Age-related changes in the numbers of mammotrophs, somatotrophs and mammosomatotrophs in the anterior pituitary gland of female rats: A flow cytometric study

Senoo, Tadashi; Sakurai, Yoko; Ooka, Hiroshi

doi:10.1016/0047-6374(95)01614-6

Cited by 15 publications

(15 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A high proportion of mammosomatotrophs at 9 days is in keeping with the data of Hoeffler et al (1985), and Shinkai et al (1995) also found an increase in mammosomatotrophs with age in normal females. At some ages in our study, the females had fewer mammosomatotrophs than males, but we interpret this cautiously since mammosomatotrophs vary with the oestrous cycle (Kineman et al 1991) and this was not monitored in our study.…”

Section: Discussionsupporting

confidence: 75%

“…FACS analysis has previously been used (Hatfield & Hymer 1985, Shinkai et al 1995 to purify and/or count pituitary cells, either after immunostaining or by using cell-specific green fluorescent protein expression in transgenic mice (Magoulas et al 2000). Although more convenient and objective than manual cell counting, it has its own methodological concerns.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Increased lactotrophs despite decreased somatotrophs in the dwarf (dw/dw) rat: a defect in the regulation of lactotroph/somatotroph cell fate?

Tierney

Robinson²

2002

Journal of Endocrinology

View full text Add to dashboard Cite

The dwarf (dw/dw) rat differs from all other rodent models of GH deficiency in that its pituitary prolactin (PRL) content is normal or even increased. We have now studied this throughout postnatal development, using a combination of immunocytochemistry, RIA and fluorescenceactivated cell sorting (FACS) and analysis. Compared with normal Albino Swiss (AS) rats, adult dw/dw rats showed a profound reduction in pituitary GH content accompanied by increased PRL content, significantly so in females (AS vs dw/dw; P<0·01). Somatotroph hypoplasia was evident in the adult dw/dw rats, with most GH +ve cells showing weak immunostaining, whereas many more strongly stained PRL cells were evident in pituitary sections from dw/dw rats. FACS analysis confirmed both somatotroph hypoplasia and relative lactotroph hyperplasia in dw/dw rats at all ages studied (9-144 days); the difference in somatotrophs increased with age whereas the difference in lactotrophs declined with age. At 9 days, the percentage of lactotrophs was 10-fold higher in dw/dw rats than in AS rats. Young dw/dw rats also had a higher proportion of mammosomatotrophs than AS rats, although this difference disappeared as the mammosomatotroph proportions increased with age in both strains. GHRH released GH from both dw/dw and AS cells maintained in culture for 5 days. The sensitivity to GHRH and the amount of GH released was lower in the dw/dw cultures, mostly explained by their fewer GH cells and lower initial GH content. GHRH increased cAMP in AS but not in dw/dw cultures, even when these were greatly enriched for dw/dw somatotrophs by FACS sorting prior to culture. These results suggest that GHRH-induced cAMP stimulation is required for trophic effects on GH synthesis and somatotroph proliferation, but is not required for GHRH-stimulated GH release. The inverse changes in somatotroph and lactotroph numbers suggest that the dw/dw mutation disturbs the mechanism that specifies and retains appropriate numbers of somatotrophs in their differentiated state, and results in a higher proportion of the remaining cells progressing to lactotrophs. The dw/dw phenotype is thus not confined to somatotrophs.

show abstract

Section: Discussionsupporting

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Increased lactotrophs despite decreased somatotrophs in the dwarf (dw/dw) rat: a defect in the regulation of lactotroph/somatotroph cell fate?

Tierney

Robinson²

2002

Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…Humans have a high proportion of these cells, which are an intermediate form between mammotrophs secreting PRL and somatotrophs secreting GH (36). Furthermore, it has been found in rats that the numbers of mammosomatotrophs increase markedly with age (37). Using young swine in this study might be part of the reason for not observing any PRL release.…”

Section: Discussionmentioning

confidence: 82%

Ipamorelin, the first selective growth hormone secretagogue

Raun

Hansen²,

Johansen³

et al. 1998

European Journal of Endocrinology

View full text Add to dashboard Cite

The development and pharmacology of a new potent growth hormone (GH) secretagogue, ipamorelin, is described. Ipamorelin is a pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH 2 ), which displays high GH releasing potency and efficacy in vitro and in vivo. As an outcome of a major chemistry programme, ipamorelin was identified within a series of compounds lacking the central dipeptide Ala-Trp of growth hormone-releasing peptide (GHRP)-1.In vitro, ipamorelin released GH from primary rat pituitary cells with a potency and efficacy similar to GHRP-6 (EC 50 ¼ 1.3Ϯ0.4 nmol/l and E max ¼ 85Ϯ5% vs 2.2Ϯ0.3 nmol/l and 100%). A pharmacological profiling using GHRP and growth hormone-releasing hormone (GHRH) antagonists clearly demonstrated that ipamorelin, like GHRP-6, stimulates GH release via a GHRP-like receptor.In pentobarbital anaesthetised rats, ipamorelin released GH with a potency and efficacy comparable to GHRP-6 (ED 50 ¼ 80Ϯ42 nmol/kg and E max ¼ 1545Ϯ250 ng GH/ml vs 115Ϯ36 nmol/kg and 1167Ϯ120 ng GH/ml).In conscious swine, ipamorelin released GH with an ED 50 ¼ 2.3Ϯ0.03 nmol/kg and an E max ¼ 65Ϯ0.2 ng GH/ml plasma. Again, this was very similar to GHRP-6 (ED 50 ¼ 3.9Ϯ1.4 nmol/kg and E max ¼ 74Ϯ7 ng GH/ml plasma). GHRP-2 displayed higher potency but lower efficacy (ED 50 ¼ 0.6 nmol/kg and E max ¼ 56Ϯ6 ng GH/ml plasma).The specificity for GH release was studied in swine. None of the GH secretagogues tested affected FSH, LH, PRL or TSH plasma levels. Administration of both GHRP-6 and GHRP-2 resulted in increased plasma levels of ACTH and cortisol. Very surprisingly, ipamorelin did not release ACTH or cortisol in levels significantly different from those observed following GHRH stimulation. This lack of effect on ACTH and cortisol plasma levels was evident even at doses more than 200-fold higher than the ED 50 for GH release.In conclusion, ipamorelin is the first GHRP-receptor agonist with a selectivity for GH release similar to that displayed by GHRH. The specificity of ipamorelin makes this compound a very interesting candidate for future clinical development.

show abstract

“…Thereafter, surprisingly, no information is available about the existence and distribution of MS cells in swine adenohypophysis. Since MS cells are occasionally present throughout adenohypophysis in sheep [37,38], mice [29] and goats [31] Existence and distribution of MS cells In swine adenohypophysis, numerous cells were immunostained with each anti-GH and anti-PRL antiserum. GH cells and PRL cells were first detected in fetuses of 17.5 cm and 33.0 cm body lengths, respectively.…”

mentioning

confidence: 99%

“…The bihormonal cells were ascertained immunocytochemically in intact adult rats and designated as mammosomatotrophs or somatomammotrophs (MS cells) [24]. The existence of MS cells has been reported in rats [17,22,24,25], the musk shrew [17], bats [18], mice [29,30], the rhesus monkeys [1], humans [21,23], bovine [9,12], sheep [37,38] and goats [31]. It is now proposed that possible functions of MS cells are as transitional cells for the conversion of GH cells to PRL cells [2,3,14,26,27], or as progenitor cells for GH cells and PRL cells [23].…”

mentioning

confidence: 99%