The regulation of GH secretion by sex steroids

Chowen, Julie A.; Frago, Laura M.; Argente, Jesús

doi:10.1530/eje.0.151u095

Cited by 108 publications

(72 citation statements)

References 43 publications

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“…This adds another argument in favor of the selectivity of AR invalidation in the nervous system and strongly suggests that the mechanisms underlying the lipolytic effect of AR reside primarily in peripheral tissues. Together, these data point out the major role of central AR signaling pathway in the organizational and/or activational effects of T on somatostatin and GHRH (GH-releasing hormone) neurons (Chowen et al, 2004).…”

Section: Discussionmentioning

confidence: 78%

Conditional Inactivation of Androgen Receptor Gene in the Nervous System: Effects on Male Behavioral and Neuroendocrine Responses

Raskin¹,

Gendt²,

Duittoz³

et al. 2009

J. Neurosci.

192

221

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Testosterone (T) profoundly influences central sexual differentiation and functions. In the brain, T signals either directly through androgen receptor (AR) or indirectly through estrogen receptor (ER) following aromatization into E2 (17-␤-estradiol).As T, through AR, also controls peripheral male sexual differentiation, the relative contribution of central AR in T-mediated regulation of behavioral and neuroendocrine responses still remains unclear. To address this question, we generated, by using Cre-loxP technology, mice selectively lacking AR expression in the nervous system. The mutant male urogenital tract was normally developed, and mice were able to produce offspring. Nonetheless, sexual motivation and performance as well as aggressive behaviors were affected. Only a low percentage of males displayed a complete sexual behavior and offensive attacks. The latency to show masculine behaviors was increased and copulation length prolonged. Erectile activity during mating was also altered. These alterations occurred despite increased levels of T and its metabolites, and an unaffected number of ER␣-immunoreactive cells. Olfactory preference and neuronal activation, mapped by Fos immunoreactivity, following exposure to estrus female-soiled bedding were also normal. At comparable T levels, greater differences in masculine behaviors were observed between gonadectomized control and mutant males. AR invalidation in the nervous system also disrupted the somatotropic axis since mutant males exhibited growth retardation and decreased serum levels of insulin-like growth factor I. Our findings show that central AR is required in T-induced regulation of male-typical behaviors and gonadotrope and somatotropic axes. This genetic model offers a unique opportunity in the understanding of AR's role in cerebral functions of T.

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Section: Discussionmentioning

confidence: 78%

Conditional Inactivation of Androgen Receptor Gene in the Nervous System: Effects on Male Behavioral and Neuroendocrine Responses

Raskin¹,

Gendt²,

Duittoz³

et al. 2009

J. Neurosci.

192

221

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“…In the post-pubertal animal, androgens and oestrogens modulate hypothalamic somatostatin and GHRH synthesis respectively. These effects may be direct as somatostatin neurons express the androgen receptor and many GHRH neurons are oestrogen receptor positive [48] (Figure 3).…”

Section: The Epigenetic Bases Of Sexual Dimorphismmentioning

confidence: 99%

Sexual dimorphism in environmental epigenetic programming

Gabory

Attig

Junien

2009

Molecular and Cellular Endocrinology

249

196

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The phenotype of an individual is the result of complex interactions between genotype and current, past and ancestral environment leading to a lifelong remodelling of our epigenomes. The vast majority of common diseases, including atherosclerosis, diabetes, osteoporosis, asthma, neuropsychological and autoimmune diseases, which often take root in early development, display some degree of sex bias, very marked in some cases. This bias could be explained by the role of sex chromosomes, the different regulatory pathways underlying sexual development of most organs and finally, lifelong fluctuating impact of sex hormones. A substantial proportion of dimorphic genes expression might be under the control of sex-specific epigenetic marks. Environmental factors such as social behaviour, nutrition or chemical compounds can influence, in a gender-related manner, these flexible epigenetic marks during particular spatiotemporal windows of life. Thus, finely tuned developmental program aspects, for each sex, may be more sensitive to specific environmental challenges, particularly during developmental programming and gametogenesis, but also throughout the individual's life under the influence of sex steroid hormones and/or sex chromosomes. An unfavourable programming could thus lead to various defects and different susceptibility to diseases between males and females. Recent studies suggest that this epigenetic programming could be sometimes transmitted to subsequent generations in a sex specific manner and lead to transgenerational effects (TGEs).This review summarizes the current understanding in the field of epigenetic programming and highlights the importance of studying both sexes in epidemiological protocols or dietary interventions both in humans and in experimental animal models.

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“…Desnutrição e jejum prolongado estão associados com níveis elevados de GH, enquanto que a obesidade diminui sua secreção basal e pós-estímulo (49).…”

Section: Fatores Fisiológicos Na Secreção Do Ghunclassified

“…As vantagens da medida do IGF-I, em comparação à medida do GH, consistem na facilidade de dosagem, pois é necessária somente uma coleta, e no fato de que, por ter meia-vida longa, representa mais adequadamente os níveis de GH do que uma única medida aleatória de GH (49).…”

Section: Insulin Growth Factor I (Igf-i)unclassified

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Ensaios para a medida de hormônio do crescimento (GH) e IGF-I: aspectos metodológicos e suas implicações no diagnóstico e seguimento da acromegalia

Casagrande

Czepielewski

2007

Arq Bras Endocrinol Metab

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RESUMOA dosagem do GH no soro é essencial para confirmar ou excluir o seu excesso. Na acromegalia, a ausência de critérios clínicos suficientemente sensíveis para monitorizar o sucesso do tratamento faz com que o GH sérico seja o procedimento de escolha e, para isso, é essencial que a sua dosagem seja realizada de forma confiável, capaz de permitir interpretações uniformes. Vários critérios hormonais têm sido propostos para caracterizar remissão da acromegalia, incluindo níveis séricos de GH randômico inferior a 2,5 µg/l, nadir de GH durante o teste de tolerância oral a glicose inferior a 1,0 µg/l e IGF-I normal para sexo e idade. A importância do tratamento adequado consiste na possibilidade de reverter a mortalidade prematura da acromegalia através da diminuição dos níveis de GH para valores menores que 2,5 µg/l. Com o surgimento de ensaios ultra-sensíveis para medida do GH, tornaram-se necessários critérios mais estritos para determinar cura ou remissão da doença. Nesta revisão, descreveremos aqui as modificações decorrentes da evolução dos ensaios, as conseqüências nos resultados de GH e os pontos de corte propostos na literatura para caracterização da atividade e remissão da acromegalia. ABSTRACT Growth Hormone (GH) and IGF-I Assays: Methodological Aspects and its Implications in Acromegaly Diagnosis and Follow-Up.Growth hormone quantification in serum is essential for confirming or ruling out its excess. The absence of clinical criteria sufficiently sensitive to evaluate the treatment success enables GH as the key diagnostic procedure and for that, its measurements must be done in a reliable way and must allow uniform interpretation. Several different biochemical criteria for remission have been suggested in the past, including a random GH measurement less than 2.5 µg/l, mean GH value from a day curve less than 2.5 µg/l, nadir GH value after an oral glucose tolerance test (OGGT) less than 1.0 µg/l and a normal age-related IGF-I level. The importance of adequate treatment is highlighted by data indicating that lowering GH levels to less than 2.5 µg/l reverses the premature mortality of acromegaly. With the advances of ultrasensitive assays for GH measurement, strictest remission criteria to determine remission or cure were necessary. In this review, we describe the changes of assay methodology and its consequences in serum GH results and cut off point values to define activity and remission of acromegaly.

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The regulation of GH secretion by sex steroids

Cited by 108 publications

References 43 publications

Conditional Inactivation of Androgen Receptor Gene in the Nervous System: Effects on Male Behavioral and Neuroendocrine Responses

Conditional Inactivation of Androgen Receptor Gene in the Nervous System: Effects on Male Behavioral and Neuroendocrine Responses

Sexual dimorphism in environmental epigenetic programming

Ensaios para a medida de hormônio do crescimento (GH) e IGF-I: aspectos metodológicos e suas implicações no diagnóstico e seguimento da acromegalia

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