scholarly journals EFFECTS OF NALTREXONE ON THE ETHANOL-INDUCED CHANGES IN THE RAT CENTRAL DOPAMINERGIC SYSTEM

2005 ◽  
Vol 40 (4) ◽  
pp. 297-301 ◽  
Author(s):  
Y.-K. LEE
Keyword(s):  
Dopaminergic System ◽  
Induced Changes

Photoperiodic modulation of the dopaminergic control of pulsatile LH secretion in sheep

1994 ◽  
Vol 143 (1) ◽  
pp. 25-32 ◽  
Author(s):  
D J Tortonese ◽  
G A Lincoln
Keyword(s):  
Dopaminergic System ◽  
Pulse Frequency ◽  
Inhibitory System ◽  
Pulsatile Gnrh ◽  
Photoperiodic Regulation ◽  
Series Of Experiments ◽  
Induced Changes ◽  
Lh Secretion ◽  
Short Days ◽  
Sustained Increase

Abstract This study was conducted to investigate whether the photoperiodic regulation of the seasonal changes in pulsatile LH secretion in the ram involves changes in the activity of inhibitory hypothalamic dopaminergic (DA) pathways. To test this hypothesis, a series of experiments was carried out in Soay rams in which the effects of a DA-D2 receptor antagonist (sulpiride) or a DA-D2 receptor agonist (bromocriptine) on the pulsatile secretion of LH were determined under both long and short days. In each experiment blood samples were collected every 10 min for 8 h starting at the time of vehicle, sulpiride or bromocriptine injections to assess concentrations of LH. Sulpiride (0·59 mg/kg, s.c.) administered to rams under long days induced an immediate and sustained increase in the secretion of LH that lasted for approximately 4 h (P<0·05; ANOVA); this LH response reflected both a rise in mean concentrations (0·247 ± 0·03 vs.0·452 ± 0·1 μg/1) and an increase in the frequency of LH pulses (0·5±0·5 vs. 2·33±0·42 pulses/8 h; P<0·01). In contrast, under short days sulpiride had no effect. Bromocriptine (0·06 mg/kg, s.c.) administered to rams under long days, when LH concentrations were low, was without effect, but when given to rams under short days significantly (P<0·05) suppressed mean LH concentrations (0·627 ±0·08 vs. 0·320 ± 0·02 μg/l) and LH pulse frequency (4·86 ±0·46 vs. 2·43 ±0·37 pulses/8 h). In an additional experiment, pimozide (total dose: 0·16 mg/kg, i.m.), a DA antagonist less specific for DA-D2 receptors than sulpiride, was ineffective in modifying LH secretion in sexually inactive rams exposed to long days. These results are consistent with the hypothesis that an inhibitory dopaminergic system is involved in the regulation of pulsatile LH secretion in the ram. The induced changes in LH pulse frequency under long days (increased by sulpiride) and under short days (decreased by bromocriptine) indicate that, under both photoperiods, DA acts within the hypothalamus, via a specific DA-D2 receptor, to influence pulsatile GnRH secretion. A photoperiodic-induced activation of this inhibitory system may therefore represent the mechanism whereby long days suppress LH secretion and lead to the sexually inactive state characteristic of the non-breeding season. Journal of Endocrinology (1994) 143, 25–32

scholarly journals Imaging cocaine-induced changes in the mesocorticolimbic dopaminergic system of conscious rats

2004 ◽  
Vol 139 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Marcelo Febo ◽  
Annabell C. Segarra ◽  
Jeffrey R. Tenney ◽  
Mathew E. Brevard ◽  
Timothy Q. Duong ◽  
...  
Keyword(s):  
Dopaminergic System ◽  
Conscious Rats ◽  
Induced Changes ◽  
Mesocorticolimbic Dopaminergic System

Differential effects of nicotine against stress-induced changes in dopaminergic system in rat striatum and hippocampus

2000 ◽  
Vol 387 (2) ◽  
pp. 171-177 ◽  
Author(s):  
Robert Pawlak ◽  
Yumiko Takada ◽  
Hiroshi Takahashi ◽  
Tetsumei Urano ◽  
Hayato Ihara ◽  
...  
Keyword(s):  
Dopaminergic System ◽  
Rat Striatum ◽  
Differential Effects ◽  
Induced Changes

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Drug Induced Changes in Cell Organelles

1968 ◽  
Vol 26 ◽  
pp. 110-111
Author(s):  
Sarah A. Luse
Keyword(s):  
Clinical Medicine ◽  
Cell Organelles ◽  
Riboflavin Deficiency ◽  
Drug Induced ◽  
New Era ◽  
Health And Disease ◽  
In The Beginning ◽  
Cellular Pathology ◽  
Induced Changes ◽  
The Impact

In the mid-nineteenth century Virchow revolutionized pathology by introduction of the concept of “cellular pathology”. Today, a century later, this term has increasing significance in health and disease. We now are in the beginning of a new era in pathology, one which might well be termed “organelle pathology” or “subcellular pathology”. The impact of lysosomal diseases on clinical medicine exemplifies this role of pathology of organelles in elucidation of disease today.Another aspect of cell organelles of prime importance is their pathologic alteration by drugs, toxins, hormones and malnutrition. The sensitivity of cell organelles to minute alterations in their environment offers an accurate evaluation of the site of action of drugs in the study of both function and toxicity. Examples of mitochondrial lesions include the effect of DDD on the adrenal cortex, riboflavin deficiency on liver cells, elevated blood ammonia on the neuron and some 8-aminoquinolines on myocardium.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

Immunogold localization of calmodulin in root caps of the maize Cultivar Merit

1990 ◽  
Vol 48 (3) ◽  
pp. 674-675
Author(s):  
P.T. Nguyen ◽  
C. Uphoff ◽  
C.L. Stinemetz
Keyword(s):  
Calcium Binding ◽  
Calcium Transport ◽  
Primary Role ◽  
Immunogold Localization ◽  
Root Tips ◽  
Electrical Currents ◽  
Considerable Evidence ◽  
Maize Cultivar ◽  
Gravity Response ◽  
Induced Changes

Considerable evidence suggest that the calcium-binding protein calmodulin (CaM) may mediate calcium action and/or transport important in the gravity response of plants. Calmodulin is present in both shoots and roots and is capable of regulating calcium transport in plant vesicles. In roots calmodulin is concentrated in the tip, the gravisensing region of the root; and is reported to be closely associated with amyloplasts, organelles suggested to play a primary role in gravi-perception. Inhibitors of CaM such as chlorpromazine, calmidazolium, and compound 48/80 interfere with the gravitropic response of both snoots and roots. The magnitude of the inhibition corresponded well with the extent to which the drug binds to endogenous CaM. Compound 48/80 and calmidazolium block gravi-induced changes in electrical currents across root tips, a phenomenon thought to be associated with the sensing of the gravity stimulus.In this study, we have investigated the subcellular distribution of CaM in graviresponsive and non-graviresponsive root caps of the maize cultivar Merit.

Identifying groups of airborne particles by ordination

1994 ◽  
Vol 52 ◽  
pp. 856-857
Author(s):  
M. Shlepr ◽  
C. M. Vicroy
Keyword(s):  
Elemental Analysis ◽  
Energy Dispersive Spectroscopy ◽  
Manufacturing Process ◽  
Spatial Representation ◽  
Airborne Particles ◽  
Common Source ◽  
Data Set ◽  
Microelectronics Industry ◽  
Induced Changes ◽  
Source Materials

The microelectronics industry is heavily tasked with minimizing contaminates at all steps of the manufacturing process. Particles are generated by physical and/or chemical fragmentation from a mothersource. The tools and macrovolumes of chemicals used for processing, the environment surrounding the process, and the circuits themselves are all potential particle sources. A first step in eliminating these contaminants is to identify their source. Elemental analysis of the particles often proves useful toward this goal, and energy dispersive spectroscopy (EDS) is a commonly used technique. However, the large variety of source materials and process induced changes in the particles often make it difficult to discern if the particles are from a common source.Ordination is commonly used in ecology to understand community relationships. This technique usespair-wise measures of similarity. Separation of the data set is based on discrimination functions. Theend product is a spatial representation of the data with the distance between points equaling the degree of dissimilarity.

Sign in / Sign up

Export Citation Format

Share Document