Blood pressure, heart rate, hormonal and other acute responses to rubber-ring castration and tail docking of lambs

Peers, Arianne; Mellor, D. J.; Wintour, E. M.; Dodic, Miodrag

doi:10.1080/00480169.2002.36251

Cited by 43 publications

(25 citation statements)

References 32 publications

(39 reference statements)

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“…This is especially true for the sheep, where male offspring of ewes exposed to glucocorticoid early in pregnancy are not hypertensive at 3 months but do become hypertensive by a year of age [39,54]. Female offspring of the same treatment were found to be hypertensive at 4 months and the degree of hypertension amplified with age such that by 7 years of age the mean arterial pressure was approximately 15mmHg higher than offspring from saline infused control ewes [54]. With relation to the kidney, it has been speculated that a low nephron endowment could in part be compensated by individual glomeruli undergoing hypertrophy.…”

Section: Age At Studymentioning

confidence: 93%

Barker and Brenner: A Basis for Hypertension?

Moritz¹,

Bertram

2006

CHYR

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In the large majority of cases, the underlying cause of hypertension is unknown. In the late 1980's, Barry Brenner and colleagues suggested that individuals with a reduced nephron endowment were more likely to develop hypertension. This was followed soon after by the report from epidemiologist, David Barker and co-workers, of a link between low birth weight and an increased risk of adult cardiovascular disease, including hypertension. It was proposed that a low birth weight was indicative of a fetus having been exposed to a suboptimal intrauterine environment and somehow being "programmed" to develop adult disease. What is the evidence for a link between these two hypotheses, and does low birth weight, associated with a decrease in nephron endowment, provide in part, a basis for essential hypertension? In the past 20 years, intensive clinical and basic research has attempted to answer these questions using a variety of approaches. In normal human populations, low birth weight has been correlated with a low nephron number and both these factors have been shown to be associated with elevated blood pressure in adulthood. Animal models, especially those employing maternal protein deficiency or glucocorticoid exposure, have in general reproduced this phenomenon with offspring born of low birth weight having a reduced nephron number and hypertension in adulthood. However, experimental evidence is accumulating that low birth weight and a reduction in nephron endowment can occur independently of one another and do not always result in adult hypertension. In particular, the timing and nature of the in utero insult, the gender of the fetus and the subsequent postnatal environment may modify the outcome significantly.

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Section: Age At Studymentioning

confidence: 93%

Barker and Brenner: A Basis for Hypertension?

Moritz¹,

Bertram

2006

CHYR

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“…Pain-induced distress experienced by animals has been assessed by measuring changes in plasma cortisol concentrations (Herd 1989;Mellor and Murray 1989;Robertson et al 1994;Molony et al 1995;Morisse et al 1995;Lester et al 1996;Peers et al 2002). It is not always appropriate to use the plasma cortisol response as an indicator of distress, but if an animal has an unpleasant experience which results in a signifi cant elevation of plasma cortisol concentration then it may be used as a guide in assessing the comparative intensity of that experience.…”

Section: Introductionmentioning

confidence: 99%

The effect of different combinations of lignocaine, ketoprofen, xylazine and tolazoline on the acute cortisol response to dehorning in calves

Stafford¹,

Mellor

Todd

et al. 2003

New Zealand Veterinary Journal

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Combining ketoprofen and local anaesthesia minimised the cortisol response, and by inference the pain-induced distress, following amputation dehorning in calves. Xylazine reduced the initial cortisol response to dehorning but not as much as when local anaesthesia was also given. The increase in cortisol concentration from 3-8 h after dehorning in calves given xylazine alone or in combination with local anaesthesia suggests that calves experienced pain-induced distress during this time and that xylazine had no long-term analgesic effect. Tolazoline, used to reverse the sedative effects of xylazine, caused a marked cortisol response in calves via a mechanism which remains unclear.

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“…To avoid seasonal variations in sex hormone levels, 18,19 female animals were oophorectomized at 1 year of age (performed under general anesthesia; see below), and males had castration and tail docking performed at 2 months of age. 20 (The animal ethics committee of the Howard Florey Institute requires all males to be castrated and tail docked at weaning.) In addition, because it is our intention to study these animals for several more years, animals are kept on a farm for long periods between experiments.…”

Section: Animalsmentioning

confidence: 99%

Programming Effects of Short Prenatal Exposure to Dexamethasone in Sheep

et al. 2002

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Abstract-Recent studies have linked fetal exposure to a suboptimal intrauterine environment with adult hypertension. The aims of the present study were to see whether prenatal dexamethasone administered intravenously to the ewe between 26 to 28 days of gestation (1) resulted in high blood pressure in male and female offspring and whether hypertension in males was modulated by testosterone status, and (2) altered gene expression for angiotensinogen and angiotensin type 1 (AT 1 ) receptors in the brain in late gestation and in the adult. Basal mean arterial pressure (MAP) at 2 years of age was significantly higher in wethers exposed to prenatal dexamethasone (group D; 106Ϯ5 mm Hg, nϭ9) compared with the control group (group S; 91Ϯ3 mm Hg, nϭ8; PϽ0.01). Infusion of testosterone for 3 weeks had no effect on MAP in either treatment group. Key Words: brain Ⅲ glucocorticoids Ⅲ hypertension, experimental Ⅲ sheep E pidemiological evidence suggests that babies born small for gestational age have an increased incidence of adultonset diseases or dysfunction, including syndrome X (hypertension, non-insulin-dependent diabetes mellitus, and hyperlipidemia). [1][2][3] It is hypothesized that a suboptimal intrauterine environment during a critical stage of development permanently alters, or "programs," the development of fetal tissues. This may ensure the short-term survival of the fetus but also may bring adverse consequences in postnatal life.Animal models using maternal undernutrition or restriction of specific dietary components (iron, protein), either throughout pregnancy or during parts of gestation, have confirmed that restriction of fetal growth leads to elevated blood pressure in the progeny of rats. 4 -6 A second type of animal model has examined the long-term/programming effects caused by prenatal glucocorticoid exposure. When adult rats were exposed to large doses of carbenoxolone (an 11␤-hydroxysteroid dehydrogenase [HSD] inhibitor, which blocks placental inactivation of endogenous glucocorticoids) throughout gestation, offspring were of low birth weight and had high blood pressure. 7-9 The synthetic glucocorticoid dexamethasone, which is poorly metabolized by placental 11␤-HSD, given throughout rat pregnancy resulted in offspring with high blood pressure. 10 In the sheep, we 11 have shown that exposure to dexamethasone, for 2 days very early in gestation (at a mean age of 27 days of the 150-day gestation period) results in hypertensive female offspring by 3 to 4 months of age. This hypertension amplifies with age and is associated with an increased cardiac output. 12 By 7 years of age, these animals had developed left ventricular hypertrophy with reduced cardiac functional reserve. 13 In these studies, only female offspring were studied. However, in many models, the programming effects of the prenatal treatment are only seen in male offspring, 14 or they were more pronounced in male offspring compared with female offspring. 4 These studies proposed that programming, at least in some models, may be gender specific....

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Blood pressure, heart rate, hormonal and other acute responses to rubber-ring castration and tail docking of lambs

Cited by 43 publications

References 32 publications

Barker and Brenner: A Basis for Hypertension?

Barker and Brenner: A Basis for Hypertension?

The effect of different combinations of lignocaine, ketoprofen, xylazine and tolazoline on the acute cortisol response to dehorning in calves

Programming Effects of Short Prenatal Exposure to Dexamethasone in Sheep

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