半胱亚磺酸脱羧酶和牛磺酸转运体mRNA在成年小鼠睾丸间质细胞的表达

为检测成年小鼠睾丸间质细胞是否存在牛磺酸生物合成关键酶半胱亚磺酸脱羧酶(CSD)和牛磺酸转运体(TauT)mRNA的表达,通过Percoll分离液分离纯化成年小鼠睾丸间质细胞,运用RT-PCR方法测定睾丸间质细胞中CSD和TauT mRNA表达情况。结果显示,成年小鼠睾丸间质细胞存在CSD和TauT mRNA表达。说明成年小鼠睾丸间质细胞能通过CSD途径合成牛磺酸以及睾丸间质细胞可能存在牛磺酸的转运活动。     

Vacuolar degeneration of skeletal muscle in transgenic mice overexpressing ORP150

ORP150 is a hypoxic stress-induced protein located in the endoplasmic reticulum. Transgenic mice overexpressing ORP150 (ORP-Tg) exhibit vacuolar degeneration in the heart. To determine whether vacuolization is present in skeletal muscle, we pathologically examined ORP-Tg mice. After 60 days of age, severe vacuolization was found in the soleus muscles of the hind legs of the ORP-Tg mice. Immunohistochemical staining of ORP150 revealed co-localization of ORP150 and vacuolization in the affected cells. Electron microscopy revealed a marked increase in the number of rough-surfaced endoplasmic reticula (rER) and distention of the cisterna. These findings suggest that overexpression of ORP150 causes accumulation of ORP150 in the rER, resulting in vacuolar degeneration in the skeletal muscle of ORP-Tg mice.     

活体电穿孔方法提高外源GRF基因在小鼠肌肉组织中的表达

向小鼠后肢小腿肌注pGRF表达质粒并加以电穿孔条件,注射剂量分别为5,10,50μg,于注射前及注射后10,20,30d测体质量,并采血分离血清测血清GRF水平。结果显示,5μgpGRF质粒电穿孔组注射后10dGRF分别比对照组、5μgpGRF质粒组升高44.73%(P0.05),12.86%(P0.05);血清中GRF水平升高。30d累积增重,5μgpGRF质粒电穿孔组分别比对照组、5μgpGRF质粒组高11.46%,6.75%(P0.05);10μgpGRF质粒组分别比对照组和10μgpGRF质粒电穿孔组高19.52%(P0.05),19.42%(P0.05)。50μgpGRF质粒组45d累积增重分别比对照组、pGRF质粒电穿孔组高14.00%,12.00%(P0.05)。结果表明,电穿孔处理可提高GRF基因在小鼠肌肉中的表达。     

Idiopathic skeletal muscle necrosis in bluegills

Skeletal muscle degeneration and necrosis in a wild population of bluegills (Lepomis macrochirus) were investigated. Hemorrhage and large areas of muscle necrosis were evident at necropsy. Histologically, muscle fibers were granular, vacuolated, and fragmented. Ultrastructural alterations included mitochondrial swelling, clumping and loss of actin and myosin fibrils, swelling of T tubules, and loss of continuity of the sarcolemma. An etiologic agent was not identified.     

Estrogen receptor in bovine skeletal muscle

In connection with investigations of the anabolic action of estrogens, we examined skeletal muscle of veal calves for estradiol receptors. The high speed supernatant of muscle homogenate was incubated with .5 nM 3H-estradiol and for the determination of nonspecific binding with .5 nM 3H-estradiol plus 13 nM estradiol at 0 C overnight. After treatment with charcoal two times, the supernatant was analyzed by agar gel electrophoresis. Specific binding was found in the typical position of cytosolic estradiol receptor. Ninety percent of 3H-estradiol binding was suppressed by estradiol-17 beta, zeranol, estrone or diethylstilbestrol, but was not affected by testosterone, dihydrotestosterone, trenbolone or progesterone. The specific binding activity varied between .3 and 2.0 fmol/mg protein and the dissociation constant of the receptor was Kd = 60 pM. After an enrichment up to 42 fmol/mg cytosolic protein using heparin sepharose, the receptor remained unchanged as determined by agar gel electrophoresis. Although uterine tissue generally contains 1,000 times more estradiol receptors, these results clearly demonstrate that skeletal muscle also contains estradiol receptors with identical properties. This indicates that one possible component of the anabolic action of estrogens may be the direct stimulation of the muscle via the estradiol receptor.     

Changes of insulin-mediated protein kinases phosphorylation and the expression of IGFBP-3 in skeletal muscle of streptozotocin-diabetic mice

The purpose of the present study was to investigate potential changes in expression and activation of Ser/Thr protein kinases as well as in the level of insulin-like growth factor-binding proteins (IGFBPs) in skeletal muscle of streptozotocin (STZ)-diabetic mice. We have examined the basal and insulin-mediated phosphorylation of protein kinase B (PKB), protein kinase Czeta (PKCzeta), p70(S6k), mitogen-activated protein kinase (MAPK)/p90(rsk) pathway and the expression of IGFBP-3, -4, and -5 in mice selected for body weight gain (line C) and reduction (line L). Apart from IGFBP-3 level, which was higher in C line, the diabetes-associated changes in signaling components examined in present work were similar in both lines of mice. The expression of PKB in skeletal muscle was similar in control and diabetic mice. Insulin increased the Ser473 phosphorylation of PKB in both experimental groups however, in diabetic mice the insulin-dependent PKB phosphorylation was more evident in comparison to control group. Neither protein level nor insulin-stimulated p70(S6k) activation were modified by STZ-diabetes. Basal PKC phosphorylation was augmented in muscle of diabetic mice and it was not increased following insulin injection. No apparent differences in levels of p42(MAPK), p44(MAPK) and p90(rsk) protein in gastrocnemius muscles between control and STZ-treated mice were observed. Basal phosphorylation of p90(rsk) in diabetic mice was markedly elevated in comparison to the control. In muscle of C-line mice, insulin stimulated the p90(rsk) activity to the same extent in both experimental groups (+22% over appropriate basal value). Insulin-mediated stimulation of p90(rsk) in muscle of L-line mice amounted to +26% and +14%, for control and diabetic mice, respectively. Protein level of IGFBP-3 in muscle of diabetic C-line mice was augmented by approx. 28% when compared to the control, whereas the expression of IGFBP-4 and -5 was not modified by STZ-diabetes. In conclusion: diabetes-associated changes in the insulin signaling in skeletal muscle involve: 1) enhanced insulin-dependent phosphorylation of PKB; 2) increased basal phosphorylation of PKC and its resistance to stimulatory action of insulin; 3) increased basal phopshorylation of p90(rsk), and 4) augmented IGFBP-3 protein level, which can potentially contribute to disruption of anabolic signals in this tissue.