Search results for "STRAINS"
showing 10 items of 589 documents
Vitamin E deficiency and the susceptibility to lipid peroxidation of mouse cardiac and skeletal muscles
1984
Effects of a short-term vitamin E deficiency on some lipid peroxidative properties were investigated in mouse cardiac and skeletal muscles. The concentration of vitamin E decreased 35.8% in 5 weeks and 61.2% in 12 weeks in skeletal muscle. The corresponding decrease in cardiac muscle was 65.7% in 12 weeks. Simultaneously the susceptibility of muscle homogenates to in vitro lipid peroxidation increased with 48.6% (5 weeks) and 44.5% (12 weeks) in skeletal muscle and with 101.8% (12 weeks) in cardiac muscle. Highly significant negative correlations were observed between the concentration of vitamin E and in vitro lipid peroxidation in cardiac and skeletal muscles. Also the sensitivity to Fe2+…
Pineal ?synaptic? ribbons and spherules during the estrous cycle in rats
1983
In previous studies pineal "synaptic" ribbons have been shown to undergo striking numerical changes under various physiological and experimental conditions and to be regulated by beta-adrenergic mechanisms. The aim of the present investigation was to study the numbers of pineal "synaptic" ribbons and spherules in Wistar rats throughout the estrous cycle and to compare them with those in males. There were no statistically significant differences in the numbers of ribbons and spherules between males and females and in the females at the different stages of the estrous cycle, indicating that the structures in question, in vivo, do not appear to be regulated by naturally occurring changes of se…
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…
Characterization of rodent pineal astrocytes by immunofluorescence microscopy using a monoclonal antibody (J1-31).
1987
In previous studies pineal astrocytes have been characterized immunohistochemically mainly by use of antisera to glial fibrillary acidic protein. Because of the recent demonstration of this protein in non-astrocytic cells the question of its specificity as an astrocytic marker has been raised. A possible alternative tool for characterizing pineal astrocytes is the J1-31 monoclonal antibody, which is directed against a 30 000 dalton astrocytic protein clearly distinguishable from glial fibrillary acidic protein. Immunofluorescence microscopy of this antibody in the pineal gland of rat and guinea-pig revealed a staining pattern similar to that obtained by glial acidic fibrillary protein antis…
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…
A possible role for cyclic guanosine monophosphate in the rat pineal gland.
1990
Abstract Adrenergic stimulation of pinealocytes induces an increase of both cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). However, for cGMP no biological effects have been demonstrated so far. Therefore we tested the effects of the analog 8-bromo-cGMP on synaptic ribbon numbers and on melatonin synthesis as reflected by N -acetyltransferase (NAT) activity in the rat pineal gland in vitro. Incubation for 6 h with 8-bromo-cGMP did not change the activity of serotonin NAT but in increased the number of synaptic ribbons. These results indicate that cGMP is involved as a second messenger in the regulation of synaptic ribbon numbers in the rat pineal gland.
No Correlation of Pineal "Synaptic" Ribbon Numbers and Melatonin Formation in Individual Rat Pineal Glands
1984
As previous circadian studies of pineal "synaptic" ribbon numbers and melatonin formation suggested that a positive correlation of the two variables exists, in the present investigation this problem was examined in individual pineal glands of rats killed at 1200 h and 2400 h, respectively. For this purpose, one half of the gland was processed for electron microscopy and the ribbons were counted in an area of 20,000 micron2 tissue; in the other half serotonin N-acetyltransferase (NAT) activity and melatonin content were determined. No correlation was found to exist between ribbon numbers and pineal NAT activity, pineal melatonin levels and serum melatonin levels, either at day- or at nightti…
Effects of an artificial magnetic field on serotonin N-acetyltransferase activity and melatonin content of the rat pineal gland
1983
In the present study the effects of artificial magnetic fields on pineal serotonin-N-acetyltransferase (NAT) activity and melatonin content in male Sprague-Dawley rats were investigated to study the secretory activity of the pineal gland. Experimental inversion of the horizontal component of the natural magnetic field, performed at night-time, led to a significant decrease of both parameters investigated. During day-time, this effect was less conspicuous. During night-time, inversion of the horizontal component is followed by a reduced pineal secretory activity for about 2 h. After 24 h exposure to the inverted horizontal component, return to the natural condition was followed by a renewed …
The effects of a number of short-term exogenous stimuli on pineal serotonin-N-acetyltransferase activity in rats
1984
The present study deals with the question as to what extent the sympathetically innervated rat pineal gland is affected by a number of short-term exogenous stimuli given during day-time, as assessed by measuring pineal serotonin-N-acetyltransferase activity (NAT) which is directly proportional to melatonin formation. In male Sprague-Dawley rats kept under LD 12:12 pineal NAT was statistically significantly depressed by physical immobilization for 2 hours, swimming for 15 min in water of 10 and 30 degrees C, exposure for 2 hours to cold (5 degrees C) or heat (40 degrees C), noise (90 db) for 2 hours and hunger for 17 hours. An increase in NAT was noted after swimming for 15 min in water of 2…
Lack of effect of oxytocin on the numbers of ?synaptic? ribbons, cyclic guanosine monophosphate and serotonin N-acetyltransferase activity in organ-c…
1993
In addition to the stimulating influence of the sympathetic system on the function of the mammalian pineal gland, neuropeptides such as neuropeptide Y, vasoactive intestinal polypeptide and arginine-vasopressin (AVP) are thought to function as modulators. Since AVP has been shown to influence pineal melatonin synthesis, the aim of the present study was to investigate the possible effects of the second hypothalamic nonapeptide oxytocin (OT), which likewise has been detected in the pineal gland. We therefore studied "synaptic" ribbon (SR) numbers, N-acetyltransferase (NAT) activity and the intracellular concentration of cyclic guanosine monophosphate (cGMP) following in vitro incubation of ra…