The MT1, but not MT2, gene is expressed in mesenteric artery (MA) and perivascular adipose tissue (PVAT) derived from MA (MA-PVAT). a RT-PCR analysis of MT1 mRNA expression in MA, MA-PVAT, and eye. Total RNA isolated from rat tissues was subjected to RT-PCR using specific primers for MT1 (316 bp) cDNA. Non-reversely transcribed samples (-RT, RNA instead of cDNA) and negative controls (PCR-neg.co, water instead of cDNA; RT-neg.co, water instead of RNA) are also shown. b RT-PCR analysis of MT2 mRNA expression in MA, PVAT derived from MA (MA-PVAT), and eye. Total RNA isolated from rat tissues was subjected to RT-PCR using specific primers for MT2 (390 bp; nested PCR, upper panel) and β-actin (496 bp; ACTB, lower panel) cDNAs. Two individual samples per tissue are shown. c Relative gene expression levels of MT1 in rat MA (n = 6) and PVAT derived from MA (MA-PVAT, n = 5). The experiments were carried out in technical triplicates for each sample. The distribution of data is displayed by box plots. The box represents the range from the first to third quartiles; the band near the middle of the box is the median, and the lines above and below the box indicate the locations of the minimum and maximum value. The asterisk indicates a significant difference (p < 0.05)
Melatonin is released by the pineal gland and can modulate cardiovascular system function via the G protein-coupled melatonin receptors MT1 and MT2. Most vessels are surrounded by perivascular adipose tissue (PVAT), which affects their contractility. The aim of our study was to evaluate mRNA and protein expression of MT1 and MT2 in the mesenteric a...
The hypotensive effects of melatonin are based on a negative correlation between melatonin levels and blood pressure in humans. However, there is a positive correlation in nocturnal animals that are often used as experimental models in cardiovascular research, and the hypotensive effects and mechanism of melatonin action are often investigated in rats and mice. In rats, the hypotensive effects of melatonin have been studied in normotensive and spontaneously or experimentally induced hypertensive strains. In experimental animals, blood pressure is often measured indirectly during the light (passive) phase of the day by tail-cuff plethysmography, which has limitations regarding data quality and animal well-being compared to telemetry. Melatonin is administered to rats in drinking water, subcutaneously, intraperitoneally, or microinjected into specific brain areas at different times. Experimental data show that the hypotensive effects of melatonin depend on the experimental animal model, blood pressure measurement technique, and the route, time and duration of melatonin administration. The hypotensive effects of melatonin may be mediated through specific membrane G-coupled receptors located in the heart and arteries. Due to melatonin’s lipophilic nature, its potential hypotensive effects can interfere with various regulatory mechanisms, such as nitric oxide and reactive oxygen species production and activation of the autonomic nervous and circadian systems. Based on the research conducted on rats, the cardiovascular effects of melatonin are modulatory, delayed, and indirect. Does melatonin have blood pressure-lowering effects, and are nocturnal animals suitable for testing the hypotensive effects of melatonin? The hypotensive effects of melatonin depend on the experimental animal model, blood pressure measurement method, route, time and duration of melatonin administration.
Melatonin is a simple compound with a proper chemical name N-acetyl-5-methoxy tryptamine and known as a hormone controlling circadian rhythm. Humans produce melatonin at night which is the reason for sleeping in the night and awakening over the day. Melatonin interacts with melatonin receptors MT1 and MT2 but it was also revealed that melatonin is a strong antioxidant and it also has a role in regulation of cell cycle. Currently, melatonin is used as a drug for some types of sleep disorder but the recent research points to the fact that melatonin can also serve for the other purposes including prophylaxis or therapy of lifestyle diseases, cancer, neurodegenerative disorders and exposure to chemicals. This review summarizes basic facts and direction of the current research on melatonin. The actual literature was scrutinized for the purpose of this review.