The local differential effect of prostacyclin, prostaglandin E2 and prostaglandin F2 alpha on mammary blood flow of lactating goats

Biological and pharmacological activities of noscapine: Focusing on its receptors and mechanisms

Noscapine has been mentioned as one of the effective drugs with potential therapeutic applications. With few side effects and amazing capabilities, noscapine can be considered different from other opioids-like structure compounds. Since 1930, extensive studies have been conducted in the field of pharmacological treatments from against malaria to control cough and cancer treatment. Furthermore, recent studies have shown that noscapine and some analogues, like 9-bromonoscapine, amino noscapine, and 9-nitronoscapine, can be used to treat polycystic ovaries syndrome, stroke, and other diseases. Given the numerous results presented in this field and the role of different receptors in the therapeutic effects of noscapine, we aimed to review the properties, therapeutic effects, and the role of receptors in the treatment of noscapine.

Effect of Type of Pregnancy on Transcriptional and Plasma Metabolic Response in Sheep and Its Further Effect on Progeny Lambs

Simple Summary

The present study was carried out in order to determine the effect of type of pregnancy on the mammary gland development, evaluated through the transcriptional expression of genes that are associated to angiogenesis and cell turnover/lactogenesis and the metabolic response of the animals. For this, six twin and seven single-bearing ewes were fed with naturalized pasture from day −45 pre-partum until day +70 post-partum, taking samples of mammary tissue and plasma at different times from the birth until weaning. The results showed the type of pregnancy could only explain a few differences in the transcriptional expression of in some genes that are involved in angiogenesis and cell turnover/lactogenesis in the mammary gland tissue, which had no impact on the metabolic status of ewes or the metabolic response in plasma, performance, and muscle transcriptional expression of the lambs.

Abstract

The following study was performed in order to determine the effect of type of pregnancy on the transcriptional expression of genes that are engaged in angiogenesis and cell turnover/lactogenesis in the ewe mammary gland, evaluating its impact on the plasma metabolic response. In addition, an assessment of its further influence on plasma metabolic response, performance, and muscle transcriptional expression of lipogenic enzymes in progeny lambs was made. Thirteen Ile de France sheep (six twin- and seven single-bearing ewes) were allocated to graze ad libitum naturalized pasture from d 45 pre-partum to day 70 post-partum, while keeping their lambs on the same diet until day 60 after weaning. The samples were collected at different times and analyzed by qRT-PCR and plasma metabolic indicators. The data were processed using SPSS package. The results showed that twin-bearing ewes overexpressed VEGFR1 at birth, and BCL2 at birth and day 35 post-partum; however, single-bearing ewes overexpressed CAIV and IGF1 at day 35 post-partum. Similar metabolite concentrations in blood plasma were found between groups of ewes. The plasma metabolic response in lambs was similar between groups and it did not influence their performance, where a similar transcriptional expression of lipogenic enzymes in muscle was observed. Therefore, the type of pregnancy can explain the slight differences in mRNA expression that were found in angiogenesis and cell turnover/lactogenesis in mammary gland, although these differences not only did not affect the plasma metabolic response in ewes, but they also had no influence on plasma metabolic response, performance, and muscle transcriptional expression of their lambs.

Regulation of fluid flow through the mammary gland of dairy cows and its effect on milk production: a systematic review

Dairy milk consists of more than 85% water. Therefore, understanding the regulation of fluid absorption in the mammary gland is relevant to improving milk production. In recent decades, studies using different approaches, including blood flow, transmembrane fluid flow, tight junction, fluid flow of the paracellular pathway and functional mammary epithelial cell state, have been conducted aiming to investigate how mammary gland fluid absorption is regulated. However, the relationship between regulation mechanisms of fluid flow and milk production has not been studied systematically. The present review summarizes a series of key milk yield regulatory factors mediated by whole-mammary fluid flow, including milk, mammary blood flow, blood/tissue fluid-cell fluid flow and cell-alveolus fluid flow. Whole-mammary fluid flow regulates milk production by altering transporter activity, ion channels, local microcirculation-related factors, driving force of fluid transport (osmotic pressure or electrochemical gradient), cellular connection state and a cell volume sensitive mechanism. In addition, whole-mammary fluid flow plays important roles in milk synthesis and secretion. Knowledge gained from fluid flow-mediated regulatory mechanisms of the dairy mammary gland will lead to a fundamental understanding of lactation biology and will be beneficial for the improvement of dairy productivity. © 2017 Society of Chemical Industry.

Role of endothelial cells in bovine mammary gland health and disease

The bovine mammary gland is a dynamic and complex organ composed of various cell types that work together for the purpose of milk synthesis and secretion. A layer of endothelial cells establishes the blood–milk barrier, which exists to facilitate the exchange of solutes and macromolecules necessary for optimal milk production. During bacterial challenge, however, endothelial cells divert some of their lactation function to protect the underlying tissue from damage by initiating inflammation. At the onset of inflammation, endothelial cells tightly regulate the movement of plasma components and leukocytes into affected tissue. Unfortunately, endothelial dysfunction as a result of exacerbated or sustained inflammation can negatively affect both barrier integrity and the health of surrounding extravascular tissue. The objective of this review is to highlight the role of endothelial cells in supporting milk production and regulating optimal inflammatory responses. The consequences of endothelial dysfunction and sustained inflammation on milk synthesis and secretion are discussed. Given the important role of endothelial cells in orchestrating the inflammatory response, a better understanding of endothelial function during mastitis may support development of targeted therapies to protect bovine mammary tissue and mammary endothelium.

Inhibition of local blood flow control systems in the mammary glands of lactating cows affects uptakes of energy metabolites from blood

To test the effect of mammary blood flow on net uptakes of milk precursors by the mammary glands, inhibitors of nitric oxide synthase (NOS) and cyclooxygenase (COX) were infused into the mammary circulation of 4 lactating cows. Inhibitors were infused in a 4×4 Latin square design, where treatments were infusion for 1 h of saline, NOS inhibitor (Nω-nitro-l-arginine methyl ester hydrochloride), COX inhibitor (indomethacin), or both NOS + COX inhibitors into one external iliac artery. Para-aminohippuric acid was also infused to allow for estimation of iliac plasma flow (IPF), of which approximately 80% flows to the mammary glands. Blood samples were collected before, during, and after inhibitor infusion from the contralateral external iliac artery and ipsilateral mammary vein. Inhibition of COX and NOS each produced a decrease in IPF, although the NOS effect was smaller and IPF continued to be depressed throughout the recovery period. The combination of COX and NOS inhibition produced a 50% depression in IPF and there was no carryover into the recovery period. Treatments that depressed IPF also increased arterial concentrations of acetate, β-hydroxybutyrate (BHBA), and glucose. Similarly, arteriovenous differences of acetate, BHBA, and glucose were all increased during IPF depression. To correct for a potential effect of arterial concentration, arteriovenous differences were normalized to arterial concentration, producing an extraction percentage. Inhibition of COX increased glucose extraction and tended to increase acetate and BHBA extraction. Dual inhibition only increased BHBA extraction and had no effect on mammary extraction of other metabolites. These extractions did not increase because clearances of glucose and TAG decreased as IPF decreased, and clearances of acetate and BHBA tended to decrease. Net uptake of TAG was depressed by dual NOS/COX inhibition, whereas uptakes of acetate, BHBA, and glucose were not affected by any of the treatments. To separate effects of flow from effects of arterial concentration, uptakes were regressed against IPF and arterial concentration simultaneously. According to the slopes of the regressions, a 10% decrease in IPF from the mean observed during saline infusion resulted in 3.8, 7.3, and 10.4% decreases in uptakes of acetate, glucose, and triacylglycerol, respectively. These findings indicate that mammary blood flow affects milk precursor uptake, and that clearance should not be assumed constant to predict mammary uptakes of milk precursors in situations where blood flow is changing.

Mammary remodeling in primiparous and multiparous dairy goats during lactation

Milk production is generally lower but lactation persistency higher in primiparous (PP) than in multiparous (MP) goats. This may be related to differences in development and maintenance of mammary gland function, but the underlying mechanisms are not well understood. The present study aimed to elucidate whether differences in lactational performance between PP and MP mammary glands are related to the time course of development and maintenance, not only of the mammary epithelial cell (MEC) population, but also of the mammary vasculature that sustains synthetic activity. Mammary biopsies were obtained from both mammary glands of 3 PP and 6 MP (>or=2 parity) dairy goats at parturition (d 1), d 10, 60, and 180 of lactation. Gene transcription relating to MEC turnover and vascular function was quantified by real-time reverse transcription-PCR, mammary morphology was characterized (quantitative histology), and cell turnover was determined (terminal deoxynucleotidyl transferase dUTP nick end labeling assay and Ki-67). Primiparous glands showed higher expression for the genes involved in angiogenesis; namely, vascular endothelial growth factor receptor 2, and angiopoietin 1 and 2 and their receptor, a few days after parturition (d 10). Primiparous glands also had higher rates of MEC proliferation in early lactation. It therefore appears that initiation of lactation is associated with development and growth of the mammary gland into early lactation, which continues for a longer period in PP compared with MP glands. In addition, MEC survival was found to be higher in PP glands throughout lactation, and MEC in PP glands underwent more extensive differentiation. This could explain the reported flatter lactation curve and higher lactation persistency in PP glands. Although some of the genes included in this study were differentially expressed in PP and MP glands during the course of lactation, it was not possible to identify any specific genomic factor(s) that could account for the differences between PP and MP glands with respect to mammary development and MEC survival during lactation. It remains to be established why parity number affects MEC and vascular development and survival during lactation, and, in particular, which regulatory mechanisms are involved.

The histamine H1 receptor is not involved in local control of mammary blood flow in dairy cows

Low concentrations of the essential amino acid histidine in circulation have been shown to increase mammary blood flow and it has been suggested that this effect is mediated by histamine. The hypotheses tested in this experiment were that interstitial histamine concentrations in the mammary gland are related to arterial His concentrations and that mammary blood flow is reduced by extracellular histamine via H(1) receptors. The hypotheses were tested by infusing saline or chlorpheniramine, a blocker of the H(1) histamine receptor, into the arterial supply of the mammary glands of lactating cows infused with 44 g/h of amino acid mixtures with or without His for 10 h. Infusates were administered in a 2 x 2 factorial arrangement within a 4 x 4 Latin square to 4 multiparous Holstein cows in mid lactation. Exclusion of His from the infusate decreased protein content in milk from the infused udder half from 3.98 to 3.77%, and increased arterial alpha-aminonitrogen concentration from 3.2 to 3.4 mM. Neither the decreased arterial His concentration nor the H(1) blocker affected plasma flow to the infused udder half. We conclude that histamine is not involved in the regulation of mammary blood flow. The H(1) blocker decreased milk production in the infused udder half from 4.6 to 3.5 kg without affecting protein, fat, and lactose percentages, suggesting an inhibition of milk ejection. Cows on chlorpheniramine ate less feed during the infusion than saline-infused cows, which resulted in lower arterial concentrations and mammary uptakes of acetate. The efficiency of plasma triacylglycerol uptake across the mammary glands was decreased by chlorpheniramine but net uptake of long-chain fatty acids was not affected. The mechanism by which an amino acid deficiency influences mammary blood flow does not involve histamine signaling through the H(1) receptor and remains unidentified.

Mammary uptake and excretion of prostanoids in relation to mammary blood flow and milk yield during pregnancy-lactation and somatotropin treatment in dairy goats

Mammary arterious-venous differences (A-V) and excretion into milk of four prostanoids were related to changes in milk yield and milk vein blood velocity (MBV) in goats at different stages of pregnancy and lactation, and during somatotropin (ST) treatment in mid-lactation. Arterial concentrations and mammary A-V for the vasodilators prostacyclin (PGI(2)) and prostaglandin (PG) E(2) (measured as 6-keto-PGF(1 alpha) and bicyclic PGE(2), respectively) decreased from late pregnancy to lactation. A-V were negatively correlated to MBV (r = -0.32 to -0.34). Arterial concentrations of the vasoconstrictors PGF(2 alpha) and TXA(2) (measured as TXB(2)) changed similarly, but no A-V across the mammary gland were found. The vasodilator to vasoconstrictor ratio in plasma was around 1:1, and in skimmed milk around 0.29-0.49 due to significantly higher TXB(2) levels in milk compared to plasma. Close linear correlations were established between milk yield and excretion of TXB(2) into milk (r = 0.80, P < 0.001), and between MBV and PGE(2) excretion into milk (r = 0.69, P < 0.001). ST treatment stimulated MBV and mammary prostanoid supply, and decreased prostanoid concentration in milk vein plasma. The high arterial levels of prostaglandins during pregnancy most likely reflected uterine synthesis. Our results support a role for PGI(2) and PGE(2) in local mammary blood flow regulation during lactation. Increased mammary uptake of these two prostanoids may be involved in the mammary blood flow response to ST. TXA(2) may be synthesized by mammary epithelial as well as vascular cells, and TXA(2) may be an important factor in regulation of mammary function.

Responses to potential vasoactive substances of isolated mammary blood vessels from lactating sows

The purpose of the investigation was to examine the response of the milk vein and the mammary artery to potential vasoactive substances in lactating sows. The response on artery and vein segments from the same sow was measured for the following substances: noradrenaline (NA), serotonin (5-HT), prostaglandin F2alpha (PGF2alpha), prostacyclin (PGI2), histamine (Hi) and potassium (K+). Interestingly, the contractile force in the mammary vein segments expressed per weight unit (mN/mg) was 1.5-2.5 fold larger than in the artery segments when NA, 5-HT and PGF2alpha were used, but similar for K+, Hi and PGI2. In vein segments, the order of sensitivity to the substances expressed by their pD2 values was 5-HT > NA = PGF2alpha > Hi > K+. The present findings suggest that NA, 5-HT, PGF2alpha, PGI2, and Hi are involved in mammary blood flow regulation in the sow, and the mammary venous system may be as important as the mammary arterial system in this regulation.

Regulation of blood flow in the mammary microvasculature

Although milk yield of cows and goats is known to be closely related to the total flow of blood through the udder, a number of studies suggest that milk yield can vary independently. No studies have attempted to measure the proportion of total flow that is nutritive. Within the mammary gland, capillary networks form a basket-like architecture surrounding each alveolus. Notably, flow in individual capillaries is not constant and varies among capillaries. Capillary flow (measured by intravital microscopy) was decreased by oxytocin, which generally increased total flow in the mammary artery, suggesting that the proportion of total flow that is nutritive can vary. In addition to classic metabolic regulators (e.g., carbon dioxide and oxygen) of tissue blood flow, the mammary gland produces a number of vasodilatory compounds, including parathyroid hormone-related protein, insulin-like growth factor-I, prostacyclin, nitric oxide, and endothelin. All of these compounds have been shown to alter mammary blood flow. Mammary tissue also contains kallikrein and angiotensin-converting enzyme, which convert circulating kinins and angiotensin, respectively, into potent vasoactive compounds. A number of these compounds are produced by epithelial cells themselves, providing a mechanism for the functioning epithelium to control its own blood supply and, hence, nutrient flow for milk synthesis. In this review, we examine the nature of the mammary microcirculation, its behavior under different conditions, and some of the regulatory features of the mammary microvasculature.