scholarly journals Kisspeptin across the human lifespan:evidence from animal studies and beyond

2016 ◽  
Vol 229 (3) ◽  
pp. R83-R98 ◽  
Author(s):  
Sophie A Clarke ◽  
Waljit S Dhillo
Keyword(s):  
Genetic Testing ◽  
Animal Studies ◽  
Pubertal Development ◽  
Hormone Secretion ◽  
Large Body ◽  
Healthy Development ◽  
Knockout Animal ◽  
Gonadotrophin Secretion ◽  
Gonadotrophin Releasing Hormone

Since its first description in 1996, the KISS1 gene and its peptide products, kisspeptins, have increasingly become recognised as key regulators of reproductive health. With kisspeptins acting as ligands for the kisspeptin receptor KISS1R (previously known as GPR54 or KPR54), recent work has consistently shown that administration of kisspeptin across a variety of species stimulates gonadotrophin release through influencing gonadotrophin-releasing hormone secretion. Evidence from both animal and human studies supports the finding that kisspeptins are crucial for ensuring healthy development, with knockout animal models, as well as proband genetic testing in human patients affected by abnormal pubertal development, corroborating the notion that a functional kisspeptin receptor is required for appropriate gonadotrophin secretion. Given the large body of evidence that exists surrounding the influence of kisspeptin in a variety of settings, this review summarises our physiological understanding of the role of these important peptides and their receptors, before proceeding to describe the varying role they play across the reproductive lifespan.

Determinants of the annual pattern of reproduction in mature male Merino and Suffolk sheep: responses to a nutritional stimulus in the breeding and non-breeding seasons

2003 ◽  
Vol 15 (1) ◽  
pp. 1 ◽  
Author(s):  
Maria J. Hötzel ◽  
Stephen W. Walkden-Brown ◽  
James S. Fisher ◽  
Graeme B. Martin
Keyword(s):  
Luteinizing Hormone ◽  
Breeding Season ◽  
Follicle Stimulating Hormone ◽  
Hormone Secretion ◽  
Pulse Frequency ◽  
Mature Male ◽  
Scrotal Circumference ◽  
Gonadotrophin Secretion ◽  
Gonadotrophin Releasing Hormone ◽  
Breeding Seasons

This study was designed to test whether an acute improvement in diet would increase gonadotrophin secretion and testicular growth in strongly photoperiod-responsive Suffolk rams and weakly photoperiod-responsive Merino rams in both the breeding (February–March) and the non-breeding (July–August) seasons. Mature rams (n = 5 or 6) of these breeds were fed a maintenance diet (0.9 kg chaff + 100 g lupin grain) or the same diet supplemented with 1.5 kg lupin grain for 42 days in each season. Lupin grain is a rich source of both energy and protein. Testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured in plasma from blood sampled every 20 min for 24 h on Days −1, 12 and 35 relative to the change in feeding. In rams supplemented with lupins, body mass increased in both breeds in both seasons (P < 0.001). Scrotal circumference and LH pulse frequency increased with lupin supplementation in both seasons (P < 0.003) in Merinos, but only during the breeding season (P < 0.003) in Suffolks. Plasma FSH concentrations were affected by diet only during the breeding season, being elevated on Day 12 in lupin-supplemented rams of both breeds (P < 0.05). It was concluded that Merino rams exhibit reproductive responses to improved nutrition irrespective of time of the year, whereas Suffolk rams respond to nutrition only when the hypothalamic reproductive centres are not inhibited by photoperiod. Thus, Suffolks do respond to nutrition, just as Merinos do, but only when photoperiod allows. This difference between breeds appears to be a result of differences in the neuroendocrine pathways that control pulsatile gonadotrophin-releasing hormone secretion.

Phoenixin and Its Role in Reproductive Hormone Release

2019 ◽  
Vol 37 (04) ◽  
pp. 191-196 ◽  
Author(s):  
Sophie A. Clarke ◽  
Waljit S. Dhillo
Keyword(s):  
Animal Species ◽  
Hormone Secretion ◽  
Physiological Role ◽  
Peptide Sequence ◽  
Reproductive Hormone ◽  
Dependent Manner ◽  
Hormone Release ◽  
Gastrointestinal Tissue ◽  
Gonadotrophin Releasing Hormone

AbstractPhoenixin is novel neuropeptide, recently identified following the description of a peptide sequence highly conserved across several animal species, including humans, cows, and pigs. Expressed both centrally in the hypothalamus and arcuate nucleus and peripherally in cardiac and gastrointestinal tissue, it appears to modulate reproductive hormone secretion in a gonadotrophin-releasing hormone–dependent manner and may also influence anxiety and memory. While there remains much to be described regarding its signaling, this review assesses the currently available literature in both animal and human studies to summarize our understanding of the physiological role of this novel neuropeptide, and its function in reproductive hormone release.

scholarly journals Hypoxia and Mitochondrial Dysfunction in Pregnancy Complications

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 405 ◽  
Author(s):  
Xiang-Qun Hu ◽  
Lubo Zhang
Keyword(s):  
Pregnancy Complications ◽  
Intrauterine Growth Restriction ◽  
Animal Studies ◽  
Major Effect ◽  
Causative Role ◽  
Therapeutic Approaches ◽  
Maternal Complications ◽  
Mitochondrial Ros ◽  
Subsequent Risk

Hypoxia is a common and severe stress to an organism’s homeostatic mechanisms, and hypoxia during gestation is associated with significantly increased incidence of maternal complications of preeclampsia, adversely impacting on the fetal development and subsequent risk for cardiovascular and metabolic disease. Human and animal studies have revealed a causative role of increased uterine vascular resistance and placental hypoxia in preeclampsia and fetal/intrauterine growth restriction (FGR/IUGR) associated with gestational hypoxia. Gestational hypoxia has a major effect on mitochondria of uteroplacental cells to overproduce reactive oxygen species (ROS), leading to oxidative stress. Excess mitochondrial ROS in turn cause uteroplacental dysfunction by damaging cellular macromolecules, which underlies the pathogenesis of preeclampsia and FGR. In this article, we review the current understanding of hypoxia-induced mitochondrial ROS and their role in placental dysfunction and the pathogenesis of pregnancy complications. In addition, therapeutic approaches selectively targeting mitochondrial ROS in the placental cells are discussed.

scholarly journals The MAL Protein, an Integral Component of Specialized Membranes, in Normal Cells and Cancer

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1065
Author(s):  
Armando Rubio-Ramos ◽  
Leticia Labat-de-Hoz ◽  
Isabel Correas ◽  
Miguel A. Alonso
Keyword(s):  
Epithelial Cells ◽  
Large Body ◽  
Original Description ◽  
Cell Types ◽  
Future Research ◽  
Transmembrane Segments ◽  
Epsilon Toxin ◽  
Proteolipid Proteins ◽  
Polarized Epithelial Cells

The MAL gene encodes a 17-kDa protein containing four putative transmembrane segments whose expression is restricted to human T cells, polarized epithelial cells and myelin-forming cells. The MAL protein has two unusual biochemical features. First, it has lipid-like properties that qualify it as a member of the group of proteolipid proteins. Second, it partitions selectively into detergent-insoluble membranes, which are known to be enriched in condensed cell membranes, consistent with MAL being distributed in highly ordered membranes in the cell. Since its original description more than thirty years ago, a large body of evidence has accumulated supporting a role of MAL in specialized membranes in all the cell types in which it is expressed. Here, we review the structure, expression and biochemical characteristics of MAL, and discuss the association of MAL with raft membranes and the function of MAL in polarized epithelial cells, T lymphocytes, and myelin-forming cells. The evidence that MAL is a putative receptor of the epsilon toxin of Clostridium perfringens, the expression of MAL in lymphomas, the hypermethylation of the MAL gene and subsequent loss of MAL expression in carcinomas are also presented. We propose a model of MAL as the organizer of specialized condensed membranes to make them functional, discuss the role of MAL as a tumor suppressor in carcinomas, consider its potential use as a cancer biomarker, and summarize the directions for future research.

POSSIBLE ROLE OF 5α-ANDROSTANE-3α,17β-DIOL IN THE CONTROL OF FOLLICLE-STIMULATING HORMONE SECRETION IN THE IMMATURE FEMALE RAT

1982 ◽  
Vol 92 (1) ◽  
pp. 37-42 ◽  
Author(s):  
H. M. A. MEIJS-ROELOFS ◽  
P. KRAMER ◽  
L. GRIBLING-HEGGE
Keyword(s):  
Inhibitory Action ◽  
Combined Treatment ◽  
Hormone Secretion ◽  
Inhibitory Effect ◽  
Ovariectomized Rats ◽  
Female Rat ◽  
Immature Rat ◽  
Rat Strain ◽  
Intact Rats

A possible role of 5α-androstane-3α,17β-diol (3α-androstanediol) in the control of FSH secretion was studied at various ages in ovariectomized rats. In the rat strain used, vaginal opening, coincident with first ovulation, generally occurs between 37 and 42 days of age. If 3α-androstanediol alone was given as an ovarian substitute, an inhibitory effect on FSH release was evident with all three doses tested (50, 100, 300 μg/100 g body wt) between 13 and 30 days of age; at 33–35 days of age only the 300 μg dose caused some inhibition of FSH release. Results were more complex if 3α-androstanediol was given in combined treatment with oestradiol and progesterone. Given with progesterone, 3α-androstanediol showed a synergistic inhibitory action on FSH release between 20 and 30 days of age. However, when 3α-androstanediol was combined with oestradiol a clear decrease in effect, as compared to the effect of oestradiol alone, was found between 20 and 30 days of age. Also the effect of combined oestradiol and progesterone treatment was greater than the effect of combined treatment with oestradiol, progesterone and 3α-androstanediol. At all ages after day 20 none of the steroid combinations tested was capable of maintaining FSH levels in ovariectomized rats similar to those in intact rats. It is concluded that 3α-androstanediol might play a role in the control of FSH secretion in the immature rat, but after day 20 the potentially inhibitory action of 3α-androstanediol on FSH secretion is limited in the presence of oestradiol.

scholarly journals Including the animal standpoint in critical public relations research

2021 ◽  
Vol 10 (2) ◽  
pp. 139-161
Author(s):  
Núria Almiron ◽  
Laura Fernández
Keyword(s):  
Political Economy ◽  
Public Relations ◽  
Animal Studies ◽  
Critical Animal Studies ◽  
Essential Step ◽  
Challenges And Opportunities ◽  
Discourse Studies ◽  
Theoretical Paper ◽  
Short Explanation

In this paper we argue that adopting critical animal studies perspectives in critical public relations can not only be very fruitful, but that it is also a necessity if the aims of the latter are to be achieved. To this end, this text introduces the challenges and opportunities that the field of critical animal studies brings to critical public relations studies. First, a short explanation of what critical animal studies is and why it can contribute to critical public relations studies is provided. Then the main fields of research where this contribution can be most relevant are discussed, including ethics, discourse studies and political economy. The final aim of this theoretical paper is to expand research within the field of critical public relations by including a critical animal studies approach. Eventually, the authors suggest that embracing the animal standpoint in critical public relations is an essential step to furthering the study of power, hegemony, ideology, propaganda or social change and to accomplishing the emancipatory role of research.

scholarly journals Role of Matrix Gla Protein in the Complex Network of Coronary Artery Disease: A Comprehensive Review

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 737
Author(s):  
Marko Kumric ◽  
Josip A. Borovac ◽  
Tina Ticinovic Kurir ◽  
Dinko Martinovic ◽  
Ivan Frka Separovic ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Complex Network ◽  
Vascular Calcification ◽  
Vitamin K ◽  
Clinical Decision Making ◽  
Large Body ◽  
Matrix Gla Protein ◽  
Artery Disease

Coronary artery disease (CAD) is widely recognized as one of the most important clinical entities. In recent years, a large body of accumulated data suggest that coronary artery calcification, a process highly prevalent in patients with CAD, occurs via well-organized biologic processes, rather than passively, as previously regarded. Matrix Gla protein (MGP), a vitamin K-dependent protein, emerged as an important inhibitor of both intimal and medial vascular calcification. The functionality of MGP hinges on two post-translational modifications: phosphorylation and carboxylation. Depending on the above-noted modifications, various species of MGP may exist in circulation, each with their respective level of functionality. Emerging data suggest that dysfunctional species of MGP, markedly, dephosphorylated-uncarboxylated MGP, might find its application as biomarkers of microvascular health, and assist in clinical decision making with regard to initiation of vitamin K supplementation. Hence, in this review we summarized the current knowledge with respect to the role of MGP in the complex network of vascular calcification with concurrent inferences to CAD. In addition, we discussed the effects of warfarin use on MGP functionality, with concomitant implications to coronary plaque stability.

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