynamic properties to closely spaced stimulus pairs as well.