During the last decade, the GH axis has become the compelling focus of remarkably active and broad-ranging basic and clinical research. Molecular and genetic models, the discovery of human GHRH and its receptor, the cloning of the GHRP receptor, and the clinical availability of recombinant GH and IGF-I have allowed surprisingly rapid advances in our knowledge of the neuroregulation of the GH-IGF-I axis in many pathophysiological contexts. The complexity of the GHRH/somatostatin-GH-IGF-I axis thus commends itself to more formalized modeling (154, 155), since the multivalent feedback-control activities are difficult to assimilate fully on an intuitive scale. Understanding the dynamic neuroendocrine mechanisms that direct the pulsatile secretion of this fundamental growth-promoting and metabolic hormone remains a critical goal, the realization of which is challenged by the exponentially accumulating matrix of experimental and clinical data in this arena. To the above end, we review here the pathophysiology of the GHRH somatostatin-GH-IGF-I feedback axis consisting of corresponding key neurotransmitters, neuromodulators, and metabolic effectors, and their cloned receptors and signaling pathways. We propose that this system is best viewed as a multivalent feedback network that is exquisitely sensitive to an array of neuroregulators and environmental stressors and genetic restraints. Feedback and feedforward mechanisms acting within the intact somatotropic axis mediate homeostatic control throughout the human lifetime and are disrupted in disease. Novel effectors of the GH axis, such as GHRPs, also offer promise as investigative probes and possible therapeutic agents. Further understanding of the mechanisms of GH neuroregulation will likely allow development of progressively more specific molecular and clinical tools for the diagnosis and treatment of various conditions in which GH secretion is regulated abnormally. Thus, we predict that unexpected and enriching insights in the domain of the neuroendocrine pathophysiology of the GH axis are likely be achieved in the succeeding decades of basic and clinical research.

Pathophysiology of the neuroregulation of growth hormone secretion in experimental animals and the human

Polycystic ovary syndrome (PCOS) is characterized by a constellation of clinical symptoms that include irregular menses due to chronic oligo-ovulation, phenotypic features of hyperandrogenism, and obesity The term “polycystic ovary” refers to ovarian morphology with increased ovarian stroma and a ring of cortical follicles Core biochemical features include hyperandrogenism and insulin resistance The pathogenesis of PCOS remains a topic of debate Treatment of PCOS typically focuses on mitigating the impact of hyperandrogenism, insulin resistance, and chronic oligo-ovulation and restoring fertility when desired

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Polycystic ovary syndrome.

The stress system in the human brain in depression and neurodegeneration.

http://www.gruberpeplab.com/teaching/psych231_fall2013/documents/231_Kudielkaa2008.pdf

Why do we respond so differently? Reviewing determinants of human salivary cortisol responses to challenge.

The polycystic ovary syndrome (PCOS) is a condition characterized by hyperandrogenism and chronic oligo-anovulation. However, many features of the metabolic syndrome are inconsistently present in the majority of women with PCOS. Approximately 50% of PCOS women are overweight or obese and most of them have the abdominal phenotype. Obesity may play a pathogenetic role in the development of the syndrome in susceptible individuals. In fact, insulin possesses true gonadotrophic function and an increased insulin availability at the level of ovarian tissue may favour excess androgen synthesis. Obesity, particularly the abdominal phenotype, may be partly responsible for insulin resistance and associated hyperinsulinemia in women with PCOS. Therefore, obesity-related hyperinsulinemia may play a key role in favouring hyperandrogenism in these women. Other factors such as increased estrogen production rate, increased activity of the opioid system and of the hypothalamic-pituitary-adrenal axis, decreased sex hormone binding globulin synthesis and, possibly, high dietary lipid intake, may be additional mechanisms by which obesity favours the development of hyperandrogenism in PCOS. Irrespective of the pathogenetic mechanism involved, obese PCOS women have more severe hyperandrogenism and related clinical features (such as hirsutism, menstrual abnormalities and anovulation) than normal-weight PCOS women. This picture tends to be more pronounced in obese PCOS women with the abdominal phenotype. Body weight loss is associated with beneficial effects on hormones, metabolism and clinical features. A further clinical and endocrinological improvement can also be achieved by adding insulin-sensitizing agents and/or antiandrogens to weight reduction programmes. These obviously emphasize the role of obesity in the pathophysiology of PCOS.

Obesity and the polycystic ovary syndrome

Anovulation in women with polycystic ovary syndrome (PCOS) is the direct effect of high local androgen concentrations on the ovary. Antiandrogens are substances that prevent androgens from expressing their activity on target tissues. Flutamide is a nonsteroid antiandrogen that has been found effective in hirsute patients, although its mechanism of action is unclear. Eight girls, ranging in age from 16–19 yr, with moderate to severe hirsutism and menstrual irregularities were enrolled in this study. The basal hormonal pattern showed anovulatory cycles; increased concentrations of LH, androstenedione, and testosterone; and increased LH/FSH ratio. A baseline ultrasound scan revealed polycystic ovaries in all patients. All were given 250 mg flutamide twice a day for 6 months. LH, FSH, androstenedione, testosterone, estradiol, and progesterone were evaluated before treatment, every 4 days during the third month of treatment, and on day 24 of the sixth month of treatment. Hirsutism improved, androgen levels dro...

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Hormonal effects of flutamide in young women with polycystic ovary syndrome

Intrauterine growth retardation is a pathology which is found in 3-10% of all pregnancies and it is associated with around 20-25% of all fetal intrauterine deaths and with long-term neurologic sequelae. It presents an increased risk of distress during labor and delivery and a greater risk of perinatal mortality. The causes of IUGR and the cardiac and venous Doppler in normal fetuses are analyzed, and the hemodynamic cardiac modifications in IUGR fetus are discussed. The fetal cardiac function in intrauterine growth retardation shows a redistribution of the fetal cardiac output, which tends to favor the left ventricle as the mechanism to compensate for the uteroplacental insufficiency. The Doppler velocity indices are modified as the fetal condition progressively deteriorates and they represent an important tool for the management of the complicated pregnancy.

Intrauterine growth retardation and fetal cardiac function

Objective Flutamide is a non-steroid antiandrogen that specifically blocks the androgen receptor. We have investigated the effect of flutamide treatment on the adrenal androgen response to corticotrophin releasing factor (CRF) in eight patients with polycystic ovary syndrome (PCOS). Patients Eight women with moderate to severe hirsutism, ranging in age from 19 to 23 years were enrolled in the study. Basal hormonal pattern showed anovulatory cycles, increased concentrations of LH, androstenedione and testosterone and increased LH/ FSH ratio. A baseline ultrasound scan revealed polycystic ovaries in all patients. Each received 250 mg of Flutamide twice a day for 6 months. Measurements Before treatment and at the end of the sixth month, women were evaluated for hirsutism score and a CRF test was performed to evaluate ACTH, cortisol and adrenal androgen responses. Results Androstenedione (delta 4), DHEA-S, 17-hydroxy-progesterone, testosterone and free-testosterone showed significantly reduced responses after six months of flutamide therapy whereas ACTH and cortisol response were similar to those before treatment. Clinical improvement in the degree of hirsutism was observed in all patients. The Ferriman-Gallwey scores decreased from a mean of 22 +/- 2 to 8 +/- 1.5. Conclusion Flutamide induces a significant reduction in adrenal androgen response to the CRF test but not in the response of ACTH and cortisol. The finding that flutamide does not alter the pituitary-adrenal axis shows that flutamide acts by reducing adrenal androgens. These results demonstrate that flutamide is not only effective in the treatment of hirsutism but also reduces adrenal androgen secretion.

Effects of flutamide on pituitary and adrenal responsiveness to corticotrophin releasing factor (CRF)

The hypothalamo‐pituitary‐adrenal (HPA) axis is modulated by sex hormones. Few data exist on the relation between acute estrogen deficit and HPA axis response to corticotropin-releasing hormone (CRH). The effects of a sudden drop in estradiol levels on basal and CRH-stimulated levels of ACTH, cortisol, testosterone, androstenedione and 17-hydroxyprogesterone (17-OHP) were assessed in nine premenopausal women (44‐48 years of age), before and after ovariectomy. The CRH test was performed before and 8 days after ovariectomy. A significant reduction in ACTH and adrenal steroids but not in cortisol response to CRH was observed after ovariectomy. The ratio of Dmax androstenedione/17-OHP after CRH stimulation was substantially the same before and after ovariectomy, whereas Dmax 17-OHP/cortisol was significantly lower in ovariectomized women showing increased 21- and 11b-hydroxylase activity. The results show that the acute estrogen deficit induces changes in the HPA axis characterized by reduced stimulated secretion of ACTH and steroids but normal stimulated cortisol production.

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D. D'Antona

Papers

Hormonal effects of flutamide in young women with polycystic ovary syndrome

Intrauterine growth retardation and fetal cardiac function

Effects of flutamide on pituitary and adrenal responsiveness to corticotrophin releasing factor (CRF)

Hypothalamo-pituitary-adrenal axis and adrenal function before and after ovariectomy in premenopausal women.

Growth hormone secretion in premenopausal women before and after ovariectomy: effect of hormone replacement therapy