Complex regulation of GH autofeedback under dual-peptide drive: studies under a pharmacological GH and sex steroid clamp

Hormone therapy for sexual function in perimenopausal and postmenopausal women

BACKGROUND

The perimenopausal and postmenopausal periods are associated with many symptoms, including sexual complaints. This review is an update of a review first published in 2013.

OBJECTIVES

We aimed to assess the effect of hormone therapy on sexual function in perimenopausal and postmenopausal women.

SEARCH METHODS

On 19 December 2022 we searched the Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, LILACS, ISI Web of Science, two trials registries, and OpenGrey, together with reference checking and contact with experts in the field for any additional studies.

SELECTION CRITERIA

We included randomized controlled trials that compared hormone therapy to either placebo or no intervention (control) using any validated assessment tool to evaluate sexual function. We considered hormone therapy: estrogen alone; estrogen in combination with progestogens; synthetic steroids, for example, tibolone; selective estrogen receptor modulators (SERMs), for example, raloxifene, bazedoxifene; and SERMs in combination with estrogen.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. We analyzed data using mean differences (MDs) and standardized mean differences (SMDs). The primary outcome was the sexual function score. Secondary outcomes were the domains of sexual response: desire; arousal; lubrication; orgasm; satisfaction; and pain. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 36 studies (23,299 women; 12,225 intervention group; 11,074 control group), of which 35 evaluated postmenopausal women; only one study evaluated perimenopausal women. The 'symptomatic or early postmenopausal women' subgroup included 10 studies, which included women experiencing menopausal symptoms (symptoms such as hot flushes, night sweats, sleep disturbance, vaginal atrophy, and dyspareunia) or early postmenopausal women (within five years after menopause). The 'unselected postmenopausal women' subgroup included 26 studies, which included women regardless of menopausal symptoms and women whose last menstrual period was more than five years earlier. No study included only women with sexual dysfunction and only seven studies evaluated sexual function as a primary outcome. We deemed 20 studies at high risk of bias, two studies at low risk, and the other 14 studies at unclear risk of bias. Nineteen studies received commercial funding. Estrogen alone versus control probably slightly improves the sexual function composite score in symptomatic or early postmenopausal women (SMD 0.50, 95% confidence interval (CI) (0.04 to 0.96; I² = 88%; 3 studies, 699 women; moderate-quality evidence), and probably makes little or no difference to the sexual function composite score in unselected postmenopausal women (SMD 0.64, 95% CI -0.12 to 1.41; I² = 94%; 6 studies, 608 women; moderate-quality evidence). The pooled result suggests that estrogen alone versus placebo or no intervention probably slightly improves sexual function composite score (SMD 0.60, 95% CI 0.16 to 1.04; I² = 92%; 9 studies, 1307 women, moderate-quality evidence). We are uncertain of the effect of estrogen combined with progestogens versus placebo or no intervention on the sexual function composite score in unselected postmenopausal women (MD 0.08 95% CI -1.52 to 1.68; 1 study, 104 women; very low-quality evidence). We are uncertain of the effect of synthetic steroids versus control on the sexual function composite score in symptomatic or early postmenopausal women (SMD 1.32, 95% CI 1.18 to 1.47; 1 study, 883 women; very low-quality evidence) and of their effect in unselected postmenopausal women (SMD 0.46, 95% CI 0.07 to 0.85; 1 study, 105 women; very low-quality evidence). We are uncertain of the effect of SERMs versus control on the sexual function composite score in symptomatic or early postmenopausal women (MD -1.00, 95% CI -2.00 to -0.00; 1 study, 215 women; very low-quality evidence) and of their effect in unselected postmenopausal women (MD 2.24, 95% 1.37 to 3.11 2 studies, 1525 women, I² = 1%, low-quality evidence). We are uncertain of the effect of SERMs combined with estrogen versus control on the sexual function composite score in symptomatic or early postmenopausal women (SMD 0.22, 95% CI 0.00 to 0.43; 1 study, 542 women; very low-quality evidence) and of their effect in unselected postmenopausal women (SMD 2.79, 95% CI 2.41 to 3.18; 1 study, 272 women; very low-quality evidence). The observed heterogeneity in many analyses may be caused by variations in the interventions and doses used, and by different tools used for assessment.

AUTHORS' CONCLUSIONS

Hormone therapy treatment with estrogen alone probably slightly improves the sexual function composite score in women with menopausal symptoms or in early postmenopause (within five years of amenorrhoea), and in unselected postmenopausal women, especially in the lubrication, pain, and satisfaction domains. We are uncertain whether estrogen combined with progestogens improves the sexual function composite score in unselected postmenopausal women. Evidence regarding other hormone therapies (synthetic steroids and SERMs) is of very low quality and we are uncertain of their effect on sexual function. The current evidence does not suggest the beneficial effects of synthetic steroids (for example tibolone) or SERMs alone or combined with estrogen on sexual function. More studies that evaluate the effect of estrogen combined with progestogens, synthetic steroids, SERMs, and SERMs combined with estrogen would improve the quality of the evidence for the effect of these treatments on sexual function in perimenopausal and postmenopausal women.

Effects of oral versus transdermal estradiol plus micronized progesterone on thyroid hormones, hepatic proteins, lipids, and quality of life in menopausal women with hypothyroidism: a clinical trial

OBJECTIVE

The aim of the study was to evaluate the effects of usual doses of oral estradiol with transdermal estradiol and the effects of these estrogens plus micronized progesterone (MP) in menopausal women with primary hypothyroidism.

METHODS

Twenty women were randomized to 12 weeks of treatment with estradiol 1 mg tablets or estradiol 1 mg gel. Then, women with a uterus received a 100 mg capsule of oral MP. Thyroid function, thyroxine-binding globulin (TBG), sex hormone-binding globulin (SHBG), insulin-like growth factor 1 (IGF-1), lipid profiles, and quality of life were measured at baseline and after 12 and 24 weeks.

RESULTS

Oral estradiol led to an increase in total T4 levels (5.84 ± 1.11 vs 8.41 ± 1.61 μg/dL; P < 0.001); changes in thyroid-stimulating hormone (TSH) levels were clinically important in 3 of 10 participants who needed to increase their dose of levothyroxine. Significant changes were detected in hepatic proteins with oral estradiol: TBG and SHBG levels increased (15.29 ± 3.87 vs 20.84 ± 5.49 μg/mL, P < 0.001; 61.85 ± 33.6 vs 121.4 ± 49.36 nmol/L, P < 0.001; respectively), whereas IGF-1 levels decreased (152 ± 38.91 vs 96 ± 17.59 ng/mL; P < 0.001). Transdermal estradiol alone did not significantly affect the thyroid function. Transdermal estradiol plus MP led to a decrease in TSH levels (1.79 ± 1.05 vs 1.09 ± 0.52 mIU/L; P = 0.04), while total T4 levels increased (7.54 ± 1.34 vs 9.95 ± 2.24 μg/dL; P = 0.01). Hormonal therapy had a greater impact on depressed mood and vasomotor symptoms.

CONCLUSIONS

Total T4 and TBG levels increase after oral estradiol in women with hypothyroidism and it may cause clinical changes in TSH levels. Conversely, transdermal estradiol alone or plus MP does not cause major changes in thyroid function in these women.

A summary of the influence of exogenous estrogen administration across the lifespan on the GH/IGF-1 axis and implications for bone health

Bone growth, development, and remodeling are modulated by numerous circulating hormones. Throughout the lifespan, the extent to which each of the hormones impacts bone differs. Understanding the independent and combined impact of these hormones on controlling bone remodeling allows for the development of more informed decision making regarding pharmacology, specifically the use of hormonal medication, at all ages. Endocrine control of bone health in women is largely dictated by the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis and the hypothalamic-pituitary-ovarian (HPO) axis. Growth hormone, secreted from the pituitary gland, stimulates cells in almost every tissue to secrete IGF-1, although the majority of circulating IGF-1 is produced hepatically. Indeed, systemic IGF-1 concentrations have been found to be correlated with bone mineral density (BMD) in both pre- and post-menopausal women and is often used as a marker of bone formation. Sex steroids produced by the ovaries, namely estradiol, mediate bone resorption through binding to estrogen receptors on osteoclasts and osteoblasts. Specifically, by increasing osteoclast apoptosis and decreasing osteoblast apoptosis, adequate estrogen levels prevent excessive bone resorption, which helps to explain the rapid decline in bone mass that occurs with the menopausal decrease in estrogen production. Though there are documented correlations between endogenous estrogen concentrations and GH/IGF-1 dynamics, this relationship changes across the lifespan as sex-steroid dynamics fluctuate and, possibly, as tissue responsiveness to GH stimulation decreases. Aside from the known role of endogenous sex steroids on bone health, the impact of exogenous estrogen administration is of interest, as exogenous formulations further modulate GH and IGF-1 production. However, the effect and extent of GH and IGF-1 modulation seems to be largely dependent on age at administration and route of administration. Specifically, premenopausal women using combined oral contraceptive therapy (COC), post-menopausal women taking oral hormone therapy (HT), and both pre- and post-menopausal women using a transdermal form of estrogen therapy (COC or HT) demonstrate disparate GH/IGF-1 responses to exogenous estrogen. This review serves to summarize what is currently known regarding the influence of exogenous estrogen administration across the lifespan on the GH/IGF-1 axis and implications for bone health.

Network identification of hormonal regulation

Relations among hormone serum concentrations are complex and depend on various factors, including gender, age, body mass index, diurnal rhythms and secretion stochastics. Therefore, endocrine deviations from healthy homeostasis are not easily detected or understood. A generic method is presented for detecting regulatory relations between hormones. This is demonstrated with a cohort of obese women, who underwent blood sampling at 10 minute intervals for 24-hours. The cohort was treated with bromocriptine in an attempt to clarify how hormone relations change by treatment. The detected regulatory relations are summarized in a network graph and treatment-induced changes in the relations are determined. The proposed method identifies many relations, including well-known ones. Ultimately, the method provides ways to improve the description and understanding of normal hormonal relations and deviations caused by disease or treatment.

V. Gender determines ACTH recovery from hypercortisolemia in healthy older humans

OBJECTIVE

Available clinical data raise the possibility that stress-adaptive mechanisms differ by gender. However, this notion has not been rigorously tested in relation to cortisol-mediated negative feedback.

MATERIALS/METHODS

Degree of ACTH inhibition during and recovery from an experimental cortisol clamp was tested in 20 healthy older subjects (age 60±2.2 y). Volunteers received oral placebo or ketoconazole (KTCZ) to inhibit adrenal steroidogenesis along with i.v. infusions of saline or a low vs high physiological dose of cortisol in a prospectively randomized double-blind, placebo-controlled design. ACTH and cortisol concentrations were measured every 10 min during the feedback-clamp phase and thereafter (recovery or escape phase). Corticosteroid-binding globulin (CBG) was measured, and free cortisol concentrations were calculated.

RESULTS

Gender did not determine mean ACTH concentrations during the saline or cortisol feedback-clamp phases per se. However, women had markedly impaired ACTH recovery after stopping both low- and high-dose cortisol infusions compared with men (P=0.005, KTCZ/low-dose cortisol arm; and P=0.006, KTCZ/high-dose cortisol arm). Decreased ACTH recovery in women was accompanied by lower total and free cortisol concentrations, pointing to heightened feedback inhibition of hypothalamo-pituitary drive of ACTH secretion as the main mechanism.

CONCLUSIONS

In summary, gender or a factor related to gender, such as sex steroids or body composition, determines recovery of ACTH secretion from cortisol-enforced negative feedback. Attenuated ACTH recovery in post-menopausal women may have relevance to sex differences in stress-related adaptations.

Hormone therapy for sexual function in perimenopausal and postmenopausal women

BACKGROUND

The perimenopausal and postmenopausal periods are associated with many symptoms, including sexual complaints.

OBJECTIVES

To assess the effect of hormone therapy (HT) on sexual function in perimenopausal and postmenopausal women.

SEARCH METHODS

We searched for articles in the Cochrane Menstrual Disorders and Subfertility Group (MDSG) Specialised Register, CENTRAL, MEDLINE, EMBASE, CINAHL, PsycINFO, LILACS, ClinicalTrials.gov, Current Controlled Trials, WHO International Clinical Trials Registry Platform, ISI Web of Knowledge and OpenGrey. The last search was performed in December 2012.

SELECTION CRITERIA

We included randomised controlled trials comparing HT to either placebo or no intervention (control). We considered as HT estrogens alone; estrogens in combination with progestogens; synthetic steroids (for example tibolone); or selective estrogen receptor modulators (SERMs) (for example raloxifene, bazedoxifene). Studies of other drugs possibly used in the relief of menopausal symptoms were excluded. We included studies that evaluated sexual function using any validated assessment tool. The primary outcome was a composite score for sexual function and the scores for individual domains (arousal and sexual interest, orgasm, and pain) were secondary outcomes. Studies were selected by two authors independently.

DATA COLLECTION AND ANALYSIS

Data were independently extracted by two authors and checked by a third. Risk of bias assessment was performed independently by two authors. We contacted study investigators as required. Data were analysed using standardized mean difference (SMD) and relative risk (RR). We stratified the analysis by participant characteristics with regard to menopausal symptoms. The overall quality of the evidence for the primary outcome was evaluated using the GRADE criteria.

MAIN RESULTS

The search retrieved 2351 records from which 27 studies (16,393 women) were included. The 'symptomatic or early post-menopausal' subgroup included nine studies: perimenopausal women (one study), up to 36 months postmenopause (one study), up to five years postmenopause (one study), experiencing vasomotor or other menopausal symptoms (five studies), or experiencing hot flushes and sexual dysfunction (one study). The 'unselected postmenopausal women' subgroup included 18 studies, which included women regardless of menopausal symptoms and permitted the inclusion of women with more than five years since the final menstrual period. No studies were restricted to women with sexual dysfunction. Only five studies evaluated sexual function as a primary outcome. Eighteen studies were deemed at high risk of bias, and the other nine studies were at unclear risk of bias. Twenty studies received commercial funding.Findings for sexual function (measured by composite score):For estrogens alone versus control, in symptomatic or early postmenopausal women the SMD and 95% CI were compatible with a small to moderate benefit in sexual function for the HT group (SMD 0.38, 95% CI 0.23 to 0.54, P < 0.00001, 3 studies, 699 women, I² = 55%, high-quality evidence). In unselected postmenopausal women, the 95% CI was compatible with no effect to a small benefit (SMD 0.16, 95% CI -0.02 to 0.34, P = 0.08, 2 studies, 478 women, I² = 44%, low-quality evidence). The subgroups were not pooled because of considerable heterogeneity.For estrogens combined with progestogens versus control, in symptomatic or early postmenopausal women the 95% CI was compatible with a small to moderate benefit for sexual function in the HT group (SMD 0.42, 95% CI 0.19 to 0.64, P = 0.0003, 1 study, 335 women, moderate-quality evidence). In unselected postmenopausal women, the 95% CI was compatible with no effect to a small benefit (SMD 0.09, 95% CI -0.02 to 0.20, P = 0.10, 3 studies, 1314 women, I² = 0%, moderate-quality evidence). The subgroups were not pooled because of considerable heterogeneity.For tibolone versus control, in symptomatic or early postmenopausal women the 95% CI was compatible with no effect to a small benefit for sexual function in the HT group (SMD 0.13, 95% CI 0.00 to 0.26, P = 0.05, 1 study, 883 women, low-quality evidence). In unselected postmenopausal women, the 95% CI was compatible with no effect to a moderate benefit (SMD 0.38, 95% CI 0.04 to 0.71, P = 0.03, 2 studies, 142 women, I² = 0%, low-quality evidence). In the combined analysis, the 95% CI was compatible with no effect to a small benefit (SMD 0.17, 95% CI 0.04 to 0.29, P = 0.008, 3 studies, 1025 women, I² = 20%).For SERMs versus control, in symptomatic or early postmenopausal women the 95% CI was compatible with no effect to a moderate benefit for sexual function in the HT group (SMD 0.23, 95% CI -0.04 to 0.50, P = 0.09, 1 study, 215 women, low-quality evidence). In unselected postmenopausal women, the 95% CI was compatible with small harm to a small benefit (SMD 0.04, 95% CI -0.20 to 0.29, P = 0.72, 1 study, 283 women, low-quality evidence). In the combined analysis, the 95% CI was compatible with no effect to a small benefit (SMD 0.13, 95% CI -0.05 to 0.31, P = 0.16, 2 studies, 498 women, I² = 2%).A comparison of SERMs combined with estrogens versus control was only evaluated in symptomatic or early postmenopausal women. The 95% CI was compatible with no effect to a small benefit for sexual function in the HT group (SMD 0.21, 95% CI 0.00 to 0.43, P = 0.05, 1 study, 542 women, moderate-quality evidence).

AUTHORS' CONCLUSIONS

HT treatment with estrogens alone or in combination with progestogens was associated with a small to moderate improvement in sexual function, particularly in pain, when used in women with menopausal symptoms or in early postmenopause (within five years of amenorrhoea), but not in unselected postmenopausal women. Evidence regarding other HTs (synthetic steroids and SERMs) is of low quality and we are uncertain of their effect on sexual function. The current evidence does not suggest an important effect of tibolone or of SERMs alone or combined with estrogens on sexual function. More studies evaluating the effect of synthetic steroids, SERMS and the association of SERM + estrogens would improve the quality of the evidence for the effect of these treatments on sexual function in peri and postmenopausal women. Future studies should also evaluate the effect of HT solely among women with sexual complaints.

Regulated recovery of pulsatile growth hormone secretion from negative feedback: a preclinical investigation

Although stimulatory (feedforward) and inhibitory (feedback) dynamics jointly control neurohormone secretion, the factors that supervise feedback restraint are poorly understood. To parse the regulation of growth hormone (GH) escape from negative feedback, 25 healthy men and women were studied eight times each during an experimental GH feedback clamp. The clamp comprised combined bolus infusion of GH or saline and continuous stimulation by saline GH-releasing hormone (GHRH), GHRP-2, or both peptides after randomly ordered supplementation with placebo (both sexes) vs. E(2) (estrogen; women) and T (testosterone; men). Endpoints were GH pulsatility and entropy (a model-free measure of feedback quenching). Gender determined recovery of pulsatile GH secretion from negative feedback in all four secretagog regimens (0.003 ≤ P ≤ 0.017 for women>men). Peptidyl secretagog controlled the mass, number, and duration of feedback-inhibited GH secretory bursts (each, P < 0.001). E(2)/T administration potentiated both pulsatile (P = 0.006) and entropic (P < 0.001) modes of GH recovery. IGF-I positively predicted the escape of GH secretory burst number and mode (P = 0.022), whereas body mass index negatively forecast GH secretory burst number and mass (P = 0.005). The composite of gender, body mass index, E(2), IGF-I, and peptidyl secretagog strongly regulates the escape of pulsatile and entropic GH secretion from autonegative feedback. The ensemble factors identified in this preclinical investigation enlarge the dynamic model of GH control in humans.