Sprague-Dawley Rats

PURPOSE The main goal of experiment three was to test a rat’s ability to be conditioned to perform a behavior, and then relearn the same behavior after an extinction period. After ensuring that the rat was conditioned on a continuous reinforcement schedule (CRF), the next goal in the experiment was to extinct the previously learned behavior of lever pressing and receiving a food pellet. Once the behavior was extinct, the rat was reconditioned to lever press on a conditioned reinforcement schedule. The goal of the experiment was to demonstrate that a behavior could be learned, extinct, and then relearned.

As described before, an endocrine disruptor is a chemical with the potential to alter hormone action within the body. When in the body, these components have the potential to interact with a multitude of hormones, signaling disturbance of homeostasis. Many ubiquitous environmental chemicals, including natural chemicals and numerous artificial chemicals have the potential to be harmful, but there is “evidence for two environmental agents: ionizing radiation and the estrogen agonist diethylstilbestrol (DES)” (Birnbaum, & Fenton 2009). Scientist have confirmed this by analyzing the impact of ionizing radiation’s is through diagnostic assessment of pregnant women. Doll and Wakeford (1997), scientist from the National Center for Biotechnology Information, concluded that “low doses of X ray to the fetus, especially during

In addition to the 52-week toxicity in infant monkeys, the 2010 Swiss mice study has also been cited in the general aspartame debate. Before this study occurred, previous lifespan experiments conducted on Sprague-Dawley rats have shown that aspartame exposure, starting from prenatal life, increases carcinogenetic effects in rats . This study aimed to validate aspartame’s link to causing cancer in rats . Furthermore, rodents—rats and mice—were used in this study because they, like primates, are one of the four super-orders of placental mammals . There were six groups of 62-112 male and female mice, which were treated with aspartame . They were fed at dosages of 32,000, 16,000, 8,000, 2,000, or 0 ppm from 12 days of conception to death . After

Having a rat model with a more-human like liver will allow investigators to better understand normal and diseased human liver physiology and biochemistry (82). It will allow us to test and compare the ability to repopulate livers with different cell sources which have had limited success in the mouse (3). Primary human hepatocytes have been shown to efficiently repopulate recipient livers (32), however with limited access to large quantities, researchers must examine whether other types of hepatic stem cells can act as potential donors as well. Having an efficient model that can be used to perform repopulation experiments in short periods of time could in theory lead to new therapies for patients. It could

The goal was to estimate the amount of motoneurons present in the different sections in the SNB of 9 Sprague-Dawley rats. Previously, the adults’ rats were killed and injected with saline and formalin in the heart. They had their spinal cords removed and mounted in four consecutive sections through the lower lumbar spinal cord (5th, 7th, 9th, and 11th). The sections were stained with thionin and photomicrographs were made for each rat. So, four photos for each rat.

Existence of male breast cancer carriers indirectly proves the synthetic chemicals carcinogenic. Interrupted by environmental chemicals, male hormone-synthesis pathways function abnormally to produce a higher amount of estrogen, the female sex hormone, and long-term accumulation of estrogen in male breast leads to a significantly higher risk of breast cancer. As more and more researches got conducted based on the evidently carcinogenic synthetic chemicals, scientists have hypothetically proposed a list of carcinogenic chemicals.

As a result, evidence was proven that the lab animals tested with the endocrine-disrupting chemicals, distinctively increased in size and weight. From the University of California, Bruce Blumberg was one of the first scientists to notice a link between the disrupting chemicals and obesity in the lab animals; resulting in his theory to be that “obsesogens” were causing the animals to gain fat. Obsesogens are classified as common chemicals found in our environment and are endocrine-disruptors that appear to be most dangerous when taken in small quantities. From the University of Missouri, Fred Vom Saal was researching on the effects of Bisphenol-A (an endocrine-disruptor) and injected them with a small dose of BPA equivalent to the amount a human would ingest in a day. Results have shown that it had caused reproductive abnormalities of weight gain. From the U.S National Institute for Environmental Health Sciences (NIEHS), Retha Newbold studied the health effects on D.E.S, which is a hormone replacement drug, have found to be linked with ovarian cancer. Newbold’s research experiment was to inject the rats with D.E.S, and results significantly showed the animals became obese due to the chemical. All the experiments conducted, had shown that the endocrine disrupting chemical did indeed include a link to the obesity in the lab

In a 1983 study, American researchers found that high doses of Red No. 40 administered to adult rats and their offspring resulted in “significantly reduced reproductive success, parental and offspring weight, brain weight, [and] survival” as well as behavioral abnormalities. Though the U.S. Food and Drug Administration approved its use over twenty years ago, there is enough uncertainty about the safety of Red No. 40 that it is banned in Austria, Belgium, Denmark, France, Germany, Sweden, and Switzerland.

The subjects were compromised of 45 adults male Japanese quail. These quail were around 2-3 months of age. Male quail were strictly selected for the study on the basis of a pretest for sexual behavior. During this “pretest”, a female quail was placed in the home cage of each male quail for approximately 5 minutes. Only the subjects of whom copulated were selected for the actual experiment. All of the subjects wee drug and sexually naïve prior to the experiment. “All experimental procedures were approved by and carried out under the guidelines set by the Animal Care and Use Committee at the University of Kentucky” (Bolin, 2012).

Recently, Paris ushered in a group of uninvited “guests”—clustered rats. Some people have already met with them. For instance, “Nadine Mahe des Portes” (para.1) stepped on one rat on the way home. And, as result of rats, Parisians may have the possibility of tripped over them on the sidewalk. Differing from before, rats “brazenly feed in broad daylight” (para.3). They were “all over the park”, “sauntering across the footpaths”, “merrily grazing in the undergrowth” and far more bothered by “pigeons competing with them for breadcrumbs” (para.5), which are used to feed pigeons by tourists and local people. Rats “foraging for food” regularly scampered through the “children's play area” and trash bins, “sowing panic” (para.8). People often use a

In the current study, 40 Long-Evans male rats will be assessed in the back-test at approximately 23 and 30 days of age to determine the coping profile of each individual rat. After profiling is completed, 24 rats with the most representative coping profiles will be identified yielding three groups: 8 active copers, 8 passive copers, and 8 flexible copers. In week two, the rats will be trained to perform attentional set shifting tasks (AST) which requires them to dig for a food reward (fruit loops). The rats will have to discriminate between specific salient variables such odors and digging mediums to successfully complete the trial and obtain their food reward. The rats will progress from simple discrimination AST (e.g., from one smell to another)

Foradori, Hinds, Hanneman, and Handa (2009a) conducted a study to determine the impact of atrazine and its adverse effects on rats to test the impact of atrazine on the reproductive system. The female rats had their ovaries surgically removed and were given estrogen and progesterone hormones to stimulate the release of two important hormones needed for ovulation–gonadotropin releasing hormone (GnRH) from the brain and luteinizing hormone (LH) from the pituitary gland. The sterile rats were fed varying doses of atrazine to test if the herbicide interfered with the release of gonadotropin releasing hormone and luteinizing hormone. Findings show that gonadotropin releasing hormone activity and luteinizing hormone levels were significantly lower in animals fed atrazine, regardless of dose because atrazine reduces the activity of the gonadotropin releasing hormone neurons in the brain and blocks the luteinizing hormone surge that controls ovulation in vertebrates (Foradori et al 2009a). The experiments done by Cooper, Stoker, Tyrey, Goldman, and McElroy support these findings explain that the effect of atrazine on luteinizing hormone and prolactin secretion is mediated by means of taking action at the site of the hypothalamus,

The diets were continued throughout gestation and lactation for the females after conception. Their results suggested that the rats receiving 2 % of the food additive BVO in their feed became completely infertile. At 1 % of BVO, the rats suffered impaired fertility, reduced maternal body weight and reduced litter sizes but no evidence of malformations. Besides, postnatal mortality was high at this dose and impaired growth was observed among the survivors. Another experiment that done by Munro et al. (1969) found that all rats had arrested testicular development, thyroid hyperplasia, fatty changes in the liver, myocarditis, renal tubular epithelial changes and reduced liver enzyme activities when fed with semi-purified diet containing 0, 0.5% or 2.5% of brominated cottonseed oil for 80

The brown rat (rattus norvegicus) is a small brown rodent that has bilateral symmetry which means it can be divided into halves. A full grown brown rat can be up to 10 inches long. It usually weighs 8.1 ounces. Brown rats are different than other rats because the top of their head is slanted, like a triangle, and their tail is shorter than their body. Brown rats have brown fur. Their stomachs are lighter brown or gray.

The herbicide atrazine has been shown to affect the reproductive system development in rats. Mothers were dosed with atrazine and their offspring showed a delay in vaginal opening in the females and a higher incidence of prostate inflammation in the males. Atrazine has also been shown to affect hormone metabolism in women, which may have possible implications for breast