MAMMARY GLAND PROLACTIN RECEPTOR AND PITUITARY PROLACTIN SECRETION IN LACTATING MICE WITH DIFFERENT LACTATIONAL PERFORMANCE

1978 ◽  
Vol 88 (1) ◽  
pp. 94-98 ◽  
Author(s):  
Hiroshi Nagasawa ◽  
Reiko Yanai
Keyword(s):  
Mammary Gland ◽  
Prolactin Receptor ◽  
Correlation Coefficients ◽  
Binding Activity ◽  
Prolactin Secretion ◽  
Mammary Tumour ◽  
Receptor Sites ◽  
Lactational Performance ◽  
Pituitary Prolactin

ABSTRACT SHN female mice, a high mammary tumour strain, are superior to SLN, a low mammary tumour strain, in lactational performance. Mammary gland prolactin receptor and pituitary prolactin secretion during lactation were compared between these strains. The binding activity, the number of receptor sites per mg tissue and the association constant were measured by the in vitro incubation of mammary gland slices with 125I-labelled bovine prolactin, and the pituitary and plasma levels of prolactin were assayed by homologous radioimmunoassay. There was only a slight difference between strains in any of the parameters for prolactin receptor and for prolactin secretion on either day 4 or day 9 of the first lactation. Almost all the correlation coefficients between each parameter for prolactin receptor and the pituitary or plasma level of prolactin were not statistically significant. These findings suggest that any parameter for prolactin examined in this study is not always directly indicative of lactational performance and further show that the individual variation in the pituitary prolactin secretion during lactation is not so great as to alter the prolactin receptor.

MAMMARY NUCLEIC ACIDS AND PITUITARY PROLACTIN SECRETION DURING PROLONGED LACTATION IN MICE

1976 ◽  
Vol 70 (3) ◽  
pp. 389-395 ◽  
Author(s):  
H. NAGASAWA ◽  
R. YANAI
Keyword(s):  
Mammary Gland ◽  
Dna Content ◽  
Rna Synthesis ◽  
Prolactin Secretion ◽  
Nucleic Acid Content ◽  
Plasma Prolactin ◽  
Litter Weight ◽  
Dna And Rna ◽  
Pituitary Prolactin

SUMMARY Lactation was prolonged until 61 days by repeated renewal of litters every week after day 12 in primiparous C3H/He strain mice. On days 12, 19, 40 and 61 of lactation, litters were removed for 5 h and after 1 h of resuckling the synthesis of DNA and RNA in the mammary gland was estimated by the incorporation of [3H]thymidine and [14C]uridine into mammary DNA and RNA in vitro respectively. Mammary nucleic acid content and pituitary and plasma levels of prolactin were also assayed. Nulliparous mice were similarly treated on day 19 of pregnancy. The percentage gain in litter weight per week was highest between days 5 and 12 of lactation, declined until days 26–33 and became steady thereafter. Mammary DNA synthesis was extremely high on day 19 of pregnancy, decreased on day 12 of lactation to less than one-fifteenth of that on day 19 of pregnancy and increased linearly thereafter. Changes in mammary DNA content were not so marked, but DNA content was high on days 12 and 19 of lactation. RNA synthesis was highest on day 19 of pregnancy, abruptly decreased on days 12 and 19 of lactation and increased again with the advance of lactation. Mammary RNA content, RNA:DNA and 14C:3H ratios increased from day 19 of pregnancy to days 12–19 of lactation and decreased on days 40 and 61. While the pituitary levels of prolactin were almost constant during lactation, they were significantly higher than those on day 19 of pregnancy. There were only slight differences in plasma prolactin levels at any stage.

Ruminants express a prolactin receptor of Mr 33 000—36 000 in the mammary gland throughout pregnancy and lactation

1993 ◽  
Vol 139 (1) ◽  
pp. 37-49 ◽  
Author(s):  
J. J. Smith ◽  
A. V. Capuco ◽  
I. H. Mather ◽  
B. K. Vonderhaar
Keyword(s):  
Mammary Gland ◽  
Developmental Stages ◽  
Developmental Regulation ◽  
Prolactin Receptor ◽  
Binding Activity ◽  
Receptor Type ◽  
Mammary Tissue ◽  
Cross Linking ◽  
Developmental Variation ◽  
Pregnancy And Lactation

ABSTRACT Developmental variation in the expression of the prolactin receptor in the ruminant mammary gland was investigated. Affinity chromatography revealed that bovine prolactin and human GH each bound to the same mammary gland proteins, yielding fractions enriched in binding activity and a protein of Mr 36 000, assumed to be a bovine prolactin receptor. Affinity cross-linking of 125I-labelled human GH to mammary microsomes confirmed that the Mr 36 000 protein was a bovine prolactin receptor. Binding assays of receptors in microsomes from the mammary tissue of cows and ewes at various stages of the lactational/reproductive cycle indicated developmental regulation of receptor concentration, but not receptor type, as no other bovine prolactin receptor type was detected by affinity cross-linking. These results suggest that differences in the response to prolactin in the mammary gland at various developmental stages in ruminants are not due to the expression of different forms of the prolactin receptor, and the lack of a prolactin effect on established lactation in ruminants is not due to the absence of the Mr 36 000 form of the prolactin receptor. Journal of Endocrinology (1993) 139, 37–49

ONSET OF OESTROGEN-INDUCED PROLACTIN SECRETION AND DNA SYNTHESIS BY THE RAT PITUITARY GLAND

1977 ◽  
Vol 72 (1) ◽  
pp. 35-39 ◽  
Author(s):  
JOAN JACOBI ◽  
H. M. LLOYD ◽  
J. D. MEARES
Keyword(s):  
Dna Synthesis ◽  
Pituitary Gland ◽  
Prolactin Secretion ◽  
Male Rat ◽  
Serum Prolactin ◽  
Rat Pituitary ◽  
The Times ◽  
Pituitary Prolactin

SUMMARY The times of onset of oestrogen-induced prolactin secretion and DNA synthesis were studied in the pituitary gland of the male rat. At intervals from 3 to 96 h after injection of 10 mg diethylstilboestrol dipropionate, serum and pituitary prolactin concentrations were measured by radioimmunoassay and pituitary DNA synthesis by incorporation of [3H]thymidine in vitro. Serum prolactin was raised significantly from 6 h onwards and DNA synthesis was increased from 30 h onwards. Pituitary prolactin concentration began to increase at 30 h. Significant correlations were obtained between serum prolactin and DNA synthesis from 24 to 72 h but not during the period of prolactin secretion from 6 to 24 h.

Progesterone and EGF inhibit mouse mammary gland prolactin receptor and beta-casein gene expression

1994 ◽  
Vol 267 (5) ◽  
pp. C1467-C1472 ◽  
Author(s):  
S. Nishikawa ◽  
R. C. Moore ◽  
N. Nonomura ◽  
T. Oka
Keyword(s):  
Gene Expression ◽  
Mammary Gland ◽  
Prolactin Receptor ◽  
Mammary Epithelium ◽  
Mouse Mammary Gland ◽  
Mrna Levels ◽  
Casein Gene ◽  
Beta Casein

Regulation of mouse mammary gland long-form prolactin receptor (PRL-RL) mRNA levels by progesterone and epidermal growth factor (EGF) and the relationship between PRL-RL and beta-casein gene expression were examined in vivo and in vitro. PRL-RL and beta-casein mRNA levels increased approximately 6- and 15-fold from the pregnant to the lactating period, respectively, when normalized to the level of beta-actin mRNA. Ovariectomy of pregnant mice rapidly reduced the serum concentration of progesterone and increased the level of PRL-RL and beta-casein mRNAs approximately three- and fourfold compared with sham-operated animals 24 h after the operation. Injection of progesterone, but not estrogen, inhibited the increase in both mRNA levels. PRL-RL and beta-casein mRNA levels in cultured mammary epithelium increased in response to insulin, hydrocortisone, and prolactin, whereas progesterone or EGF caused inhibition. The combination of EGF and progesterone produced a greater inhibition than either hormone alone. These results indicate that both progesterone and EGF serve as negative regulators of lactogenesis.

Possible Direct Effect of Serotonin on Pituitary Prolactin Secretion: in vivo and in vitro Studies

1987 ◽  
Vol 25 (3) ◽  
pp. 160-170 ◽  
Author(s):  
F. López ◽  
D. González ◽  
E. Aguilar
Keyword(s):  
Direct Effect ◽  
Prolactin Secretion ◽  
In Vitro Studies ◽  
Pituitary Prolactin

Ritonavir and Saquinavir Directly Stimulate Anterior Pituitary Prolactin Secretion, in Vitro

2002 ◽  
Vol 15 (1) ◽  
pp. 65-68 ◽  
Author(s):  
G. Orlando ◽  
L. Brunetti ◽  
M. Vacca
Keyword(s):  
Protease Inhibitors ◽  
Anterior Pituitary ◽  
Dopamine Release ◽  
Prolactin Secretion ◽  
Hiv Protease ◽  
Type I ◽  
Endogenous Dopamine ◽  
Pituitary Prolactin ◽  
Hiv 1

An association between human immunodeficiency virus type I (HIV-1) protease inhibitors (Pis) and galactorrhoea/hyperprolactinemia adverse effect has recently been reported in four HIV-1-infected women treated with Pis (indinavir, nelfinavir, ritonavir or saquinavir). This could be explained by a direct effect of ritonavir and saquinavir on anterior pituitary prolactin (PRL) release, and/or an indirect effect of Pis on the secretion of hypothalamic dopamine, which is the main PRL inhibitory factor. Anterior pituitaries were explanted from adult male Wistar rats, the cells were trypsin dispersed, plated into multiwell cultures and incubated for 1 h with either ritonavir or saquinavir (0.01 nM-1mM). PRL release into the incubation medium was evaluated by radioimmunoassay. Hypothalamic neuronal endings (synaptosomes) were prepared by tissue homogenization, incubated with [3H]dopamine, substituting for the endogenous dopamine pool, and perfused with ritonavir or saquinavir, both basally and during depolarization (K+ 15 mM)-induced dopamine release. Beta-emission from 2 min perfusate fractions, corresponding to [3H]dopamine release, was detected by liquid scintillation scanning. We found that both ritonavir and saquinavir are able to significantly stimulate PRL secretion, with saquinavir slightly more effective than ritonavir. On the contrary, both protease inhibitors do not modify either basal or depolarization-induced dopamine release. We can speculate that HIV Pis despite a high affinity for the catalytic site of HIV protease, could also bind to and inhibit homologous mammalian proteins in the anterior pituitary that are involved in PRL secretion.

Inhibition by early treatment with bromocriptine of spontaneous mammary tumour development in rats with no side-effects

1982 ◽  
Vol 101 (1) ◽  
pp. 51-55 ◽  
Author(s):  
H. Nagasawa ◽  
S. Morii
Keyword(s):  
Later Life ◽  
Mammary Glands ◽  
Prolactin Secretion ◽  
Mammary Tumour ◽  
Tumour Development ◽  
One Year ◽  
And Function ◽  
Pituitary Prolactin ◽  
Temporary Inhibition ◽  
Marked Suppression

Abstract. Temporary inhibition by CB-154 (bromocriptine) of pituitary prolactin secretion, which induced a decline in mammary gland DNA synthesis for 4–11 weeks of age, resulted in a marked suppression of spontaneous mammary tumour development in rats after one year of age. The treatment had no effect on reproduction and subsequent lactation immediately after the CB-154 injection or growth and function of the mammary glands and pituitary prolactin secretion in later life.

Size heterogeneity of prolactin secreted from and stored in the rat anterior pituitary gland in vitro

1984 ◽  
Vol 4 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Andrew M. Bentley ◽  
Teresa K. Surowy ◽  
Michael Wallis
Keyword(s):  
Anterior Pituitary ◽  
Relative Proportion ◽  
Gel Filtration ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Pituitary Glands ◽  
Dimeric Form ◽  
Size Heterogeneity ◽  
Pituitary Prolactin

The size heterogeneity of rat pituitary prolactin was investigated using anterior pituitary glands from female rats incubated in vitro and gel filtration on Sephadex G-100. Monomeric prolactin was preferentially secreted compared with dimeric and ‘trimeric” material. When glands were incubated with dopamine, prolactin secretion was inhibited and the relative proportion of dimer in the gland (but not the medium) was decreased. Morphine sulphate reversed the effect of dopamine on prolactin secretion and on the proportion of prolactin in the gland that was in the dimeric form. The results suggest that monomeric prolactin is more readily secreted than dimer, and that dopamine decreases the production or stability of the dimer.

scholarly journals RAB6 GTPase is a crucial regulator of the mammary secretory function controlling STAT5 activation

2020 ◽  
Author(s):  
Surya Cayre ◽  
Marisa M. Faraldo ◽  
Sabine Bardin ◽  
Stéphanie Miserey-Lenkei ◽  
Marie-Ange Deugnier ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Prolactin Receptor ◽  
Retrograde Transport ◽  
Mammary Epithelial ◽  
Epithelial Cell Line ◽  
Rab Gtpases ◽  
Membrane Expression ◽  
Transport Pathways

ABSTRACTThe Golgi-associated RAB GTPases, RAB6A and RAB6A’, regulate anterograde and retrograde transport pathways from and to the Golgi. In vitro, RAB6A/A’ have been reported to be involved in several cellular functions, including, in addition to transport, cell division, migration, adhesion and polarity. However, their role remains poorly described in vivo, in particular in epithelial tissues. Here, we generated BlgCre; Rab6aF/F mouse presenting a specific deletion of Rab6a in the mammary luminal secretory lineage during gestation and lactation. Rab6a loss severely impaired the differentiation, maturation and maintenance of the secretory tissue, compromising lactation. It led to a decreased activation of STAT5, a key regulator of the lactogenic process primarily governed by prolactin. Data obtained with a human mammary epithelial cell line suggested that defective STAT5 activation might originate from a perturbed transport of the prolactin receptor, altering its membrane expression and signaling cascade. Despite the major functional defects observed upon Rab6a deletion, the polarized organization of the mammary epithelial bilayer was preserved. Altogether, our data reveal a crucial role for RAB6A/A’ in the lactogenic function of the mammary gland. They also suggest that the trafficking pathways controlled by RAB6A/A’ depend on cell type specialization and tissue context.SUMMARY STATEMENTThis study reveals a role for the Golgi-associated RAB GTPases, RAB6A/A’, in the lactogenic function of the mammary gland.

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