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R Y Moore

Publications and source records attributed to R Y Moore.

At least 91 records · Page 5Linked to original sources
PubMed1988

Retinohypothalamic projections in the hamster and rat demonstrated using cholera toxin.

The organization of retinohypothalamic tract (RHT) projections in the rat and hamster was studied using anterograde transport of cholera toxin conjugated to HRP (CT-HRP). In both species the major RHT projections lead to the suprachiasmatic nuclei (SCN). This projection begins in the rostral SCN as a loose plexus in the hamster and a a dense aggregation of terminals along the chiasmal border in the rat. Through the remainder of the SCN there is a very dense terminal plexus in the ventral and lateral part of the nucleus with fewer terminals present medially. The RHT projection to the SCN is greater contralaterally in the rat whereas in the hamster the contralateral and ipsilateral projections are approximately equal. In addition to projections to the SCN, the RHT projects to the anterior hypothalamic area, the retrochiasmatic area and lateral hypothalamic area in both species. The anterior hypothalamic projections are more extensive in the hamster than in the rat and extend into the perifornical region, the dorsal hypothalamus and zona incerta. The SCN and anterior hypothalamic projections are continuous with a projection to the retrochiasmatic area and, in the hamster, with a projection extending into the subparaventricular zone with some axons and terminals continuing into the paraventricular nucleus. In contrast to these, the lateral hypothalamic projection in the rat is more extensive than in the hamster. Albino and pigmented rats show identical projections. In addition to the hypothalamic projections, there is in the hamster a small projection along the base of the telencephalon to the anterior amygdaloid area and cortical amygdaloid nucleus and a very sparse projection to the anterior thalamic nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Loss of entrainment and anatomical plasticity after lesions of the hamster retinohypothalamic tract.

The suprachiasmatic nuclei receive photic input information directly through a retinohypothalamic tract (RHT) and indirectly through a projection from the intergeniculate leaflet of the lateral geniculate complex, the geniculohypothalamic tract (GHT). Prior work has established that the RHT is sufficient for entrainment, but has not shown whether it is necessary because it has not been possible to transect that pathway. The present study addresses this problem by employing knife cuts to sever the RHT in male hamsters. Three knife cut procedures were used and one of these succeeded in separating the SCN from the optic chiasm in 8 animals with limited damage to the chiasm and the SCN. The effectiveness of the RHT lesion was confirmed by cholera toxin-HRP histochemistry which demonstrated that the knife cuts eliminate the normal retinal innervation of the SCN while sparing projections to thalamic and tectal visual centers. In a light-dark cycle, the lesioned animals exhibit free-running rhythms indicating that the RHT is necessary for entrainment. A surprising observation is the presence of extensive axonal sprouting of retinal fibers in brains of animals with RHT lesions. The newly-formed axons grow extensively into the SCN, anterior hypothalamus and basal forebrain, but form anomalous axonal plexuses which have no evident function.

Animals↗
PubMed1988

Enkephalin-like immunoreactivity in neurons in the human pineal gland.

Adult human pineal glands were prepared for immunohistochemical analysis using antisera against Leu-enkephalin, neuropeptide Y, dopamine-beta-hydroxylase and vasoactive intestinal polypeptide. The material shows small neurons located in septae and along the capsule of the gland which exhibit enkephalin-like immunoreactivity. The neurons have fairly extensive dendritic arbors and immunoreactive axons are present in the septae and beneath the capsule, particularly in a perivascular location, and occasionally extend into lobules of the gland among parenchymal cells. No consistent immunoreactivity was observed with other antisera but bundles of axons exhibiting dopamine-beta-hydroxylase or neuropeptide Y-like immunoreactivity are observed in some of the material in a perivascular location.

Adult↗
PubMed1988

Neuropeptide Y localization in the rat suprachiasmatic nucleus and periventricular hypothalamus.

Electron microscopic immunocytochemical localization of neuropeptide Y (NPY) was used to examine the morphology and synaptology of afferents in the rat suprachiasmatic nucleus and periventricular hypothalamus. NPY-like immunoreactivity in both areas is restricted to axon terminals which contain lucent, pleomorphic vesicles, occasional dense core vesicles and which establish asymmetric synaptic contacts with distal dendrites and spines. The data demonstrate that NPY-containing axon terminals in these two functionally distinct systems are of identical morphology and exert their effects upon neuronal activity via classical synaptic contacts.

Animals↗
PubMed1988

Development of a fetal circadian rhythm after disruption of the maternal circadian system.

The role of maternal circadian rhythms in the development of the fetal circadian system was investigated in the rat. Pregnant females were subjected to procedures known to disrupt circadian function, ablation of the maternal suprachiasmatic nuclei (SCN) or housing in constant illumination, on gestational day 10. Circadian function was assessed in fetuses at gestational day 22 by analysis of glucose utilization in hypothalamic slices in vitro using the 2-deoxyglucose method. Fetuses from control females exhibit a robust rhythm in glucose utilization in the SCN. In contrast, the SCN of fetuses from females with SCN lesions, or housed in constant illumination, show no significant day-night difference in glucose utilization. Analysis of individual brains indicates, however, that this apparent disruption in the development of circadian rhythmicity in metabolism in the fetal SCN is due to a desynchronization of individual fetuses resulting from the loss of maternal entraining influences. Thus, the fetal SCN is capable of developing a circadian rhythm in glucose utilization independent of the maternal circadian system.

Animals↗
PubMed1988

Electrical and metabolic activity of suprachiasmatic nucleus neurons in hamster hypothalamic slices.

Single unit neuronal activity and glucose utilization were studied in the suprachiasmatic nucleus (SCN) in hypothalamic slices from the golden hamster brain in vitro. An apparent circadian rhythm was observed both in SCN single unit activity and in glucose utilization. These observations indicate that the brain slice method is useful for the analysis of pacemaker function in hamster SCN.

Action Potentials↗
PubMed1988

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.

Activity Cycles↗
PubMed1988

Lateral geniculate lesions block circadian phase-shift responses to a benzodiazepine.

Several pharmacological treatments, including application of an excitatory neurotoxin to the lateral geniculate nucleus (LGN) and systemic administration of triazolam, a clinically effective benzodiazepine, can elicit large phase shifts in a circadian rhythm according to the time of administration. The hypothesis that the LGN might mediate the effect of triazolam on circadian clock function was tested. Bilateral lesions of the LGN, which destroyed the connection from the intergeniculate leaflet to the suprachiasmatic nucleus, blocked phase-shift responses to triazolam. The requirement of an intact LGN for triazolam to shift circadian phase suggests that the LGN may be a site through which stimuli gain access to the circadian clock to modulate rhythm phase and entrainment.

Animals↗
PubMed1988

Effects of melatonin on 2-deoxy-[1-14C]glucose uptake within rat suprachiasmatic nucleus.

Previously, we have demonstrated that metabolic activity, shown by autoradiographic determination of 2-deoxy-[1-14C]glucose (2-DG) uptake, within the rat hypothalamic suprachiasmatic nuclei (SCN) was inhibited by subcutaneous injection of 1 mg/kg melatonin. To determine whether this effect was specific to a particular time of day, the effects of melatonin on 2-DG uptake were studied in several hypothalamic areas, including the SCN, supraoptic nuclei (SON), lateral hypothalamic area (LHA), and anterior hypothalamic area (AHA) every 4 h throughout the circadian day. In a second experiment, the effects of different melatonin doses were studied at the time of day at which melatonin had its maximal effect to determine the dose-response relationship of melatonin-induced inhibition of SCN 2-DG uptake. The data indicate that melatonin inhibited 2-DG uptake in the SCN alone at one time of day, primarily at circadian time (CT) 6 and CT10, 2-6 h before subjective dusk, and secondarily at CT22, just before subjective dawn. This effect was dose dependent with a 50% effective dose of 1.49 +/- 2.30 micrograms/kg. The temporal and dose-response characteristics of these effects are similar to those characterizing the entraining effects of melatonin on circadian patterns of locomotion and drinking.

Animals↗
PubMed1988

Comparative anatomy of the mammalian hypothalamic suprachiasmatic nucleus.

A detailed analysis of the cytoarchitecture, retinohypothalamic tract (RHT) projections, and immunohistochemical localization of major cell and fiber types within the hypothalamic suprachiasmatic nuclei (SCN) was conducted in five mammalian species: two species of opossum, the domestic cat, the guinea pig, and the house mouse. Cytoarchitectural and immunohistochemical studies were conducted in three additional species of marsupial mammals and in the domestic pig. The SCN in this diverse transect of mammalian taxonomy bear striking similarities. First, the SCN are similar in location, lying close to the third ventricle (3V) dorsal to the optic chiasm (OC), with a cytoarchitecture characterized by small, tightly packed neurons. Second, in all groups studied, the SCN receive bilateral retinal input. Third, the SCN contain immunohistochemically similar elements. These similarities suggest that the SCN developed characteristic features early in mammalian phylogeny. Some details of SCN organization vary among the species studied. In marsupials, vasopressin-like immunoreactive (VP-LI) and vasoactive intestinal polypeptide-like immunoreactive (VIP-LI) cells codistribute primarily in the dorsomedial aspects of the SCN, while in eutherians, VP-LI and VIP-LI cells are separated into SCN subnuclei. Furthermore, the marsupial RHT projects to the periventricular dorsomedial region, whereas the eutherian RHT projects more ventrally in the SCN into the zone that typically contains VIP-LI perikarya.

Animals↗
PubMed1987

Noradrenaline and neuropeptide Y innervation of the rat hypothalamus are differentially affected by 6-hydroxydopamine.

The neuropeptide Y (NPY) innervation of the hypothalamus is thought to arise largely from noradrenaline (NA) neurons of the medullary tegmentum in the rat. This view was tested in this study by analyzing the effects of intraventricular injections of 6-hydroxydopamine (6-OHDA) on hypothalamic NA and NPY innervation. 6-OHDA markedly depletes or eliminates the NA innervation of the hypothalamus, as demonstrated by dopamine-beta-hydroxylase immunohistochemistry, but does not affect the NPY innervation of the hypothalamus. These results indicate that the hypothalamic NPY innervation arises in large part from intrinsic NPY-producing neurons rather than from medullary neurons in which NA and NPY coexist.

Animals↗
PubMed1987

Noradrenaline neuron plasticity in developing rat brain: effects of neonatal 6-hydroxydopamine demonstrated by dopamine-beta-hydroxylase immunocytochemistry.

The present study was conducted to assess the morphological changes produced by neonatal administration of 6-hydroxydopamine (6-OHDA) in the noradrenergic innervation of the developing and adult rat brain. As demonstrated by dopamine-beta-hydroxylase (DBH) immunohistochemistry, the major alterations are the following. First, neocortical and hippocampal noradrenergic innervation is permanently eliminated by the treatment, with lesser effects on other telencephalic structures. These changes appear by postnatal day 5 and are permanent in nature. In adult treated animals, most thalamic nuclei are hyperinnervated by DBH-immunoreactive axons as are the cerebellum and a number of brainstem nuclei. The hyperinnervation of these structures occurs after postnatal day 20, and is extremely specific, with the pattern of organization and distribution of noradrenergic axons in treated animals identical to that of controls. In contrast, the noradrenergic innervation of the hypothalamus is relatively unaffected by 6-OHDA treatment. The principal exception is the development of an anomalous plexus of DBH immunoreactive axons in the lateral hypothalamus. The timing and organization of the changes produced by neonatal 6-OHDA administration are consistent with the hypothesis that noradrenergic neurons, and particularly those of the locus coeruleus, are programmed to produce a defined amount of axon and terminal field, with any developmental loss resulting in a 'pruning effect' such that the total terminal field appears conserved. Given the specificity of the hyperinnervation, inductive influences from the target nuclei probably play a major role in determining the pattern of the noradrenergic innervation.

Animals↗
PubMed1987

Retinohypothalamic projection and suprachiasmatic nucleus of the house sparrow, Passer domesticus.

The distribution of retinohypothalamic projections and the organization of the suprachiasmatic region of the hypothalamus was investigated in the house sparrow (Passer domesticus). Retinohypothalamic projections (RHT) were studied by two anterograde tracing methods, and hypothalamic organization was investigated immunohistochemically with antisera against a number of substances known to be present in the mammalian suprachiasmatic nucleus (SCN): bombesin (BBS), glutamic acid decarboxylase (GAD), 5-hydroxytryptamine (5HT), neuropeptide Y (NPY), neurotensin (NT), somatostatin (SS), substance P (SP), vasoactive intestinal polypeptide (VIP), and arginine vasopressin (AVP). Observations from these experiments were analysed within the framework of a cytoarchitectural study using Nissl-stained material. From this study, we have identified an area in the anterior hypothalamus which we believe is an avian homologue of the mammalian SCN. This area contains a nucleus located in close apposition to the optic chiasm between the dorsal supraoptic decussation (DSD) and the ventral lateral geniculate body (GLv) for much of its rostrocaudal extent. The central portion of this nucleus contains neurons that exhibit GAD- and BBS-like immunoreactivity and is the terminal field for the RHT. For this reason, we term this nucleus the visual SCN. It also contains axon plexuses exhibiting 5HT-like, SP-like, and NPY-like immunoreactivity and is bordered ventrally by AVP-like, SP-like, and NT-like immunoreactive cells and medially by VIP-like and SS-like immunoreactive cells. Although it is not established that these cell groups together compose a single suprachiasmatic nucleus, the organization in the avian brain of a nuclear complex with a retinorecipient area surrounded by nonvisual components would be very similar to that of the mammalian SCN.

Animals↗
PubMed1987

Effects of calcium ions on glucose utilization in the rat suprachiasmatic nucleus in vitro.

The role of calcium ions in maintenance of the circadian rhythm in glucose utilization in the suprachiasmatic nucleus (SCN) of the hypothalamus was investigated in vitro in a rat hypothalamic slice preparation using the 2-deoxyglucose (2-DG) method. In normal Krebs solution, 2-DG uptake of adult and embryonic day 22 rat SCN was higher in subjective day than in subjective night. In calcium-free Krebs solution, however, 2-DG uptake of adult and embryonic SCN was low in both subjective day and night periods. These results indicate that the SCN rhythm in metabolic activity is dependent on calcium ions in both adult and embryonic rats. Since immunohistochemical and ultrastructural analysis of synapse formation has shown very few synapses in the SCN of embryonic day 22 rats, it is suggested that the development and maintenance of the circadian rhythm in metabolism demonstrated by the 2-DG method depends on intracellular calcium-mediated events rather than synaptic transmission.

Animals↗
PubMed1987

Melatonin inhibits metabolic activity in the rat suprachiasmatic nuclei.

The pineal hormone melatonin has been implicated in the regulation of circadian rhythms and in photoperiodic control of reproduction. The effects of melatonin require the hypothalamic suprachiasmatic nucleus (SCN), a principal pacemaker controlling circadian rhythms. To determine whether SCN activity was directly affected by exogenous melatonin, rats received either melatonin or saline injections 15 min before administration of 2-deoxy-[1-14C]glucose (2-DG) at two times of day, circadian time (CT) 10 and CT14, and the brains of these rats were processed for autoradiographic determination of 2-DG uptake within the SCN. We report that SCN 2-DG uptake was inhibited by melatonin at CT10, when 2-DG uptake is normally high, and unaffected at CT14, when 2-DG uptake is normally low. This indicates that the SCN may be neural substrates through which melatonin exerts at least some of its effects on mammalian physiology.

Animals↗
PubMed1987

Glutamic acid decarboxylase-like immunoreactivity in brainstem auditory nuclei of the rat.

The distribution of GABA-producing neurons in the brainstem auditory nuclei of the rat was investigated immunohistochemically by using an antibody to glutamic acid decarboxylase (GAD). In the cochlear nuclei, GAD immunoreactive neurons are present only in the superficial granular and molecular layers, whereas terminals are found in all subdivisions of the nuclei and are particularly dense surrounding large spherical cells and one type of stellate cell. In the superior olivary complex, GAD immunoreactive neurons are located in the lateral olivary nucleus and throughout the periolivary region. Immunoreactive terminals are distributed along dendrites of principal cells of the medial and lateral olivary nuclei and are clustered around somata of globular neurons of the nucleus of the trapezoid body. An extremely dense band of immunoreactive somata and terminals is present along the ventral edge of the olivary complex. The ventral, intermediate, and dorsal nuclei of the lateral lemniscus contain small fusiform GAD-immunoreactive neurons and a moderately dense plexus of immunoreactive terminals. The inferior colliculus contains a large population of GAD-immunoreactive perikarya and an extremely dense accumulation of immunoreactive terminals in the central, dorsomedial, and external nuclei. These observations indicate that GABA systems are involved in function at all levels of the brainstem auditory pathway.

Animals↗
PubMed1987

Localization of neuropeptides in efferent terminals of the eye in the marine snail, Bulla gouldiana.

Like several other opisthobranch molluscs, the marine snail Bulla gouldiana possesses two circadian pacemakers, one in each eye. The two ocular pacemakers are mutually coupled such that: the circadian rhythms of spontaneous electrical activity recorded from the optic nerve are normally synchronous and; if experimentally desynchronized the rhythms will return to the synchronized state. This coupling of the pacemakers is mediated by efferent fibers in the optic nerve, terminating in neuropil adjacent to the basal retinal neurons (BRNs), the putative circadian pacemaker cells. Attempts to identify neurotransmitters in efferent terminals that may be involved in the coupling process have failed. In the present study we demonstrate axons in the optic nerve and axon terminals adjacent to the BRNs that exhibit FMRF-amide- (molluscan cardioexcitatory peptide) and NPY-like (neuropeptide-Y) immunoreactivity. The pattern of immunoreactivity to both antisera is identical. Blocking studies indicate that both antisera are recognizing the same site, most likely the arginine-phenylalanine-amide terminus of FMRF, or an FMRF-like molecule. We conclude that FMRF is a candidate for the chemical mediator involved in the interaction between the two ocular pacemakers in Bulla gouldiana.

Animals↗