Xia Cheng

Nitric oxide synthase expression in foetal placentas of cows with retained fetal membranes.

The objectives of this study were to investigate relationship of retained fetal membranes (RFM) to expression of NOS and NOS mRNA and to analyze pathohistological changes and the distribution of nitric oxide synthase (NOS) in foetal placentas of cows with RFM. Twenty cows were assigned to two groups, a control group (no retained fetal membranes, NRFM, n = 10) and a diseased group (RFM, n = 10). The endpoint method was used to detect the nitric oxide (NO) content and nitric oxide synthase (NOS) activity in foetal placental tissue fluid and the fluorescent quantitation PCR was used to measure the expression of NOS mRNA. Immunohistochemistry and hematoxylin-eosin staining were used to observe pathohistological changes. Tissue from RFM cows showed fibronecrosis of the chorionic villi, and a decreased number of trophoblastic cells. The majority of trophoblastic cells displayed vacuolar degeneration. Interstitium vessels were distended and congested. Expression of induced nitric oxide synthase (iNOS) protein and iNOS mRNA was significantly higher (P < 0.05) in the cytoplasm of placental villus trophoblastic cells in the RFM group. But expression of endothelial nitric oxide synthase (eNOS) protein and eNOS mRNA was significantly lower (P<0.05) in the RFM group. The NO content and NOS activity of cows with RFM were significantly higher (P < 0.05). A high expression of iNOS protein and iNOS mRNA in the cow foetal placenta could produce high content of NO, which might inhibit uterine contraction. So over expression of iNOS protein and iNOS mRNA might be an important agent of retained fetal membranes in cows, and it may be a potential diagnosis biomarker.

Effects of leptin on the expression of Ob-Rb mRNA in the cultured adipocytes of newborn calf

The effects of additional leptin on the long type receptor (Ob-Rb mRNA) for adipocytes of new born calf were tested by means of competitive reverse transcription polymerase chain reaction (RT-PCR). A sample of fine monolayer adipose cells were first obtained and recombination leptins of calf (5 ng/mL · 12 h) were added. No additive was adopted as tester in the adipose cell. Total RNA was determined at 4, 12, 24, 36, 48 and 72 h, and duplicated three times in every treatment in the single factor duplicating test. The result, compared with the group of testers, was that the quantity of Ob-Rb mRNA in adipose cell cultures was also significantly higher (P<0.01) at the beginning stage. Following this tendency, the quantity was gradually lower with cultured time going on in 12–24 h, and the quantity was in stable level (P > 0.05) from 48 to 72 h. It was shown that leptin could improve the level of expression of Ob-Rb in cultured adipose cells of new born calf within a definite time.