Pituitary development and physiology

Ovarian teratoma with pituitary tissue: A case report

Ovarian cysts and specifically ovarian teratomas are a common finding in young patients. These cysts display histological cell types from all three cells lines: endodermal, ectodermal and mesodermal origins. A 22-year-old woman who displayed classic signs of cortisol excess – excessive weight gain, difficultly losing weight and abdominal striae – was found to have a 10 cm mature teratoma cyst. This patient presented with ovarian torsion, a common complication of ovarian cysts, and was treated surgically. Pathology was significant for an ovarian teratoma with pituitary secreting cells, most significantly cells secreting adrenocorticotropic hormone (ACTH).

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Ovarian torsion is a common gynecologic emergency occurring with a variety of ovarian cysts.

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Ovarian dermoid cysts are benign mature cystic teratomas that are composed of ectodermal, endodermal and mesodermal elements.

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Rarely these dermoid tumors will secrete hormones.

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Pituitary cells within an ovarian dermoid can increase systemic adrenocorticotropic hormone (ACTH) levels.

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ACTH-secreting ovarian dermoid cysts can cause a Cushing-like syndrome.

A new approach to the diagnosis of short stature

Growth is the task of children. We review the normal process of linear growth from the fetus through adolescence and note that growth is the result of age- and gender-dependent interactions among key genetic, environmental, dietary, socioeconomic, developmental, behavioral, nutritional, metabolic, biochemical, and hormonal factors. We then define the wide range of normative data at each stage of growth and note that a pattern within this range is generally indicative of good general health and that growth significantly slower than this range may lead to growth faltering and subsequent short stature. Although not often emphasized, we detail how to properly measure infants and children because height velocity is usually determined from two height measurements (both relatively large values) to calculate the actual height velocity (a relatively much smaller number in comparison). Traditionally the physiology of growth has been taught from an endocrine-centric point-of-view. Here we review the hypothalamic-pituitary-end organ axes for the GH/IGF-1 and gonadal steroid hormones (hypothalamic-pituitary-gonadal axis), both during "mini"-puberty as well as at puberty. However, over the past few decades much more emphasis has been placed on the growth plate and its many interactions with the endocrine system but also with its own intrinsic physiology and gene mutations. These latter, whether individually (large effect size) or in combination with many others including endocrine system-based, may account in toto for meaningful differences in adult height. The clinical assessment of children with short stature includes medical, social and family history, physical exam and importantly proper interpretation of the growth curve. This analysis should lead to judicious use of screening laboratory and imaging tests depending on the pre-test probability (Bayesian inference) of a particular diagnosis in that child. In particular for those with no pathological features in the history and physical exam and a low, but normal height velocity, may lead only to a bone age exam and reevaluation (re-measurement), perhaps 6 months later. he next step depends on the comfort level of the primary care physician, the patient, and the parent; that is, whether to continue with the evaluation with more directed, more sophisticated testing, again based on Bayesian inference or to seek consultation with a subspecialist pediatrician based on the data obtained. This is not necessarily an endocrinologist. The newest area and the one most in flux is the role for genetic testing, given that growth is a complex process with large effect size for single genes but smaller effect sizes for multiple other genes which in the aggregate may be relevant to attained adult height. Genetics is a discipline that is rapidly changing, especially as the cost of exome or whole gene sequencing diminishes sharply. Within a decade it is quite likely that a genetic approach to the evaluation of children with short stature will become the standard, truncating the diagnostic odyssey and be cost effective as fewer biochemical and imaging studies are required to make a proper diagnosis.

Molecular Mechanisms Governing Embryonic Differentiation of Pituitary Somatotropes

Pituitary somatotropes secrete growth hormone (GH), which is essential for normal growth and metabolism. Somatotrope defects result in GH deficiency (GHD), leading to short stature in childhood and increased cardiovascular morbidity and mortality in adulthood. Current hormone replacement therapies fail to recapitulate normal pulsatile GH secretion. Stem cell therapies could overcome this problem but are dependent on a thorough understanding of somatotrope differentiation. Although several transcription factors, signaling pathways, and hormones that regulate this process have been identified, the mechanisms of action are not well understood. The purpose of this review is to highlight the known players in somatotrope differentiation while emphasizing the need to better understand these pathways to serve patients with GHD.

Loss of Foxm1 Results in Reduced Somatotrope Cell Number during Mouse Embryogenesis

FOXM1, a member of the forkhead box transcription factor family, plays a key role in cell cycling progression by regulating the expression of critical G1/S and G2/M phase transition genes. In vivo studies reveal that Foxm1 null mice have a 91% lethality rate at e18.5 due to significant cardiovascular and hepatic hypoplasia. Thus, FOXM1 has emerged as a key protein regulating mitotic division and cell proliferation necessary for embryogenesis. In the current study, we assess the requirement for Foxm1 in the developing pituitary gland. We find that Foxm1 is expressed in the pituitary at embryonic days 10.5-e18.5 and localizes with markers for active cell proliferation (BrdU). Interestingly, direct analysis of Foxm1 null mice at various embryonic ages, reveals no difference in gross pituitary morphology or cell proliferation. We do observe a downward trend in overall pituitary cell number and a small reduction in pituitary size in e18.5 embryos suggesting there may be subtle changes in pituitary proliferation not detected with our proliferation makers. Consistent with this, Foxm1 null mice have reductions in both the somatotrope and gonadotrope cell populations.

Cell Type-Specific Sexual Dimorphism in Rat Pituitary Gene Expression During Maturation

The most obvious functional differences between mammalian males and females are related to the control of reproductive physiology and include patterns of GnRH and gonadotropin release, the timing of puberty, sexual and social behavior, and the regulation of food intake and body weight. Using the rat as the best-studied mammalian model for maturation, we examined the expression of major anterior pituitary genes in five secretory cell types of developing males and females. Corticotrophs show comparable Pomc profiles in both sexes, with the highest expression occurring during the infantile period. Somatotrophs and lactotrophs also exhibit no difference in Gh1 and Prl profiles during embryonic to juvenile age but show the amplification of Prl expression in females and Gh1 expression in males during peripubertal and postpubertal ages. Gonadotrophs exhibit highly synchronized Lhb, Fshb, Cga, and Gnrhr expression in both sexes, but the peak of expression occurs during the infantile period in females and at the end of the juvenile period in males. Thyrotrophs also show different developmental Tshb profiles, which are synchronized with the expression of gonadotroph genes in males but not in females. These results indicate the lack of influence of sex on Pomc expression and the presence of two patterns of sexual dimorphism in the expression of other pituitary genes: a time shift in the peak expression during postnatal development, most likely reflecting the perinatal sex-specific brain differentiation, and modulation of the amplitude of expression during late development, which is secondary to the establishment of the hypothalamic-pituitary-gonadal and -thyroid axes.

Pediatric sellar and suprasellar lesions

Masses arising in the sella turcica and the suprasellar region are common in children. The type and frequency of the various lesions encountered in childhood differ from the adult presentation. This article reviews the embryology of the pituitary gland and its normal appearance in childhood as well as the imaging and clinical findings of the common and some of the uncommon lesions arising in the sella turcica, the pituitary stalk, the suprasellar cistern and the lower third ventricle in the pediatric population.

Visceral brain-body information transfer

Organisms interact with their environments through various afferent (sensory) and efferent (motor) mechanisms. While the usual environment of interest has been external to the organism, the internal environment is also of fundamental importance. This article briefly reviews many of the interactive mechanisms between the brain and the visceral environment, along with identification of relevant brain structures and linkages related to these peripheral functions (particularly the hypothalamus). Afferent and efferent neural (autonomic nervous system) and chemical (endocrine, immune, and blood-brain barrier and circumventricular organs) pathways are described, and potential unifying principles (emotion and, especially, homeostasis, including allostasis and stress) are identified. The importance of bidirectional (afferent, efferent) communication is emphasized. These systems of visceral brain-body information transfer are major connections between the central nervous system and the body through which and by which many psychosomatic processes occur.

The rebirth of neuroscience in psychosomatic medicine, Part I: historical context, methods, and relevant basic science

Neuroscience was an integral part of psychosomatic medicine at its inception in the early 20th century. Since the mid-20th century, however, psychosomatic research has largely ignored the brain. The field of neuroscience has burgeoned in recent years largely because a variety of powerful new methods have become available. Many of these methods allow for the noninvasive study of the living human brain and thus are potentially available for integration into psychosomatic medicine research at this time. In this first paper we examine various methods available for human neuroscientific investigation and discuss their relative strengths and weaknesses. We next review some basic functional neuroanatomy involving structures that are increasingly being identified as relevant for psychosomatic processes. We then discuss, and provide examples of, how the brain influences end organs through "information transfer systems," including the autonomic, neuroendocrine, and immune systems. The evidence currently available suggests that neuroscience holds great promise for advancing the goal of understanding the mechanisms by which psychosocial variables influence physical disease outcomes. An increased focus on such mechanistic research in psychosomatic medicine is needed to further its acceptance into the field of medicine.