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.

Peliosis in Spontaneous Adenomas of the Rat Pituitary. An Electron Microscopic Study

1982 ◽  
Vol 40 ◽  
pp. 352-353
Author(s):  
G. Ilse ◽  
K. Kovacs ◽  
J. Beri ◽  
F. Zak
Keyword(s):  
Electron Microscopy ◽  
Adrenal Cortex ◽  
Microscopic Study ◽  
Sprague Dawley ◽  
Electron Microscopic ◽  
Cell Adenoma ◽  
Prolactin Cell ◽  
Sprague Dawley Rats ◽  
Rat Pituitary ◽  
Long Evans

Lakes of blood are frequently observed in spontaneous prolactin cell adenomas of the rat pituitary. The lesions resemble peliosis, a disorder found mainly in the liver but also in the adrenal cortex. In order to reconstruct the events involved in the formation of these blood lakes, 25 spontaneous prolactin cell adenomas and 1 non-prolactin cell adenoma were harvested from adult female Long-Evans and Sprague-Dawley rats and investigated by electron microscopy.

Light and electron microscopic investigation of adenohypophyses of germfree, food-restricted, and germfree-food restricted aging, male lobund-wistar rats

1988 ◽  
Vol 46 ◽  
pp. 352-353
Author(s):  
G. Ilse ◽  
K. Kovacs ◽  
N. Ryan ◽  
T. Sano ◽  
L. Stefaneanu ◽  
...  
Keyword(s):  
Wistar Rats ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Aging Male ◽  
Sprague Dawley ◽  
Electron Microscopic ◽  
Sprague Dawley Rats ◽  
Old Rats ◽  
Ad Libitum ◽  
Microscopic Findings

Germfree state and food restriction have been shown to increase life span and delay tumor occurrence in rats. We report here the histologic, immunocytochemical and electron microscopic findings of adenohypophyses of aging, male Lobund-Wistar rats raised at Lobund Laboratories. In our previous study, the morphologic changes in the adenohypophyses of old rats have been extensively investigated by histology, immunocytochemistry and electron microscopy. Lactotroph adenomas were frequent in Long-Evans and Sprague-Dawley rats, whereas gonadotroph adenomas were frequent in Sprague-Dawley and Wistar rats.Male Lobund-Wistar rats were divided into four groups: 1) conventional, which were raised under normal non-germfree environment and received food ad libitum; 2) germfree-food ad libitum; 3) conventional environment-food restricted and 4) germfree-food restricted. The adenohypophyses were removed from 6-month-, 18-month- and 30-month-old rats. For light microscopy, adenohypophyses were fixed in formalin and embedded in paraffin.

Strain Differences Occurring in an Experimental Study of Punishment

1965 ◽  
Vol 16 (2) ◽  
pp. 531-536 ◽  
Author(s):  
Morton H. Kleban
Keyword(s):  
Experimental Study ◽  
Empirical Evidence ◽  
Wistar Rats ◽  
Strain Differences ◽  
Training Procedure ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Y Maze ◽  
Minimum Number ◽  
The Difference

Forty-three Sprague-Dawley and 43 Wistar rats were given reward training for 40 trials in a Y-maze. On the next 20 trials, control groups were continued under the same training procedure, and 50% shock trials were introduced in the training of the remaining rats. For the extinction training, the reward was shifted to the opposite arm and 50% shock was continued for the no-delay and 30-sec. delay shock groups. The most significant results were that in the 30-sec. delay groups, the delay helped the Sprague-Dawley rats reverse in a minimum number of trials, whereas the Wistar rats showed strong indications of response stereotypy. The findings with respect to the Sprague-Dawley rats supported the empirical evidence on the effectiveness of delay in overcoming response persistence and the findings on the Wistar rats supported the empirical evidence on omission in punishment. The difference in response to punishment between the two albino strains emphasizes the need for experimental study of strain factors. Experiments should be repeated with several animal strains to remedy over-generalization from single strains and to help elaborate our understanding of the interaction present between punishment and strains.

Orally administered L-arginine does not alter right ventricular hypertrophy in chronically hypoxic rats

1994 ◽  
Vol 266 (2) ◽  
pp. R559-R563 ◽  
Author(s):  
T. C. Resta ◽  
B. R. Walker
Keyword(s):  
Right Ventricular ◽  
Pulmonary Circulation ◽  
Wistar Rats ◽  
Chronic Hypoxia ◽  
Chronic Administration ◽  
Hypoxic Exposure ◽  
Sprague Dawley ◽  
Pulmonary Vasodilation ◽  
Pulmonary Vasodilators ◽  
Sprague Dawley Rats

Evidence suggests that nitric oxide synthesis within the pulmonary circulation may be attenuated during chronic hypoxia in Wistar rats due to reduced L-arginine availability. In contrast, chronically hypoxic Sprague-Dawley rats exhibit normal endothelium-dependent pulmonary vasodilation. The purpose of the present study was to determine whether 1) Wistar rats demonstrate greater right ventricular (RV) hypertrophy in response to chronic hypoxia than Sprague-Dawley rats and 2) chronic administration of L-arginine would diminish this response in Wistar rats. L-Arginine had no effect on the degree of hypoxia-induced RV hypertrophy or polycythemia in either strain of rat. However, Wistar rats demonstrated greater hypoxia-induced RV hypertrophy and polycythemia compared with Sprague-Dawley rats. To determine whether chronically hypoxic Wistar rats indeed exhibit impaired endothelium-dependent pulmonary vasodilation, isolated lungs from control and chronically hypoxic Wistar rats were administered the endothelium-dependent pulmonary vasodilators A23187 or vasopressin. Vasodilatory responses to either agent were unaffected by chronic hypoxic exposure. We conclude that endothelium-dependent pulmonary vasodilation is maintained in the pulmonary circulation of chronically hypoxic Wistar and Sprague-Dawley rats.

Early signs of toxicity in testes and sperm of rats exposed to low cadmium doses

2017 ◽  
Vol 33 (7) ◽  
pp. 576-587 ◽  
Author(s):  
Marcela Fátima Medina ◽  
María Celeste Arrieta ◽  
Marcela Noemí Villafañe ◽  
Sandra María Roxana Klyver ◽  
Iris María Aybar Odstrcil ◽  
...  
Keyword(s):  
Wistar Rats ◽  
Chronic Toxicity ◽  
Microscopic Level ◽  
Anthropogenic Activity ◽  
Dependent Manner ◽  
Light Microscopic Level ◽  
Cd Toxicity ◽  
Early Signs ◽  
Transmission Electron ◽  
Outer Dense Fibers

The cadmium (Cd) concentration in the environment has increased as a consequence of anthropogenic activity. The objective of this study was to determine early signs of Cd toxicity in testes and sperm as possible biomarkers. The dose orally administered to Wistar rats was within the range where chronic toxicity can appear. At the light microscopic level, gonads presented preserved cytoarchitecture throughout treatment; however, after the second month, transmission electron microscopy (TEM) revealed disruption of the blood–testis barrier. The study of sperm with light microscopy showed defects in gamete morphology after 2 months of treatment. Another parameter that revealed alteration was sperm motility after 3 months of treatment. TEM was used to analyze the flagellum, which in the midpiece showed aberrant mitochondria and displacement of outer dense fibers in relation to the central axoneme after 2 months. The data obtained were associated with Cd concentration in the testes, an increase in its levels being observed in a time-dependent manner. The results provided in this study demonstrated that early signs of Cd toxicity were observed in gonads and gametes during the second month of the treatment, generating morphological and functional alterations in the sperm that could lead to infertility.

Does oxytocin play a role in the onset of maternal behaviour in the rat?

1984 ◽  
Vol 101 (3) ◽  
pp. 353-357 ◽  
Author(s):  
E. L. M. Bolwerk ◽  
H. H. Swanson
Keyword(s):  
Wistar Rats ◽  
Single Injection ◽  
Rapid Onset ◽  
Maternal Responsiveness ◽  
Control Group ◽  
Maternal Behaviour ◽  
Sprague Dawley ◽  
Untreated Control Group ◽  
Sprague Dawley Rats ◽  
Oestradiol Benzoate

ABSTRACT Oxytocin is released during parturition and may also play a role in maternal behaviour. Oxytocin, injected in the cerebral ventricles, has been reported to accelerate the onset of maternal behaviour in oestrogen-pretreated virgin Sprague—Dawley rats within 2 h of injection. This study was an attempt to replicate and extend these findings in Wistar rats. In the first experiment, 16 virgin females were ovariectomized and a cannula was placed into the cerebral ventricle. Forty-eight hours after a single injection of 24 μg oestradiol benzoate (OB), 400 ng oxytocin or saline were injected into the ventricle. In the second experiment three groups were observed: an untreated control group plus two ovariectomized and cannulated groups treated with OB in a regimen designed to mimic pregnancy. After 10 days of OB administration they received an injection of either saline or oxytocin (400 ng) into the ventricle. Immediately after this injection they were exposed to the pups and observations started. In both experiments no rat became maternal in the first 1·5 h after the intracerebroventricular injection. Oxytocin therefore did not induce a rapid onset of maternal responsiveness in oestrogen-pretreated Wistar rats. J. Endocr. (1984) 101, 353–357

Oxytocin resistance in Brattleboro rat adipocytes and comparative studies on insulin or oxytocin responsiveness in normal rat adipocytes

1983 ◽  
Vol 61 (11) ◽  
pp. 1418-1425 ◽  
Author(s):  
K. Hanif ◽  
H. J. Goren ◽  
R. M. Geonzon ◽  
K. Lederis ◽  
M. D. Hollenberg
Keyword(s):  
Calcium Concentration ◽  
Maximal Response ◽  
Sprague Dawley ◽  
Assay Medium ◽  
Rat Adipocytes ◽  
Sprague Dawley Rats ◽  
Normal Rat ◽  
Increased Sensitivity ◽  
Long Evans ◽  
Treatment Use

We have evaluated factors, other than genetic, which might be related to the lack of an oxytocin-mediated insulinlike response (glucose oxidation; lipogenesis) in adipocytes from Brattleboro rats, homozygous for the diabetes insipidus trait (HoDI rats). The manoeuvres used in an attempt to restore the glucoregulatory responses to oxytocin in HoDI cells (increased glucose in the fat pad digestion medium; increased calcium concentration in the oxidation assay; estrogen treatment; use of [1-14C]glucose as substrate; inclusion of adenosine in the assay medium; vasopressin replacement therapy) uniformly failed to result in oxytocin activation of HoDI adipocytes, in contrast, the contractile responses of estrogenized HoDI rat uteri were indistinguishable from those of estrogenized normal rats. We conclude that the nonresponsiveness of the Brattleboro adipocytes to the glucoregulatory actions of oxytocin is not due to factors related to the conditions of the bioassay. On the other hand, in normal fat cells (from Sprague–Dawley and Long Evans rats), oxytocin responsiveness was augmented by a number of the manoeuvres mentioned above, most notably by the inclusion of either calcium (10 mM) or adenosine (10 μM) in the assay medium. Nonetheless, the maximum oxytocin responsiveness of adipocytes from Long Evans or Sprague–Dawley rats, under all conditions of assay, was still only a fraction (less than 20%) of the maximal response to insulin. The effect of adenosine on oxytocin action (increased sensitivity, without an effect on the maximum response) is in keeping with the previously observed effects of this nucleoside on the action of insulin; our results thus pointed to a new parallel in the action of insulin and oxytocin.

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