NOPR Collection:

Progesterone receptors on human spermatozoa

2016-07-20T04:29:34Z

Title: Progesterone receptors on human spermatozoa Authors: Shah, Chirag; Modi, Deepak; Gadkar, Sushama; Sachdeva, Geetanjali; Puri, Chander Abstract: Progesterone, primarily recognized as a female steroid hormone, is reported to affect several sperm functions especially capacitation, motility and acrosome reaction. These effects of progesterone on the spermatozoa are mediated via the progesterone bindings sites/progesterone receptor (PR) on the acrosomal membrane. These receptors in response to progesterone increase the intercellular Ca²⁺ levels and stimulate Ca²⁺ influx in the mature human spermatozoa via non-genomic mode of actions. Characterization of this receptor reveals that the sperm PR is masked protein and is exposed to the surface by some non-ionic detergents. Localized on to the acrosome region of the spermatozoa, these receptors are recognized by most antibodies directed towards the C-terminal region of the conventional PR. The estimated molecular weight of PR on spermatozoa varies from 27 kDa to 85 kDa. At the molecular level, sequences encoding for the entire DNA and hormone binding domains of the conventional PR are detected in the mRNA derived from spermatozoa. No insertions, deletions or mutations a re detected in this region. These results are suggestive of the fact that at least the C terminal region of the conventional PR is conserved in the sperm. It is hypothesized that post-translational modifications or peptide splicing of the conventional PR in spermatozoa may possibly lead to the variant of the steroid hormone receptor. Detailed characterization of the sperm PR will be important in understanding the alternate non-genomic mode of action of steroid hormone receptors. Page(s): 773-780

Epididymis as a target for contraception

2016-07-20T04:36:10Z

Title: Epididymis as a target for contraception Authors: Khole, Vrinda Abstract: Advantage of using a vaccine based on sperm antigens is that it can be used both in males and females as individuals who have antisperm antibodies are usually infertile but otherwise healthy. Several sperm specific antigens identified as prospective candidates for immunocontraception are of testicular origin. For the purpose of immunocontraception it may be desirable not to disrupt spermatogenes is and testicular function. Concept of post testicular maturation of spermatozoa has been very well established. During post testicular voyage spermatozoa undergo a series of complex and sequential events which transforms the immature immotile spermatozoa into mature sperm. Acquisition of functional maturity is necessary for progressive motility, zona pellucida recognition culminating in sperm egg binding. Importance of epididymal maturation is highlighted by the fact that high percentage of male in fertility in human origiates from the malfunction of the epididymis. The epididymis has also shown to be involved in sperm storage and provides an adequate environment for final maturation of the sperm. It provides a conducive microenvironment by virtue of which the spermatozoa are protected during the storage. In view of this it is imperative that more attention needs to be focused on epididymal antigens. The information obtained will enable us to identify epididymal antigens relevant to fertility and also help in infertility diagnosis. Page(s): 764-772

Embryo-endometrial proteases during early mammalian development

2016-07-20T04:31:39Z

Title: Embryo-endometrial proteases during early mammalian development Authors: Seshagiri, P B; Lalitha, H S; Mishra, A; Sireesha, G V Abstract: In mammals, extensive remodeling of uterine endometrial matrix occurs during reproductive cycle and blastocyst implantation. This is regulated by a variety of molecules such as hormones, growth factors, cytokines and proteases. In this article, we review the current state or knowledge available on various proteases and their inhibitors functionally involved in the embryo-endometrial tissues and present some data on endometrial proteases in hamsters and rats during estrous cycle and early pregnancy. We demonstrate the presence of at least four gelat inolytic activities in endometrial samples, belonging to gelatinase-A and -B categories and their dependence on calcium/zinc ions for enzyme activity and, their interrelationships between zymogen and active forms. We believe that the embryo-endometrial proteases are essential for hatching or blastocysts and for the dynamic remodeling of endometrial tissue occurring during the critical peri implantation period. Page(s): 756-763

Expression and regulation of integrin receptors in human trophoblast cells: Role of estradiol and cytokines

2016-07-20T04:35:21Z

Title: Expression and regulation of integrin receptors in human trophoblast cells: Role of estradiol and cytokines Authors: Das, Chandana; Basak, Sayantani Abstract: Embryo implantation and placentation are dynamic cellular events that require not only synchrony between the maternal environment and the embryo, but also complex cell-cell communication amongst the implanting blastocyst and the receptive endomatrium through integrins, a large family of proteins involved in the attatchment, migration, invasion and control of cellular functions. Integrins display dynamic temporal and spatial patterns of expression by the trophoblast cells during early pregnancy in humans. However, the precise mechanism of embryo implantation and the modulation of the integrin receptors during blastocyst attachment and further implantation remin elusive in the humans. The present study elucidates the expression and hormonal modulation of fibronectin, vitronectin and laminin integrin receptors by estradiol and IL-1α in human trophoblast cells. Human first trimester trophoblast cells showed the induction of the classical estrogen receptor (ER)-α by its own ligand ,estradiol. Treatment with either estradiol or IL- 1α induced the expressions of α₄α₅α₆ and α_v, integrin receptor subunits at both the mRNA and protein levels, while expression of β₁ remained unaltered. Furthermore estradiol upregulated the expression of IL- 1α, thereby suggesting the possibility that estrogen may either directly or via the proinflammatory cytokine induces the expression of the cell surface integrin receptors. The findings delineate the role of hormones and the cytokines in modulating the adhesiveness and attatchment of the trophoblast cells. This may reflect the in vivo scenario where the implanting embryo is surrounded by a hormone-cytokine rich uterine microenvironment that may preisely regulate the expression of integrins and thereby facilitate implantation. Page(s): 748-755