ABSTRACT
Type 2 diabetes mellitus (T2DM) is a common cause of erectile dysfunction (ED). It has been demonstrated that G protein-coupled receptor kinase 2 (GRK2) overexpression contributes to diabetic endothelial dysfunction and oxidative stress, which also underlies ED in T2DM. We hypothesized that GRK2 overexpressed and attenuated endothelial function of the cavernosal tissue in a rat model of T2DM. T2DM rats were established by feeding with a high-fat diet (HFD) for 2 weeks and then administering two intraperitoneal (IP) injections of a low dose of streptozotocin (STZ), followed by continuous feeding with a HFD for 6 weeks. GRK2 was inhibited by IP injection of paroxetine, a selective GRK2 inhibitor, after STZ injection. Insulin challenge tests, intracavernous pressure (ICP), GRK2 expression, the protein kinase B (Akt)/endothelial nitric oxide synthase (eNOS) pathway, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit gp91phox, nitric oxide (NO), reactive oxygen species (ROS) production, and apoptosis in cavernosal tissue were examined. Less response to insulin injection was observed in T2DM rats 2 weeks after HFD. Markedly increased GRK2 expression, along with impaired Akt/eNOS pathway, reduced NO production, increased gp91phox expression and ROS generation, increased apoptosis and impaired erectile function were found in T2DM rats. Inhibition of GRK2 with paroxetine ameliorated Akt/eNOS signaling, restored NO production, downregulated NADPH oxidase, subsequently inhibited ROS generation and apoptosis, and ultimately preserved erectile function. These results indicated that GRK2 upregulation may be an important mechanism underlying T2DM ED, and GRK2 inhibition may be a potential therapeutic strategy for T2DM ED.
ABSTRACT
<p><b>OBJECTIVE</b>To study the mechanism of male infertility caused by varicocele by evaluating the effects of hyperbaric oxygenation (HBO) therapy on the testicular tissue morphology and function of rabbit model with varicocele(VC).</p><p><b>METHODS</b>Twenty-four mature male rabbits were randomly divided into three groups: pseudo-operation, VC model and VC model administered by HBO. Experimental varicocele was induced by partial ligation of the left "lumbotesticular" trunk vein in rabbits. HBO was administered to one of the two groups of VC model rabbits after the operation. Weight and volume of both testes, parameters of seminal fluid, histological changes of testicular tissues, MTDs, TFI, and Sertoli cell index (SI) of seminiferous tubules were studied.</p><p><b>RESULTS</b>The average weight and volume of the left testes significantly increased in the rabbits treated by HBO. The semen quality was improved, and MTDs increased significantly compared with VC group(P < 0.0001). The testicular tissue morphology became nearly normal in VC + HBO group.</p><p><b>CONCLUSIONS</b>1. Both the structure and spermatogenetic function of testes can be damaged by the presence of varicocele; 2. Chronic ischemia, anoxia and microcircular dysfunction may be the key process and essential factor that make varicocele contributive to testicular damage and spermatogenetic dysfunction; 3. HBO can effectively alleviate, even eliminate, chronic ischemia, anoxia and microcircular dysfunction in testicular tissues with varicocele, and thus protect the structure and functions of testes.</p>