Search results for "Nucleus"
showing 10 items of 1803 documents
Ultrastructural observations on the central innervation of the guinea-pig pineal gland.
1981
In the present study the central innervation of the guinea-pig pineal gland was investigated. The habenulae and the pineal stalk contain myelinated and non-myelinated nerve fibres with few dense-cored and electron-lucent vesicles. Some myelinated fibres leave the main nerve fibre bundles, lose their myelin-sheaths and terminate in the pineal gland. Although direct proof is lacking, the non-myelinated fibres appear to end near the site where the bulk of the myelinated fibres are located. Here a neuropil area exists where synapses between non-myelinated fibre elements are abundant. Neurosecretory fibres were also seen. The results support the concept of functional interrelationships between h…
Direct projections to the rat pineal gland via the stria medullaris thalami. An anterograde tracing study by use of horseradish peroxidase.
1986
The possible presence of a direct nervous projection from the paraventricular nucleus (PVN) of the hypothalamus to the pineal gland of the rat was investigated by means of the anterograde neuron-tracing method using horseradish peroxidase. The tracer was injected unilaterally into the PVN and the animals were allowed to survive between 12 and 26 h. Numerous peroxidase-positive fibers were observed, ipsilateral to the injection site, in the stria medullaris thalami and could be followed into the medial habenular nucleus and the habenular commissure. From there, fibers penetrated into the deep pineal gland (lamina intercalaris), and further into the pineal stalk. These data support results of…
Electron microscopic study on the larval and adult corpus allatum of Oncopeltus fasciatus dallas (insecta, heteroptera)
1973
1. The ultrastructure of the corpora allata of last larval instars and adults of Oncopeltus was studied. The unpaired gland undergoes submicroscopic alterations and shows signs of degradation in old animals. The organ is partly covered and penetrated by corpus cardiacum tissue. Axons with different types of neurosecretory granules form synaptoid contacts with the corpus allatum cells.
Regulation of noradrenergic coerulean neuronal firing mediated by 5-HT2 receptors: involvement of the prepositus hypoglossal nucleus.
1991
Abstract Previous studies have indicated a 5-HT2-mediated inhibitory influence on unit activity in the locus coeruleus. In the present work, attempts were made to determine which area(s) of the brain is (are) involved in this effect: (1) Microiontophoretic application of serotoninergic compounds (quipazine, ketanserin, RU 24969 (Roussel Uclaf), 8-hydroxy-2(di-n-propylamino) tetralin (8-OH-DPAT), metergoline, serotonin) in the locus coeruleus, did not alter the coerulean discharge. Local microinjection of quipazine or ketanserin in the area of the locus coeruleus, as well as in one of its major afferents, the prepositus hypoglossi, had no effect on the unit activity in the locus coeruleus. 1…
Morphological investigation of the deep pineal of the rat.
1980
The results presented here reveal that in adult Sprague-Dawley and Wistar rats the pineal gland represents a complex rather than a single organ. Regularly one can distinguish (i) pineal tissue in the intercommissural region as a deep pineal, (ii) a superficial pineal, which represents the major part of the pineal complex, and (iii) nearly always a parenchymal stalk of variable length. The volume of the deep pineal with the adjacent parenchymal stalk exhibits great interindividual variation. It amounts to 127 +/- 39 X 10(5) mum3 (mean +/- standard deviation). The histological appearance of the deep and superficial pineal tissue is fairly similar. The intrinsic cells of the deep and superfici…
Rat pineal arylalkylamine-N-acetyltransferase: cyclic AMP inducibility of its gene depends on prior entrained photoperiod.
2003
The nocturnal biosynthesis of melatonin in the rat pineal depends on strongly enhanced expression of the enzyme N-acetyltransferase [arylalkylamine N-acetyltransferase (AA-NAT); EC 2.3.1.87]. AA-NAT transcription is stimulated during darkness by adrenergic inputs to the pineal from the suprachiasmatic nucleus (SCN). Nocturnal activation of the AA-NAT promotor following stimulation of pinealocyte adrenoceptors involves cAMP-dependent stimulation of protein kinase A (PKA). The nocturnal rise in AA-NAT depends on the lighting conditions. As compared with light/dark (LD) 12:12, the delay between dark onset and the nocturnal rise in AA-NAT is shortened under long photoperiods and prolonged under…
Melatonin binding sites in brain of the 2-day-old chicken: An autoradiographic localisation
1990
Melatonin, released in a circadian manner from the avian pineal gland into the circulation, is concentrated in distinct brain areas, possibly by receptor-mediated uptake mechanisms. For anatomical localisation of putative melatonin receptors in birds, cryostat-cut, coronal 15 microns brain sections of 2-day-old chicken were investigated by means of in vitro receptorautoradiography, using 125I-melatonin as a ligand. Binding occurred in brain structures receiving or mediating visual or auditory sensory input. Binding characteristics were investigated in homogenates of a brain region labelled by 125I-melatonin and showed to be specific and saturable (Kd: 87.2 pM; Bmax: 16.1 fmol/mg protein). R…
Daily oscillation of gene expression in the retina is phase-advanced with respect to the pineal gland
2007
Abstract The photoreceptive retina and the non-photoreceptive pineal gland are components of the circadian and the melatonin forming system in mammals. To contribute to our understanding of the functional integrity of the circadian system and the melatonin forming system we have compared the daily oscillation of the two tissues under various seasonal lighting conditions. For this purpose, the 24-h profiles of the expression of the genes coding for arylalkylamine N-acetyltransferase (AA-NAT), nerve growth factor inducible gene-A (NGFI-A), nerve growth factor inducible gene-B (NGFI-B), retinoic acid related orphan receptor β (RORβ), dopamine D4 receptor, and period2 (Per2) have been simultane…
Neurochemistry of olivocochlear neurons in the hamster.
2009
The present study was conducted to characterize the superior olivary complex (SOC) of the lower brain stem in the pigmented Djungarian hamster Phodopus sungorus. Using Nissl-stained serial cryostat sections from fresh-frozen brains, we determined the borders of the SOC nuclei. We also identified olivocochlear (OC) neurons by retrograde neuronal tracing upon injection of Fluoro-Gold into the scala tympani. To evaluate the SOC as a putative source of neuronal nitric oxide synthase (nNOS), arginine-vasopressin (AVP), oxytocin (OT), vasoactive intestinal polypeptide (VIP), or pituitary adenylate cyclase-activating polypeptide (PACAP) that were all found in the cochlea, we conducted immunohistoc…
Neuropeptide Y (NPY)-like immunoreactivity in peripheral and central nerve fibres of the golden hamster (Mesocricetus auratus) with special respect t…
1986
Inforimation on the ambient lighting conditions is conveyed from the retina to the pineal organ by a neuronal pathway involving the suprachiasmatic nucleus (SCN) which acts as a circadian pacemaker. In the hamster, circadian rhythms have been shown to be influenced by injection of neuropeptide Y (NPY) into the SCN. Since NPY-immunoreactive nerve fibres are present in the rat and guinea-pig pineal glands it appeared of interest to investigate the hamster pineal as part of the circadian rhythm generating/regulating system. For comparison kidney, small intestine and cerebral cortex were studied. Like in the other rodent species so far investigated only a few of the abundant sympathetic nerve f…