Distribution of lactotroph subpopulations in different regions of the rat pituitary

Hu, Limin; Lawson, David M.

doi:10.1016/0024-3205(94)00316-5

Cited by 8 publications

(7 citation statements)

References 19 publications

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“…While others have examined the effects of E 2 on lactotropes, to our knowledge no one has examined the effects of E 2 and P 4 , alone or in combination, in a complete study [18, 28]. Our findings confirm the previous findings [29]that both E 2 and E 2 +P 4 treatments increase the abundance of lactotropes in the anterior pituitary. Curiously, both E 2 and P 4 treatments increased the incidence of lactotropes releasing PRL.…”

Section: Discussionsupporting

confidence: 83%

Ovarian Steroids Modulate Responsiveness to Dopamine and Expression of G-Proteins in Lactotropes

1998

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The effects of chronic ovarian steroid treatment on the secretory activity of individual lactotropes and the mechanisms modulating their responsiveness to dopamine (DA) were studied. Female rats were ovariectomized (OVX) and implanted with Silastic capsules containing progesterone (P₄), 17β), 17β-estradiol (E₂) or both E₂ (E₂+P₄). Ten days after surgery, anterior pituitaries were enzymatically dispersed and the reverse hemolytic plaque assay (RHPA) was performed to assess the release of prolactin (PRL) from individual lactotropes. RHPA was combined with immunocytochemistry (ICC) for PRL, G_αs or G_iα3/G_αo proteins. E₂ treatment alone or in combination with P₄ increased the percentage of immunoreactive lactotropes among anterior pituitary cells. Incidence of active (plaque-forming) lactotropes, however, was increased both in P₄-, and E₂-treated rats and E₂+P₄ treatment increased it even further. While P₄ treatment did not affect the frequency distribution of lactotropes, both E₂ and E₂+P₄ treatments increased the large plaque-forming lactotrope population. This increase was reflected by the significantly greater mean plaque areas of lactotropes from E₂- and E₂+P₄-treated rats compared to OVX or P₄-treated animals. The responsiveness of lactotropes to DA from P₄-treated rats did not differ from that of OVX rats: thus challenge with 1 µM DA inhibited the release of PRL, while 100 pM DA had no effect. E₂ and E₂+P₄ treatments, however, profoundly changed the lactotrope’s responsiveness: challenge with 1 µM DA had no effect and 100 pM DA resulted in moderate stimulation of PRL release in E₂+P₄ rats. Double-label ICC revealed that ovarian steroid treatments did not affect the expression of G_αs in lactotropes. The incidence of G_iα3/G_αo-immunoreactive lactotropes, however, decreased after E₂ treatment, alone or in combination with P₄. Although expression of G_αs was similar in all plaque-forming cells regardless of plaque size, lactotropes expressing G_iα3/G_αo were more likely to form small plaques in all treatment groups. These data suggest: (1) ovarian steroid treatment recruits quiescent lactotropes to release PRL; (2) E₂ treatment alone or in combination with P₄ increases the amount of PRL rleased by individual lactotropes; (3) E₂-induced alterations in the frequency distribution and lactotrope responsiveness to DA may be due in part to a decreased expression of G_iα3/G_αo.

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Section: Discussionsupporting

confidence: 83%

Ovarian Steroids Modulate Responsiveness to Dopamine and Expression of G-Proteins in Lactotropes

1998

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“…Such a clear to-pographical difference in the distribution of PRL cell subtypes between the two regions has thus been found for the first time. This appears to be consistent with previous results obtained with the RHPA technique, showing functional differences between the two parts of the pituitary (Boockfor and Frawley 1987;Nagy et al 1991;Porter and Frawley 1992;Hu and Lawson 1994). We have applied both LM-RHPA and EM-RHPA methods to dispersed cells from the two zones of the male rat anterior pituitary, to achieve further morpho-functional insights.…”

Section: Discussionsupporting

confidence: 89%

“…Two regions have been delineated, viz. an "inner" zone in the vicinity of the neurointermediate lobe and an "outer" zone en-compassing the periphery of the gland (Boockfor and Frawley 1987;Sasaki and Iwama 1988;Mukherjee et al 1991;Nagy et al 1991;Porter and Frawley 1992;Hu and Lawson 1994). Such regional differences in the responsiveness to thyrotropin-releasing hormone (TRH) and dopamine have been observed in the lactating female rat (Boockfor and Frawley 1987;Nagy et al 1991).…”

Section: Introductionmentioning

confidence: 99%

Structural and functional differences between prolactin cells from the inner and outer zones of the male rat anterior pituitary

Vila-Porcile

Barret

1996

Cell and Tissue Research

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The aim of this study was to compare the ultrastructure of prolactin cells in the inner and outer zones of the male rat anterior pituitary, and to relate their morphological features to their secretory activity, by means of standard and ultrastructural reverse hemolytic plaque assays (RHPA). The immuno-ultrastructural study showed that in the inner pituitary small-granulated cells represented 52% of the prolactin cells, there being only 5% with large granules, whereas the prolactin cells with large granules accounted for 52% in the outer zone, with only 7% being small-granulated. Percentages of cells with intermediate-sized granules were 43% and 41%, respectively. Analysis of RHPA data revealed that, under basal conditions, prolactin cells secreted more actively in the inner zone than in the outer zone. Stimulation with thyrotropin-releasing hormone or KCl treatment increased the percentage of secretors and the sizes of hemolytic plaques in both zones. However, in response to thyrotropin-releasing hormone, the increase in number of secretors was always higher in the outer zone, whereas the enlargement of plaque sizes was greater for the "inner" cells. These findings are in favor of the small-granulated cells, which predominate in the inner zone, being in a stage of active secretion and responsiveness.

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“…In previous research, density gradient centrifugation has been used to isolate specific hormone-producing cells (prolactin and GH cells: [2], prolactin cells: [6], LH cells: [12], GH cells: [11, 13, 16]). The purities of fractions did not exceed 75%, and the fractions were referred to as specific cell type-“enriched” fractions.…”

Section: Discussionmentioning

confidence: 99%

“…Distinguishing and isolating specific types of living cells are important in investigating their specific functions, and many such attempts have been made. One method, density gradient centrifugation [2, 6, 9, 12], resulted in fractions of limited purity. Recently, transgenic techniques combined with fluorescence-activated cell sorting have achieved sufficient purity for specific cell types, but only a small number of applications have been reported [7].…”

Section: Introductionmentioning

confidence: 99%

Live Staining and Isolation of Specific Hormone-Producing Cells from Rat Anterior Pituitary by Cytochemistry with Lectins and Cholera Toxin B Subunit

Kikuchi

Kusumoto

Fujiwara

et al. 2011

Acta Histochem. Cytochem

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Anterior pituitary glands contain five types of hormone-producing cells. Distinguishing and isolating specific types of living cells are essential for studying their function. Although many such attempts have been made, the results have been disappointing. In the present study, we labeled specific types of living hormone-producing cells by using potential differences in sugar chains on the cell surfaces. Cytochemical analysis with lectins and cholera toxin B subunit revealed that PNA, S-WGA, and cholera toxin B subunit recognized sugar chains specific to prolactin cells, ACTH cells, and GH cells, respectively, and that UEA-I recognized most of prolactin cells and GH cells. Next, fluorescence-activated cell sorting was used to isolate GH cells labeled by fluoresceinated cholera toxin B. The purity of the GH cell fraction estimated by immunocytochemistry and quantitative real-time PCR for cell type-specific genes was more than 98%, which was higher than that reported in earlier studies, including those using transgenic animals. We conclude that cytochemistry with lectins and cholera toxin B subunit is a straightforward, acceptable method of isolating specific types of anterior pituitary cells and that the cells isolated by this method can serve as useful materials in the study of anterior pituitary cells.

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Distribution of lactotroph subpopulations in different regions of the rat pituitary

Cited by 8 publications

References 19 publications

Ovarian Steroids Modulate Responsiveness to Dopamine and Expression of G-Proteins in Lactotropes

Ovarian Steroids Modulate Responsiveness to Dopamine and Expression of G-Proteins in Lactotropes

Structural and functional differences between prolactin cells from the inner and outer zones of the male rat anterior pituitary

Live Staining and Isolation of Specific Hormone-Producing Cells from Rat Anterior Pituitary by Cytochemistry with Lectins and Cholera Toxin B Subunit

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