Rapid Changes in Anterior Pituitary Cell Phenotypes in Male and Female Mice after Acute Cold Stress (original) (raw)
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Development and sexual dimorphism of the pituitary gland
Life Sciences, 2007
The pituitary gland plays a central role in sexual development and brain function. Therefore, we examined the effect of age and gender on pituitary volume in a large sample of healthy children and adults. Volumetric magnetic resonance imaging (MRI) was conducted in one hundred and fifty four (77 males and 77 females) healthy participants. Males were between the ages of 7 to 35 years (16.91 ± 5.89 years) and females were 7 to 35 years of age (16.75 ± 5.75 years). Subjects were divided into subgroups of age (7 to 9, 10 to 13, 14 to 17, 18 to 21, 22 and older) and sex (male/female). Pituitary gland volume differed between sexes when comparing the age groups (F = 3.55, df = 2, 143, p = 0.03). Females demonstrated larger pituitary glands than males in the age 14 to 17 year old groups (p = 0.04). Young (19 years and under) and old (20 years and older) females demonstrated a correlation between pituitary volume and age. Males did not show this relationship. These findings provide additional evidence for gender differences in the normative anatomy of the pituitary and may have relevance for the study of various childhood onset neuropsychiatric disorders in which pituitary dysfunction has been implicated.
Endocrinology, 2005
Anterior pituitary (AP) is formed by five different cell types, each one producing a different AP hormone whose secretion is regulated by a specific hypothalamic-releasing hormone (HRH). On the other hand, a significant number of AP cells express multiple HRH receptors (multiresponsive cells). Plastic changes in expression of HRH receptors in individual AP cells are involved in critical endocrine events. Here we have characterized the changes in functional responses to CRH, LHRH, TRH, and GHRH in individual AP cells throughout the whole life span of the rat. To this end, calcium responses to the HRHs were followed by single-cell imaging in freshly dispersed AP cells prepared from rats of different ages (0 -540 postnatal days). Three different cell pools were identified: 1) monoresponsive cells, holding a single class of HRH receptor; 2) multiresponsive cells; and 3) nonresponsive cells. The relative abundance of each pool changed with age. Nonresponsive cells were abundant at birth, multiresponsive cells were abundant at puberty, and monoresponsive cells dominated at senescence. The relative abundance of each HRH receptor changed largely with age but not gender. In addition, the contribution of monoresponsive and multiresponsive cells to responses to each HRH changed very much with age. Thus, the anterior pituitary shows large changes in cell populations typed by functional responses to HRHs during maturation, puberty, and senescence.
Sexual dimorphism in the age changes of the pituitary lactotrophs in rats
Mechanisms of Ageing and Development, 1997
It is known that aging is associated with alterations in hypothalamic and pituitary functions. In the present study, we have undertaken a quantitative immunohistochemical assessment of the lactotroph cell population as well as prolactin (PRL) secretion, in male and female rats of different ages. Pituitaries from young (3 months), old (20 months) and senescent (29 months) male and female Sprague-Dawley rats were processed for the immunohistochemical detection of lactotrophs. Serum PRL was measured by a homologous RIA. Additionally, the in vitro PRL secretory activity was estimated by perifusion of pituitary cells from senescent animals. Analysis of morphometric parameters revealed age-related changes of PRL cell population in animals of both sexes. The cell density (CD), surface density (SD) and volume density (VD) decreased with age in both male and female rats. However, CD as well as SD appeared to have increased in females when compared to males, either in young or old animals, while VD was higher only in old females. The pituitaries of senescent females displayed chromophobic microadenomas on a background of diffuse PRL cell hyperplasia. Prolactin serum levels showed a marked increase with age in females, but only a modest elevation in males. In senescent females, PRL production per cell was reduced. We conclude that in rats, there exists a clear sexual dimorphism in the age-related changes of pituitary PRL cells.
Endocrinology, 2002
In the pituitary, CRH-binding protein (CRH-BP) neutralizes the ACTH-releasing activity of CRH. Because sexual dimorphisms exist at multiple levels of the hypothalamic-pituitaryadrenal axis, these studies examined expression of pituitary CRH-BP in the male and female mouse pituitary. Ribonuclease protection assays and 125 I-CRH cross-linking assays demonstrate greater expression of pituitary CRH-BP in female than male mice. Normalized CRH-BP mRNA levels in female mice are 2.58 times greater at proestrus than diestrus. Ovariectomy reduces pituitary CRH-BP mRNA levels to 11% of sham-ovariectomy control levels, and estradiol benzoate treatment restores CRH-BP mRNA to control levels. These data suggest that estrogen positively regulates pituitary CRH-BP. Dual in situ hybridization analysis reveals that CRH-BP expression increases significantly in proopiomelanocortinexpressing cells at proestrus, compared with metestrus (P ؍ 0.003), suggesting that CRH-BP expression is estrogen regulated in corticotropes. Further studies reveal that approximately 80% of the CRH-BP transcripts in the proestrus mouse pituitary localize to prolactin-expressing cells, a novel site for CRH-BP expression. CRH-BP mRNA levels increase significantly at proestrus, compared with metestrus in prolactinpositive cells (P < 0.0001). This robust, estrogen-regulated expression of CRH-BP in lactotropes in female mice suggests that the pituitary is an important site for interactions between the hypothalamic-pituitary-adrenal axis and other endocrine systems. (Endocrinology 143: 4730-4741, 2002
Journal of Endocrinology, 1986
Anterior pituitary glands were removed from male rats at 5, 10, 15, 18, 21, 28, 30, 40, 45, 50 and 90 days of age, and the multiple forms of FSH present within them were separated by polyacrylamide gel–isoelectric focusing (PAGE–IEF; pH range 3·0–8·0). Gel eluents were analysed for FSH content by radioimmunoassay (RIA) and a specific radioreceptor assay (RRA). All pituitaries studied exhibited one or more peaks of immunoactive FSH within a pH range of 7·0–3·0; the major peak exhibited an isoelectric point (pi) of 4·9–4·0. Between 25 and 56% of anterior pituitary FSH obtained from rats 5–30 days old focused within a pH range of 4·9–4·5, whilst in older animals (≥40 days) this pH range contained 17–27% of the total FSH recovered. In contrast, in animals 40–90 days old, the greatest proportion of immunoactive FSH (42–62% of the total immunoactivity recovered) focused within a pH range of 4·4–4·0; further, only these groups of animals exhibited a significant proportion of anterior pitui...
Brain Research, 2004
Using immunocytochemical and morphometric methods, we examine changes with age of growth hormone-releasing hormone (GHRH) in the arcuate nucleus (ARC), changes of somatostatin (SS) in the periventricular nucleus (PeN) of the hypothalamus, and changes of growth hormone (GH) cells in the anterior pituitary in male C57BL/6J mice at 2 months old (2 M), 4 M, 12 M and 24 M. The number of GHRH-ir neurons decreased significantly with age. The number of SS-ir neurons did not differ significantly between these all age groups. The volume of the anterior pituitary and the number of adenohypophysial parenchymal cells fell dramatically from 4 to 12 M. The proportion of GH-ir cells decreased significantly with age, and in absolute number from 4 to 12 M and in size from 2 to 4 M and from 4 to 12 M. These results suggest that the reduction in GH-ir cells in male mice is modulated by the reduction in GHRH-ir neurons, but not by SS-ir neurons.
Pfl�gers Archiv - European Journal of Physiology, 2004
The existence of bihormonal anterior pituitary (AP) cells co-storing growth hormone and either prolactin (mammosomatotrope) or gonadotropins (somatogonadotrope) has been described. These cells have been proposed to be involved in ''paradoxical'' secretion [secretion of an AP hormone induced by a non-related hypothalamic releasing factor (HRH) and transdifferentiation (a phenotypic switch between different cell types without cell division]. Here we combine calcium imaging (to assess HRH responsiveness) and multiple sequential immunoassay of the six AP hormones to perform a single-cell phenotypic study of multifunctional somatotropes, mammotropes and gonadotropes in the normal male and female mouse pituitaries. AP cell phenotypes differed from the classic view, showing multiple HRH-receptor expression and/or hormone storage. Mammosomatotropes represented only 5-6% of somatotropes and were poorly responsive to HRHs, suggesting that their contribution to paradoxical secretion should be very limited. Somatogonadotropes were present only in females and contained adrenocorticotropic hormone. They responded to growth hormonereleasing hormone but failed to respond to gonadotropin-releasing hormone (LHRH). Other polyhormonal cells identified include (1) gonadocorticotropes, restricted to females, where they make up more than 50% of all the gonadotropes and contain other AP hormones; (2) gonadomammotropes, which are present preferentially in female cells and respond to LHRH; and (3) gonadothyrotropes, which are present similarly in male and female pituitaries.