Renal and Myocardial Adrenoceptors in Steroid Contraceptive‐induced Hypertension in Rats

Geraghty, Dominic P.; Byrne, KB; Ga, McPherson; Burcher, Elizabeth

doi:10.1111/j.1440-1681.1990.tb01357.x

Cited by 8 publications

(3 citation statements)

References 28 publications

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“…Many previous studies (3,17,19,24,42,49) showed that contraceptives or estrogen treatment induce hypertension in humans and animals. However, the mechanisms on the pressor effect of estrogen are still inconsistent with each other.…”

Section: Discussionmentioning

confidence: 99%

Estrogen replacement suppresses stress-induced cardiovascular responses in ovariectomized rats

Morimoto¹,

Kurahashi²,

Shintani-Ishida³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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We assessed the hypothesis that chronic estrogen replacement in ovariectomized rats has the beneficial effect of suppressing stress-induced cardiovascular responses through endothelial nitric oxide synthase (eNOS). We employed a radiotelemetry system to measure blood pressure and heart rate (HR). Female Wistar rats aged 11 wk were ovariectomized and implanted with radiotelemetry devices. After 4 wk, the rats were assigned either to a placebo-treated group (Placebo; n=6) or a group treated with 17beta-estradiol (Estrogen; n=8) subcutaneously implanted with either placebo- or 17beta-estradiol (1.5 mg/60-day release) pellets under anesthesia. These rats underwent either of the two types of stress after 4 wk of estrogen or placebo treatment. Cage-switch stress and restraint stress rapidly and continuously elevated the mean arterial pressure (MAP) and HR both in the Placebo and Estrogen groups. However, the MAP and HR responses to cage-switch stress and the MAP but not HR response to restraint stress were attenuated significantly in the Estrogen group compared with the Placebo group. A NOS inhibitor, NG-nitro-L-arginine methyl ester, given in drinking water, reduced the difference in the pressor response to cage-switch between the Estrogen and Placebo groups. In addition, Western blot analysis showed that eNOS expression in the mesentery was increased in the Estrogen group compared with the Placebo group. Thus for the first time we showed that mesenteric eNOS overexpression could explain at least partly why chronic estrogen treatment suppressed the enhanced cardiovascular responses to psychological stress in the ovariectomized rat.

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Section: Discussionmentioning

confidence: 99%

Estrogen replacement suppresses stress-induced cardiovascular responses in ovariectomized rats

Morimoto¹,

Kurahashi²,

Shintani-Ishida³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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“…Ethinyl Estradiol (30μg/day; Fisher Scientific) and Levonorgestrel (30μg/day; Fisher Scientific), a progestin, were dissolved in 0.01ml of sesame oil and delivered subcutaneously at the nape of the neck daily for 8days, the approximate duration of two estrous cycles, during mid to late adolescence (p50–p58), with control animals receiving vehicle. Although, a wide range of rodent doses of EE2 and Levonorgestrel have been reported ( Santoru et al, 2014 ; Prakapenka et al, 2018 ; Olaniyi and Olatunji, 2019 ), the doses chosen here aimed to match those used consistently for suppressing ovulation and mimicking effects observed in humans, such as increased blood pressure ( Geraghty et al, 1990 ), and for comparability to existing rodent literature on subcutaneous delivery of Levonorgestrel and EE2 ( Follesa et al, 2002 ; Simone et al, 2015 ). Many doses for orally delivered EE2 and Levonorgestrel in rats also fall in this range ( Nowaczyk-Dura and Czekaj, 1998 ; Guerra et al, 2002 ; Olatunji et al, 2017 ; Olaniyi and Olatunji, 2019 ).…”

Section: Methodsmentioning

confidence: 99%

Adolescent Development of Biological Rhythms in Female Rats: Estradiol Dependence and Effects of Combined Contraceptives

2021

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Adolescence is a period of continuous development, including the maturation of endogenous rhythms across systems and timescales. Although, these dynamic changes are well-recognized, their continuous structure and hormonal dependence have not been systematically characterized. Given the well-established link between core body temperature (CBT) and reproductive hormones in adults, we hypothesized that high-resolution CBT can be applied to passively monitor pubertal development and disruption with high fidelity. To examine this possibility, we used signal processing to investigate the trajectory of CBT rhythms at the within-day (ultradian), daily (circadian), and ovulatory timescales, their dependence on estradiol (E2), and the effects of hormonal contraceptives. Puberty onset was marked by a rise in fecal estradiol (fE2), followed by an elevation in CBT and circadian power. This time period marked the commencement of 4-day rhythmicity in fE2, CBT, and ultradian power marking the onset of the estrous cycle. The rise in circadian amplitude was accelerated by E2 treatment, indicating a role for this hormone in rhythmic development. Contraceptive administration in later adolescence reduced CBT and circadian power and resulted in disruption to 4-day cycles that persisted after discontinuation. Our data reveal with precise temporal resolution how biological rhythms change across adolescence and demonstrate a role for E2 in the emergence and preservation of multiscale rhythmicity. These findings also demonstrate how hormones delivered exogenously in a non-rhythmic pattern can disrupt rhythmic development. These data lay the groundwork for a future in which temperature metrics provide an inexpensive, convenient method for monitoring pubertal maturation and support the development of hormone therapies that better mimic and support human chronobiology.

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“…Ethinyl Estradiol (EE2, 30µg/day) and Levonorgestrel (30 µg/day), a progestin, were dissolved in in 0.01 mL of sesame oil and delivered subcutaneously at the nape of the neck daily for the duration of two estrous cycles during mid to late adolescence (p50 to p58). Although a wide range of rodent doses of EE2 and Levonorgestrel have been reported(114–116), the doses chosen here aimed to match those used consistently for suppressing ovulation and mimicking effects observed in humans, such as increased blood pressure(117), and for comparability to existing rodent literature on subcutaneous delivery of Levonorgestrel and EE2(118–120). Many doses for orally delivered EE2 and Levonorgestrel in rats also fall in this range(82,115,121,122).…”

Section: Methodsmentioning

confidence: 99%

Adolescent Development of Biological Rhythms: Estradiol Dependence and Effects of Combined Contraceptives

Grant¹,

Wilbrecht

Kriegsfeld

2021

Preprint

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Purpose: Adolescence is a period of continuous development, including the maturation of endogenous rhythms across systems and timescales. Although these dynamic changes are well recognized, their continuous structure and hormonal dependence have not been systematically characterized. Given the well-established link between core body temperature (CBT) and reproductive hormones in adults, we hypothesized that high-resolution CBT can be applied to passively monitor pubertal development and disruption with high fidelity. Methods: To examine this possibility, we used signal processing to investigate the trajectory of CBT rhythms at the within-day (ultradian), daily (circadian), and ovulatory timescales, their dependence on estradiol, and the effects of hormonal contraceptives. Results: Puberty onset was marked by a rise in fecal estradiol (fE2), followed by an elevation in CBT and circadian power. This time period marked the commencement of 4-day rhythmicity in fE2, CBT, and ultradian power marking the onset of the estrous cycle. The rise in circadian amplitude was accelerated by E2 treatment, indicating a role for this hormone in rhythmic development. Contraceptive administration in later adolescence reduced CBT and circadian power and resulted in disruption to 4-day cycles that persisted after discontinuation. Conclusions: Our data reveal with precise temporal resolution how biological rhythms change across adolescence and demonstrate a role for E2 in the emergence and preservation of multiscale rhythmicity. These findings also demonstrate how hormones delivered exogenously in a non-rhythmic pattern can disrupt rhythmic development. These data lay the groundwork for a future in which temperature metrics provide an inexpensive, convenient method for monitoring pubertal maturation and support the development of hormone therapies that better mimic and support human chronobiology.

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Renal and Myocardial Adrenoceptors in Steroid Contraceptive‐induced Hypertension in Rats

Cited by 8 publications

References 28 publications

Estrogen replacement suppresses stress-induced cardiovascular responses in ovariectomized rats

Estrogen replacement suppresses stress-induced cardiovascular responses in ovariectomized rats

Adolescent Development of Biological Rhythms in Female Rats: Estradiol Dependence and Effects of Combined Contraceptives

Adolescent Development of Biological Rhythms: Estradiol Dependence and Effects of Combined Contraceptives

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