Effect of age on body weight, heart rate and blood pressure in pair-caged, male, Fischer 344 rats
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The effect of a continuous 5-day ACTH infusion (40 U/24 h) on adrenocorticoid function, electrolyte metabolism, and blood pressure was investigated in eight normotensive children and eight patients with hypertension of unknown origin. There was a continuous rise of plasma cortisol and deoxycorticosterone in all patients. Plasma aldosterone rose transiently in the normotensive and the hypertensive group. A transient kaliuresis and a continuous fall in serum K+ were observed in all patients. ACTH induced sodium retention and weight gain. The observed increase in systolic blood pressure correlated significantly with the cumulative sodium retention in the normotensive and the hypertensive groups. No correlation between sodium retention and diastolic pressure was found. ACTH on a low salt diet (10 meq/24 h) produced a blood pressure rise which was smaller than that on regular salt. The blood pressure rise did not correlate with any of the hormones measured. This study provides evidence for an unidentified ACTH-stimulable adrenal factor capable of raising blood pressure in normotensive children and patients with juvenile hypertension. The ACTH-induced blood pressure rise is only partly salt dependent and the mechanism of the rise remains unclear.
Essential hypertension
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BODY WEIGHT increase and skeletal growth have been reported in normal rats injected with testosterone. Some workers have only been able to demonstrate growth under limited conditions, and others have failed to demonstrate it. Age of animals, sex, dosage and length of treatment seem to have been some of the factors leading to the variable results. Rubinstein and Solomon (1940) found that small doses of testosterone propionate (50 µg. daily) stimulated the growth of normal and castrated male rats, whereas Rubinstein, Abarbanel and Kurland (1939) had earlier found that larger doses (1.0 mg. daily) depressed the growth rate. Shay, Gershon-Cohen, Paschkis and Fels (1941) found that testosterone in general had effects opposite to those of estrogen, that is, stimulated growth and depressed pituitary weight in normal female rats. No effect on growth was observed by them when male rats were injected from birth with 1 mg.
Testosterone propionate
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Although the relationship between an increase in adipose tissue and a rise in blood pressure has long been recognized, the mechanism linking these two phenomena has yet to be fully understood. Recently, it has become evident that adipose tissue is a rich source of metabolically active molecules, including free fatty acids, leptin and angiotensinogen, the precursor of angiotensin II. The latter finding has prompted speculation on the possible role of adipocyte-derived angiotensinogen in the relationship between body weight and blood pressure. Therefore we examined the relationship between blood pressure, angiotensinogen, body mass index (BMI) and leptin levels in healthy normotensive subjects who are genetically predisposed to the development of hypertension.We studied 40 subjects with a positive family history of hypertension and 51 subjects with a negative family history. After the blood pressure measurements, blood samples were collected for the assessment of angiotensinogen, leptin, glucose, insulin, renin activity and electrolytes. Oral glucose tolerance was studied by an oral glucose tolerance test (75 g glucose).Plasma angiotensinogen was significantly correlated with both BMI (r=0.29, P < 0.01) and plasma leptin (r=0.40, P < 0.001). While plasma angiotensinogen and blood pressure were positively correlated only in subjects with a positive family history of hypertension (r=0.33, P< 0.05), plasma leptin was related to blood pressure in both groups (r=0.26, P=0.01). Furthermore, the insulin response to an oral glucose load was significantly related to both plasma angiotensinogen (r=0.22, P< 0.05) and plasma leptin (r=0.47, P< 0.001).These findings support the hypothesis that circulating angiotensinogen levels are related to adipose mass in young, normotensive, nonobese men. Further studies on the relationship between adipose tissue and systemic or local renin-angiotensin systems appear warranted.
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Adult male and female spontaneously hypertensive rats (SHR-Okamoto, Kyoto) were gonadectomized when they were 17 weeks old. Intact SHR showed a progressive increase of their blood pressure with growth, attaining systolic pressure levels of 194-208 in males and 163-173 mmHg in females when they were 29-30 weeks old. During this same period, the gonadectomized animals showed a significant reduction in blood pressure ranging from 168-175 in males and from 158-163 mmHg in females. These studies indicate that male and female SHR gonadectomized at 17 weeks of age do not show the progressive blood pressure rise that occurs in intact SHR. There was no change in heart rate in either sex. Corticosterone (B) levels in plasma were increased in the orchidectomized males, and 18-OH-DOC levels in plasma were increased in the adrenal glands of ovariectomized females indicating that these hormonal changes probably do not play a role in SHR hypertension. It appears that gonadal and other hormones are involved in the pathogenesis of SHR hypertension.
Corticosterone
Pathogenesis
Spontaneously hypertensive rat
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Congenitally obese Zucker rats showed greater food intake, less running in activity wheels and greater body weight and fat content than the normal phenotype. Their food intake, running and body weight did not change significantly with the phase of the oestrous cycle. Ovariectomy had no effect on these variables or on body composition. Oestradiol replacement had little effect. Zucker rats of normal weight, however, showed a normal pattern of responses to the oestrous cycle, ovariectomy and oestradiol administration. The central regulation of energy balance and body weight appear to be insensitive to oestrogens in the obese Zucker rat.
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To explore the anti-hypertension effect of Pu-erh tea extract on SHR.Pu-erh tea extract was administered to SHR for 4 weeks with 0.25,0.5,1.0,2.0 g/kg doses.The blood pressure and heart rate of animals were measured once every week,and the body weight was also measured weekly in the research.Results showed that the mean blood pressure,systolic pressure and diastolic pressure of spontaneous hypertension rats were significantly reduced in the treatment with 1.0 g/kg and 2.0 g/kg Pu-erh tea extract,compared with that of model group(P0.01).The body weight of animal in 2.0 g/kg Pu-erh tea extract group was lower when compared with model group,but the heart rate of this group was higher than model group.The heart rate and the increase of body weight of tested animal in the other dose group were non-significantly difference.Conclusions: The Pu-erh tea extract shows dose-dependent antihypertensive effect in spontaneous hypertension rats.
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1. In the course of an experiment in which acute effects of perorally applied ethanol alone (0.5 g/kg of body weight) or in combination with diazepam (5 mg) and meclophenoxate (100 mg) on verbal learning were studied, the values of the blood pressure, the body temperature and the heart rate of experimental subject were simultaneously registered with the help of polyphysiograph Physiomat. 2. The method of artificial conditioned speech connections was adopted. The experimental subjects were 16 healthy and unfatigued volunteers - university students (8 females, 8 males, age 21 years). The investigation-sets consisted of two optic, two complex tactile, and two acoustic associations. Three trials were always carried out: before, and one and two hours after the administration of the studied drugs. 3. The values of the blood pressure, the body temperature and the heart rate were not significantly influenced by the applied substances. Only two hours after application of ethanol in combination with diazepam, a marked decrease of systolic and diastolic blood pressure was registered in comparison with the values observed after application of placebo.
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IN A PKEVTOUS paper (Simpson, Marx, Becks and Evans 1943) it was suggested that the well-known effect of testosterone propionate on body weight might be mediated through the pituitary. This hypothesis was supported by the failure of testosterone propionate to produce a significant increase in body weight and skeletal dimensions in hypophysectomized, young, male rats. On the other hand, Leonard (1943) reported partial maintenance of weight in hypophysectomized male rats when he injected 10-12 mg. of testosterone over a 10-day period, whereas the controls lost weight. Tyslowitz (1943) has also noted acceleration of growth in hypophysectomized rats. Kochakian (1943) induced nitrogen retention in an hypophysectomized, castrated dog with 25 mg. of testosterone propionate per day.
Testosterone propionate
Hypophysectomy
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There was no significant difference in body weight between neonatally ovariectomized (OvX) rats whether given oil treatment or 90 mug testosterone propionate (TP) on day 3, when examined up to 23 weeks of age. When these two animals were injected with oestradiol benzoate (3 mug/day for 2 weeks), the neonatally OvX TP treated rats showed a significantly smaller depression in body weight than did the control neonatally OxX rats. Measurement of food intake also showed that TP treated rats responded significantly less to the depressant effects of oestrogen than did the controls. These data are consistent with the hypothesis that the ovary does restrain body weight in TP rats but that androgen treatment in the neonatal period may not have a specific effect on growth but may alter the sensitivity of growth regulating processes to the inhibitory effects of oestrogen.
Testosterone propionate
Corn oil
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