Photoreceptors in the rat retina are specifically vulnerable to both hypoxia and hyperoxia

2005 ◽  
Vol 22 (4) ◽  
pp. 501-507 ◽  
Author(s):  
JOHN WELLARD ◽  
DONALD LEE ◽  
KRISZTINA VALTER ◽  
JONATHAN STONE
Keyword(s):  
Outer Nuclear Layer ◽  
Great Majority ◽  
Significant Rise ◽  
Sprague Dawley ◽  
Rat Retina ◽  
Oxygen Levels ◽  
Sprague Dawley Rats ◽  
Four Levels ◽  
Dying Cells ◽  
Photoreceptor Death

The current study aims to assess the vulnerability of photoreceptors in rat retina to variations in tissue oxygen levels. Young adult Sprague-Dawley rats were exposed to air with the concentration of oxygen set at 10% (hypoxia), 21% (room air, normoxia), and four levels of hyperoxia (45%, 65%, 70%, and 75%), for up to 3 weeks. Their retinas were then examined for cell death, using the TUNEL technique. Hypoxia (10% oxygen) for 2 weeks caused a limited but significant rise in the frequency of TUNEL+ (dying) cells in the retina, the great majority (> 90%) being located in the outer nuclear layer (ONL). Hyperoxia also induced an increase in the frequency of TUNEL+ cells, again predominantly in the ONL. The increase rose with duration of exposure, up to 2 weeks. At 2 weeks exposure, the increase was limited yet significant at 45% oxygen, and maximal at 65%. Where the frequencies of TUNEL+ cells were high, it was evident that photoreceptor death was maximal in the midperipheral retina. The adult retina is vulnerable to maintained shifts in oxygen availability to the retina, both below and above normal. The vulnerability is specific to photoreceptors; other retinal neurons appeared resistant to the exposures tested. Shifts in retinal oxygen levels caused by variations in ambient light, by the persistence of light through the normally dark (night) half of the day–night cycle, or by depletion of the photoreceptor population, may contribute to photoreceptor death in the normal retina.

Role of renal interstitial hydrostatic pressure in natriuresis of systemic nitric oxide inhibition

1993 ◽  
Vol 264 (3) ◽  
pp. F411-F414 ◽  
Author(s):  
J. A. Haas ◽  
A. A. Khraibi ◽  
M. A. Perrella ◽  
F. G. Knox
Keyword(s):  
Nitric Oxide ◽  
Hydrostatic Pressure ◽  
Fractional Excretion ◽  
Urinary Sodium Excretion ◽  
Renal Perfusion ◽  
Significant Rise ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Suprarenal Aorta ◽  
Fractional Excretion Of Sodium

Systemic inhibition of nitric oxide synthesis with NG-monomethyl-L-arginine (L-NMMA) increases renal perfusion pressure (RPP) and urinary sodium excretion. Increased RPP has been proposed as one of the mechanisms for the natriuresis caused by intravenous infusion of L-NMMA. We tested the hypothesis that increases in renal interstitial hydrostatic pressure (RIHP) are required for the natriuresis of L-NMMA infusion. Experiments were performed in four groups of Sprague-Dawley rats in which partial aortic clamping and/or bilateral renal decapsulation was performed to control RPP and RIHP. Infusion of L-NMMA (15 mg/kg bolus + 500 micrograms.kg-1 x min-1 continuous infusion) increased RPP (delta+ 14 +/- 1 mmHg), RIHP (delta+ 3.6 +/- 0.7 mmHg), and fractional excretion of sodium (FENa; delta 2.4 +/- 0.6%, P < 0.005). When RPP was prevented from increasing by controlling RPP with an adjustable clamp around the suprarenal aorta, RIHP and FENa did not significantly change. When only RIHP was held constant by bilateral renal decapsulation, FENa was not significantly increased (delta+ 0.68 +/- 0.36%, not significant), despite a significant rise in RPP (delta+ 18 +/- 2 mmHg, P < 0.001). Control of both RPP and RIHP prevented the increase in FENa. Thus, when renal interstitial pressure was controlled, the infusion of L-NMMA did not result in an increase in FENa. These results demonstrate that an increase in RIHP is a necessary component in the natriuresis due to systemic infusion of L-NMMA.

Selective activation of norepinephrine- and epinephrine-secreting chromaffin cells in rat adrenal medulla

1992 ◽  
Vol 263 (3) ◽  
pp. R716-R721 ◽  
Author(s):  
R. R. Vollmer ◽  
A. Baruchin ◽  
S. S. Kolibal-Pegher ◽  
S. P. Corey ◽  
E. M. Stricker ◽  
...  
Keyword(s):  
Cold Exposure ◽  
Chromaffin Cells ◽  
Statistical Significance ◽  
Significant Rise ◽  
Significant Decline ◽  
Synthetic Activity ◽  
Sprague Dawley ◽  
Selective Activation ◽  
Sprague Dawley Rats ◽  
Contrast Exposure

The differential effects of insulin-induced hypoglycemia and cold exposure on adrenal medullary epinephrine (Epi) and norepinephrine (NE) cells were investigated in male Sprague-Dawley rats. In rats fasted overnight, insulin produced a marked hypoglycemia that resulted in a 70% decrease in adrenal medullary Epi content 3 h after the insulin was administered. No change in NE content was observed. Plasma Epi concentration was increased markedly after insulin, with a smaller increment in NE. In contrast, exposure to a 4 degrees C environment selectively reduced adrenal NE content, with the effect reaching statistical significance at 18 h. Cold exposure also led to a significant rise in plasma NE but not Epi. Both insulin-induced hypoglycemia and cold exposure significantly elevated adrenal dopamine, indicating that catecholamine synthesis was stimulated. Further evidence of enhanced catecholamine formation was the observation that inhibition of synthesis with alpha-methyl-p-tyrosine (AMT) greatly augmented the ability of insulin-induced hypoglycemia to selectively reduce adrenal medullary Epi content. Similarly, in cold-exposed animals, AMT pretreatment accelerated the NE depletion so that a significant decline was observed at 3 h. These results support the conclusion that the two major populations of adrenal catecholamine-secreting cells may be preferentially stimulated by different stressors. Moreover, augmented synthetic activity functions to maintain catecholamine stores in both Epi- and NE-secreting cells.

Colonization of Neural Allografts by Host Microglial Cells: Relationship to Graft Neovascularization

1997 ◽  
Vol 6 (3) ◽  
pp. 221-230 ◽  
Author(s):  
Nathan A. Pennell ◽  
Wolfgang J. Streit
Keyword(s):  
Blood Vessels ◽  
Great Majority ◽  
Active Role ◽  
Microglial Cells ◽  
Sprague Dawley ◽  
Functional Roles ◽  
Sprague Dawley Rats ◽  
Close Proximity ◽  
Quantitative Image ◽  
Phenotype Characteristic

In order to illuminate functional roles of microglial cells within neural allografts, we have transplanted both whole and microglial and endothelial cell-depleted E14 neural cell suspensions into the intact striatum of Sprague-Dawley rats. Following posttransplantation times of up to 30 days, the intrastrial allografts were analyzed histochemically using the Griffonia simplicifolia B4 isolectin, a marker for both microglia and blood vessels. Our results indicate that both whole and depleted suspension grafts develop identically in terms of neovascularization and microglial colonization. In both types of transplants microglial cells appeared before any blood vessels were apparent. The main phase of graft vascularization occurred between days 7 and 10 posttransplantation and neovascularization was complete by day 21, as revealed by quantitative image analysis. Microglial cells, which were present as ameboid cells during early posttransplantation times, underwent continuing cell differentiation with time that paralleled graft vascular development. By 30 days posttransplantation microglia within the grafts had assumed the fully ramified phenotype characteristic of resting adult microglia. During graft development and vascularization, microglia were often seen in close proximity to ingrowing blood vessels and vascular sprouts. In conclusion, our study has shown that microglial colonization of grafts and graft vascularization occurs independent of donor-derived microglial and endothelial cells, and suggests that the great majority of microglia and vessels within the graft are host derived. We hypothesize that the host microglia invading the allografts play an active role in promoting graft neovascularization.

Effect of reduction in renal artery pressure on atrial natriuretic peptide-induced natriuresis

1987 ◽  
Vol 252 (1) ◽  
pp. F146-F153 ◽  
Author(s):  
C. L. Davis ◽  
J. P. Briggs
Keyword(s):  
Arterial Pressure ◽  
Atrial Natriuretic Peptide ◽  
Renal Artery ◽  
Natriuretic Peptide ◽  
Significant Rise ◽  
Sprague Dawley ◽  
Artery Pressure ◽  
Sprague Dawley Rats ◽  
Natriuretic Effect ◽  
Atrial Natriuretic

Studies were undertaken in anesthetized male Sprague-Dawley rats to investigate the effects of lowering renal arterial pressure within the autoregulatory range (to 85-95 mmHg) on the renal response to atriopeptin II (AP II) and atrial extract (AE). The natriuresis and diuresis produced by bolus injections of AP II at three dose levels (250-1,000 ng) was abolished or substantially reduced at lowered arterial pressure (85 mmHg). When renal artery pressure was lowered at the same time as an AE infusion was begun it completely blocked the natriuresis and diuresis. When pressure was reduced after 45 min of AE infusion the natriuresis was blunted, but not fully abolished. The effect of prior reduction in renal arterial pressure on the response to AP II (100 ng/min) and furosemide was compared; the AP II natriuresis was prevented when arterial pressure was lowered to 90 mmHg, but the natriuretic effect of furosemide was only slightly diminished. There was no significant rise in glomerular filtration rate (GFR) with AP II and no correlation between GFR changes and the Na excretory response. Reducing renal arterial pressure prior to, at the same time as, or 45 min after beginning an infusion of atrial natriuretic peptide substantially blunts or completely abolishes the natriuresis. Reductions in renal arterial pressure may block the natriuretic and diuretic effects of these compounds by interfering with their hemodynamic actions or by causing sufficient enhancement of salt reabsorption to limit delivery to terminal nephron segments.

scholarly journals The Intoxication Effects of Methanol and Formic Acid on Rat Retina Function

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Dong-Mei Liu ◽  
Shu Zhou ◽  
Jie-Min Chen ◽  
Shu-Ya Peng ◽  
Wen-Tao Xia
Keyword(s):  
Formic Acid ◽  
Oscillatory Potentials ◽  
Control Group ◽  
Sprague Dawley ◽  
Rat Retina ◽  
Elapsed Time ◽  
Sprague Dawley Rats ◽  
Photopic Erg ◽  
Group B ◽  
Retinal Functions

Objective. To explore the potential effects of methanol and its metabolite, formic acid, on rat retina function.Methods. Sprague-Dawley rats were divided into 3- and 7-day groups and a control. Experimental groups were given methanol and the control group were provided saline by gavage. Retinal function of each group was assessed by electroretinogram. Concentrations of methanol and formic acid were detected by GC/HS and HPLC, respectively.Results. The a and b amplitudes of methanol treated groups decreased and latent periods delayed in scotopic and photopic ERG recordings. The summed amplitudes of oscillatory potentials (OPs) of groups B and C decreased and the elapsed time delayed. The amplitudes of OS1, OS3, OS4, and OS5 of group B and OS3, OS4, and OS5 of group C decreased compared with the control group. The IPI1 of group B and IPI1-4 of group C were broader compared with the control group and the IPI1-4 and ET of group B were broader than group C. Conclusions. Both of scotopic and photopic retinal functions were impaired by methanol poisoning, and impairment was more serious in the 7-day than in the 3-day group. OPs, especially later OPs and IPI2, were more sensitive to methanol intoxication than other eletroretinogram subcomponents.

Ultrastructural Investigation of Spontaneous Pituitary Adenomas in Aging Sprague-Dawley Rats

1982 ◽  
Vol 40 ◽  
pp. 216-217
Author(s):  
D. J. McComb ◽  
J. Beri ◽  
F. Zak ◽  
K. Kovacs
Keyword(s):  
Microscopic Study ◽  
Pituitary Adenomas ◽  
Wistar Rats ◽  
Microscopic Level ◽  
Sprague Dawley ◽  
Prolactin Cells ◽  
Light Microscopic Level ◽  
Ultrastructural Investigation ◽  
Sprague Dawley Rats ◽  
Long Evans

Investigation of the spontaneous pituitary adenomas in rat have been limited mainly to light microscopic study. Furth et al. (1973) described them as chromophobic, secreting prolactin. Kovacs et al. (1977) in an ul trastructural investigation of adenomas of old female Long-Evans rats, found that they were composed of prolactin cells. Berkvens et al. (1980) using immunocytochemistry at the light microscopic level, demonstrated that some spontaneous tumors of old Wistar rats could contain GH, TSH or ACTH as well as PRL.

Early Development of Drug-Induced Hepatic Necrosis

1971 ◽  
Vol 29 ◽  
pp. 576-577
Author(s):  
F. G. Zaki ◽  
E. Detzi ◽  
C. H. Keysser
Keyword(s):  
Early Development ◽  
Hepatic Necrosis ◽  
Screening Tests ◽  
Dense Matrix ◽  
Sprague Dawley ◽  
Electron Microscopic ◽  
Drug Induced ◽  
Hepatocellular Damage ◽  
Sprague Dawley Rats ◽  
Microscopic Studies

This study represents the first in a series of investigations carried out to elucidate the mechanism(s) of early hepatocellular damage induced by drugs and other related compounds. During screening tests of CNS-active compounds in rats, it has been found that daily oral administration of one of these compounds at a dose level of 40 mg. per kg. of body weight induced diffuse massive hepatic necrosis within 7 weeks in Charles River Sprague Dawley rats of both sexes. Partial hepatectomy enhanced the development of this peculiar type of necrosis (3 weeks instead of 7) while treatment with phenobarbital prior to the administration of the drug delayed the appearance of necrosis but did not reduce its severity.Electron microscopic studies revealed that early development of this liver injury (2 days after the administration of the drug) appeared in the form of small dark osmiophilic vesicles located around the bile canaliculi of all hepatocytes (Fig. 1). These structures differed from the regular microbodies or the pericanalicular multivesicular bodies. They first appeared regularly rounded with electron dense matrix bound with a single membrane. After one week on the drug, these vesicles appeared vacuolated and resembled autophagosomes which soon developed whorls of concentric lamellae or cisterns characteristic of lysosomes (Fig. 2). These lysosomes were found, later on, scattered all over the hepatocytes.

Ultrastructural investigation of spontaneous pituitary gonadotroph cell adenomas in aging Sprague-Dawley rats

1983 ◽  
Vol 41 ◽  
pp. 702-703
Author(s):  
D. J. McComb ◽  
J. Beri ◽  
F. Zak ◽  
K. Kovacs
Keyword(s):  
Electron Microscopy ◽  
Animal Model ◽  
Epoxy Resin ◽  
Immunoelectron Microscopy ◽  
Tumor Type ◽  
Gonadal Function ◽  
Sprague Dawley ◽  
Male And Female ◽  
Reticulin Fibers ◽  
Sprague Dawley Rats

Gonadotroph cell adenomas of the pituitary are infrequent in human patients and are not invariably associated with altered gonadal function. To date, no animal model of this tumor type exists. Herein, we describe spontaneous gonadotroph cell adenomas in old male and female Sprague-Dawley rats by histology, immunocytology and electron microscopy.The material consisted of the pituitaries of 27 male and 38 female Sprague Dawley rats, all 26 months of age or older, removed at routine autopsy. Sections of formal in-fixed, paraffin-embedded tissue were stained with hematoxylin-phloxine-saffron (HPS), the PAS method and the Gordon-Sweet technique for the demonstration of reticulin fibers. For immunostaining, sections were exposed to anti-rat β-LH, anti-ratβ-TSH, anti-rat PRL, anti-rat GH and anti-rat ACTH 1-39. For electron microscopy, tissue was fixed in 2.5% glutaraldehyde, postfixed in 1% OsO4 and embedded in epoxy-resin. Tissue fixed in 10% formalin, embedded in epoxy resin without osmification, was used for immunoelectron microscopy.

Freeze-etch studies of epiphyseal growth plate cartilage reveal matrix vesicles associated with calcification

1978 ◽  
Vol 36 (2) ◽  
pp. 670-671
Author(s):  
Russell N. A. Cecil ◽  
H. Clarke Anderson
Keyword(s):  
Chromic Acid ◽  
Light And Electron Microscopy ◽  
Matrix Vesicles ◽  
Matrix Vesicle ◽  
Glycerol Solution ◽  
Sprague Dawley ◽  
Epiphyseal Growth Plate ◽  
Growth Plates ◽  
Sprague Dawley Rats ◽  
Tibial Epiphyseal

Unfixed proximal tibial epiphyseal growth plates were studied by freeze-etch to confirm the presence of extracellular calcifying matrix vesicles and to determine the substructure of matrix vesicle membranes as compared to plasma and other membranes of intact chondrocytes. Growth plates from 6-10 week old Sprague-Dawley rats were cut into 1x3 mm blocks whose long dimension was oriented either perpendicular or parallel to the long axis of the tibia. Some blocks were fixed at pH 7. 0 in 0. 2M cacodylate - buffered 2. 5% glutaraldehyde for 1 hour at 4ÅC. The blocks were immersed in 30% glycerol solution at 4ÅC for 1 hour, frozen in liquid nitrogen, and then fractured, etched for 2 minutes, and coated with platinum, carbon and 0. 2% Formvar solution. The replicas were cleaned with chromic acid, floated onto Formvar coated grids, and examined with a Phillips EM 300 electron microscope.Fixed and unfixed specimens appeared similar in ultrastructure. Chondrocytes, matrix, and matrix vesicles were identified. In specimens fractured parallel to the long axis of the tibia, the reserve, proliferative, hypertrophic, and calcifying zones could be discerned as described by light and electron microscopy.

Sarcolemmal permeability changes during early myocardial anoxia

1978 ◽  
Vol 36 (2) ◽  
pp. 642-643
Author(s):  
M. Ashraf ◽  
L. Landa ◽  
L. Nimmo ◽  
C. M. Bloor
Keyword(s):  
Cell Membrane ◽  
Membrane Permeability ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Cell Membrane Permeability ◽  
Enzyme Release ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Sarcolemmal Permeability ◽  
Membrane Changes

Following coronary artery occlusion, the myocardial cells lose intracellular enzymes that appear in the serum 3 hrs later. By this time the cells in the ischemic zone have already undergone irreversible changes, and the cell membrane permeability is variably altered in the ischemic cells. At certain stages or intervals the cell membrane changes, allowing release of cytoplasmic enzymes. To correlate the changes in cell membrane permeability with the enzyme release, we used colloidal lanthanum (La+++) as a histological permeability marker in the isolated perfused hearts. The hearts removed from sprague-Dawley rats were perfused with standard Krebs-Henseleit medium gassed with 95% O2 + 5% CO2. The hypoxic medium contained mannitol instead of dextrose and was bubbled with 95% N2 + 5% CO2. The final osmolarity of the medium was 295 M osmol, pH 7. 4.

Sign in / Sign up

Export Citation Format

Share Document