Bihormonal Cells Secreting Both Prolactin and Gonadotropins in Normal Rat Pituitary Cells.

Fukami, Kazuyuki; Tasaka, Keiichi; Mizuki, Jirou; Kasahara, Kanji; Masumoto, Nobuyuki; Miyake, Akira; Murata, Yuji

doi:10.1507/endocrj.44.819

Cited by 11 publications

(11 citation statements)

References 24 publications

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“…The size of this gonadomammotrope pool has been reported to reach 2.5-5% of the mammotropes and 15-18% of the gonadotropes [14]. These figures are close to the ones found here for female mice (Fig.…”

Section: Discussionsupporting

confidence: 91%

“…Cells able to secrete both gonadotropins and PRL have been described in rat AP [14]. The size of this gonadomammotrope pool has been reported to reach 2.5-5% of the mammotropes and 15-18% of the gonadotropes [14].…”

Section: Discussionmentioning

confidence: 99%

“…For example, mammosomatotropes store and release GH and PRL [13]. Polyhormonal corticotropes, [4,5,9], somatogonadotropes [6,7,8] and cells storing and releasing LH and PRL [14] have also been reported. In addition, some GH cells become thyrosomatotropes after a thyroidectomy [19] or protracted primary hypothyroidism [33].…”

Section: Introductionmentioning

confidence: 99%

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Phenotypic characterization of multi-functional somatotropes, mammotropes and gonadotropes of the mouse anterior pituitary

Alonso

Núñez

García‐Sancho

2004

Pflugers Arch - Eur J Physiol

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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 hormone-releasing 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.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

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Phenotypic characterization of multi-functional somatotropes, mammotropes and gonadotropes of the mouse anterior pituitary

Alonso

Núñez

García‐Sancho

2004

Pflugers Arch - Eur J Physiol

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“…Mammosomatotropes that store and release GH and PRL (13) have been regarded as an intermediate stage for conversion of somatotropes into mammotropes, a phenotypic switch between mature cell types without cell division called transdifferentiation (13,31). Polyhormonal corticotropes (4), somatogonadotropes (5,6,8), and cells storing and releasing LH and PRL (14) have also been reported. Polyhormonal thyrotropes containing both TSH and GH (thyrosomatotropes) cells have been observed after thyroidectomy (18) or protracted primary hypothyroidism (30).…”

mentioning

confidence: 99%

Anterior pituitary thyrotropes are multifunctional cells

Alonso

Núñez

García‐Sancho

2004

American Journal of Physiology-Endocrinology and Metabolism

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Anterior pituitary (AP) contains some unorthodox multifunctional cells that store and secrete two different AP hormones (polyhormonal cells) and/or respond to several hypothalamic-releasing hormones (HRHs; multiresponsive cells). Multifunctional cells may be involved in paradoxical secretion (secretion of a given AP hormone evoked by a noncorresponding HRH) and transdifferentiation (phenotypic switch between different mature cell types without cell division). Here we combine calcium imaging (to assess responses to the four HRHs) and multiple sequential immunoassay of the six AP hormones to perform a single-cell phenotypic study of thyrotropes in normal male and female mice. Surprisingly, most of the thyrotropes were polyhormonal, containing, in addition to thyrotropin (TSH), luteinizing hormone (40 -42%) and prolactin (19 -21%). Thyrotropes costoring growth hormone and/or ACTH were found only in females (24% of each type). These results suggest that costorage of the different hormones does not happen at random and that gender favors certain hormone combinations. Our results indicate that thyrotropes are a mosaic of cell phenotypes rather than a single cell type. The striking promiscuity of TSH storage should originate considerable mix-up of AP hormone secretions on stimulation of thyrotropes. However, response to thyrotropin-releasing hormone was much weaker in the polyhormonal thyrotropes than in the monohormonal ones. This would limit the appearance of paradoxical secretion under physiological conditions and suggests that timing of hormone and HRH receptor expression during the transdifferentiation process is finely and differentially regulated. anterior pituitary; hypothalamic releasing factors; paradoxical secretion THE ANTERIOR PITUITARY (AP) contains five main cell types, somatotropes, mammotropes, corticotropes, thyrotropes, and gonadotropes, which secrete growth hormone (GH), prolactin (PRL), ACTH, thyrotropin (TSH), and gonadotropins [follicle-stimulating hormone (FSH) and luteinizing hormone (LH)], respectively. Thyrotropes are the least abundant cell type, amounting to ϳ5-8% of all the AP cells. However, this cell type plays a pivotal role in control of metabolism through regulation of thyroid activity. In the classic view, each AP cell type stores a single hormone in which secretion is specifically regulated by a particular hypothalamic-releasing hormone (HRH). Thus thyrotropes are believed to store and release TSH and express functional thyrotropin-releasing hormone (TRH) receptors involved in hypothalamic control of TSH secretion. However, in the last decade, this "one cell-one hormone" hypothesis has been challenged repeatedly. It has been reported, for example, that many pituitary cells may store and release more than one AP hormone. Mammosomatotropes that store and release GH and PRL (13) have been regarded as an intermediate stage for conversion of somatotropes into mammotropes, a phenotypic switch between mature cell types without cell division called transdifferentiation (13, 31). Polyhormona...

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“…In Xenopus, there is some overlap in the distribution of LH and prolactin cells. In the rat pituitary gland a population of cells expresses both LH and prolactin (Fukami et al 1997) and therefore it is not surprising that LH and prolactin cells both lack melatonin receptors. In the present study, no co-localization of Mel 1a receptor immunoreactivity with prolactin was observed in Xenopus frogs (and co-localization of the Mel 1c receptor in lactotrophs appears unlikely).…”

Section: Melatonin Receptor and Prolactinmentioning

confidence: 99%

Differential distribution of melatonin receptors in the pituitary gland of Xenopus laevis

2003

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A major target site for melatonin action is thought to be the pituitary gland. We have detected differential expression and co-localization of the Mel(1a) and Mel(1c) receptors in cells of the Xenopus laevis pituitary gland. Sections of Xenopus pituitary glands were labeled with Mel(1a) and/or Mel(1c) antibodies, in combination with antibodies to arginine vasotocin (AVT), alpha-melanocyte stimulating hormone (alpha-MSH), prolactin (PRL), and luteinizing hormone (LH). Mel(1a) immunoreactivity was localized to cells of the pars intermedia and to elements within the pars nervosa. Mel(1c) immunoreactivity was also localized to the pars nervosa, and significant labeling was also observed in discrete clusters of cells in the pars distalis. Mel(1a) was absent from the pars distalis, while Mel(1c) was absent from the pars intermedia. Mel(1a) and Mel(1c) were co-localized in the pars nervosa. AVT was present in the pars nervosa, and appeared to be localized to the cell clusters of the pars distalis in which the Mel(1c) receptor was localized. alpha-MSH co-localized with the Mel(1a) receptor in the pars intermedia. LH appeared to localize to many of the cells in the pars distalis, with the notable exception of the Mel(1c) receptor-positive clusters of cells. PRL did not appear to co-localize with either melatonin receptor. The pattern of differential expression of the Mel(1a) and Mel(1c) receptors suggests that the receptors specifically mediate the cellular response to melatonin binding in the specific cell populations.

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Bihormonal Cells Secreting Both Prolactin and Gonadotropins in Normal Rat Pituitary Cells.

Cited by 11 publications

References 24 publications

Phenotypic characterization of multi-functional somatotropes, mammotropes and gonadotropes of the mouse anterior pituitary

Phenotypic characterization of multi-functional somatotropes, mammotropes and gonadotropes of the mouse anterior pituitary

Anterior pituitary thyrotropes are multifunctional cells

Differential distribution of melatonin receptors in the pituitary gland of Xenopus laevis

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