Diabetes mellitus (DM) causes male infertility through the suppression of spermatogenesis and testosterone biosynthesis. The impact of DM on male reproduction has mainly been investigated in adulthood, therefore we aimed to study the developmental effects of DM, induced in early life, on testicular cell population and fertility. Neonatal (NDM) and prepubertal DM (PDM) were induced in immature rats by streptozotocin administration on day 1 or day 10, respectively. Germ (GCs) and somatic cells (Sertoli—SCs and Leydig cells—LCs) were counted in pubertal (25 day) and post-pubertal (45 day) rats in tandem with the measurement of serum testosterone levels and the protein expression of androgen receptor. Glucose levels were higher in PDM than in NDM. Incomplete spermatogenesis and reduced GC number were found in PDM but not in NDM. LC number, testosterone, and luteinizing hormone (LH) levels were differently altered by both types of DM with a pronounced negative impact of PDM. Protein expression of androgen receptor in SCs was altered only in PDM. Reduced sperm concentration and motility was found in both groups. Thus, our results provide new insights into different mechanisms of action of PDM and NDM on developing germ cells that involved disturbances in androgen production by Leydig cells and androgen action in Sertoli cells.

Increasing environmental contamination with microplastics (MPs) raises significant concerns regarding their potential impact on reproductive health. This study evaluated the effects of prolonged oral exposure to fluorescent polystyrene microplastics (FPS-MPs) of different sizes on the male reproductive system in Wistar rats. Juvenile male rats at 21 days of age were exposed to FPS-MPs of 1 µm and 5 µm for 52 days, covering the period of sexual maturation and a complete spermatogenesis cycle. Body weight, reproductive organ indices, serum levels of testosterone (T), estradiol (E2), follicle-stimulating hormone (FSH), and luteinizing hormone (LH), as well as sperm motility and morphology, were assessed. Reproductive potential and accumulation of microplastics in reproductive tissues were also evaluated. No significant differences were observed in body weight or most reproductive organ indices, except for a slight reduction in the left epididymis index in the group exposed to 5 µm particles. FPS-MPs induced size-dependent changes in the hormonal profile, including decreases in T and E2 and compensatory increases in FSH and LH, as well as impairments in sperm quality, which were more pronounced in rats exposed to smaller particles. In conclusion, fertility potential remained preserved, while FPS-MPs accumulated in the testes and epididymides, demonstrating subclinical, size-dependent effects on the male reproductive system.

Recent studies reveal a significant link between environmental pollution and diabetes. Оur study investigated the changes in some bioelements’ concentrations (Se, Fe, Cr and Mn) in the testis of adult diabetic rats with concomitant exposure to cadmium chloride (CdCl2). Diabetes was induced in newborn Wistar rats by a single i.p. injection of 100 mg/kg streptozotocin on postnatal day 1 alone or in combination of oral maternal Cd exposure at a daily dose of 5 mg/kg until postnatal day 25. Hyperglycemia was validated in all experimental groups on day 45 and 65. Testicular weight index was significantly reduced in Cd-exposed alone group and concomitant with diabetes on postnatal day 65. The analysis of five elements in the testicular homogenates by inductively coupled plasma mass spectrometry (ICP-MS) showed significantly increased Cd content in the Cd-exposed groups alone and in combination with diabetes which was more pronounced on day 45 compared to day 65, thus indicating metal clearance. The diabetic rats also significantly accumulated Cd. In all experimental groups Se content was elevated while Cr, Mn and Fe were reduced. In conclusion, our data show that exposure to Cd in early life is a diabetogenic factor with deteriorating effects on glucose profile in diabetic condition. This is associated with bioelements’ homeostasis leading to decreased relative testis weight in adulthood with possible impact on sperm quality. Moreover, our experimental model provides new data about possible role of maternal Cd administration in inducing metabolic reprogramming in the offspring.