大鼠阴茎海绵体NOSⅠ、NOSⅢ mRNA和蛋白表达研究

目的 :探讨正常大鼠阴茎海绵体中一氧化氮合酶 (NOS) Ⅰ和 Ⅲ mRNA和蛋白的表达。　方法 :取雄性SD大鼠阴茎组织 ,应用高度特异性抗体经免疫沉淀、Western印迹分析技术分别检测NOSⅠ 、NOS Ⅲ 蛋白的表达 ;RT PCR方法检测NOSⅠ和NOS Ⅲ mRNA的表达。　结果 :正常大鼠阴茎海绵体组织中有NOSⅠ 和NOS ⅢmRNA和蛋白的表达 ,并且NOSⅢmRNA和蛋白的表达明显多于NOSⅠmRNA和蛋白的表达。　结论 :不同的NOS亚型可能共同参与阴茎勃起的调控。     

Effect of aging on expression of nitric oxide synthase I and activity of nitric oxide synthase in rat penis

Aim: To investigate the effect of aging on the expression of nitric oxide synthase I (NOS I) and the activity of NOS in rat penis. Methods: Sixty male rats from 3 age groups (adult, old and senescent) were investigated. The expression of NOS I protein and mRNA in rat penis were detected by Western blot and RT-PCR respectively and the NOS activity, with ultraviolet spectrophotometry. Results: In the old and senescent group, NOS I protein expression was significantly decreased as compared with the adult. NOS I mRNA expression was well correlated with the protein expression. NOS activity was not statistically different between the adult and old groups, but it was significantly reduced in the senescent compared with the adult group (P<0.01). Conclusion: The aging-induced decreases in NOS I expression and NOS activity may be one of the main mechanisms leading to erectile dysfunction in the senescent rats.     

Experimental Chronic Renal Failure-Associated Erectile Dysfunction: Molecular Alterations in Nitric Oxide Synthase Pathway and IGF-I System

Chronic renal failure causes wide-ranging disturbances in male erectile function, and the dysfunction usually is not corrected by hemodialysis. In this study, erectile function and expression of nitric oxide synthase (NOS) isoforms, insulin-like growth factor-I (IGF-I), and IGF-I binding proteins were assessed in rats in which uremia had been produced by 5/6 nephrectomy. In the animals that suffered renal failure, there was a significantly lower rise in intracavernosal pressure in response to electrical stimulation, and the mean patency period after cavernous nerve stimulation was significantly increased. The amount of neuronial NOS mRNA was significantly higher in the penile tissues and major pelvic ganglia (MPG) of uremic rats than in control animals. There consistently were higher levels of nNOS and endothelial NOS in the penile tissues and MPG of rats with renal failure, and there was a significant decrease in the amount of IGF-I gene expression in the MPG of these animals. Expression of the IGF binding proteins 2 and 4 but not 5 also was reduced. This preliminary work demonstrates that impairment of erection in chronic renal failure in the rat is attributable to a disturbance in NOS gene expression with concomitant changes in IGF-I. These discoveries may permit an improved therapeutic approach to men with erectile dysfunction associated with chronic renal failure.     

衰老对大鼠阴茎海绵体NOS I的表达和NOS活性的影响

目的 :探讨衰老对大鼠阴茎海绵体一氧化氮合酶Ⅰ (NOSⅠ)mRNA、蛋白的表达和NOS活性的影响。　方法 :30只雄性SD大鼠按不同月龄分为成年组、老年组和衰老组 ,应用Western印迹、RT PCR方法分别检测不同年龄组阴茎海绵体NOSⅠ蛋白及mRNA的表达 ;用紫外分光光度计测定不同年龄组阴茎海绵体NOS的活性。　结果 :成年组NOSⅠ 蛋白的表达量最高 ,老年组和衰老组显著降低 ,分别为成年组的 75 .6 %和 6 1.2 % ;NOSⅠmRNA的表达与蛋白表达的变化一致 ;老年组NOS活性与成年组差异无显著性 (P >0 .0 5 ) ,衰老组NOS活性明显降低 ,是成年组的70 .4 % ,并且差异非常显著 (P <0 .0 1)。　结论 :衰老引起NOSⅠ 蛋白及mRNA的表达降低和NOS活性的显著降低 ,可能是老年性阴茎勃起功能障碍的主要机制之一。     

Novel nitric oxide signaling mechanisms regulate the erectile response

Nitric oxide (NO) is a physiologic signal essential to penile erection, and disorders that reduce NO synthesis or release in the erectile tissue are commonly associated with erectile dysfunction. NO synthase (NOS) catalyzes production of NO from L-arginine. While both constitutively expressed neuronal NOS (nNOS) and endothelial NOS (eNOS) isoforms mediate penile erection, nNOS is widely perceived to predominate in this role. Demonstration that blood-flow-dependent generation of NO involves phosphorylative activation of penile eNOS challenges conventional understanding of NO-dependent erectile mechanisms. Regulation of erectile function may not be mediated exclusively by neurally derived NO: Blood-flow-induced fluid shear stress in the penile vasculature stimulates phosphatidyl-inositol 3-kinase to phosphorylate protein kinase B, which in turn phosphorylates eNOS to generate NO. Thus, nNOS may initiate cavernosal tissue relaxation, while activated eNOS may facilitate attainment and maintenance of full erection.     

Mechanical strain stimulates nitric oxide production by rapid activation of endothelial nitric oxide synthase in osteocytes.

Previous studies have indicated that physiological levels of dynamic mechanical strain produce rapid increases in nitric oxide (NO) release from rat ulna explants and primary cultures of osteoblast-like cells and embryonic chick osteocytes derived from long bones. To establish the mechanism by which loading-induced NO production may be regulated, we have examined: nitric oxide synthase (NOS) isoform mRNA and protein expression, the effect of mechanical loading in vivo on NOS mRNA expression, and the effect of mechanical strain on NO production by bone cells in culture. Using Northern blot analyses, in situ hybridization, and immunocytochemistry we have established that the predominant NOS isoform expressed in rat long bone periosteal osteoblasts and in a distinct population of cortical bone osteocytes is the endothelial form of NOS (eNOS), with little or no expression of the inducible NOS or neuronal NOS isoforms. In contrast, in non-load-bearing calvariae there are no detectable levels of eNOS in osteocytes and little in osteoblasts. Consistent with these observations, ulnar explants release NO rapidly in response to loading in vitro, presumably through the activation of eNOS, whereas calvarial explants do not. The relative contribution of different bone cells to these rapid increases in strain-induced NO release was established by assessment of medium nitrite (stable NO metabolite) concentration, which showed that purified populations of osteocytes produce significantly greater quantities of NO per cell in response to mechanical strain than osteoblast-like cells derived from the same bones. Using Northern blot hybridization, we have also shown that neither a single nor five consecutive daily periods of in vivo mechanical loading produced any significant effect on different NOS isoform mRNA expression in rat ulnae. In conclusion, our results indicate that eNOS is the prevailing isoform expressed by cells of the osteoblast/osteocyte lineage and that strain produces increases in the activity of eNOS without apparently altering the levels of eNOS mRNA.     

负压吸引对糖尿病性ED大鼠阴茎海绵体组织一氧化氮合酶表达的影响

目的研究负压吸引对糖尿病性勃起功能障碍（ED）大鼠阴茎组织一氧化氮合酶（NOS）表达水平的影响。方法25只实验鼠中随机选取5只为正常对照组（A组）,其余火鼠用链脲左菌素和阿朴吗啡诱导建立Ⅰ型糖尿病性ED大鼠模型。之后把造模成功的糖尿病性ED大鼠随机分成糖尿病ED吸引组（B组）和糖尿病ED非吸引组（C组）。在B组大鼠负压吸引治疗结束后将A、B、C3组大鼠处死并取阴茎组织进行石蜡包埋。采用免疫组织化学方法检测各组大鼠阴茎组织中三种一氧化氮合酶亚型（nNOS、eNOS、iNOS）的表达情况。结果A组大鼠阴茎组织中nNOS蛋白表达水平高于B组和C组（均P〈0.001）;A组和B组大鼠阴茎组织中eNOS蛋白表达水平高于C组（均P〈0.01）;A组iNOS蛋白表达水平低于B组和C组（P〈0.01,P〈0.001）,同时B组iNOS蛋白表达水平低于C组（P〈0.01）;剩余其他各组间的比较差异无统计学意义（P〉0.05）。结论负压吸引可以通过升高阴茎组织中的eNOS和降低iNOS的表达来改善勃起功能。     

THE IMPACT OF CHRONIC RENAL FAILURE ON NITRIC OXIDE SYNTHASE ISOFORMS GENE EXPRESSION IN THE PENIS AND PELVIC GANGLIA OF RATS

PURPOSE: Patients with chronic renal failure experience a variety of physical and metabolic alterations. Uremia is often accompanied by erectile dysfunction (ED). Little information is available concerning the underlying pathophysiological mechanisms by which chronic renal failure can lead to erectile dysfunction. In this study, chronic renal failure was induced by 5/6 nephrectomy in a rat model. Cavernous nerve stimulation was used to measure the intracavernous pressure (ICP) rise. MATERIALS AND METHODS: Adult male Sprague-Dawley rats, aged between 10-12 weeks and weighing 200-250 gm. were divided into two groups. The first group (n = 20) served as a control (sham-operated) and underwent laparotomy with dissection of the perirenal fat around both kidneys. The second group (n = 40) were subjected to an excisional 5/6 nephrectomy (unilateral nephrectomy and contralateral upper and lower polar nephrectomy). Serum creatinine was measured 3 days post-operatively and at the end of the 12th week. Development of renal failure was considered if the animal had serum creatinine more than 120 microM/l. After 12 weeks, 10 animals per group were subjected to electric field stimulation (EFS) of the cavernous nerve with simultaneous recording of ICP-rise and systemic blood pressure. Northern and western blot analyses were used to determine the mRNA expression and protein contents of NOS isoforms (neuronal and endothelial) in the penile tissues and MPG. RESULTS: This remnant kidney model resulted in renal failure in 20 of 40 animals. The ICP-rise after cavernous nerve stimulation in the renal failure group was significantly impaired, 7.7+/-2.9 cm. H2O, as compared to control rats, 55.5+/-1.2 cm. H2O (p<0.001). The latency period after cavernous nerve stimulation was significantly increased in renal failure rats (6.9+/-0.95 sec.) in comparison to controls (2.4+/-0.25 sec.). Six of ten uremic animals had significantly lower testosterone (<1 nmol./l.) levels compared to non-uremic rats (3.6 nmol./l.) (p<0.005). Northern blot analysis revealed that renal failure rats had significantly higher levels of nNOS mRNA in the MPG and penile tissues than controls. There was no change in eNOS mRNA in either group. Western blot analysis demonstrated that eNOS and nNOS protein contents in the MPG and penile tissues of renal failure rats were significantly higher than those of controls. CONCLUSION: This report demonstrates that impairment of erection in renal failure rats, as determined by ICP-rise, was present in spite of elevated neuronal nitric oxide synthase mRNA and its protein in the MPG and penile tissues. Further studies are needed to determine whether erectile dysfunction is a result of post-translational changes, circulating inhibitory substances or other factors.     

丹参对大鼠缺血再灌注肾组织一氧化氮合成酶mRNA表达的影响

目的：探讨丹参对肾缺血再灌注损作保护效应的分子机制。方法：以大鼠缺血再灌汪肾损伤为模型，采用组织细胞原位杂交有图像分析技术技术，检测cNOS（eNOS和nNOS）及iNOSmRNA在缺血再灌注肾组织中的表达，并测定肾组织NOS总活性有血肌酐（Cr）。结果：①3种NOS在正常肾组织中均有表达，其中eNOS表达最丰富，cNOS／iNOS比值为2．29。②缺血时，肾组织NOS总活性显著下降，3种NOSmRNA在皮质、髓质有小球中的表达均下调，以eNOS最显著，cNOS／iNOS比值呈下降（2．01）趋势。③再灌注后，3种NOSmRNA的表达明显上调，以iNOSmRNA最明显，cNOS／iNOS的比值降至1．77。④肾缺血注射丹参后再灌注，iNOSmRAN表达明显下调，而nNOSmRAN则显著上调，cNOS／iNOS比值处于正常范围（2．14），Cr含量下降至正常水平。结论：①皮质肾小管上皮中iNOS活性升同与再灌汪后肾功能进一步受损密切相关。②缺血再灌注肾损伤中，丹参抑制iNOSmRNA和促进cNOSmRNA的表达是其介导肾保护效应的重要分子机制。③cNOS／iNOS比值的恒定对肾血流量和肾小球滤过率（GFR）的调节可能具有重要的意义。     

A specific method for measurement of nitric oxide synthase enzymatic activity in peritoneal biopsies

A specific method for measurement of nitric oxide synthase enzymatic activity in peritoneal biopsies. BACKGROUND: Nitric oxide (NO) is synthesized by NO synthase (NOS) isoforms that are expressed in the peritoneum. Thus far, NOS activity in the peritoneum has been assessed by nonspecific methods. We describe the application of a specific method for determination of NOS activity in rat and human peritoneal biopsies. METHODS: The L-citrulline assay is based on the stoechiometric production of NO and L-[3H]-citrulline from L-[3H]-arginine by NOS. The assay is technically difficult when applied on small samples with relatively low levels of NOS activity, which required specific procedures for extraction and samples processing. Reaction parameters ensuring assay linearity in the peritoneum were defined. Peritoneum lysates were also used for immunoblot analysis to identify the NOS isoforms involved. RESULTS: A significant NOS activity is detected in the normal peritoneum because of both Ca2+-dependent and Ca2+-independent NOS. The specificity of NOS activity has been demonstrated by various controls, including the NOS inhibitor L-NMMA. Competition experiments with L-valine and amino acid analyses have reasonably excluded the interference of endogenous arginase and L-arginine, which both might underestimate NOS activity. The procedure is sensitive; it detects a high range of NOS activities as well as the appropriate NOS isoforms in various tissues and conditions, as shown by correlations with immunoblot studies. CONCLUSIONS: We have adapted and characterized the L-citrulline assay to measure specific NOS activities within the peritoneum. The peritoneum lysate assayed for NOS activity can also be used for characterizing NOS isoform expression by immunoblot analysis.     

Temporal expression of nitric oxide synthase isoforms in healing Achilles tendon.

We investigated the temporal expressions of the three nitric oxide synthase (NOS) isoforms by semi-quantitative polymerase chain reaction (PCR) assays and by immunoblot analysis, following Achilles tendon transection in rats. Four days after injury, there were increases in the steady-state levels of mRNA for all three NOS isoforms, with peaks for the inducible isoform (iNOS) (23-fold increase) at day 4, the endothelial isoform (eNOS) (24-fold increase) at day 7 and the neuronal isoform (bNOS) (seven-fold increase) at day 21. The temporal expression of NOS isoforms at a protein level was consistent with the results at the mRNA level. We have previously shown a five-fold increase in the NOS activity, as detected by 3H-arginine to 3H-citrulline conversion, at day 7 postinjury. These findings indicate that all three NOS isoforms are expressed during tendon healing with differential expression patterns during the various phases of tendon healing. These findings may prove clinically relevant with respect to strategies for regulating tendon healing.     

大鼠阴茎组织一氧化氮合成酶基因表达的检测及意义

应用ＲＴ－ＰＣＲ方法测定大鼠阴茎组织中ＮＯＳｍＲＮＡ的含量。结果显示，大鼠阴茎组织中存在ＮＯＳｍＲＮＡ表达，其表达程度约为小脑的３０％。老龄大鼠与２月龄大鼠相比阴茎组织中ＮＯＳｍＲ－ＮＡ表达水平显著降低，提示阴茎组织中ＮＯＳｍＲＮＡ表达下降可能是阳萎年龄依赖性的原因之一。     

Renal expression of constitutive NOS and DDAH: separate effects of salt intake and angiotensin

BACKGROUND: Nitric oxide (NO) is generated from NO synthase (NOS) isoforms. These enzymes can be inhibited by asymmetric dimethylarginine, which is inactivated by N(G)-N(G)-dimethylarginine dimethylaminohydrolase (DDAH). The neuroneal (nNOS) type I and endothelial (eNOS) type III constitutive NOS isoforms are expressed predominantly in the macula densa and microvascular endothelium of the renal cortex, respectively. DDAH is expressed at sites of NOS expression. Since NO may coordinate the renal responses to angiotensin II (Ang II) and changes in salt intake, we tested the hypothesis that salt intake regulates the expression of nNOS, eNOS and DDAH by Ang II acting on type 1 (AT(1)) receptors. METHODS: Groups (N = 6) of rats were adapted to low-salt (LS) or high-salt (HS) intakes for 10 days. Other groups of LS and HS rats received the AT(1) receptor antagonist losartan for six days (to test the effects of salt independent of AT(1) receptors). A further group of HS rats received an infusion of Ang II for six days (to test the effect of Ang II independent of salt intake). RESULTS: Compared with HS rats, there was a significant (P < 0.05) increase in LS rats of nNOS protein in kidney and immunohistochemical expression in the macula densa, and of eNOS protein expression and immunohistochemical expression in the microvascular endothelium, and of DDAH protein expression. Losartan prevented these effects of salt on the expression of eNOS or DDAH, both of which were also increased by Ang II infusions in HS rats. In contrast, losartan did not prevent the effects of salt on nNOS expression, which was unresponsive to Ang II infusion. The generation of NO(2)(-) released by slices of renal cortex, in the presence of saturating concentrations of L-arginine, was increased by LS, compared to HS, independent of losartan and by Ang II during HS. CONCLUSION: The expressions of eNOS in cortical microvascular endothelium and DDAH in kidney are enhanced by Ang II acting on AT(1) receptors. The expression of nNOS in the macula densa is enhanced by salt restriction independent of Ang II or AT(1) receptors.     

Neuronal and endothelial nitric oxide synthase isoforms: quantification of protein and mRNA in the normal rat penis

Nitric oxide synthase (NOS) is an important enzyme for erection. We evaluated the content of neuronal (nNOS) and endothelial (eNOS) isoforms and their mRNA in the penis and major pelvic ganglion (MPG) of adult male rats by Western and Northern blot analysis. The cerebellum was evaluated as a control. nNOS protein and its mRNA were detected in abundance in the MPG, cerebellum, pelvic urethra and within the crura of the penis. In contrast, the penile urethra, neurovascular bundle and the shaft of penis contained smaller amounts of this protein. eNOS protein was most abundant in the penile and pelvic parts of the urethra, whereas a moderate level was found in the penile shaft, crura, neurovascular bundle, MPG and cerebellum. Similarly eNOS mRNA was abundant in the penile and pelvic parts of the urethra, MPG and cerebellum. Penile shaft, crura and neurovascular bundle showed moderate amounts of eNOS mRNA. In conclusion, nNOS and its mRNA are most abundant in the MPG and crura of penis whereas eNOS is most abundant in the urethra and to a lesser extent present in the penis. Importantly eNOS protein and mRNA were demonstrated in the MPG, where eNOS function has to be studied.