Hormone responsiveness of cultured Sertoli cells obtained from adult rats after their rapid isolation under less harsh conditions.

During adulthood, testicular Sertoli cells (Sc) coordinate all stages of germ cell (Gc) development involved in sperm production. However, our understanding about the functions of adult Sc is limited because of the difficulties involved in the process of isolating these cells from the adult testis, mainly because of the presence of large number of advanced Gc which interfere with Sc isolation at this age. Most of our knowledge about Sc function are derived from studies which used pre-pubertal rat Sc (18 ± 2-day old) as it is easy to isolate and culture Sc at this age. To this end, we established a less time consuming and less harsh procedure of isolating Sc from adult (60 days of age) rat testis for facilitating research on Sc-mediated regulation of spermatogenesis during adulthood. The cells were isolated using collagenase digestion at higher temperature, reducing the exposure time of cells to the enzyme. Step-wise digestion with intermittent removal of small clusters of tissue helped in increasing the yield of Sc. Isolated Sc were cultured and treated with FSH and testosterone (T) to evaluate their hormone responsiveness in terms of lactate, E2 , cAMP production. Adult Sc were found to be active and produced high amounts of lactate in a FSH-independent manner. FSH-mediated augmentation of cAMP and E2 production by adult Sc was less as compared with that by pre-pubertal Sc obtained from 18-day-old rats. Androgen-binding ability of adult Sc was significantly higher than pre-pubertal Sc. Although T treatment remarkably augmented expression of Claudin 11, it failed to augment lactate production by adult Sc. This efficient and rapid procedure for isolation and culture of functionally viable adult rat Sertoli cells may pave the way for determining their role in regulation and maintenance of spermatogenesis.

Prolactin activation of the long form of its cognate receptor causes increased visceral fat and obesity in males as shown in transgenic mice expressing only this receptor subtype.

To date the best defined function of prolactin (PRL) is its action on the ovary and mammary gland, although it has also been shown to have an effect on lipid metabolism. Using mice engineered to express only the long form of the prolactin receptor (PRL-RL), we demonstrate that PRL acting through PRL-RL alone causes severe adipose accumulation in visceral fat of males at 6 months of age. The increase in visceral fat accumulation is attributed to loss of adipose-derived leptin, which results in diminished lipolysis. The reduction in leptin also corresponds to decreased activation of AMP-activated protein kinase (AMPK), which further results in diminished fatty acid oxidation and increased fatty acid synthesis. Interestingly, the blunted AMPK response was only observed in adipose tissue and not in liver suggesting that this PRL mediated effect is tissue specific. A glucose tolerance study inferred that PRL-RL mice may suffer from insulin resistance or a reduction in insulin production that is not due to aberrant expression of glucose transporter 4 (Glut4). Collectively, our findings demonstrate that PRL signaling through the long form receptor causes reduced fatty acid oxidation, increased lipid storage, glucose intolerance, and obesity. These findings are of great importance towards understanding the etiology of obesity associated with hyperprolactinemia in humans as well as the role of PRL as a metabolic regulator in adipose tissue.

Blood stage malaria antigens induce different activation-induced cell death programs in splenic CD4+T cells.

CD4(+) T cells respond to antigen immunization through a process of activation, clonal expansion to generate activated effector T cells followed by activation-induced clonal deletion of the responding T cells. While loss of responding T cells in post-activation death by apoptosis is a major factor regulating immune homeostasis, the precise pathways involved in downsizing of Plasmodium falciparum antigen-induced T cell expansions are not well characterized. We report in this study that splenic CD4(+) T cells from mice immunized with nonreplicating immunogens like OVA or recombinant blood stage P. falciparum antigens, PfMSP-3 and PfMSP-1(19) or crude parasite antigen (PfAg) undergo sequential T cell activation, proliferation followed by activation-induced cell death (AICD) in a dose- and time-dependent manner after Ag restimulation. While PfMSP-3 and OVA-induced AICD was mediated through a death receptor-dependent apoptotic program, PfMSP-1(19) and PfAg-induced AICD was via a mechanism dependent on the activation of mitochondria apoptosis signalling pathway through Bax activation. These results provide insights into the mechanism through which two blood stage merozoite antigens trigger different apoptotic programs of AICD in splenic CD4(+) T cells.