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21.
To evaluate whether the median eminence (ME) is a site of action of CRF (corticotropin releasing factor) on GH secretion and
to determine the possible role of estradiol and progesterone in modifying theses secretion, we injected CRF (0.25, 0.75, 1,
and 1.5 nmol of peptide dissolved in 1 μl of water) directly into the ME in three experimental groups of rats: Long-term ovariectomized
(OVX); OVX primed by estradiol (OVX±E) and OVX primed by estradiol plus progesterone (OVX±EP). Blood was collected to determine
GH (30, 60, 90, and 120 min postinjection) Serum T3, T4, and glucose levels were measured in OVX±E rats 30 min postinjection. CRF at all doses studied significantly decreased serum
GH levels in the three experimental groups. Serum T3, T4, and glucose levels were unchanged after CRF administration. The results suggest that: CRF inhibits “per se” GH secretion,
at least in part, by a central action in the ME. The inhibitory effect of CRF on GH is independent of the estrogen/progesterone
status of the animal. CRF at ME levels may participate in a variety of stress-related responses, including growth inhibition,
through GH suppression. 相似文献
22.
Böhm Manfred Lippoldt Andrea Wienen Wolfgang Ganten Detlev Bader Michael 《Molecular and cellular biochemistry》1996,163(1):217-221
TGR(mREN2)27 is a transgenic rat harboring the murine Ren-2 gene and exhibit fulminant hypertension and marked heart hypertrophy. In order to study the role of angiotensin II in the increase of cardiac mass, these animals were treated with anti-hypertensive and non-antihypertensive doses of the angiotensin II receptor AT1 antagonist Telmisartan for 9 weeks. All doses led to significant reductions of heart hypertrophy detected by the evaluation of the diameter of cardiac muscle bundles. We conclude from this study that cardiac hypertrophy in TGR(mREN2)27 is characterized by an increased volume of cardiomyocytes and an unchanged amount of fibrous tissue and that angiotensin II plays an important role in the mechanisms leading to this phenotype. 相似文献
23.
Ian R. Record Jennifer K. McInerney Ivor E. Dreosti 《Biological trace element research》1996,53(1-3):27-43
Previous studies have shown that tea consumption can impair trace element metabolism, particularly iron status, and increase
the risk of anemia in humans and animals. More recently, however, evidence has been accumulating to show that, in animals,
consumption of green tea or its polyphenols is associated with a reduction of the incidence and severity of a variety of experimentally
induced cancers. In this study we have monitored the growth, trace element status, including hematological parameters of weanling
rats given either (1) water, (2) 1% black tea, (3) 1% green, tea, or (4) 0.2% crude green tea extract as their sole drinking
fluid while consuming diets containing either adequate or low amounts of iron. With the exception of manaanese, none of the
trace elements studied (iron, copper, zinc, and manganese) or the hematological indices measured were affected by the type
of beverage supplied, even though the polyphenol extract was shown to chelate metals in vitro and all the animals fed the
low iron diet were shown to be anemic. There appeared to be an effect of black and green teas on manganese balance in, both
the first and last weeks of the study. A lower level of brain managanese was associated with green tea consumption, and a
higher level of this element in the kidneys of animals fed black tea. The results demonstrate that both black and green teas
and a green tea polyphenol extract do not represent a risk to animals consuming the beverages as their sole fluid intake with
respect to iron availability, although the interactions with manganese deserve further study. 相似文献
24.
Stephen Maren 《Molecular neurobiology》1996,13(1):1-22
Numerous studies in both rats and humans indicate the importance of the amygdala in the acquisition and expression of learned
fear. The identification of the amygdala as an essential neural substrate for fear conditioning has permitted neurophysiological
examinations of synaptic processes in the amygdala that may mediate fear conditioning. One candidate cellular mechanism for
fear conditioning is long-term potentiation (LTP), an enduring increase in synaptic transmission induced by high-frequency
stimulation of excitatory afferents. At present, the mechanisms underlying the induction and expression of amygdaloid LTP
are only beginning to be understood, and probably involve both theN-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) subclasses of glutamate receptors. This article
will examine recent studies of synaptic transmission and plasticity in the amygdala in an effort to understand the relationships
of these processes to aversive learning and memory. 相似文献
25.
KIBENGE, MOLLY T AND CATHERINE B CHAN. Identification of biochemical defects in pancreatic islets of fa/fa rats: a developmental study. Obes Res. 1995;3:171–178. Adult obese (fa/fa) Zucker rats hypersecrete insulin in response to glucose and other secretagogues. Functional changes in islet ot2-adrenoceptors (8) and glycolytic regulation (9) have been reported. In this study, the development of these biochemical lesions in islets isolated from suckling (3 week old) and weanling (5 week old) lean and fa/fa rats was investigated and compared to results in adult animals. Glucose (15 mM)-induced insulin secretion was inhibited by mannoheptulose (MH) in lean (n=8) but not fa/fa (n=10) adult rats, indicating loss of sensitivity of glucokinase to competitive inhibition. Sensitivity to MH was somewhat reduced in the islets of 3- and 5-week-old fa/fa (n=7 and 12) compared to lean (n=15 and 9) rats, requiring 30–100 fold higher concentrations to achieve significant inhibition. At 3 weeks of age fa/fa rats did not differ from lean controls in either islet insulin content or body weight, but both parameters were increased in fa/fa rats by 5 weeks. The presence of altered α2-adrenoceptor function in fa/fa rats could not be confirmed in this study. Unlike the previous report, prazosin did not antagonize α2-agonist mediated inhibition of insulin secretion. The presence of defective regulation of the glycolytic pathway by mannoheptulose in suckling and weanling rats may contribute to development of hyperinsulinemia in fa/fa rats. 相似文献
26.
Chronic Administration of Lithium Chloride Increases Immunodetectable Glial Fibrillary Acidic Protein in the Rat Hippocampus 总被引:3,自引:0,他引:3
Abstract: We studied the effect of treating rats with lithium salts on the content and in vitro phosphorylation rate of the astrocyte cell marker, glial fibrillary acidic protein (GFAP), in brain slices. Rats were fed a diet incorporating lithium chloride until the concentration of Li+ in serum reached 0.6–1.2 m M , a range similar to that achieved in clinical practice. Hippocampal tissue was analyzed for immunoreactive GFAP by a dot assay, and slices of hippocampus and caudate nucleus were labeled with [32 P]-phosphate to determine the in vitro rate of phosphorylation of GFAP. Compared with controls, the level of immunoreactive GFAP in the hippocampus from lithium-treated rats was increased 34%, and GFAP in hippocampal slices incorporated 39% more 32 P. This effect of lithium was apparently not confined to the hippocampus because the in vitro rate of phosphorylation of GFAP in caudate slices was also increased in the treated rats. 相似文献
27.
低浓度氢清除法测定大鼠局部脑血流量 总被引:2,自引:0,他引:2
利用氢清除法测量动物局部脑血流量已被广泛应用于研究中。本文采用低于爆炸范围下限的3%H2浓度,它可以与任何比例的氮氧气体安全混合,且可避免吸纯氢期间的短暂缺氧,更为严格地控制了实验条件,增加了安全和准确性。本工作对吸100%H2和吸3%H2以及吸3%H21-1.5min和吸3%H25min测得脑血流量分析作了比较,结果表明短期低浓度氢清除法能较好地反映动物的局部脑血流量。 相似文献
28.
以雌激素含量明确的避孕药物作诱导剂观察了其对离乳Wistsar大鼠性成熟的影响,结果显示在给予避孕药后体重、乳腺、阴门、阴道上皮细胞、卵巢、子宫均发生类似人体假性性早熟变化,而肾上腺、脑垂体、甲状腺等与对照组比较均未见明显差异。 相似文献
29.
《Reproductive biology》2023,23(1):100724
Fluoride is a common environmental contaminant that has harmful effects on human health when it is present in high concentrations. Fluoride enters the bloodstream after being absorbed by the gastrointestinal system when fluoride-contaminated groundwater is consumed by people. The aim of the present study was to determine whether polyphenol-rich nano Moringa oleifera (NMO) could protect rat testicles from sodium fluoride (NaF) damage by evaluating sperm quality, sex hormones, testicular oxidative status, histopathology, and StAR gene expression. Twenty-eight adult Wistar rats were divided equally and randomly into four groups: group one received distilled water; group two received NMO at a dosage of 250 mg/kg/body weight; group three received NaF at a dosage of 10 mg/kg/body weight; and group four received NaF and NMO. The rats were orally administrated daily for a duration of eight weeks. The study's findings demonstrated that, in comparison to rats exposed to NaF alone, co-administration of NMO and NaF enhanced sperm motility and viability, decreased sperm morphological changes, restored the balance between oxidant and antioxidant status, improved testosterone and dehydroepiandrosterone, improved testicular histology, raised the Johnson score, and upregulated the StAR gene in testicular tissue. These findings show that NMO is promise as a prophylactic medication against sodium fluoride-induced testicular damage because administration of NMO had no adverse effects and enhanced reproductive health. 相似文献
30.
摘要 目的:探讨与分析女贞子提取物对帕金森病大鼠神经炎性反应及内质网应激蛋白激酶R样内质网激酶(PERK)/转录活化因子4(ATF4)通路的影响。方法:采用单侧注射6-羟基多巴胺(6-OHDA)毁损法建立帕金森病大鼠模型,将造模成功的大鼠36只随机平分为三组-模型组、左旋多巴组与女贞子组,每组各12只。左旋多巴组与女贞子组分别灌胃0.5 mL的左旋多巴、女贞子提取物,模型组给予无菌蒸馏水0.5 mL,2次/d,连续给药4周,检测大鼠神经炎性反应、内质网应激PERK/ATF4通路相关蛋白表达变化情况。结果:左旋多巴组与女贞子组治疗第2周、第4周的探究性反应次数显著高于模型组(P<0.05),女贞子组与左旋多巴组对比也有显著提高(P<0.05)。左旋多巴组与女贞子组治疗第2周、第4周的脑组织伊文思蓝含量显著低于模型组(P<0.05),女贞子组与左旋多巴组对比也有显著降低(P<0.05)。左旋多巴组与女贞子组治疗第2周、第4周的血清丙二醛、白介素-1β、肿瘤坏死因子-α、一氧化氮含量显著低于模型组(P<0.05),女贞子组与左旋多巴组对比也有显著降低(P<0.05)。左旋多巴组与女贞子组治疗第2周、第4周的黑质-纹状体组织PERK蛋白、ATF4蛋白相对表达水平显著低于模型组(P<0.05),女贞子组与左旋多巴组对比也有显著降低(P<0.05)。结论:女贞子提取物在帕金森病大鼠的应用能改善神经功能,降低脑组织伊文思蓝含量,还可抑制PERK/ATF4通路的激活,降低血清丙二醛、白介素-1β、肿瘤坏死因子-α、一氧化氮含量,从而持续发挥脑保护作用。 相似文献