The connections between the suprachiasmatic, ventrolateral geniculate and raphe nuclei studied by uptake of [14C]2-deoxyglucose

The [14C]2-deoxyglucose method was used to investigate the role of the ventrolateral geniculate and raphe nuclei in the control of the metabolism of the suprachiasmatic nuclei in adult female Wistar rats anaesthetized with alphaxalone. Three to seven days before the [14C]2-deoxyglucose studies a stimulating electrode was implanted or a lesion was made in the ventrolateral geniculate nucleus, or the ascending projection from the raphe nuclei was severed. Stimulation of the ventrolateral geniculate nucleus (biphasic rectangular pulses, 30 s on and 30 s off, 50 Hz, 500 microA pulse amplitude and 1 ms pulse duration) led to a significant increase in the relative metabolic activity of the ipsilateral suprachiasmatic nucleus and a smaller increase in the relative metabolic activity of the contralateral suprachiasmatic nucleus. The stimulus also increased significantly the relative metabolic activities of mainly the ipsilateral hypothalamus, midbrain central gray and reticular formation, all of which are too remote from the ventrolateral geniculate nucleus to be affected by current spread. In animals in which the ventrolateral geniculate nucleus had been lesioned, the relative metabolic activity of the suprachiasmatic nuclei was not significantly different from normal. In animals in which the ascending projection from the raphe nuclei had been severed, there was a slight, though significant increase in the relative metabolic activity of the suprachiasmatic nucleus of one side. These results, together with the effects of stimulating the suprachiasmatic nuclei [R. C. Maxwell and G. Fink, Neuroscience 23, 241-263 (1987)], show that the connections between the ventrolateral geniculate, raphe nuclei and suprachiasmatic nuclei are "metabolically functional", but that the integrity of the ventrolateral geniculate nucleus is not essential for maintaining the relative metabolic activity of the suprachiasmatic nuclei. The raphe nuclei may reduce the relative metabolic activity of the suprachiasmatic nucleus.     

Changes in the Metabolic Activity of Neurons in the Anterior Hypothalamic Nuclei in Rats during Hyperthermia,Fever, and Hypothermia

Histochemical methods were used to detect differently directed changes in the metabolic activity of neurons in the anterior hypothalamic nuclei in rats during hyperthermia, fever, and hypothermia. Hyperthermia induced by high temperatures was associated with increases in the activities of enzymes involved in energy metabolism, with increases in RNA contents in neurons in the supraoptic, paraventricular, and median preoptic nuclei of the anterior hypothalamus of the rat, which is evidence for increases in metabolic activity in the neurons of these nuclei. Endotoxin-induced fever was accompanied by decreases in the metabolic activity of neurons in the median preoptic nucleus, while activity in neurons of the supraoptic and paraventricular nuclei showed no significant change. The development of hypothermia induced by low temperatures was characterized by decreases in the metabolic activity of neurons in the supraoptic, paraventricular, and median preoptic nuclei of the anterior hypothalamus. It is suggested that the differently directed changes in metabolic activity in the neurons of the anterior hypothalamus in hyperthermia, fever, and hypothermia are associated with their roles in the central mechanisms of thermoregulation (median preoptic nucleus) and neurosecretory processes (supraoptic and paraventricular nuclei).     

Long-term suspension culture of isolated hypothalamic nuclei of the rat: morphological differentiation and release of substances influencing corticotropin and growth hormone secretion

Individual hypothalamic nuclei were removed from 17-day-old rat embryos with 300 microns punches and maintained in suspension culture. Suspension culture of isolated nuclei appears to be suitable for studying morphological and functional differentiation of neural tissue and release of bioactivity influencing corticotropin and growth hormone release. During the 4 weeks in culture, neurons and glial cells differentiated well in each nucleus studied. The fine structure of the arcuate, periventricular, ventromedial and dorsomedial nuclei resembled that of the adult nuclei with many mature synapses; in contrast, in the neuropil of cultured preoptic, paraventricular and posterior hypothalamic nuclei mature synapses were very few or absent. The release of substances influencing corticotropin and growth hormone secretion by the cultured nuclei was tested in bioassays using anterior pituitary cell cultures and radioimmunoassay of hormones released into the medium. Corticotropin-releasing bioactivity was tested at weekly intervals. Cultured preoptic and paraventricular nuclei released corticotropin-releasing activity for up to 4 weeks whereas arcuate nuclei released corticotropin-releasing activity at 1 week only. The ventromedial and dorsomedial nuclei did not release corticotropin-releasing activity. The release of substances influencing growth hormone secretion was studied between 3 and 11 days in culture. After 3 days the medium of some hypothalamic nuclei stimulated growth hormone secretion, but after 7 and 11 days all cultured nuclei strongly inhibited it. The present findings demonstrate that hypothalamic nuclei can be cultured separately and suggest that neurons capable of releasing corticotropin-releasing activity(ies) are present in the preoptic and paraventricular nuclei of the rat whereas all hypothalamic nuclei studied contain intrinsic neurons capable of synthesizing and secreting somatostatin-like bioactivity.     

Electron-histochemical and biochemical investigation of the glucose-6-phosphatase andβ-glycerophosphatase activities in nuclei of the normal liver and hepatoma-27 of rats

The presence of glucose-6-phosphatase activity was demonstrated electron-histochemically and biochemically in rat liver cell nuclei, and the histochemical reaction product was localized mainly in the perinuclear space. The activity of this enzyme in hepatoma-27 nuclei was much lower than in nuclei isolated from normal liver. A low level of-glycerophosphatase activity was detected histochemically in liver nuclei incubated at pH 6.4. No activity of this enzyme was found in hepatoma-27 nuclei. Biochemical tests revealed traces of activity in both liver and hepatoma-27 nuclei.Laboratory of Histochemistry and Electron Microscopy, Department of Pathological Anatomy of Human Tumors, Institute of Experimental and Clinical Oncology, Academy of Medical Sciences of the USSR. Laboratory of Biochemistry, Institute of Biology of Development, Academy of Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Kraevskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 78, No. 12, pp. 99–102, December, 1974.     

NO-ergic rat brain commissural neurons in the norm and during opiate administration

Using histochemical reaction demonstrating NADPH-diaphorase (NADPH-d), the dynamics of NO synthesis was studied in the rat brain raphe nuclei following intravenous injection of morphine hydrochloride. In normal conditions NADPH-d activity was demonstrated in neurons of all raphe nuclei. Acute and chronic administration of morphine in different doses (0.5 mg/kg and 5 mg/kg) was found to inhibit NO-ergic activity of the major part of raphe nuclei neurons. The depression of NADPH-d activity was unequal in different nuclei. The NO-ergic changes are caused by an activation of opiate receptors, as they depend on morphine dose, while the application of opiate antagonist naloxone restores the NO-ergic function of raphe neurons. Formation of tolerance to opiate analgetic effect is accompanied by a significant, though short-lasting increase of NO synthesis activity. It is suggested that the changes in NO-ergic function of raphe neurons may influence brain serotonin balance after opiate administration.     

Running wheel activity in hamsters with hypothalamic damage

The amount of wheel running activity by hamsters sustaining damage to the suprachiasmatic nuclei, adjacent hypothalamic areas or lateral geniculate nuclei was examined with numerical and actogram methods. The various hypothalamic lesions reduced activity in a region-specific fashion. Damage to the suprachiasmatic nuclei was associated with the most profound decrease in activity. Reduced daily wheel running was not necessarily correlated with lower activity levels as estimated from the actogram. Some animals with greatly reduced activity had actogram records with apparent increases in activity. The inconsistency between the actogram and numerical analysis was the product of an interaction between changes in running rate and length of activity bouts after lesions. These data indicate a role for the suprachiasmatic region in the regulation of level of activity. The analyses also show that the standard actogram can be a very poor index of changes in activity.     

The structure of the mouse mammary tumor virus: isolation and characterization of the core.

A procedure was developed for preparing cell fractions rich in chloroplasts, nuclei, and pea enation mosaic virus (PEMV)-induced cytopathological structures (vesicles). Those fractions from infected pea plants which contained nuclei or vesicles also contained actinomycin D-insensitive RNA polymerase activity and PEMV-specific hybridizable RNA. The fraction from infected plants containing predominantly chloroplasts had little of this polymerase activity or RNA, as was the case with all fractions from healthy plants. The significance of the polymerase activity in the nuclei and vesicles is discussed, as well as the potential role of the vesicles in the virus infection cycle.     

Nuclear localization of non-specific acid phosphatase(s) activity in rat vaginal epithelium

The nuclear localization of non-specific acid phosphatase(s) in rat vaginal epithelial cells (VEC) by histochemical and biochemical techniques has been reported in the present work. By different histochemical methods, the enzyme activity was predominantly localized in certain nuclei but not in all of them, however, within the nucleus nucleoli are free from the enzyme activity. This enzyme is diffused in the nucleoplasm and perhaps tightly associated with the nuclear proteins. Very little activity was seen in the cytoplasm in the selective population of VEC. After 12 h treatment of estradiol 17beta in vivo the VEC lose the enzyme activity in the basal and intermediate layers, and the activity remains within the nuclei of luminal cells. Enzyme assay in low and high salt extracts of the isolated nuclei of the VEC with or without the enzyme inhibitors indicates that this enzyme may be present in isoforms in the VEC. No activity was observed in these cells at alkaline pH.     

Involvement of serotonin and catecholamine metabolism in cats trained to perform a delayed response task

The effects of the acquisition of a delayed response task on the central catecholamine and serotonin metabolism were investigated in normal, undrugged cats. The training (11 consecutive days) produced an increased serotonin content in the piriform lobe, mesencephalon without the raphe nuclei and medulla without the raphe nuclei, whereas the 5-hydroxyindoleacetic acid level was increased in the piriform lobe and mesencephalon without the raphe nuclei, but decreased in the pons without the raphe nuclei. The noradrenaline content was decreased by the training in the frontal cortex and piriform lobe, whereas the dopamine concentration was increased in the piriform lobe. Tryptophan hydroxylase activity was increased in the piriform lobe, in the mesencephalon without the raphe nuclei and in the raphe nuclei of the mesencephalon, pons and medulla whereas training did not produce any significant effect on the dopamine β-hydroxylase activity.These results indicate the involvement of an active biochemical mechanism fulfilled by the serotoninergic mesolimbic system in association with the noradrenergjc pontocorticolimbic system and the limbic dopaminergic system. They also suggest that these well localized biochemical changes reflect processes involved in the performance criterion of the delayed response task.     

Regional brain variations of cytochrome oxidase activity and motor co-ordination in staggerer mutant mice

A mutant mouse with cerebellar cortical atrophy, staggerer, was examined in tests of motor activity and co-ordination as well as in regional brain metabolism as assessed by cytochrome oxidase activity. Compared with non-ataxic controls, staggerer mutants had inferior performances in the open field, the wooden beam, the wooden edge, and the rotorod tests. An increase in cytochrome oxidase activity in the deep cerebellar nuclei and in some cerebellar efferent regions, such as the lateral vestibular nucleus, the parvicellular red nucleus, and the ventral tegmental area, was found in staggerer mutant mice. Abnormally high cytochrome oxidase activity in the interpositus and the dentate nuclei was linearly correlated with poor performance on the wooden beam and on the rotorod. High cytochrome oxidase activity in the lateral vestibular nucleus was also associated with poor performance on the wooden beam. Moreover, high cytochrome oxidase activity in the fastigial nucleus was associated with poor performance on the wooden beam but with high motor activity in the open field. These results indicate that a lack of innervation of Purkinje cells to the deep cerebellar nuclei is in part the cause of motor co-ordination deficits in staggerer mutant mice.     

The differential response of astrocytes within the vestibular and cochlear nuclei following unilateral labyrinthectomy or vestibular afferent activity blockade by transtympanic tetrodotoxin injection in the rat

In this study, we investigated whether changes in the vestibular neuronal activity per se influence the pattern of astrocytes morphology, glial fibrillary acidic protein (GFAP) expression and ultimately their activation within the vestibular nuclei after unilateral transtympanic tetrodotoxin (TTX) injections and after unilateral inner ear lesion. The rationale was that, theoretically the noninvasive pharmacological functional blockade of peripheral vestibular inputs with TTX, allowed us to dissociate the signals exclusively related to the shutdown of the resting activity of the first-order vestibular neurons and from neuronal signals associated with trans-ganglionic changes in first order vestibular neurons induced by unilateral labyrinthectomy (UL). Since the cochlea was removed during the surgical procedure, we also studied the astrocytic reaction within the deafferented cochlear nuclei. No significant changes in the distribution or relative levels of GFAP mRNA expression, relative levels of GFAP protein or immunoreactivity for GFAP were found in the ipsilateral vestibular nuclei at any post-TTX injection times studied. In addition, no sign of microglia activation was observed. In contrast, a robust increase of the distribution and relative levels of GFAP mRNA expression, protein levels and immunoreactivity was observed in the deafferented vestibular and cochlear nuclei beginning at 1 day after inner ear lesion. GFAP mRNA expression and immunoreactivity in the cochlear nucleus was qualitatively stronger than in the ipsilateral vestibular nuclei. The results suggest that astrocyte activation in the vestibular nuclei is not related to drastic changes of vestibular nuclei neuronal activity per se. Early trans-ganglionic changes due to vestibular nerve dendrites lesion provoked by the mechanical destruction of vestibular receptors, most probably induced the glial reaction. Its functional role in the vestibular compensation process remains to be elucidated.     

Activity of DNA-dependent RNA polymerases A and B in spleen nuclei of mice infected with Rauscher leukemia virus]

The activity of DNA-dependent RNA polymerase A and B in isolated nuclei of spleens of mice infected with Rauscher leukemia virus was studied. A 3-fold increase in the activity of both RNA-polymerases in leukemic spleens was established. Study of the properties of RNA-polymerase B from nuclei of spleens of mice infected with Rauscher virus in comparison with the enzyme from normal tissue revealed the existence of some specific features in the enzyme from leukemic cells. The nature of the increased activity of RNA-polymerase B in leukemic cells is discussed.     

No-Ergic Neurons of the Cervical Nucleus of the Rat Brain in Normal Conditions and After Administration of Opiates

Histochemical reactions for NADPH-diaphorase (NADPH-d) were used to study the dynamics of NO synthesis activity in the cervical nuclei of the rat brain after i.v. administration of morphine hydrochloride. In normal conditions, NADPH-d activity was found in neurons in all the cervical nuclei. Acute and chronic administration of morphine at different doses (0.5 and 5 mg/kg) suppressed the NO-ergic activity of most cervical neurons. Decreases in the level of NADPH-d activity were different in different nuclei. NO-ergic changes were due to activation of opiate receptors, as they were dependent on the dose of morphine used, and treatment with the opiate antagonist naloxone restored the NO-ergic function of cervical neurons. Formation of tolerance to the analgesic effect of opiates was accompanied by significant but short-lived increases in NO synthesis activity. It is suggested that changes in the NO-ergic functions of cervical neurons may affect the balance of serotonin in the brain during opiate treatment.     

Lewy body disease: thalamic cholinergic activity related to dementia and parkinsonism

Within the spectrum of Lewy body disease cognitive impairment occurs in PD with dementia (PDD) and dementia with Lewy bodies (DLB). Although neocortical cholinergic deficits are associated with cognitive impairments in PDD and DLB, no neurochemical study has been published describing the thalamic cholinergic activity whereas the thalamus plays a major role in modulating cortical activity. Choline acetyltransferase (ChAT) activity was analyzed in reticular (Re), mediodorsal (MD) and centromedian (CM) thalamic nuclei in series of nine controls, five DLB with parkinsonism (DLB + P), five DLB without parkinsonism (DLB - P), six PD without dementia and 14 PDD cases. Significant reductions in ChAT were apparent in PDD as follows: in Re and MD nuclei compared with controls; in MD and CM nuclei compared with DLB + P; and in MD compared with PD. Increased ChAT activity was found in CM nuclei in DLB + P compared with DLB - P. These findings show that significant thalamic presynaptic cholinergic deficits occur only in cases of combined cortical and subcortical neurodegeneration in which dementia developed after prolonged parkinsonism.     

Distributions of beta+ decayed nuclei generated in the CH2 and H2O targets by the target nuclear fragment reaction using therapeutic MONO and SOBP proton beam

In proton radiotherapy, the irradiation dose can be concentrated on a tumor. To use this radiotherapy efficiently in the clinical field, it is necessary to evaluate the proton-irradiated area and condition. The proton-irradiated area can be confirmed by coincidence detection of pair annihilation gamma rays from beta+ decayed nuclei generated by target nuclear fragment reaction of irradiated proton nuclei and nuclei in the irradiation target. In this study, we performed experiments of proton irradiation to a polyethylene (PE:CH2) target containing 12C nuclei, which is a major component of the human body, and a gelatinous water (H2O) target containing 16O nuclei at different proton irradiation energy levels under different beam conditions of mono-energetic Bragg peak and spread-out Bragg peak. The distribution of the activity in the target after proton irradiation was measured by a positron emission tomography (PET) apparatus, and compared with the calculated distribution. The temporal dependence of the activity distribution during the period between the completion of proton irradiation and the start of measurement by the PET apparatus was examined. The activity by clinical proton irradiation was 3 kB/cc in the PE target and 13 kB/cc in the water target, indicating that the intensity was sufficient for the evaluation of the distribution. The range of the activity distribution against the physical range was short (several millimeter water equivalent length), indicating the presence of target dependence. The range difference in the water target was slightly large with time dependence until the start of measurement. The difference of the lateral widths with full width half at maximum in the distributions of the measured irradiated dose and activity was within 1 mm.     

Serotonergic control of phrenic motoneuronal activity at the level of the spinal cord of the rabbit

The role of serotonin (5-hydroxytryptamine, 5-HT)-mediated modulation of phrenic motoneuronal activity was evaluated by microapplication of 5-HT and methysergide into the phrenic nuclei of the rabbit. 5-HT facilitated phrenic nerve activity (PNA) considerably resulting in a long-lasting augmentation of the peak amplitude of integrated PNA. In contrast, the blockade of intrinsically active 5-HT by methysergide decreased PNA and led to a strong reduction of the peak amplitude of integrated PNA. MDL 72222 was ineffective. Blockade of 5-HT receptors by preceding administration of methysergide effectively abolished the effects of microinjected 5-HT. Respiratory timing was unaffected by both the agonist and the antagonist. These results suggest that a considerable portion of the facilitatory influence of caudal raphe nuclei on central respiratory activity takes place at the phrenic nuclei level.     

Postnatal development of the basolateral complex of rabbit amygdala: a stereological and histochemical study

The aim of the study was to estimate developmental changes in the rabbit basolateral complex (BLC) by stereological and histochemical methods. Material consisted of 45 brains of New Zealand rabbits (aged from 2 to 180 days, P2 to P180) of both sexes, divided into nine groups. The following parameters were estimated: volume of the cerebral hemisphere; volume of the whole BLC and of particular BLC nuclei; neuronal density and total number of neurons in these nuclei. Developmental changes in acetylcholinesterase (AChE) activity in the BLC were also examined. The volume of the cerebral hemisphere increased until P30, whereas volumes of nuclei increased for longer--until P90. The density of neurons in all nuclei studied reached the level characteristic for an adult animal at about P30. The total number of neurons in the dorsolateral division of the lateral nucleus (Ldl) stabilized the earliest--between P30 and P60, whereas in the ventromedial division of the lateral nucleus (Lvm), basomedial (BM) and basolateral (BL) nuclei the number stabilized later--between P60 and P90. AChE activity appears minimal in the BLC on P2, reaches a maximum on P30 and then decreases to the level characteristic of an adult animal on P60. AChE activity was greater in BL than in other nuclei in all age groups. Reaching adult AChE activity 1 month earlier than the total number of neurons in the BLC may indicate a role of the cholinergic system in BLC maturation.     

Norepinephrinergic afferents and cytology of the macaque monkey midline, mediodorsal, and intralaminar thalamic nuclei

The midline and intralaminar thalamic nuclei (MITN), locus coeruleus (LC) and cingulate cortex contain nociceptive neurons. The MITN that project to cingulate cortex have a prominent innervation by norepinephrinergic axons primarily originating from the LC. The hypothesis explored in this study is that MITN neurons that project to cingulate cortex receive a disproportionately high LC input that may modulate nociceptive afferent flow into the forebrain. Ten cynomolgus monkeys were evaluated for dopamine-beta hydroxylase (DBH) immunohistochemistry, and nuclei with moderate or high DBH activity were analyzed for intermediate neurofilament proteins, calbindin (CB), and calretinin (CR). Sections of all but DBH were thionin counterstained to assure precise localization in the mediodorsal and MITN, and cytoarchitecture was analyzed with neuron-specific nuclear binding protein. Moderate-high levels of DBH-immunoreactive (ir) axons were generally associated with high densities of CB-ir and CR-ir neurons and low levels of neurofilament proteins. The paraventricular, superior centrolateral, limitans and central nuclei had relatively high and evenly distributed DBH, the magnocellular mediodorsal and paracentral nuclei had moderate DBH-ir, and other nuclei had an even and low level of activity. Some nuclei also have heterogeneities in DBH-ir that raised questions of functional segregation. The anterior multiformis part of the mediodorsal nucleus but not middle and caudal levels had high DBH activity. The posterior parafascicular nucleus (Pf) was heterogeneous with the lateral part having little DBH activity, while its medial division had most DBH-ir axons and its multiformis part had only a small number. These findings suggest that the LC may regulate nociceptive processing in the thalamus. The well established role of cingulate cortex in premotor functions and the projections of Pf and other MITN to the limbic striatum suggests a specific role in mediating motor outflow for the LC-innervated nuclei of the MITN.     

Possible neurotransmitters of the dorsal column afferents: effects of dorsal column transection in the cat

We investigated quantitative changes in markers of possible neurotransmitters in the dorsal column nuclei following transection of the dorsal column in the cat. Seven days after unilateral transection of the dorsal column at the upper cervical level, choline acetyltransferase activity and concentrations of glutamate, aspartate, gamma-aminobutyrate and substance P were measured throughout the longitudinal axis of the dorsal column nuclei. In addition, high-affinity uptake of choline, D-aspartate and gamma-aminobutyrate into the synaptosomal fraction of the dorsal column nuclei were also measured. Choline acetyltransferase activity and high-affinity choline uptake were reduced by approx. 30% on the caudal to the obex. Reduction of high-affinity uptake of D-aspartate by approx. 30% was observed on the operated side in the central part of these nuclei, although the decrease in glutamate and aspartate was not significant in the nuclei on the operated side compared with that on the intact side. No significant changes were found in the high-affinity uptake of gamma-aminobutyrate or the contents of gamma-aminobutyrate and substance P in any areas of the dorsal column nuclei. These results suggest that not only glutamate and/or aspartate but also acetylcholine may be neurotransmitter candidates for the ascending fibres terminating in the dorsal column nuclei, whereas there may be few fibres containing substance P or gamma-aminobutyrate in the dorsal column.     

Asymmetries of vestibular dysfunction in major depression

Depression is characterized by alterations in the circadian secretion of hormones, sleep and motor activity, all of which are regulated by suprachiasmatic nuclei (SCN). The vestibular system in the inner ear registers the amount of motor activity. To test the integrity of this motion sensitive system in depression, we studied the vestibulo-ocular reflex (VOR) in depressive patients who were not taking medication and healthy control subjects, which allowed us to investigate each ear and its corresponding nerve centers. Ocular reflex movement depends on vestibular nuclei activity, and we found that at 30 degrees C stimulation the right vestibular system in depressive patients has approximately half the activity of the left side. Significant asymmetry was not detected in control subjects. We also found a significant decrease in the slow phase (16.92+/-9.13 degrees/s) of the reflex in the depressed group as compared with the control group (43.77+/-16.04 degrees/s). The vestibular nuclei of the right and left sides are hypoactive. Specifically, the right vestibular nucleus is hypoactive in depressed people and can easily be measured using VOR. These results support the abnormal asymmetries hypothesis of depression and suggest that these asymmetries also exist at the level of the brain stem or neuronal centers that are afferents to right vestibular nuclei, like SCN or raphe nuclei.