Down‐regulation of steroidogenesis‐related genes and its accompanying fertility decline in streptozotocin‐induced diabetic male rats: ameliorative effect of metformin

Abstract

Background: Metformin has long been used for glycemic control in diabetic state. Recently, other benefits of metformin beyond blood glucose regulation have emerged. Objectives: To investigate the effect of metformin on the expression of testicular steroidogenesis-related genes, spermatogenesis, and fertility of male diabetic rats. Materials and methods: Eighteen adult male Sprague Dawley rats were divided into three groups, namely normal control (NC), diabetic control (DC), and metformin-treated (300 mg/kg body weight/day) diabetic rats (D+Met). Diabetes was induced using a single intraperitoneal injection of streptozotocin (60 mg/kg b.w.), followed by oral treatment with metformin for four weeks. Results: Diabetes decreased serum and intratesticular testosterone levels and increased serum but not intratesticular levels of luteinizing hormone. Sperm count, motility, viability, and normal morphology were decreased, while sperm nuclear DNA fragmentation was increased in DC group, relative to NC group. Testicular mRNA levels of androgen receptor, luteinizing hormone receptor, cytochrome P450 enzyme (CYP11A1), steroidogenic acute regulatory (StAR) protein, 3b-hydroxysteroid dehydrogenase (HSD), and 17b-HSD, as well as the level of StAR protein and activities of CYP11A1, 3b-HSD, and 17b-HSD, were decreased in DC group. Similarly, decreased activities of epididymal antioxidant enzymes and increased lipid peroxidation were observed in DC group. Consequently, decreased litter size, fetal weight, mating and fertility indices, and increased pre-and post-implantation losses were recorded in DC group. Following intervention with metformin, we observed increases in serum and intratesticular testosterone levels, Leydig cell count, improved sperm parameters, and decreased sperm nuclear DNA fragmentation. Furthermore, mRNA levels and activities of steroidogenesis-related enzymes were increased, with improved fertility outcome. Discussion and conclusion: Diabetes mellitus is associated with dysregulation of steroidogenesis, abnormal spermatogenesis, and fertility decline. Controlling hyperglycemia is therefore crucial in preserving male reproductive function. Metformin not only regulates blood glucose level, but also preserves male fertility in diabetic state. Research has shown that DM impairs several aspects of the male reproductive function (Nna et al., 2017a). Decreased daily sperm production, sperm count, motility and viability, increased 110

Orlistat attenuates obesity‐induced decline in steroidogenesis and spermatogenesis by up‐regulating steroidogenic genes

“…After rats were deeply anaesthetized with pentobarbitone (60 mg/kg body weight, i.p. ), 24 the naso‐anal lengths (NAL) were measured to the nearest millimetre and the rats were weighed to the nearest gram. A measuring tape was used for the naso‐anal length measures.…”

“…Sperm motility was determined by previously reported method 24 . Briefly, spermatozoon was obtained from left vas deferens which was squeezed into 1 mL of normal saline and gently stirred, a drop of this was subsequently placed on the Makler's counting chamber (Sefi‐Medical Instruments) and viewed under a light microscope (Olympus BX41, Olympus Corporation).…”

“…Similarly, sperm morphology, head and tail defects were counted as abnormal spermatozoa in the sperm smear. Two hundred spermatozoa from each slide were counted, and the number of defective spermatozoa was expressed in percentage 24 …”

“…The smear was then viewed under a fluorescent microscope (Olympus BX41) with a 460‐nm filter. One hundred spermatozoa were counted for each field, and the number of sperm heads which stained orange (fragmented nDNA) was expressed as a percentage of the total spermatozoa counted 24 …”

Effect of metformin on testicular expression and localization of leptin receptor and levels of leptin in the diabetic mice

“…However, it can also be used to improve the glycemic control in patients with DM1 (Kaul, Apostolopoulou, & Roden, 2015). Metformin also has anticancer and anti‐inflammatory properties (Foretz, Guigas, Bertrand, Pollak, & Viollet, 2014) and contributes to the improvement of testicular functions in conditions of pathological conditions (Asghari, Akbari, Meghdadi, & Mortazavi, 2016; Nna et al, 2019). Since metformin has been shown to affect the leptin levels in metabolic diseases (Baruah, Kalra, & Ranabir, 2012) and to regulate the testicular functions (Nna et al, 2019), so it is hypothesized that in DM1, metformin also affects the circulating and intratesticular leptin levels and the Ob‐R localization in the testicular cells.…”