scholarly journals Metabolism of l-(U-14C)valine, l-(U-14C)leucine, l-(U-14C)histidine and l-(U-14C) phenylalanine by the isolated perfused lactating guinea-pig mammary gland

1976 ◽  
Vol 156 (3) ◽  
pp. 553-560 ◽  
Author(s):  
S R Davis ◽  
T B Mepham
Keyword(s):  
Amino Acids ◽  
Guinea Pig ◽  
Milk Protein ◽  
Mean Transit Time ◽  
Mammary Tissue ◽  
Plasma Component ◽  
Ruminant Species ◽  
The Mean ◽  
Phenyl Alanine

1. The incorporation of L-[U-14C]leucine, L[U-14C]histidine and L-[U-14C]phenylalanine into casein secreted during perfusion of isolated guinea-pig mammary glands was demonstrated. 2. The extent of incorporation of label into casein residues was consistent with their being derived from free amino acids of the perfusate plasma. 3. The mean transit time of the amino acids from perfusate into secreted casein was approx. 100 min. 4. Whereas radioactive histidine and phenylalanine were incorporated solely into milk protein, radioactivity from [U-14C]valine was also transferred to CO2 and to an unidentified plasma component, and from [U-14C]leucine to plasma glutamic acid. 5. Evidence from experiments with [U-14C]phenylalanine suggests that, as in rats, but in contrast with ruminant species, guinea-pig mammary tissue does not possess phenyl alanine hydroxylase activity. 6. The results are discussed in relation to the possible role of essential amino acid catabolism in the control of milk-protein synthesis.

Gammaglutamyltransferase activity in buffalo mammary tissue during lactation

2006 ◽  
Vol 82 (3) ◽  
pp. 351-354 ◽  
Author(s):  
M. E. Pero ◽  
N. Mirabella ◽  
P. Lombardi ◽  
C. Squillacioti ◽  
A. De Luca ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Epithelial Cells ◽  
Milk Production ◽  
Milk Protein ◽  
Water Buffalo ◽  
Alveolar Epithelial Cells ◽  
Mammary Tissue ◽  
Activity Levels ◽  
Alveolar Epithelial

AbstractIn the present study, the rôle of gammaglutamyltransferase (GGT) during lactation has been investigated in the water buffalo. GGT activity has been evaluated in the mammary tissue at 4 and 6 months after calving and during the non-lactating period. The highest GGT activity levels were found at day 120 (32·57±7·41 U per g) of lactation and were statistically higher than those at 180 (10·76±3·6 U per g) or during the non-lactating period (9·86±7·94 U per g). Histochemistry confirmed these findings and revealed that GGT reactivity was distributed throughout the cytoplasm of alveolar epithelial cells. Such results showed that the GGT production is high during lactation thus supporting the hypothesis that this enzyme plays a rôle in determining milk production in water buffalo by supporting milk protein synthesis.

Amino acid transportation, sensing and signal transduction in the mammary gland: key molecular signalling pathways in the regulation of milk synthesis

2020 ◽  
Vol 33 (2) ◽  
pp. 287-297
Author(s):  
Zhihui Wu ◽  
Jinghui Heng ◽  
Min Tian ◽  
Hanqing Song ◽  
Fang Chen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Mammary Gland ◽  
Milk Protein ◽  
Building Blocks ◽  
Branched Chain Amino Acids ◽  
Signalling Pathways ◽  
Recent Advances ◽  
Branched Chain ◽  
Molecular Signalling Pathways

AbstractThe mammary gland, a unique exocrine organ, is responsible for milk synthesis in mammals. Neonatal growth and health are predominantly determined by quality and quantity of milk production. Amino acids are crucial maternal nutrients that are the building blocks for milk protein and are potential energy sources for neonates. Recent advances made regarding the mammary gland further demonstrate that some functional amino acids also regulate milk protein and fat synthesis through distinct intracellular and extracellular pathways. In the present study, we discuss recent advances in the role of amino acids (especially branched-chain amino acids, methionine, arginine and lysine) in the regulation of milk synthesis. The present review also addresses the crucial questions of how amino acids are transported, sensed and transduced in the mammary gland.

Variations in the concentrations of free amino acids in the plasma of the dairy cow at parturition

1972 ◽  
Vol 39 (3) ◽  
pp. 355-364 ◽  
Author(s):  
R. Verbeke ◽  
E. Roets ◽  
G. Peeters
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino ◽  
Milk Protein ◽  
Sampling Period ◽  
Aminobutyric Acid ◽  
Amino Acid Utilization ◽  
Amino Acid Levels ◽  
The Mean ◽  
Peak Value

SummaryThe plasma levels of individual amino acids were studied in 6 dairy cows from 4 days before to 3 days after calving. During this sampling period, the concentrations of 13 amino acids showed significant changes. The levels of several amino acids were depressed markedly in the sample collected immediately before calving. Following parturition, the concentration of most amino acids gradually returned to values obtained 3 days before calving. The glutamine and alanine contents of the plasma rose to a peak value 1 day after calving and subsequently decreased. The mean concentrations of glycine and α-aminobutyric acid did not change before parturition but rose significantly thereafter. These observations are discussed in terms of amino-acid utilization for milk protein synthesis and gluconeogenesis at the onset of lactation. The changes in plasma amino acid levels appear to be synchronized with those reported for prolactin and progesterone in the 24 h before parturition. This may indicate an important influence of both hormones on the lactogenic process in the cow. The highly significant correlations obtained between the concentrations of 14 individual amino acids are discussed.

scholarly journals Uptake and metabolism of tryptophan by the isolated perfused guinea-pig mammary gland

1976 ◽  
Vol 158 (3) ◽  
pp. 659-662 ◽  
Author(s):  
B Mepham ◽  
A R Peters ◽  
S R Davis
Keyword(s):  
Amino Acids ◽  
Mammary Gland ◽  
Guinea Pig ◽  
Blood Plasma ◽  
Milk Protein ◽  
Absorption Studies ◽  
Uptake And Metabolism ◽  
Tryptophan Uptake

Tryptophan uptake by the isolated perfused lactating guinea-pig mammary gland was 46.5+/-4.6 mug/h per g. Results of absorption studies and the use of [methylene-14C]tryptophan suggest that tryptophan is one of the group of amino acids that are transferred almost quantitatively from blood plasma to milk protein.

scholarly journals Heat stress negatively affects the transcriptome related to overall metabolism and milk protein synthesis in mammary tissue of midlactating dairy cows

2019 ◽  
Vol 51 (8) ◽  
pp. 400-409 ◽  
Author(s):  
S. T. Gao ◽  
Lu Ma ◽  
Z. Zhou ◽  
Z. K. Zhou ◽  
L. H. Baumgard ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Heat Stress ◽  
Dairy Cows ◽  
Milk Protein ◽  
Tissue Expression ◽  
Mammary Tissue ◽  
P Value ◽  
Rna Seq ◽  
Protein Encoding

Inadequate dry matter intake only partially accounts for the decrease in milk protein synthesis during heat stress (HS) in dairy cows. Our hypothesis is that reduced milk protein synthesis during HS in dairy cows is also caused by biological changes within the mammary gland. The objective of this study was to assess the hypothesis via RNA-Seq analysis of mammary tissue. Herein, four dairy cows were used in a crossover design where HS was induced for 9 days in environmental chambers. There was a 30-day washout between periods. Mammary tissue was collected via biopsy at the end of each environmental period (HS or pair-fed and thermal neutral) for transcriptomic analysis. RNA-Seq analysis revealed HS affected >2,777 genes (false discovery rate-adjusted P value < 0.05) in mammary tissue. Expression of main milk protein-encoding genes and several key genes related to regulation of protein synthesis and amino acid and glucose transport were downregulated by HS. Bioinformatics analysis revealed an overall decrease of mammary tissue metabolic activity by HS (especially carbohydrate and lipid metabolism) and an increase in immune activation and inflammation. Network analysis revealed a major role of TNF, IFNG, S100A8, S100A9, and IGF-1 in inducing/controlling the inflammatory response, with a central role of NF-κB in the process of immunoactivation. The same analysis indicated an overall inhibition of PPARγ. Collectively, these data suggest HS directly controls milk protein synthesis via reducing the transcription of metabolic-related genes and increasing inflammation-related genes.

scholarly journals Glutathione utilization by lactating bovine mammary secretory tissue in vitro

1981 ◽  
Vol 198 (1) ◽  
pp. 243-246 ◽  
Author(s):  
C R Baumrucker ◽  
P A Pocius ◽  
T L Riss
Keyword(s):  
Amino Acids ◽  
Milk Protein ◽  
Mammary Tissue ◽  
Mammary Cells ◽  
Tissue Uptake ◽  
Radioactive Label ◽  
Gamma Glutamyltransferase ◽  
Secretory Tissue ◽  
Glutamyl Transpeptidase

gamma-Glutamyltransferase (D-glutamyl transpeptidase, EC 2.3.2.2) activity has been shown to be located predominantly on the extracellular surface of the plasma membrane of lactating bovine mammary cells. Radioactive label from both oxidized ([14C]-gamma-glutamyl) and reduced ([35S]cysteinyl) glutathione was taken up and incorporated into acid-precipitable proteins of mammary tissue. Uptake was shown to involve the transport of free amino acids, and incorporation was shown to involve the action of gamma-=glutamyltransferase. These results indicate that lactating mammary tissue utilizes the constituent amino acids of glutathione for milk-protein synthesis.

scholarly journals The effect of dilution of milk proteins with non-essential amino acids (L-alanine and L-glutamic acid) on nitrogen retention and biological value of the proteins in children

1970 ◽  
Vol 24 (3) ◽  
pp. 741-747 ◽  
Author(s):  
V.A. Daniel ◽  
T.R. Doraiswamy ◽  
M. Swaminathan ◽  
D. Rajalakshmi
Keyword(s):  
Amino Acids ◽  
Body Weight ◽  
Glutamic Acid ◽  
Milk Protein ◽  
Nitrogen Retention ◽  
Milk Proteins ◽  
Essential Amino Acids ◽  
Biological Value ◽  
The Mean ◽  
Daily Intakes

1. The effect of addition of a mixture of two non-essential amino acids (NEA), namely alanine and glutamic acid, to milk proteins on nitrogen retention and the biological value of the proteins was determined in a group of six girls aged 10–11 years.2. The mean daily intakes of milk protein by the children on three diets (1, 3 and 5 ) were 1.41, 1.10 and 0.70 g/kg body-weight. The quantities of NEA added daily to the three diets were 0.97, 0.49 and 0.97 g/kg body-weight respectively.3. Addition of NEA did not bring about any significant increase in N retention in the children. The addition of NEA to milk proteins significantly decreased the biological value of the proteins.

EFFECTS OF EXOGENOUS CORTISOL ON THE UPTAKE OF CORTICOSTEROIDS BY THE ISOLATED PERFUSED GUINEA-PIG MAMMARY GLAND

1979 ◽  
Vol 80 (3) ◽  
pp. 357-364 ◽  
Author(s):  
A. R. PETERS ◽  
T. B. MEPHAM
Keyword(s):  
Mammary Gland ◽  
Guinea Pig ◽  
Guinea Pigs ◽  
Convincing Evidence ◽  
The Mean

Assay of corticosteroids in the plasma of guinea-pigs showed that concentrations were higher in lactating than in non-lactating and male animals. In five isolated perfused mammary gland experiments in which corticosteroids were at concentrations of 1·3–3·0 μg/ml in the perfusate, equivalent to concentrations during lactation, the mean (±s.e.m.) uptake by the mammary gland was 900 ± 210 ng g−1 h−1. In five experiments in which the concentrations of corticosteroid in the perfusate were 190–580 ng/ml, the uptake by the mammary gland was significantly lower (316 ± 73 ng g−1 h−1; P < 0·05). For the ten experiments there was a significant correlation between the concentration of corticosteroid in the perfusate and uptake by the mammary gland (P < 0·05). No convincing evidence for a galactopoietic role of corticosteroids in the guinea-pig was obtained, although administration of cortisol significantly stimulated the uptake of glutamine by the perfused gland.

scholarly journals ChTX induces oscillatory contraction in guinea pig trachea: role of cyclooxygenase-2 and PGE2

2003 ◽  
Vol 284 (6) ◽  
pp. L1045-L1054 ◽  
Author(s):  
Yukihiro Yagi ◽  
Masayoshi Kuwahara ◽  
Hirokazu Tsubone
Keyword(s):  
Guinea Pig ◽  
Prostaglandin E ◽  
Receptor Subtype ◽  
Phasic Contraction ◽  
Oscillatory Frequency ◽  
Cox Inhibitor ◽  
The Mean ◽  
Cox 2 ◽  
Cox 1

We examined the possible role of cyclooxygenase (COX) in charybdotoxin (ChTX)-induced oscillatory contraction in guinea pig trachea. Involvement of prostaglandin E2 (PGE2) in ChTX-induced oscillatory contraction was also investigated. ChTX (100 nM) induced oscillatory contraction in guinea pig trachea. The mean oscillatory frequency induced by ChTX was 10.7 ± 0.8 counts/h. Maximum and minimum tensions within ChTX-induced oscillatory contractions were 68.4 ± 1.8 and 14.3 ± 1.7% compared with K+ (72.7 mM) contractions. ChTX-induced oscillatory contraction was completely inhibited by indomethacin, a nonselective COX inhibitor. Valeryl salicylate, a selective COX-1 inhibitor, did not significantly inhibit this contraction, whereas N-(2-cyclohexyloxy-4-nitro-phenyl)-methanesulfonamide, a selective COX-2 inhibitor, abolished this contraction. Exogenously applied arachidonic acid enhanced ChTX-induced oscillatory contraction. SC-51322, a selective PGE receptor subtype EP1 antagonist, significantly inhibited ChTX-induced oscillatory contraction. Exogenously applied PGE2 induced only a slight phasic contraction in guinea pig trachea, but PGE2 induced strong oscillatory contraction after pretreatment with indomethacin and ChTX. Moreover, ChTX time-dependently stimulated PGE2 generation. These results suggest that ChTX specifically activates COX-2 and stimulates PGE2 production and that ChTX-induced oscillatory contraction in guinea pig trachea is mediated by activation of EP1 receptor.

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