Alves M G, Martins A D, Vaz C V, Correia S, Moreira P I, Oliveira P F, Socorro S
CICS-UBI - Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal.
Br J Pharmacol. 2014 Feb;171(4):1033-42. doi: 10.1111/bph.12522.
Metformin is commonly used to treat type 2 diabetes (T2D). While new clinical applications have been ascribed to metformin, including treatment of anovulatory infertility, its effects on male reproduction have not been investigated. The Sertoli cell (SC) is crucial for germ cell development, exerting metabolic control of spermatogenesis, therefore, we investigated the effects of metformin on SC metabolism.
Rat SCs were cultured in the absence and presence of metformin (5, 50 and 500 μM). mRNA and protein levels of glucose transporters (GLUT1 and GLUT3), phosphofructokinase 1 (PFK 1), lactate dehydrogenase (LDH) and monocarboxylate transporter 4 (MCT4) were determined by quantitative PCR and Western blot respectively. LDH activity was assessed and metabolite production/consumption determined by (1) H-NMR.
Metformin (50 μM) decreased mRNA and protein levels of GLUT1, GLUT3, MCT4 and PFK 1 but did not affect LDH mRNA or protein levels. However, although glucose consumption was maintained in metformin-treated cells, LDH activity, lactate and alanine production were increased, indicating an enhanced glycolytic flux. No metabolic cytotoxicity was detected in SCs exposed to supra-pharmacological concentration of metformin.
Our results indicate that metformin: (i) decreases mRNA and protein levels of glycolysis-related transporters in SCs but increases their activity; and (ii) stimulates alanine production, which induces antioxidant activity and maintains the NADH/NAD(+) equilibrium. The increased lactate in metformin-treated SCs provides nutritional support and has an anti-apoptotic effect in developing germ cells. Thus, metformin can be considered as a suitable antidiabetic drug for male patients of reproductive age with T2D.
二甲双胍常用于治疗2型糖尿病（T2D）。虽然二甲双胍有了新的临床应用，包括治疗无排卵性不孕症，但其对男性生殖的影响尚未得到研究。支持细胞（SC）对生殖细胞发育至关重要，对精子发生发挥代谢控制作用，因此，我们研究了二甲双胍对支持细胞代谢的影响。
在有无二甲双胍（5、50和500μM）的情况下培养大鼠支持细胞。分别通过定量PCR和蛋白质印迹法测定葡萄糖转运蛋白（GLUT1和GLUT3）、磷酸果糖激酶1（PFK 1）、乳酸脱氢酶（LDH）和单羧酸转运蛋白4（MCT4）的mRNA和蛋白质水平。评估LDH活性，并通过（1）H-NMR测定代谢产物的产生/消耗。
二甲双胍（50μM）降低了GLUT1、GLUT3、MCT4和PFK 1的mRNA和蛋白质水平，但不影响LDH的mRNA或蛋白质水平。然而，尽管在二甲双胍处理的细胞中葡萄糖消耗得以维持，但LDH活性、乳酸和丙氨酸的产生增加，表明糖酵解通量增强。在暴露于超药理浓度二甲双胍的支持细胞中未检测到代谢细胞毒性。
我们的结果表明，二甲双胍：（i）降低支持细胞中糖酵解相关转运蛋白的mRNA和蛋白质水平，但增加其活性；（ii）刺激丙氨酸的产生，诱导抗氧化活性并维持NADH/NAD(+)平衡。二甲双胍处理的支持细胞中增加的乳酸为发育中的生殖细胞提供营养支持并具有抗凋亡作用。因此，二甲双胍可被视为适合患有T2D的育龄男性患者的抗糖尿病药物。
