scholarly journals Effect of a Short-Term and Long-Term Melatonin Administration on Mammary Carcinogenesis in Female Sprague-Dawley Rats Influenced by Repeated Psychoemotional Stress

2007 ◽  
Vol 76 (3) ◽  
pp. 371-377 ◽  
Author(s):  
M. Kassayová ◽  
E. Adámeková ◽  
B. Bojková ◽  
P. Kubatka ◽  
I. Ahlers ◽  
...  

The aim of this study was to evaluate the effect of melatonin (MEL) on N-methyl-N-nitrosourea (NMU)-induced mammary carcinogenesis in female Sprague-Dawley rats exposed to repeated psychoemotional stress - immobilization in boxes. NMU was applied intraperitoneally in two doses each of 50 mg/kg b.w. between 40 - 50 postnatal days. Melatonin was administered in drinking water at a concentration of 4 μg/ml daily from 15:00 h to 8:00 h. The application was initiated 5 days prior to the fi rst NMU dose and lasted 15 days, i.e. during the promotion phase of tumour development, or long-term until the end of the experiment (week 20). Immobilization (2 h per day) began on the third day after the second carcinogen application and lasted for 7 consecutive days. Short-term MEL administration to immobilized animals increased incidence by 22%, decreased tumour frequency per animal by 26% and reduced tumour volume gain (by 21%) when compared to the immobilized group without MEL application. Decreased frequency per animal by 28% and more than a 40% decrease in tumour volume gain and cumulative volume were the most pronounced changes in the animals drinking MEL until the end of the experiment. Long-term MEL administration reduced the number and size of mammary tumours more markedly than its short-term administration. Melatonin decreased certain attributes of mammary carcinogenesis in female rats influenced by psychoemotional stress.

Biologia ◽  
2013 ◽  
Vol 68 (4) ◽  
Author(s):  
Peter Orendáš ◽  
Ivan Ahlers ◽  
Bianka Bojková ◽  
Monika Kassayová ◽  
Peter Kubatka ◽  
...  

AbstractChemopreventive effect of non-steroidal antiinflammatory drugs (NSAIDs) in mammary carcinogenesis was reported in several studies. In this study, the effect of a nonselective cyclooxygenase inhibitor diclofenac (DICLO) in the prevention of N-methyl-N-nitrosourea (NMU)-induced mammary carcinogenesis in Sprague-Dawley female rats was evaluated. NMU was administered to animals intraperitoneally in two doses of 50 mg kg−1 b.w. within postnatal days 42-48. In experiment A (short-term administration), DICLO was administrated intramuscularly (5 mg kg−1 b.w.) every other day, starting 3 days before and for subsequent 25 days after first NMU injection. In experiment B (long-term administration), DICLO was administered in tap water (0.01 mg ml−1) continually, starting 7 days before and for subsequent 22 weeks after first NMU dose. The study was terminated 22 weeks after the first dose of NMU in both experiments. After DICLO treatment, tumor frequency per group was reduced in both variants of drug administration: in experiment A by 38% and in experiment B by 39.5%. Moreover, DICLO decreased tumor incidence by 11.5% and delayed tumor latency by 14 days in experiment B. In our preventive-curative experiments DICLO decreased some parameters of NMU-induced rat mammary carcinogenesis, mainly the tumor frequency.


1995 ◽  
Vol 20 (3) ◽  
pp. 195-205 ◽  
Author(s):  
Takashi YAMADA ◽  
Tadahiro INOUE ◽  
Akinori SATO ◽  
Kumiko YAMAGISHI ◽  
Motonobu SATO

1998 ◽  
Vol 32 (4) ◽  
pp. 477-482 ◽  
Author(s):  
Maud Palm

Chronic progressive nephrosis (CPN) in rats may not only become a problem in long-term toxicity studies but also in short-term studies, if the breeding stock is not carefully selected with respect to the kidney function. This paper presents differences in kidney function between young rats of the same strain, Sprague-Dawley, but from two different breeders ('set A' and 'set B' rats). In set A rats, protein in the urine was present in the males, which is a common finding. In set B rats, not only the males but also the females excreted protein in the urine. The method used to detect protein in the urine does not normally show a positive protein result in the young female rats. At the age of 3 months signs of chronic progressive nephrosis were observed in 55% of the males and in 15% of the females in set B. Two months later, the incidence had increased to about 70–80% in males and 50% in females. At 8 months, the incidence was similar, but the severity had increased. These values were compared with those obtained from the set A rats, none of which showed any signs of the disease at the age of 5 months and only 5% of the males and females at the age of 8 months. The results indicated that an increased excretion of protein in the urine may be used as an indicator for chronic progressive nephrosis in the rat and that not only the strain but also the source is important in selecting laboratory rats for toxicity studies.


1989 ◽  
Vol 256 (5) ◽  
pp. E682-E685 ◽  
Author(s):  
M. Kalimi

This study was conducted to investigate whether hypertension induced by long-term in vivo administration of dexamethasone in rats could be prevented by the newly synthesized potent antiglucocorticoid drug RU 486. Subcutaneous implantation of 5 mg of dexamethasone pellets in Sprague-Dawley rats resulted in a rapid increase in the blood pressure that remained elevated during the 3 wk of experimental observation. RU 486 (50 mg) administered alone surprisingly showed slight elevation of blood pressure over untreated control animals. However, the blood pressure leveled off to control levels over the next 2 wk. Interestingly, a 50-mg RU 486 pellet implanted along with 5 mg of dexamethasone effectively prevented the dexamethasone-induced increase in blood pressure. RU 486 administered together with dexamethasone prevented dexamethasone-induced diuresis and urinary Na+ excretion. However, RU 486 was unable to reverse the weight loss or involution of thymus observed by long-term treatment with dexamethasone alone. No abnormalities were found in either kidneys or hearts in any of the treated groups under microscopic examination. These results suggest that RU 486 successfully prevented the hypertension produced by the long-term administration of dexamethasone in male Sprague-Dawley rats.


2018 ◽  
Vol 42 (6) ◽  
pp. 498-505 ◽  
Author(s):  
Koffi KOUAME ◽  
Aniekan Imo PETER ◽  
Edidiong Nnamso AKANG ◽  
Misturah ADANA ◽  
Roshila MOODLEY ◽  
...  

2021 ◽  
Vol 9 (7) ◽  
pp. 1481
Author(s):  
Lin Du ◽  
Yolanda Wong Ying Yip ◽  
Him Kwan Ng ◽  
Bo Man Ho ◽  
Jing-Na He ◽  
...  

Uveitis is characterized by inflammatory lesions of intraocular structures. It is one of the important manifestations in patients with Reiter’s syndrome, an inflammatory arthritis, which is caused by enteric infection with bacteria, including Salmonella typhimurium. Corticosteroids remain the most frequently used therapies against uveitis associating with inflammatory arthritis. However, the long-term administration of steroids results in many side effects, and some uveitis patients do not respond to steroid treatment. Non-steroidal treatments are needed for uveitis patients. Our previous study found that Janus kinase (JAK) 1/2 inhibitor, ruxolitinib could suppress the expression of proinflammatory mediators in the ciliary body and iris. However, the impacts of ruxolitinib on ophthalmic features in uveitic eyes are still unknown. In this study, Salmonella typhimurium endotoxin-induced uveitis (EIU) was induced in Sprague Dawley rats by the injection of lipopolysaccharide (LPS). Compared with LPS-induced rats treated with water, ruxolitinib significantly attenuated the clinical manifestations, infiltrating cells and protein exudation in the aqueous humor, and retina–choroid thickening. Amplitudes of b-wave in both scotopic and photopic electroretinogram (ERG), and the amplitude of a-wave in scotopic ERG in EIU animals were alleviated by ruxolitinib. Collectively, we propose ruxolitinib could attenuate endotoxin-induced uveitis and rescue visual functions in rats by inhibiting the JAK2-STAT3 pathway.


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