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R Y Moore

Publications and source records attributed to R Y Moore.

At least 73 records · Page 4Linked to original sources
PubMed1991

Two alpha-herpesvirus strains are transported differentially in the rodent visual system.

Uptake and transneuronal passage of wild-type and attenuated strains of a swine alpha-herpesvirus (pseudorabies [PRV]) were examined in rat visual projections. Both strains of virus infected subpopulations of retinal ganglion cells and passed transneuronally to infect retino-recipient neurons in the forebrain. However, the location of infected forebrain neurons varied with the strain of virus. Intravitreal injection of wild-type virus produced two temporally separated waves of infection that eventually reached all known retino-recipient regions of the central neuraxis. By contrast, the attenuated strain of PRV selectively infected a functionally distinct subset of retinal ganglion cells with restricted central projections. The data indicate that projection-specific groups of ganglion cells are differentially susceptible to the two strains of virus and suggest that this sensitivity may be receptor mediated.

Animals↗
PubMed1990

GABAA/benzodiazepine receptor localization in the circadian timing system.

gamma-Aminobutyric acid (GABA) and exogenous benzodiazepines are thought to play a role in the neural regulation of circadian rhythms. Because binding sites for the benzodiazepines and GABAA ligands are functionally coupled as part of the GABAA/benzodiazepine receptor complex (GABAA/BZR), we analyzed the localization of GABA neurons and GABAA/BZR within 3 nuclei involved in circadian rhythm regulation using autoradiographic and immunohistochemical techniques. Glutamic acid decarboxylase-immunoreactive axons are present in the suprachiasmatic nuclei (SCN), intergeniculate leaflet (IGL), and dorsal raphe nucleus (DR). Immunoreactivity for the GABAA/BZ receptor complex is absent from the SCN and the IGL whereas the DR shows a dense, uniform immunoreactivity. Semiquantitative analysis of autoradiograms for [3H]diazepam and [3H]flunitrazepam binding reveals a moderate level of binding in the SCN, a low level of binding in the IGL, and the highest level of the DR. Based on both the pattern of benzodiazepine binding and of receptor immunoreactivity the DR would appear to be a likely target site for GABAA and benzodiazepine action. The SCN would also appear to be a possible target site. The results suggest the IGL is not a site for direct GABAA and benzodiazepine action, but do not exclude a role for the IGL in the neural circuitry mediating GABA and benzodiazepine interactions with the circadian system.

Animals↗
PubMed1990

Destruction of the hamster serotonergic system by 5,7-DHT: effects on circadian rhythm phase, entrainment and response to triazolam.

The role of the serotonergic system in the regulation of hamster circadian rhythms was analyzed using intraventricular injection of the selective neurotoxin, 5,7-dihydroxytryptamine (5,7-DHT). Sixty days after 5,7-DHT administration, immunoreactive serotonin in the forebrain, particularly the suprachiasmatic nuclei and intergeniculate leaflets, was severely depleted in 16 animals, moderately depleted in four and only slightly affected in four. 5,7-DHT produced an immediate and sustained advance of the onset of running wheel activity relative to the 24 h light-dark (LD) cycle. Activity onset occurred 0.7 +/- 0.07 h before lights out among 5,7-DHT-treated animals compared with 0.18 +/- 0.04 h after lights out for vehicle-infused controls. This new, advanced phase angle of entrainment was maintained throughout the 60-day period of the study while the animals remained in a LD cycle, including after an 8-h phase advance of the light cycle. 5,7-DHT treatment also delayed the offset of wheelrunning in 16 of 24 animals and reduced the likelihood of a smooth pattern of reentrainment to the shifted LD cycle. The drug treatment did not affect circadian period in constant darkness, the rate of reentrainment to an 8-h phase advance or the amount of wheelrunning activity per day. In addition, 5,7-DHT treatment had no effect on the ability of triazolam, a short-acting benzodiazepine, to accelerate the rate of reentrainment to an 8-h phase advance. These observations show that ascending projections of midbrain raphe serotonin neurons participate in the regulation of the circadian activity phase but are not required for triazolam-induced acceleration of reentrainment to a phase-advanced LD cycle.

5,7-Dihydroxytryptamine↗
PubMed1990

Neuropeptide Y localization in telencephalic and diencephalic structures of the ground squirrel brain.

The distribution of neuropeptide Y-immunoreactive (NPY-IR) perikarya, fibers, and terminals was investigated in the brain of two species of hibernatory ground squirrels, Spermophilus tridecemlineatus and S. richardsonii, by means of immunohistochemistry. In the telencephalic and diencephalic structures studied, distinct patterns of NPY-IR were observed which were essentially identical in male and female animals of both species. No differences in amount or distribution of NPY-IR structures were observed between animals which had been in induced hibernation for several months before sacrifice in March/April and those sacrificed one week after their capture in May. In some brain structures (e.g., the hypothalamic arcuate nucleus), IR cell bodies were observed only after pretreatment with colchicine. NPY-IR perikarya and fibers were found in the cerebral cortex, caudate nucleus-putamen, and dorsal part of the lateral septal nucleus. Dense fiber plexuses were seen in the lateral and medial parts of the bed nucleus of the stria terminalis. The numbers of IR perikarya observed in the medial part of the nucleus increased following intraventricular colchicine injections. The accumbens nucleus exhibited few IR cells and many fibers. Claustrum and endopiriform nuclei showed a considerable number of stained cells and fibers that increased in number and staining intensity in colchicine-treated ground squirrels. The induseum griseum showed a small band of IR cell bodies and varicose fibers. Bipolar of multipolar IR cells and varicose fibers were found in the basal nucleus of the amygdala. Dense fiber plexuses as well as IR terminals were seen in the median, medial, and lateral preoptic areas of the hypothalamus. Terminals and relatively few fibers were located in the periventricular, paraventricular, and supraoptic nuclei. The anterior, lateral, dorsomedial, and ventromedial hypothalamic nuclei contained relatively large numbers of terminals and fibers. In the suprachiasmatic nuclei, dense terminals were distributed mainly in the ventromedial subdivision. In the median eminence, immunoreactive terminals were concentrated in the external layer, with fibers predominant in the internal layer. NPY-IR perikarya were observed only in the arcuate nucleus of the hypothalamus and only following colchicine treatment. In the epithalamus (superficial part of the pineal gland and habenular nuclei), varicose fibers appeared mainly in perivascular locations (pineal) or as a dense plexus (habenular nuclei). These results from ground squirrels are discussed in comparison to those obtained in other species and with regard to considerations of the physiological role of NPY.

Animals↗
PubMed1989

Organization of lateral geniculate-hypothalamic connections in the rat.

The location and chemical identity of neurons interconnecting the lateral geniculate complex and the hypothalamus were analyzed in order to provide further information on the anatomical substrates for the entrainment of circadian rhythms. A particular objective of the study was to characterize the neurons projecting between the intergeniculate leaflet (IGL) of the lateral geniculate complex and the suprachiasmatic nucleus (SCN) and related anterior hypothalamic areas. The connectivity experiments employed five combinations of fluorescent tracer injection and were combined with immunohistochemical localization of either neuropeptide Y (NPY), met-enkephalin (mENK) or the vasoactive intestinal polypeptide (VIP)/peptide histidine isoleucine (PHI) group. IGL efferents. Injection of tracer into the SCN results in retrograde labeling of NPY-immunoreactive neurons in the IGL as would be expected from prior work. These neurons and their terminals also contain the C-flanking peptide of the NPY precursor molecule (CPON). In addition, there are two additional groups of neurons in the IGL that project either to the SCN or the contralateral IGL but do not exhibit NPY immunoreactivity. These include a substantial population of cells that project to the SCN and an even larger group of neurons which project to the contralateral IGL and contain mENK immunoreactivity. Hypothalamic efferents. Injection of tracer into the IGL results in retrograde labeling of scattered neurons throughout the SCN and immediately adjacent anterior hypothalamus ipsilaterally and also in labeling of a small number of neurons in the same areas on the contralateral side of the brain. In rare instances, individual SCN neurons appear to project to both IGLs. However, the retrochiasmatic area (RCA) contains the largest number of retrogradely labeled neurons following tracer injections into the IGL. These neurons are concentrated along the midsagittal plane and in the lateral RCA ipsilateral to the injected IGL. None of the labeled neurons in the SCN or adjacent anterior hypothalamus exhibit VIP or PHI immunoreactivity. These observations indicate that the anatomical relations between the geniculate complex and the anterior hypothalamus are more complex than previously shown. First, the geniculohypothalamic tract arises from two distinct groups of IGL neurons: one contains NPY/CPON immunoreactivity; the chemical content of the other is not characterized at the present time. Second, the commissural projection between the two IGLs is formed by a third group of neurons, and these cells contain mENK immunoreactivity. Finally, reciprocal projections from the hypothalamus to the IGL arise from neurons in the retrochiasmatic area, SCN, and adjacent anterior hypothalamus.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

The geniculohypothalamic tract in monkey and man.

The intergeniculate leaflet (IGL) of the lateral geniculate complex in rodents contains neuropeptide Y-immunoreactive (NPY-IR) neurons which project to the suprachiasmatic nucleus (SCN) of the hypothalamus. In the macaque monkey and human brain, a large portion of the pregeniculate nucleus contains NPY-IR neurons indicating that this is the primate homologue of the rodent IGL. The monkey SCN has a dense plexus of NPY-IR axons identical in location and appearance to that in rodents. As in other mammals, no NPY-IR neurons are found in the monkey SCN. In contrast, in the human SCN, the NPY-IR plexus is less dense than in the monkey and there are numerous NPY-IR neurons. This suggests that the human SCN differs in organization from that of other mammals and that the functional homologue of the mammalian geniculohypothalamic tract is local circuit NPY+ neurons within the nucleus.

Adolescent↗
PubMed1989

Two brain nuclei controlling circadian rhythms are identified by GFAP immunoreactivity in hamsters and rats.

The intergeniculate leaflet (IGL) of the lateral geniculate complex is marked by the presence of neuro-peptide Y-containing neurons that project to the suprachiasmatic nuclei (SCN) of the hypothalamus. In the present study, we demonstrate that both the IGL and SCN in the hamster and rat are specifically delineated by the presence of glial fibrillary acidic protein-like immunoreactivity. This is significantly greater than in most other diencephalic regions and is particularly dense in the hamster brain. These observations suggest that glial-neuronal interactions may participate in circadian rhythm generation and regulation.

Animals↗
PubMed1989

Cranial motor neurons contain either galanin- or calcitonin gene-related peptidelike immunoreactivity.

The demonstration of coexistence of a peptide or peptides in neurons that produce a small molecule neurotransmitter has become increasingly frequent. The calcitonin gene-related peptide (CGRP) is known to be colocalized in the cholinergic neurons of both cranial and spinal motor nuclei. The present study demonstrates that all somatic motor cranial nerve nuclei contain CGRP- and galaninlike immunoreactivity. The perikaryal content of both peptides is increased by colchicine pretreatment and by transecting axons arising from the perikarya, and both peptides are found in nerve fibers innervating striated musculature. CGRP- and galaninlike immunoreactivity appear to be present in different populations of neurons. In contrast to CGRP, galaninlike immunoreactivity was not detected in spinal motor neurons. These observations suggest that galanin and CGRP participate in the process of synaptic transmission at the neuromuscular junction of cranial motor neurons.

Animals↗
PubMed1989

Paraventricular nucleus efferents mediating photoperiodism in male golden hamsters.

Knife cuts were placed around the paraventricular nucleus of the hypothalamus (PVN) in an effort to identify the pathways mediating gonadal regression in male golden hamsters housed in a short photoperiod. Horizontal cuts dorsal to the PVN only affected photoperiodic responsiveness if they actually damaged the PVN. Coronal cuts caudal to the PVN had no effect on testes regression. Parasagittal cuts adjacent to the medial PVN had little or no effect on gonadal regression induced by short photoperiod. We conclude that efferents of the PVN arising dorsally or medially are not necessary for photoperiodic control of testes function, whereas projections from or through the lateral PVN region descending towards the spinal cord are important.

Animals↗
PubMed1989

Effects of melatonin on neuronal activity in the rat suprachiasmatic nucleus in vitro.

The pineal hormone melatonin is believed to act directly on the hypothalamic suprachiasmatic nuclei (SCN), which are principal circadian pacemakers in rodents, although direct demonstration of this is lacking. To determine whether the SCN are sensitive to melatonin electrophysiologically, we investigated the effect of melatonin on rat SCN single-unit activity in an in vitro hypothalamic slice preparation. SCN single-unit activity was inhibited by melatonin superfusion during the late subjective day in a dose-dependent manner but not at other times of day, supporting the view that melatonin acts directly on SCN neurons.

Action Potentials↗
PubMed1989

Immunohistochemical evidence for the presence of neuropeptides in the hypothalamic suprachiasmatic nucleus of ground squirrels.

The cytoarchitecture and immunocytochemical distribution of neuropeptides (corticotropin-releasing factor, CRF; neuropeptide Y, NPY; oxytocin, OXY; vasopressin, VP; and vasoactive intestinal polypeptide, VIP) were studied in the hypothalamic suprachiasmatic nuclei (SCN) in male and female ground squirrels of two species (Spermophilus tridecemlineatus and S. richardsonii). Immunoreactive (IR) perikarya were found in sections incubated with VP or VIP antisera. VP-IR cell bodies were seen in the dorsal and medial parts of the nucleus in colchicine-treated animals. IR fibers were distributed throughout the SCN. In the ventral part of the nucleus, VIP-IR cells were seen in untreated animals and were more pronounced in colchicine-treated animals. VIP-IR fibers and terminals form a dense plexus throughout the nucleus. Furthermore, NPY-IR terminals and fibers with multiple varicosities, but no IR perikarya, were present in the suprachiasmatic nuclei. Within the borders of the SCN, no cell bodies or fibers were stained with CRF or OXY antisera in any animal.

Animals↗
PubMed1989

Paraventricular nucleus projections mediating pineal melatonin and gonadal responses to photoperiod in the hamster.

Knife cuts were placed around the paraventricular nucleus of the hypothalamus (PVN) in order to identify the pathways mediating photoperiodism and pineal melatonin production in male golden hamsters. Cuts in the coronal plane caudal to the PVN, have no effect on photoperiodic control of the testes unless they actually damage the PVN. Bilateral parasagittal cuts at the medial border of the lateral hypothalamus block short photoperiod-induced gonadal regression. Nighttime levels of pineal melatonin are reduced by these cuts, but unaffected by caudal cuts. Projections from the lateral PVN region descending towards the spinal cord appear to be critical for the control of pineal melatonin production and the control of the testicular function by short photoperiod.

Animals↗
PubMed1989

Localization of spinal cord preganglionic neurons innervating the superior cervical ganglion in the golden hamster.

The retrograde neuronal tracer Fluoro-Gold (FG) was used to determine the location and distribution of preganglionic sympathetic neurons in the spinal cord of the golden hamster. FG was injected unilaterally into the superior cervical ganglia. Labeled neurons were found only ipsilateral to the injection site in segments C8 to T5 of which the segments T1 to T3 contained about 98% of the labeled cells. Neurons were found in four regions of the spinal cord: the intermediolateral nucleus (43%), the lateral funiculus (55%), the central autonomic area (1%) and the intercalated region (less than 1%). In the intermediolateral nucleus, cells often were arranged in clusters of which several were seen in each spinal segment.

Animals↗
PubMed1989

Lateral geniculate lesions alter circadian activity rhythms in the hamster.

The suprachiasmatic nucleus (SCN) receives photic input via a direct retinohypothalamic tract (RHT) and an indirect geniculohypothalamic tract (GHT). The neurons giving rise to the GHT are in the intergeniculate leaflet (IGL) of the lateral geniculate nucleus (LGN) and contain neuropeptide-Y (NPY) immunoreactivity. The present study used the neurotoxin, N-methyl aspartate (NMA), to examine the effects of lesions of the LGN on circadian wheelrunning in the hamster. The results are compared to those from control lesioned animals and animals with parasigittal cuts through the hypothalamus. The effectiveness of the lesions was examined with NPY immunohistochemistry of the SCN and IGL. NMA injections destroyed the neurons of the IGL and the adjacent ventral and dorsal divisions of the LGN and greatly reduced NPY immunoreactivity in the SCN. The results of the rhythm studies were: 1) NMA injection into the LGN area produced phase advances if the injection occurred within the 12 hr preceding activity onset and delays or no effect if injected during the 12 hr after activity onset; 2) the NMA lesions reduced the rate of reentrainment to 6 hr shifts in the LD 14:10 photoperiod and advanced the entrained phase angles by about 10 min; 3) the knife cuts advanced the entrained phase angles by about 30 min; 4) neither NMA lesions nor knife cuts altered circadian period in constant dim light. Our results indicate that the GHT is not required for entrainment or normal expression of circadian rhythmicity, but that the GHT does exert an influence on entrainment.

Animals↗
PubMed1989

Neuropeptide Y-containing neurons in the rat superior cervical ganglion: projections to the pineal gland.

The aim of this study was to investigate the localization in the superior cervical ganglia (SCG) of neuropeptide Y-containing neurons innervating the pineal gland. Following injection of the fluorescent tracer Fluoro-Gold (FG) into the superficial part of the pineal gland and retrograde axonal transport, labeled cells were observed predominantly in the rostral third to half of SCG sections (average number 239 per ganglion). Incubation of the sections with neuropeptide Y (NPY) antiserum showed that the vast majority of neurons exhibit NPY-like immunoreactivity (NPY-LI). The comparison of cells labeled with FG and those containing NPY revealed that nearly three fourths of retrogradely labeled neurons also exhibit NPY-LI. Incubation of pineal gland sections with NPY antiserum showed immunoreactive axons, relatively sparse and scattered throughout the superficial part of the organ and the pineal stalk. The present results confirm the assumption that, in rodents, pineal NPY originates from the superior cervical ganglia.

Animals↗
PubMed1989

Synaptogenesis in the rat suprachiasmatic nucleus demonstrated by electron microscopy and synapsin I immunoreactivity.

Synaptogenesis was studied in the rat suprachiasmatic nucleus (SCN) using quantitative ultrastructural analysis and synapsin I immunohistochemistry. SCN neurons are formed between embryonic days 13 and 17 (E13-E17), and the SCN is a distinct hypothalamic nucleus by E18. At E19 the nucleus is very immature and there are few synapses. Synaptogenesis proceeds slowly until P4 but increases rapidly between P4 and P10. At P10 the number of synapses per unit area is the same as in the adult SCN and all synaptic types present in the adult are evident. However, the SCN continues to increase in volume to the adult with approximately 30% of total synaptic number added between P10 and a young adult age. The appearance of synapsin I immunoreactivity correlates very precisely with the development of synapses in the SCN as shown by ultrastructural analysis between E19 and P6. The pattern of appearance of synapsin I immunoreactivity demonstrates that synaptogenesis in the SCN is significantly delayed in comparison to adjacent hypothalamic nuclei. Synapsin I immunohistochemistry is a reliable marker of synapse formation in the developing SCN. A correlation of these anatomical data with prior functional studies suggests that SCN neurons are born as individual circadian oscillators that undergo a rapid development in the first 10 days after birth to form a functional neural network subserving circadian rhythm generation and regulation.

Animals↗