Biomedical subjects

Q Lu

Publications and source records attributed to Q Lu.

275 records · Page 16Linked to original sources

PubMedDate not supplied

Expression of CB2 cannabinoid receptor mRNA in adult rat retina.

To date, two cannabinoid receptors, CB1 and CB2, have been cloned. The CB1 receptor has been found in a variety of tissues, particularly in the brain. CB2 receptor mRNA is mainly expressed in the immune system, though one group has found it in mouse cerebellum. Previous immunostaining studies in our lab demonstrated the presence of CB1 receptors in the retina though little evidence exists for the presence of CB2. The putative endogenous ligand for CB2 has been found in retina, however, suggesting that further study of CB2 in retina is warranted. Because glutamate is toxic to retinal ganglion cells in glaucoma and activation of CB2 receptors may be able to protect neurons from glutamate-induced death, we examined the expression of CB2 mRNA in adult rat retina in order to better understand possible neuroprotective mechanisms relevant to glaucoma. Using in situ hybridization, we demonstrated that CB2 cannabinoid receptor messenger RNA was clearly expressed in the adult rat retina, including the somas of retinal ganglion cells. Antisense cRNA probe detected strong signals in the retinal ganglion cell layer, the inner nuclear layer, and the inner segments of photoreceptor cells. Using reverse transcription polymerase chain reaction (RT-PCR) in both rat and mouse tissue, we obtained an RT-PCR product with the same sequence as that reported for CB2 in the GenBank database, thus confirming the presence of CB2 mRNA in retina. The presence of CB2 in retina provides new evidence for the presence of CB2 in the central nervous system (CNS) and an excellent model for its study.

Animals↗

PubMedDate not supplied

Expression and phosphorylation of mitogen-activated protein kinases during spermatogenesis and epididymal sperm maturation in mice.

The expression and phosphorylation/dephosphorylation of mitogen-activated protein (MAP) kinases during mouse spermatogenesis and epididymal sperm maturation have been investigated by immunoblotting and immunohistochemical staining with commercially available anti-ERK2 and anti-Active MAPK antibodies. Two forms of MAP kinases, p42ERK2 and p44ERK1, were expressed in a similar amount in spermatogenic cells at different stages. ERK1 and ERK2 were phosphorylated (activated) in early spermatogenic cells from primitive spermatogonia to zygotene primary spermatocytes, while only a small quantity of phosphorylated MAP kinases could be detected in pachytene primary spermatocytes and spermatids. MAP kinase activity in primative spermatogonia and preleptotene primary spermatocytes was the highest among spermatogenic cells. ERK1 and ERK2 were also present in epididymal spermatozoa, and their phosphorylation was increased while spermatozoa pass through epididymis and vas deferens for maturation. It would appear that MAP kinase activation may contribute to the mitotic proliferation of primative spermatogonia, an early phase of spermatogenic meiosis, and, later, sperm motility acquirement.

Animals↗

PubMedDate not supplied

The modulatory role of gut hormones in elemental diet and intravenous total parenteral nutrition-induced bacterial translocation in rats.

We have previously shown that parenteral and certain elemental diets promote bacterial translocation and that this diet-induced bacterial translocation can be prevented by the provision of bulk-forming dietary fiber. The goal of the current study was to test the hypothesis that fiber's protective effect on diet-induced bacterial translocation was mediated by trophic gut hormones. This hypothesis was tested by using bombesin (which stimulates gut hormone release) or the somatostatin analog Sandostatin (which inhibits gut hormone release) to modulate gut hormone release in rats receiving rat food, intravenous total parenteral nutrition, or an elemental diet. Both bombesin and fiber were effective in preventing elemental diet-induced bacterial translocation, whereas octreotide acetate abrogated the protective effect of fiber. Bombesin was also effective in limiting bacterial translocation in parenterally fed rats. Although both enteral (elemental diet) and parenteral diet-induced bacterial translocation were associated with cecal bacterial overgrowth, loss of small-bowel weight, and loss of mucosal protein content, none of these factors seemed to be primarily responsible for bacterial translocation. Because bombesin decreased the incidence of villous injury in the elemental diet-fed rats and decreased the incidence of villous injury and prevented loss of intestinal barrier function to horseradish peroxidase in the parenterally fed rats, it is possible that bombesin exerted its protective effect by limiting mucosal injury and preserving barrier function.

Animals↗

PubMedDate not supplied

Elemental diet-induced bacterial translocation associated with systemic and intestinal immune suppression.

BACKGROUND: Elemental diets can lead to a loss of intestinal barrier function, promote bacterial translocation, and impair host immune defenses. The purpose of this study was to determine the effects of i.v. and orally administered total parenteral nutrition (TPN) solution on systemic and intestinal immunity and to establish whether supplemental cellulose fiber could improve the impaired immune response. METHODS: The incidence of bacterial translocation and immune function was quantitated by measuring organ weights, immune cell population levels, and the mitogenic response of lymphocytes from the spleen, mesenteric lymph nodes and Peyer's patches of rats receiving parenteral or enteral TPN solution, with and without fiber supplementation. RESULTS: Parenteral and enterally administered TPN solution promoted bacterial translocation to the mesenteric lymph nodes, reduced immune cell population levels, and decreased the lymphocyte mitogenic response to T- and B-cell mitogens. Supplemental cellulose fiber reduced the incidence of diet-induced bacterial translocation from 84% to 31% (p < .01) and improved immune cell function. To more closely examine the relationship between bacterial translocation and impaired lymphocyte mitogenic activity, rats receiving TPN orally or i.v. were separated into two groups based on whether or not bacterial translocation occurred. Rats in which fiber prevented bacterial translocation had normal mitogenic responses, whereas the sub-group of rats in which fiber failed to prevent bacterial translocation had profound decreases in their lymphocyte mitogenic responses. CONCLUSIONS: Both parenteral and enteral elemental diets induced bacterial translocation and impaired systemic and intestinal immune function. Fiber supplementation was effective in reducing elemental diet-induced bacterial translocation and significantly prevented diet-induced impairment of lymphocyte function.

Administration, Oral↗

PubMedDate not supplied

Ecto-ATPase mRNA is regulated by FSH in Sertoli cells.

A putative messenger RNA (mRNA) sequence, designated C8, that was up-regulated in Sertoli cells prepared from hypophysectomized rats treated with testosterone, was isolated from a Sertoli cell complementary DNA (cDNA) library. The coding region of C8 exhibited 99% identity with rat brain ecto-ATPase and expressed a 60-kilodalton protein following in vitro transcription/translation. Transfection of COS7 cells with C8 cDNA resulted in a marked increase in Ca2+- and Mg2+-dependent ATPase activity in both whole cells and cell homogenates, which is consistent with localization of this enzyme in the plasma membrane. C8 ecto-ATPase steady state mRNA levels were increased within 6 hours and for 3 day, by follicle-stimulating hormone (FSH) in Sertoli cells but not in peritubular cells. In contrast, dibutyryl-cyclic adenosine monophosphate (cAMP) increased ecto-ATPase in both Sertoli and peritubular cells. Testosterone had no significant effect under these conditions. These data indicate that ecto-ATPase mRNA is positively regulated by FSH in Sertoli cells and by cAMP in both Sertoli and peritubular cells. This enzyme may play a role in the control of extracellular signaling by ATP, adenosine, or both in the cells of the seminiferous epithelium.

Adenosine Triphosphatases↗