Melatonin ameliorates diabetic hyperglycaemia-induced impairment of Leydig cell steroidogenic function through activation of SIRT1 pathway

Abstract

Background Diabetes mellitus (DM)-related complications are important health problems worldwide. The underlying mechanisms for diabetic male subfertility/infertility are considerably complicated and need to be unveiled for therapeutic intervention. Melatonin treatment was investigated to assess the beneficial effects on injured steroidogenic function in DM due to its regulatory roles in mitochondria and autophagy. Methods Diabetic hyperglycaemia was induced in rats injected with streptozotocin (STZ, 55 mg/kg/d) or simulated in TM3 Leydig cell line cultured with medium containing 30 mM D-glucose. Then, diabetic rats or the TM3 cells under high glucose were treated with melatonin. The diabetic rats were randomly divided into diabetes mellitus group (DM group), insulin treatment group (DM + INS group) and melatonin treatment group (DM + MT group). The TM3 Leydig cells were divided into a normal glucose control group (NG group), a high glucose treatment group (HG group), and a melatonin treatment group (HG + MT group). Then, Sirt1 (silent mating type information regulation 2 homologue) 1 expression was knocked down by siRNA. Results The results showed that hyperglycaemia induced a decline in steroidogenesis, accompanied by autophagy defects, mitochondrial dysfunction and oxidative stress, in rats in the DM group or TM3 Leydig cells in the HG group. Furthermore, reduced SIRT1 expression levels and hyperacetylation were found in Leydig cells of DM group. Melatonin treatment ameliorated hyperglycaemia-induced impairment of Leydig cell function with simultaneous stimulation of 5’-adenosine monophosphate activated protein kinase (AMPK)/SIRT1 activity and the expression of autophagy-related genes. With regards to mitochondrial function, it promoted mitochondrial biogenesis with elevated PGC-1α, NRF1 and mtTFA, improved mitochondrial morphology, increased BNIP3L-related mitophagy and alleviated oxidative stress. Further results revealed that knockdown of Sirt1 in Leydig cells prevented the protective effects provided by melatonin against high glucose treatment, and interestingly, neutralization of reactive oxygen species (ROS) by N-acetyl-L-cysteine pretreatment abolished the stimulatory effect of melatonin on AMPK/SIRT1 activity in Leydig cells and prevented the induction of autophagy and mitochondrial biogenesis in the context of high glucose, indicating that modulation of SIRT1 pathway by melatonin was closely linked to ROS levels and oxidative stress. Conclusions These findings suggest that SIRT1 pathway plays essential roles in the pleiotropic actions of melatonin on Leydig cells and in the prevention of hyperglycaemia-induced steroidogenic dysfunction. The stimulatory action of melatonin on SIRT1 pathway is related to oxidative stress and its antioxidant property. Our data provide new evidence for the relationship of melatonin and SIRT1 pathway in the context of hyperglycaemia, and melatonin as a combination therapy may be useful to combat DM-related complications, especially male reproductive system injury.

Protective effects of melatonin against oxidative stress induced by metabolic disorders in the male reproductive system: a systematic review and meta-analysis of rodent models

“…Previously, several studies have revealed that metabolic diseases such as obesity, diabetes, dyslipidemia, hypothyroidism, and hyperthyroidism can lead to excessive oxidative stress in the testes, while melatonin can vigorously potentiate endogenous anti-oxidant defense by upregulating SOD, GSH, and GPx ( 30 , 37 , 49 , 52 , 62 , 63 ). Melatonin can increase the testicular expression of nuclear factor erythroid 2–related factor 2 (Nrf2), which is a main transcription factor for many anti-oxidant genes and strengthens the anti-oxidant defense ( 64 ). Our meta-analysis showed that melatonin can markedly decrease the serum and tissue levels of MDA and significantly upregulate GSH; however, results were non-significant for other anti-oxidants such as SOD, CAT, and GPx.…”

“…Metabolic perturbation suppressed AMPK/SIRT1 in the testicular tissue of diabetic mice and high-fat diet-fed mice, while treatment with melatonin markedly enhanced the AMP-activated protein kinase (AMPK)/SIRT1 pathway in their testis ( 30 , 64 ). Consistently, SIRT1 knockdown abolished the protective effects of melatonin on the detrimental effects of high glucose concentration on Leydig cells ( 64 ). Previously, it has been demonstrated that SIRT1 is a master regulator of metabolism and pivotal for spermatogenesis and spermatozoa differentiation ( 66 ).…”

“…Mice with SIRT1 deletion had smaller testis, reduced number of spermatozoa, higher percentages of abnormal spermatozoa, and decreased fertility ( 66 ). In addition, melatonin treatment was shown to ameliorate impaired autophagy, mitophagy, and mitochondrial biogenesis in Leydig cells exposed to high glucose concentrations ( 64 ).…”

Melatonin Attenuates Oxidative Stress-Induced Apoptosis of Bovine Ovarian Granulosa Cells by Promoting Mitophagy via SIRT1/FoxO1 Signaling Pathway

“…Several articles reported that SIRT1 could take part in the regulation of mitophagy by melatonin [ 52 , 61 ]. In diabetic rats or Leydig cells under high glucose, melatonin improved mitophagy defects to inhibit mitochondrial injury and oxidative stress by activating protein kinase (AMPK)/SIRT1 activity [ 62 ]. Above all, these results supported our findings that melatonin promotes PINK1/PARKIN-mediated mitophagy to inhibit H 2 O 2 -induced apoptosis and mitochondrial injury of bovine ovarian granulosa cells via a SIRT1-dependent mechanism.…”

β-Nicotinamide mononucleotide activates NAD+/SIRT1 pathway and attenuates inflammatory and oxidative responses in the hippocampus regions of septic mice

“…Sirtuins (SIRTs) are evolutionally-conserved family of regulatory proteins that function as NAD + -dependent class III histone deacetylases (HDACs), which is composed of seven histone deacetylases and ADP-ribosyltransferase proteins (SIRT1-7) in mammals [ 10 ]. As the most widely investigated member of the SIRT family, SIRT1 regulates cell biology and metabolism by deacetylating histones or other multiple cytoplasmic substrates and inhibiting proinflammatory kinases or regulating transcriptional factors, such as peroxisome proliferator-activated receptor-gamma co-activator 1α (PGC-1α), forkhead boxO3a (FoxO3a), nuclear factor kappa B p65 (NF-κB p65), p38 mitogen-activated protein kinase (p38 MAPK), and p300 [ [11] , [12] , [13] , [14] , [15] ]. A large amount of evidence has confirmed that SIRT1 plays an important role in the regulation of oxidative stress, inflammation, mitochondrial function, autophagy, apoptosis, neuroprotection and aging-related diseases [ [16] , [17] , [18] , [19] ].…”